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White, Joseph F.
How bad will climate change get?
h [electronic resource] :
b factors and mechanisms of global warming /
Joseph F. White.
[Tampa, Fla. :
University of South Florida Libraries,
1 online resource (42 p.) :
Thesis (Honors)--University of South Florida, 2009.
Includes bibliographical references (p. 39-42).
A winning thesis in the Grace Allen Honors College/Library Scholar program.
t Grace Allen Scholars Theses Collection.
How Bad Will Climate Change Get? Factors and Mechanisms of Global Warming Joseph F. White A thesis submitted to the Honor's College at the University of South Florida in partial fulfillment for requirements of Honor's Degree. Submitted: April 24, 2009 Defended: April 24, 2009 Thesis Mentor: Martin Schnfeld, Ph.D. Professor of Philosophy University of South Florida Committee Member(s): Philip van Beynen, Ph.D. Assistant Professor Department of Geography
2 | Page Table of Contents Section Page I. T able of Figures II. Abstract 1. Introduction 2 How Did we Get Here? The Study of Global Warming 3 How Will it Bad? A Look Feedback Mechanisms 3 .1 Carbon Dioxide: The natural Thermostat 3 .2 Aerosols and Clouds 3 .3 Oceanic Currents 3 .4 Surface Albedo 3 .5 Soil Warming 3.6 Methane Sinks 3.7 Water Vapor 3.8 Carbon Sink in Warm Ocean 4. How Bad Will it Get? A Future Projection 4.1 Th is Probably Will Happen 4.2 This Might Happen 4.3 Let's Hope This Doesn't Happen 5. Conclusion III. References 3 4 5 5 11 10 12 16 17 21 23 27 28 30 31 33 34 35 38
3 | Page 1. Table of Figures Figure Title Figure 1: Atmospheric CO2 at Mauna Loa Observatory Figure 2: Vostok Ice Cores with Insolation Figure 3: Global Temperature Change from 1880 Figure 4: Solar Cycle V ariations Figure 5: IPCC Global Temperature Change Figure 6: IPCC GHG and Temperature Scenari o Figure 7: Long Term Mean Temperature Change Figure 8: IPCC Aerosol Chart Figure 9: Natural Aerosols Figure 10: Anthropogenic Aerosols Figure 11: Insolation Reduction From Clouds Figure 12: Change in Pressure of Walker Circulation Figure 13: Relative Al bedos Figure 14: Albedo Satellite Comparison Figure 15: Ice Melt in Arctic Figure 16: Albedo due to Snow Loss Figure 17: Bio decay Normal vs Heat Figure 18: Linear Graph of Heat Change in Decay Figure 19: Distribution of Carbon in Permafrost Figure 20: Mea sured Amount of Emissions Permafrost Figure 21: 65 million Years of Climate Change Figure 22: Methane Release in ESAS Figure 23: Water Vapor Measurement Figure 24: Acidity of Oceans since 1700's Figure 25: pH Measurements in Tatoosh, Washington Page Numb er 6 7 8 8 10 11 12 14 14 15 16 18 19 20 20 21 22 23 23 24 26 27 28 30 31
4 | Page II. Abstract This report attempted to answer the question, "How Bad Will Climate Change Get?". This was accomplished by, first, presenting a current assessm ent on the science of Global Warming. Factors and causes were analyzed with heavy emphasis on the paleoclimate record and the IPCC Fourth Assessment Report. The report, which released in 2007, is considered by many scientists to be too optimistic and con servative as it neglects to account for various feedback mechanisms and other drivers that can impact climate. Thus, the next part of this report does a thorough and complete review of all mechanisms that can drive future climates. Next, this data is syn thesized to produce a clearer projection of future climate. Ultimately, it is found that the IPCC was too conservative in its estimate because it neglected various positive feedback loops including methane clathrate release, permafrost biological decay, o cean currents, ocean acidification, water vapor, and surface albedo effects.
5 | Page 1. Intro duction Ever try to answer an impossible question that everyone in the world would love to know the answer to? This paper attempts to answer the question of "How bad will Climate Change Get ? by utilizing current peer reviewed articles and studies in climatology as references. The basics of climate and global warming science will first be analyzed followed by a lengthy segment on drivers and mechanisms th at could contribute to a future climate s state The final section will synthesize all of the presented data to produce an editorialized result that shows a possible future projection of climate change over the next 100 years. 2. How did we get here? The Study of Global Warming Climate change has been a recurring theme throughout much of the Earth's history. Many factors both external and internal have brought changes that generated large effects on the earth's climate and inhabitance. Hist orically, these changes were caused by natural factors, however, today as the earth's climate continues to warm most of the blame falls on the human race. This first segment will take an in depth look at the science of anthropogenic climate change by look ing at major studies that have progressed the field to its current position. These studies will be based not only on current atmospheric conditions but also those found in the historical record that can help understand what is occurring today. Furthermor e, it is necessary to understand the current and past conditions in order to gage the prospects of how the climate will change in the future. The earliest research that characterizes anthropogenic climate change came as early as 1824 when Joseph Fourier calculated that the earth would be mu ch cooler without an atmosphere, that's function was retaining irradiative heat. Along this same vein, John Tyndall in 1859 discovered that some gases blocked while others absorbed infrared radiation. Absorbing gases included CO 2 CH4, water vapor, and CO which are now known as greenhouse gases because they absorb and emit radiation within the thermal infrared range. This lead Arrhenius in 1896 to publish his first report on global warming based on human emissions of CO 2 which were now being emitted into the atmosphere because of the start of industrialization. This would continue for the next 100 years as growing industrialization would release more CO 2 and other greenhouse gases into the atmosphere as illustrated b y figure 1. This figure and its research, a modern form of a similar graph initiated by Dave Keeling just prior to 1960 became the stimulus for a vast amount of climate change research that occurred o ver the next 50 years ( Weart, 2004)
6 | Page Knowing that atmospheric CO 2 had a strong warming potential and was increasing, scientists would then turn to the past to help discover the effects of such a rise. They began in 1966 taking ice cores of Antarctica which accurately depicted not only temperatures but also CO 2 counts found in atmospheres as far back as 65 0,000 years as air droplets became trapped in the ice. Figure 2 displays the Vostok ice cores of Antarctica that was taken in 1999. These cores historically illustrated the c onnection between temperature and CO 2 It was clear that in times of high temperature there was also high CO 2 however, it is important to note that the CO 2 tended to lag an increase in temperature ( Jouzel et al., 1999) The ice c ores validated an early theory by mathematician Milutin Milankovitch which estimated that the earth's current climate was based on the earth's movement through space and its relative distance from the sun. This concept, as illustrated by conjunction of Figure 2's temperature and insolation measurement, shows when solar radiation was high and the sun was near the earth a warmer climate was produced in the same time period. The earth changes its distance from the sun because of a combination of eccentricity, obliquity, and precess ion which can affect the earth's orbit. Varying receipts of solar radiation would generally drive shifts in climate and dominate natural climate cycle. It is important to note that insolation was just an initial forcing and was not a large enough alone to drive the large shift from glacial to interglacial periods in Figure 2 but was bolstered by feedback mechanisms that will be discussed in depth later (Ruddiman. 2008) Figure 1 Shown here is the change in CO2 over since just before 1960 until the present day. The data was taken via weather balloons in Mauna Lao, Hawaii initially by Dr. Dave Ke eling and now monitored by NOAA. (NOAA, 2008)
7 | Page In addition to the climate record and physical science justifying a curren t warming trend, the mean earth temperature since official record keeping began in 1880, around the start of industrialization, has slowly increased as shown by Figure 3. In fact, since the start of early industrialization until 2005 the earth's average te mperature had risen around 0.75 C in around 100 years. Furthermore, the warming trend has not slowed as all ten of the warmest years on record have occurred between the years 1997 2008, a period of 11 years (NASA GISS, 2009). Generally, as stated above climate has been predominantly controlled by solar cycles and insolation for the past 650,000 years. This became the crux of many skeptic arguments in the 90's but was later proved unlikely as even in times of low solar insolation the earth still continue d to warm over the last 30 years as figure 4 shows. (Wilson et al., 2003) Greenhouse gases, particularly CO 2 are the only reasonable culprits for the warming trend as they both increased over the same period. The concept is further reiterated by taking a brief look at the planet Venus, which because of the composition and absorption of its atmosphere reflects more solar radiation back to space and subsequently receives less insolation than earth by a mechanism to be discussed later in detail called albe do. Venus, is however much warmer than earth not because of its relative distance to the sun but because its atmosphere is 96% CO 2 while earth's is only 0 .038% CO 2 (Ruddiman. 2008) Figure 2 Graph of CO2 (blue graph), temperature (red graph), and dust concentration (green graph) measured from the Vostok, Antarctica ice core as reported along with the Miankovitch insolation calculation (o range graph). (Jouzel et al., 1999)
8 | Page Figure 3 Shown here is the mean earth surface temperature as recorded by NASA's Goddard Institute from 1880 to 2008 (NASA GISS, 2009) Figure 4 Total solar cycle variation is shown here to help illustrate total insolati on. It includes allow solar activity. Graph prepared by Robert Rohode at globalwarmingart.com. (Wilson et al., 2003) (DeWitte et al. 2003)
9 | Page In an effort to decide the future risks of climate cha nge, in 2007 the Intergovernmental Panel on Climate Change released its fourth assessment on the potential effects of anthropogenic forcings over the next 100 years. The report's preparation was based on peer reviewed input from hundreds of experts in cli mate science from all over the world. The data produced was generated by global climate models that attempted to reciprocate natural and anthropogenic forcings with the aid of a computer. Their accuracy was validated by the fact, as figure 5 shows, they a ccurately predicted past climate trends based on available proxy data. The black line is what actually happened, while the shaded pink area is the predicted change based on anthropogenic greenhouse gases. The blue is what is predicted in a natural climat e cycle. The validity of the model so far is based on the black line's willingness to shadow the predicted pink area. Scientist then took the model a step further by inputting future climate conditions to help reveal possible future climates as illustrat ed by figure 6. Many scientists now claim that the data used for this model was too conservative and tended to neglect many feedback mechanisms and possible tipping points that are likely to have an impact from the continued effects of global warming. Th is exclusion has brought many scientists to question the complete validity of the data in this figure. Furthermore, in the recent years since the report's release some of its individual climate predictions including Arctic melting and ocean acidific ation were somewhat understated while other facts like aerosols were overstated within the report (Saundry et al., 2008) Feedback mechanisms have been a viable part of the natural climate cycle and can either be positive or negative. In positive feedback loo ps an end result or product promotes the creation of more products which subsequently further drives its own creation. In climate this generally means warming promotes more warming. W hile in a negative loop the production of product is slowed or seized by its own existence. This usually implies warming promotes cooling. Furthermore, some of these loops do not activate unless the climate reaches a certain temperature highlighting the potential existence of climatical tipping points. This could be somet hing as simple as a block of ice not melting at 1 o C but melting at 1 o C. Like a tipping point after the temperature crosses that 1 o C threshold the entire ice block melts. The next part of this report will take an in depth look at feedback mechanisms a nd other forcings that can potentially impact future climate. It is important to note, as this report will show, tipping points are experimentally unclear as there is little agreement on how, when, and why they will occur. Thus, this report will focus mo re on feedback mechanisms and other climate drivers as they are generally better understood.
10 | Page Figure 5 This chart was taken directly from the IPCC Fourth Assessment Report using the IPCC Global Climate Mode l to predict past trends on every continent during the last century. (Saundry et al., 2008)
11 | Page 3. How Will it get Bad? A Look at Feedback and Forcing Mechanisms 3.1 Carbon Dioxide Feedback: The Natural Thermostat Throughou t the natural record carbon dioxide atmospheric concentrations have fluctuated but have remained within 40 p.p.m.v of the mean value during glacial and interglacial periods ( as demonstrated by Figure 2) )(Zeebe et al., 2000) The reason for this stability little runaway carbon dioxide release, comes from the existence of something known as the Carbon Dioxide thermostat, a negative feedback loop that help maintain CO 2 levels through a process known as chemical weathering. At different points in the earth 's history carbon dioxide amounts reached much higher levels than current because of increased plate tectonic activity and volcanism. This reasoning helps explain why the earth 200 m y a was considerably warmer than the current earth as shown by the fossi l record. Chemical weathering was the primary mechanism that allowed CO 2 rates to return to the lower levels of the modern era and is accomplished by two reactions known as hydrolysis and dissolution. Hydrolysis, the main mechanism, works by the following reaction: Figure 6 This chart was taken directly from the IPCC Fourth Assessment Report using the IPCC Global Climate Model to predict future climate trends for the next ce ntury. The different color lines are different GCM's while the gray cone has the highest probability of occurrence. (Saundry et al., 2008)
12 | Page CO2 + H 2 O > H 2 CO 3 carbon dioxide + water carbonic acid CaSiO3 + H2CO3 > CaCO3 + H2O silicate rock + carbonic acid calcium carbonate + water Carbon dioxide combines with rain water and fo rms carbonic acid which in turn dissolves silicate rocks to yield calcium carbona te that eventually becomes incorporated and deposited in the shells of marine organisms. The dissolution reaction is similar except it involves limestone bedrock and does not return any net CO 2 to the earth. Thus, it will not be discussed in depth. Stud ies have shown that warmer temperatures cause more rapid weathering of silicate minerals. Warmer climates tend to have more precipitation which causes more rain water for weathering along with an increase in vegetation that instills soil with more CO 2 and thus allows for more hydrolysis. Consequently, chemical weathering can help prevent runaway warming from CO 2 and act as a thermostat to help control the system. If it is cold, chemical weathering slows and less CO 2 is sequestered Likewise, if it is w arm more is sequestrated (Ruddiman, 2008). This thermostat has historically been one of the earth's most reliable negative feedback mechanisms. Its importance is most readily demonstrated by the fact that the earth's climate has not blown up or shown radical shifts more often. For example, without this negative feedback, earth could end up like Venus, with a 97% CO 2 warm atmosphere.(Ruddiman. 2008) There would be little or no control systems to prevent runaway warming and carbon dioxide build up. R ichard E. Zeebe and Ken Caldeira both conducted extensive studies on the thermostat system using the Vostok ice cores (figure 2) as physical evidence in order to quantify how strong the chemical weathering effect has been historically. They found that the mean long term trend change of atmospheric CO 2 levels is no more tha n 22 p.p.m.v. over the past 65 0,000 years (Figure 7)(Zeebe et al., 2000). Figure 7 This is a modification to the vostok ice CO2 measurements done by Richard Zeebe to help show the long term mean in CO2 change. (Zeebe et al., 2000)
13 | Page With this data it was estimated that the maximum imbalance between supply and uptake due to weathering v aries 1 2% during this time period. This long term balance remains steady despite glacial and interglacial periods due to solar fluctuations. Thus, it is significant to note that the stability of the climate cycle was caused by chemical weathering, while the specific glacial highs and lows were controlled by other mechanisms. Other research also shows that this thermostat is powerful enough to reach equilibrium(i.e. the glacial cycle above) from an extreme in a few hundred thousand years. An example of this occurred 55 million years ago, when massive amounts of carbon was rapidly injected into the earth's atmosphere from the deep ocean in an event known as the Palocene Eocene thermal maximum (will be discussed more later). Evidence suggests that CO 2 leve ls in the atmosphere recovered to normal levels in just a few hundred thousand years. This shows that the climate must be warmed for a considerable amount of time before this mechanism acts as a controlling forcing to cause cooling. Because of this long response time, t he 100,000 glacial interglacial periods of the last 600,000 years prove to be too short lived and not warm enough to feel the full effect of the chemical weathering thermostat and were therefore predominantly controlled by other forcings Thus, the anthropogenic rise in CO 2 levels will also not feel full recovery from this negative feedback for a few hundred thousand years highlighting this mechanisms inefficie ncy to solve the current crisis (Zeebe et al., 2000) 3.2 Aerosols and Clouds Aerosols are particles of a liquid or a solid suspended in a gas that freely floats within the atmosphere. They can either occur naturally from volcanic eruptions, forest/grass fires, water vapor ( clouds), sea spray, and dust storms or they can have an thropogenic origins in the form of combustion for energy, slashing and burning of forests, and any other activity that places particles in the air. (Ruddiman. 2008) Studies have shown that humans contribute roughly 10% of all aerosols in the atmosphere at a given time (Saundry et al., 2008) Aerosols tend to cause a cooling trend in climate because they reflect some of the solar radiation from the sun back into space. As stated above, Venus, which is closer to the sun, receives half as much solar radiatio n as earth because its atmosphere is stocked full of aerosols the reflect the sunlight back. The IPCC climate model attempts to account for aerosols and its cooling trend as illustrated by the red line in figure 8.
14 | Page Figure 8 This chart was taken directly from the IPCC Fourth Assessment Report using the IPCC Global Climate Model to quantify past aerosol forcings for the previous century. (Saundry et al., 2008) Figure 9 This graph shows volcanism extent by looking at a quantitative measurement of aerosol/albedo streng th from 1880 2000. (Zielinski et al, 1995)
15 | Page Volcanism is the largest pro ducer of natural aerosols and is illustrated in Figure 9. Volcanic eruptions over the last 150 years have been somewhat inconsistent. As the graph shows, the effects are generally short lived and only last for a few years after an eruption. A good example of this came in 1816 (not shown on the graph) when Mount Tambora in Indonesia exploded creating a much larger amount of aerosols in the air then any of the recorded volcanoes above. 1816, because of the aerosols, became known as the year without summer b ecause the cooling trend was so strong. In subsequent years the effects were hardly felt as natural volcanism, unless continuous, has little af fect on overall climate trends (Zielinski et al, 1995) Anthropogenic trends of aerosols are slightly easier t o predict and find themselves integrated into the models of the IPCC fourth assessment report. The most common aerosol pollutants are black carbon ( smoke), organic carbon ( carbon bonded to any other molecule), and finally SO 2 ( Saundry et al., 2008) All three of these are products of industrialization and power generation and are expected to grow with world energy consumption. Figure 10 expresses the IPCC expected growth charts predicted by various models. New research, with a state of the art solar rad iation measuring sa tellite(by Nicolas Bellouin et al.) suggests that the IPCC report seems to overstate the affects of anthropogenic aerosols. He and his team found, with satellite aid that the level of solar radiation reaching the earth 's surface was hi gher than predicted by the IPCC from 2002 2005. The data showed that the IPCC model called for nearly double the irradiative reduction then what was actually observed. This would cause the IPCC to overstate the predicted cooling trend from aerosols. The reasoning for this comes from the fact that the model likely overstated both SO 2 and black carbon releasing increases. Many nations, the USA included, have begun programs to eliminate smog or aerosol causing agent s in factories and power plants ( Bellouin et al., 2005) Figure 10 T his chart was taken directly from the IPCC Fourth Assessment Report using the IPCC Global Climate Model to quantify future aerosol forcings for the next century by looking at the specific types of anthropagenic aerosols. (Saundry et al., 2008)
16 | Page It is unreasonable to discuss aerosols without a similar discussion on clouds because without aerosols there would be no clouds in the atmosphere A erosol particle s act as seed for cloud formation. Based on this fact, scientists expect as the amount of aerosols in the atmosphere increases so will the propensity for cloud formation. Clouds ( mostly water vapor) reflect sunlight while trapping heat like any other green house gas. Because of this dual nature of positive and negative feedback it is difficult to gage a cloud's net effect on the climate but most climate models fa vor a cooling trend (Ruddiman, 2008) Figure 11, the graph below illustrates the amount of cloud formation and how it relates to the reduction of cosmic rays. U ltimate ly, the more low clouds the more rays are reflected creating a reduction in solar radiati on reaching the earth's surface ( Svensmark, 2007) Research has also shown that this reduction is greatest when the clouds are low and full of moisture. It has long been assumed, as the earth continues to warm, the atmosphere will hold more moisture allowing the creation of more clouds creating a negative feedback loop and ultimately a cooling trend. New research however by David Randall and other NASA GISS scienti sts shows using new satellite data that the summer clouds of a warmer environment reflect the same amount, not more light, than winter clouds. This evidence suggests that clouds in a warmer earth have about the same cooling effect as they do in a cool cli mate. Furthermore, if clouds are formed in the upper atmosphere they can sometimes reflect more radiate heat back to the earth then sunlight into outer space. All the data above reveals the complexity of trying to gage how clouds affect the environment an d this is especially evident in computer models as cloud formation along with their effects are extraordinarily difficult to judge in future climates. Also, it is difficult to predict what type of clouds will form in the future as different types have dif ferent reflective properties. It still however remains true, and most research agrees, that aerosols produce a cooling trend along with helping the formation of clouds which can also reflect more sunlight and lead to more coolin g (Randall et al. 2003) Figure 11 This chart was taken directly from a report published in 2007 that quantified the cosmic ray reduction from clouds using a satellite. (Svensmark, 2007)7
17 | Page 3.3 Oceanic Currents W arming temperatures can impact ocean currents which can further impact climate. The ice cores have repeatedly shown that around 12,700 years ago (as figure 2 does show an extended glacial period) the Gulf stream, which flows from t he Caribbean Sea through the Atlantic Ocean and up to Greenland shifted south to around the coast of Spain causing a 10 o C drop in temperatures in Europe in the short period of around 10 years (Pelley, 2004) This stream drives the movement of warm tropic al waters to the European coast and is subsequently responsible for the continent's moderate temperatures. This event caused a 1,300 year cool period around the globe and is also thought to be responsible for drying in the America west, Africa, and Asia ( Pelley, 2004) The Gulf Stream like many ocean currents acts as a thermohaline pump which is brought on by a density gradient that is initially formed by combination of surface heat/currents and freshwater movement. In the Gulf Stream for example as warm salty water travels north driven by surface air currents, it undergoes both cooling and evaporation. The remaining water contains large quantities of dissolved salt which because increased density drops to the bottom of the ocean forming a cool deep water current. This then travels deep in the ocean until it eventually surfaces and warms The water then makes its way back to the deep water formation, driven by surface air currents which propagate a cycle known as the ocean conveyor belt. Greenland is situated near the deep water formation of the Gulf Stream and is covered by a large ice sheet that is expected to melt as the planet warms. Scientists suggest a rapid melting could cause a large influx of fresh water to the region which could reduce th e salinity of the high density water. This would render the water to o light to sink and thus shut down the deep water formation belt and ultimately switch off or move the deep water current. Similar to 12,700 years ago, this could cause cooling in Europe and other environ mental factors around the globe (Bunyard 1999) Scientists have also recently predicted in a less accepted theory, that if Greenland continues to melt slowly the fresh water could strengthen the thermohaline conveyor belt in the north A tlantic. This occurs because its movement depends on the rate which the high and low salinity water mixes. Because of equilibrium principles, the fresh water would increase the mixing reaction and thus speed up and strengthen the conveyor. This action w ould force more warm water north causing a global warming trend. As noted above, each action depends on whether a rapid melting of the Greenland ice sheet occurs which is dependent on how warm the environment becomes (Pelley, 2004) Anthropogenic warmi ng is also responsible for a recent slowing of the currents found within the tropical Pacific Ocean. As briefly mentioned above, atmospheric wind currents drive the movement of warm water surface currents. Research has recently suggested that continued a nthropogenic warming has begun to slow the Walker air circulation, a large east west overturning of air across the equatorial Pacific Ocean. Sea level pressure can be used to measure the strength of air circulation because air generally flows down it pres sure gradient and the larger the gradient the more rapid the air will flow. Data measured over the last 150 years suggest that as the climate has warmed the pressure gradient has decreased as illustrated by figure 12. Historical fluctuations in pressure are normal, however, the large drop in the 1970's could be considered a statistical outlier but it is important to note that even disregarding this result the negative
18 | Page slope of the graph is still existent. This decrease in pressure has caused the Walker equatorial circulation to somewhat weaken which in turn has caused the tropical surface currents to also weaken. Overall slowing ocean currents can cause northern latitudes to become colder while lower latitudes remain warmer as less air is transferred ab out the globe. Therefore, this mechanism can somewhat be considered negative feedback. It is also key to note that this study looks at a specific pressure system that circular coriolis force winds would flow around. The effects of warming on ocean current s are still only vaguely understood and will require more research in the future. (Vecchi et al 2006) 3.4 Surface Albedo As previously stated, because of the reflective properties of clouds, they actually induce a cooling effect on the c limate by reflecting solar energy away from the earth. On the surface of the earth this effect is also felt and is known as surface albedo. The higher the albedo, the larger percentage of heat energy is reflected and causes a larger cooling effect. Figu re 13 shows some relative albedo levels for some common earth surface coverings. The figure shows relatively high albedo levels for both snow and ice compared to water, soil, and forest. Based on this reasoning, as warming causes the permanent ice and sn ow to melt in northern latitudes there remains a strong possibility for a stronger albedo, induced warming effect. Because of this, scientists have carefully monitored both the levels of ice melting and the northern spread of forests that have been brough t on by a warmer climate. (Ruddiman 2008) Figure 12 This graph was taken directly from a report published in 2006 and shows from 1860 2000 t he change in pressure in the Walker air circulation. (Vecchi et al., 2006)
19 | Page Recent warming has caused ice and snow melting near both the northern and southern poles. This has allowed for the formation of surface ponds and increased ocean and soil exposure. The ice and snow d ecline, specifically in the Arctic, has been substantial over the recent years and is expected only to accelerate Overall, snow/ice coverage has decreased at a rate of around 9.8% per decade. (Scharien et al. 2007) Figure 15 below shows the relative de cline of ice at different reference points found within northern latitudes. The data was gathered using satellite imaging in a period of 25 years. This method of imaging can also be used to measure a medium's relative albedo rate by measuring the amount of infrared radiation it reflects. Figure 14 illustrates how much energy is reflected from melting in a period of one season. The left side of the figure is a satellite image taken at the onset of summer while the right side is taken near the end of sum mer. In that time period, because of exposed water ponds and soil, the amount of heat energy absorbed by the ground is substantially higher. In this same experiment, the researcher using statistical evidence with his results and the historical record, es timates that this heat retention can cause a possible 5C increase in local surface area temperature. This result reflect s the trend established in Figure 13, as the ice continues to melt the albedo reflection was reduced, which not only caused warming bu t also could cause more melting. This positive feedback mechanism, derailed only by cooler temperatures, is a prominent mechanism and reason to why a few scientists have started to believe the northern ice caps will be melted in the next ten years which c ould decrease total albedo by as high as 40%. (Scharien et al. 2007) Finally, these effects cannot be considered localized, as the Arctic influences many weather patterns in the northern hemisphere and thus this mechanism can contribute to an overall war ming trend. (Scharien et al. 2007) Figure 13 This figure was prepared by Hannes Grobe with common known albedo percentages. (Grobe 2000)
20 | Page Figure 14 These images were taken by satellite using an infrared came ra that can distinguish between different absorbency. The darker the image the less light is reflected back and the lower the albedo. (Scharien et al. 2007)
21 | Page Warmer temperatures in northern latitudes have also caused tundra tree boundaries to shift north replacing areas of snow and ice with vegetation. Vegetation, because of its color, as Figure 13 sugg ests, has one of the lowest albedo values Figure 16, above, shows the heat increase due to albedo from ice melting in various terrains and latitudes in the periods from 1910 1940 and 1970 2000. Across all facets melting increased, this laid the foundat ion for vegetative expansion and increased heating. As expected, the results showed that the evergreen forests, shrub, and dwarf shrub tundra produced the largest warming change because of lower albedos. These results not only reveal the heat change cha racterized by ice and snow melt but also the effects of vegetative territorial expansion. Both cases reveal a positive feedback trend that can induce further Arctic warming and melting. This trend can also cause slight increases in Figure 15 The graph above shows how the sea ice extent has changed in four different regions fr om 1982 2002, (Drobot 2007) Figure 16 This graph reveals the change in heat absorption due to recorded snow melt/return in 1910 1940 to 1970 2000 around various vegetation and at different latitudes. (Euskirchen 2007)
22 | Page CO2 sequestration as photosynthetic fauna spread north. However, most scientists minimize this effect because of increased bio decay which is discussed in the next section. (Euskirchen 2007) 3.5 Soil Warming Saprophytes, bacteria and fungus responsible for biological de cay, are always active in the soil returning organic carbon back to the atmosphere as CO 2 and methane as they breakdown animal and plant matter. Scientists believe that as the earth continues to warm the soil environment will become more favorable for sap rophytes leading to increased decay and the expulsion of more CO 2 to the atmosphere. Along this same theme, as colder permafrost begins to melt untouchable plant matter in far northern and southern latitudes will become available for decay as long as wat er levels are sufficient enough in soil for microbe growth Both of these positive feedback mechanisms have potential to cause warming by admitting more CO 2 to the atmosphere. Figure 17 shows a simple experiment that was conducted to compare the rates of decay in normal soil vs 5 o C heated soil both at constant moisture, during the summer months of 2001. As expected because of a favorable environment the rates increased as the soil was heated. By graphing the temperature vs rate of decay as figure 18 d oes it was found that the relationship is somewhat linear until around 35 o C where decay drops off sharply. Thus, as long as the soil temperature stays below 35 o C, any increase from year to year in soil temperature has the potential to emit more CO 2 into t he atmosphere as long as biomatter is present ( Eliasson et al. 2005) Figure 17 This graph shows rec orded CO2 release from biomass decay of standard soil versus 5C heated soil. ( Eliasson et al. 2005)
23 | Page Within permafrost, which coverers 22% of the globe, is an excessive amount of dead plant materia l permanently frozen in the northern latitudes. This material is sometimes t housands or millions of years old but has been able to resist decay because of its frozen state. Bogs, fens, swamps, and normal meadows all store immense amounts of organic carbon with the potential for release by saprophyte bacteria once thawed. Figure 19 below shows a few frozen soil samples in Siberia, Alaska, and Canada that contain many layers of plant matter prepped for decay. The high carbon containing layers are formed by warm periods of rapid plant growth that were later trapped as the ground f roze. ( Schuur et al. 2008) Figure 18 Above the linear relationship between temperature and growth is illustrated. Activity is a calculated quantitative way of showing bacterial growth and decay activity. ( Eliasson et al. 2005) Figure 19 Vertical distribution of soil carbon content in acti ve layer and permafrost from (a) mineral soil sediment deposits in Siberia (data from Zimov et al 2006a), (b) thaw lakes/thin peat on the North Slope of Alaska (data from Bockheim 2006) and (c) frozen peatlands in Canada (white circles; data from Kuhry 19 99) and Russia (black circles; data from Oksanen et al 2001,2003) This graph was prepared by Schuur et al. 2008.
24 | Page With consideration to the amount of carbon found in different types of soil, researchers were able to ascertain estimated amount s of green house gas release from permafrost melt due to decomposition which is displaye d in figure 20. In most environments a large amount of carbon is primed to be released upon decomposition. It is also significant to note that when oxygen was not present in anaerobic environment methane was the waste product which is a 25X more potent g reenhouse gas than CO 2 (Schuur et al. 2008) Figure 20 also shows the relative climate forcing of each style of permafrost which is a calculation derived from the aproximate amount of atmospheric heat caused by both CO2 and methane. The figure reveals th at bogs have the greatest amount of potential carbon decay which is worrisome because they are commonly f ound in all northern latitudes. Furthermore ( in Jorgenson 2008 ) it was found that the active zone of decay in Alaska tundra had expanded by 5% over t he last 5 decades highlighting a continuing trend. Recent research also shows that once the soil heats to any temperature greater then 0 o C the bacteria are quick to activate. Based on a combination of propensity of occurrence and potential carbon buildup scientists have made different estimates on how much warming it would take to melt and decay large portions of permafrost. Dr. Dutta and colleagues in 2006 suggested that if the mean average temperature of the earth rose 4 o C then around 50 Pg of C could potentially be released into the atmosphere from the thawing of 10% of Canada's permafrost alone.(Dutta et al. 2006) Other project stated that at least 100 pG of C will be released by 2100 (Schuur et al. 2008) It has proved difficult to get exact resul ts because of the many different thickness and types of permafrost found around the world. Furthermore, because microbes thrive in moist environments, soil moisture levels must also be taken into account. Despite this need for continued research the tr uth remains that this positive feedback mechanism is very powerful and has the potential to release large amounts of CO 2 into the a tmosphere as the earth warms. 3.6 Methane Sinks Large quantities of methane, an effective greenhouse gas, are current ly stored in deep oceans, cold shallow seas, tundra lakes, and anywhere else with the combination of cold, water, and methane in a form known as methane clathrate. In d eep water, benthic methanogens, methane producing organisms, are mainly responsible for the large Figure 20 This table shows the relative measured amount of emissions of both CO2 and CH4 from various types of melted permafrost during peak decay times. The relative climate forcing is simply the global warming potential weighted ratio of CO2 to CH4 to illustrate the predominate forcing. (Schuur et al. 2008)
25 | Page methane deposits. Methane clathrate is usually formed from methane being trapped within the crystalline structure of ice or deep water under high pressure. It is currently estimated that 500 2500 gigatons of carbon is currently locked up in th is formation. To help reference this number, only about 700 gigatons of C can be found in the atmosphere.(Archer 2007) Some researchers believe, most notably NASA's James Hansen, that a continued warming trend could melt off some of the permafrost that c ontains methane clathrate which could cause atmospheric release. It is important to note that two major events of natural climate change, the Permian Triassic extinction event and the Paleocene Eocene Thermal Maximum were at least somewhat caused by me thane clathrate release and have given scientists insights into the current situation. Furthermore, new evidence suggests that some methane has actually begun to bubble up in the shallow seas of the Siberian Arctic (Shakhova 2006) Paleocene Eocene Th ermal Maximum is considered one of the largest climate change events in all of natural history. Occurring around 55.8 million years ago the climate saw a 6 o C average temperature rise in the estimated short period of 10,000 20,000 years. This change quic kly transformed the globe from an already considerably warm period to even warmer period, as illustrated by figure 21 (the PETM mark ) Most of the evidence for the documented, quick warming comes from both the 13 C ratio and 18 O levels found in deep ocean and rock cores. The lowered 18 O showed, as the graph suggests, that the PETM was warm because under warm conditions the oceans contained a smaller amount of 18 O isotope to 1 6 O because o f increased evaporation rates. 13 C, the ratio of 13 C to 12 C, also dropped 2.5% during this time period which could be explained by a large in flux of a new source of carbon ( Lisiecki et al. 2005) While many factors may have been at play, some scientist s suggest the reason being the bubbling of methane clathrate as the cause for the PETM. Only this sink contains enough carbon to be responsible for the reported change in 13C and estimated 6 o C temperature change found within the record. A s the temperatu re kept rising (figure 21) the stability of the pressure locked methane clathrate in the water bonds lessoned until they eventually broke. The less pressurized clathrate in shallower oceans would bubble first because of a loss of bond stability. The free d methane would then act as a strong greenhouse gas and would promote a positive feedback loop by inducing warming which in turn could potentially liberate more methane. This scenario calls for the documented drop in 13C because liberated methane clathrate tends to have a high concentration of 12 C. The recorded 13 C represents the methane release in the atmosphere which ultimately, for this mechanism's viability, has to foreshadow the drop in 18 O, the indicato r for temperature rise. This foreshadowing does somewhat occur, however, with modern tools it is still difficult to resolve such a short time period so long ago. Furthermore, initial research suggested that the methane would need 20,000+ years to cause s uch a dramatic warming spike but new research in 2008 seemed to suggest that it could have been as little as 10,000 years as new analysis of the cores showed the potential for a much larger and faster methane clathrate release. (Thomas et al. 2002) Evid ence for this theory is found in fact that methane clathrate must be oxidized to its standard form of methane before atmospheric release. The cores showed that the benthic (deepwater) forams constructed shells with the lighter or newly released isotope of carbon after the surface or planktonic forams. In other words, the methane clathrate was oxidized near or above the surface
26 | Page which would indicate a much faster release of methane clathrate. Methane, although a strong greenhouse gas, has a very short atmo spheric half life at 7 years compared to 55 years for CO 2 (Ruddiman 2008) This fact along with a sudden, quick, and large release of methane could be the reason why the PETM was brief and powerful. In addition to the PETM, the Permian Triassic extin ction event and the start of the Ediacaran both presented a large climate change brought on or at least influenced by methane bubbling of methane clathrate 252 and 635 million years ago respectively. In the Permian extinction, where 96 percent of sea life and 70% of terrestrial life died, the record saw a 13C drop of around 10% which would necessitate a 5 times larger methane release than the PETM (Ruddiman 2008) The combination of increased volcanism from plate tectonic movement and the storage of shal low methane clathrate in permafrost allowed for the possibility of such a large methane release. Undersea p ermafrost because of its low temperature and compact ice lattice allowed for methane to be stored at shallow water in the absence of deep water pr essure. Thus, any action of warming and melting could destabilize the clathrate. Similar to this, the start of Ediacaran was most likely a snowball (complete glacial) earth which quickly changed to more temperate earth in a brief period because of a mass release of clathrate from shallow seas and lakes (Kennedy et al. 2008) These events all highlight the climate changing ability possessed by the methane stored at the bottom of the ocean shallow seas, and tundra lakes. While none of these conditions are exactly similar to today some parallels can be drawn as the present earth contains undersea permafrost which like the Permian and Ediacaran allows for the storage of clathrate in melting vulnerable shallow seas. In fact, recent dat a seems Figure 21 This graph shows the 18 O levels for benthic forams found on the ocean floor to reflect this time period. The cores were done by Lisiecki et al. 2005. This graph was prepared by Robert Rohde at globalwarmingart.com.
27 | Page to suggest tha t the shallow ocean off the Siberian shelf and tundra lakes have already started to release methane. The East Siberian Arctic S helf is one of the shallowest and broadest shelves in the entire World Ocean with an average depth of only 100 m. Historically, permafrost has existed on the ocean floor which has allowed for the formation of methane clathrate in shallow depths. These factors, along with continued warming, have created an optimal environment for large methane efflux as recent studies have shown. Figure 22, from a 2005 report, illustrates the amount of methane being released in 2003 and 2004 in g/km2/day. Some of the locations in 2004, especially the D Laptev str, produced methane efflux as high as 1700 g/km 2 per day when there is no ice coverag e while total yearly efflux from the eastern Siberian shelf could have been as high as 13.7# 10^4 g CH4 /km 2. To help contextualize the amount of methane in the ESAS currently, it was found that at some points the water contained 4,400% more methane then standard saturation limits. Although not statistically viable, it is also important to note that 2004 released considerably more methane than 2003 indicating that the problem has potential to worsen. Some scientists, even estimate that almost 50% of th e world's oceanic methane release comes from the ESAS. The recent warmer temperatures have augmented permafrost melting which has lead to both the breakdown of undersea biomatter by methanogens along with the instability to methane clathrate. Researchers fear that warming could augment both the ESAS methane efflux and other oceanic undersea permafrost shelves, including frozen tundra lakes. Furthermore, methane, because of its greenhouse qualities can further warm the earth while causing more methane re lease highlighti ng a dangerous feedback loop (Shakhova 2006) Figure 22 Estiatmated methane release in the ESAS. a) 2003, b)2004. Taken by Shakhova et al. 2007.
28 | Page 3.7 Water Vapor Warming over the last 25 years has brought about a growing increase of atmospheric water vapor as illustrated by the measurements at Boulder, Colorado (Figure 23) This is to be expected as it is readily documented that more water evaporates at higher temperatures. Furthermore, researchers estimate that 66 85% of earth's current greenhouse e ffect is caused by water vapor (Real Climate 2005) This correlation appears to host the framework for a simple positive feedback mechanism. However, as highlighted in the discussion on clouds, there are various levels of complications when dealing with atmospheric water vapor because it has the possibility to cause a multitude of p ositive and negative feedback situations. In the presence of aerosol or dust particles increased levels of water vapor can cause an increase in cloud formation and therefore some of the greenhouse properties of the vapor can be shielded. It is importa nt to note however, that if the formation of high clouds is favored then they can reflect a net plus heat energy back to the earth's surface and induce some warming. Further research has also shown that water vapor can absorb latent heat at the earth's su rface and transport it to the upper atmosphere which has a cooling potential. Finally, water vapor has an average atmospheric half life of 10 days which can help dampen effect (Gordon 2008) Despite all this, a very recent study done by the National Aero nautics and Space Administration(NASA) has openly suggested, based on evidence from a global climate model, that if water vapor levels continue to rise the temperature of the earth could also rise to the effect of 1 or 2 o C (Minschwaner et al. 2006) Thus, some scientists and global climate models agree that water vapor exhibits net positive feedback while others point to increased cloud formation There will need to be more resea rch on vapor and clouds to make an honest climate projection. Figure 23 Measured water vapor in Boulder, Colorado from 1980 1994. The data and graph were provided by NOAA.
29 | Page 3.8 Car bon Sink in a Warmer Ocean The world's oceans contend as the earth's largest accessible carbon sink which includes not only the methane clathrate discussed earlier but other forms of dissolved carbon including vast amounts of CO 2 There are two main "p umps" that allow the storage of CO 2 known as the solubility and the biological pump. These mechanisms allow for a vast amount of carbon storage and have historically been used to buffer climate change. The solubility pump works because CO 2 can dissolve in ocean water as demon strated by the reaction below (Ruddiman 2008) : CO 2 (aq) + H 2 O H 2 CO 3 HCO 3 + H + CO 3 2 + 2 H + The carbon dioxide mixes with the water to form carbonic acid, bicarbo nate, and carbonate which in itself is dependent on the current ion make up of the seawater but on average the final product has a net positive charge. It is estimated that roughly 1/3 of all anthropogenic CO 2 is abs orbed into the earth's oceans (Ruddima n 2008) However, because of gas solubility laws, the warmer oceans less dissolve carbon dioxide. The oceans have already warmed on average around 0 0.5C, although there are many discrepancies from location to location. The excess CO 2 left in the atmosp here will then promote warming highlighting the feedback loop. A recent experiment released in 2009 which measured the CO 2 uptake in the sea of Japan in the time pe riods of 1992 1999 and 1999 2007, reported that the CO 2 uptake was half as much in th e lat er dates then the former (Lee, 2009) Likewise, Cruerger et al. ( 2008 ) found using climate models out of the Max Planck Institute that warming could cause a 45% drop in CO 2 uptake potential in the southern Oceans, a 30% drop in the north Atlantic, 20 % drop near the equator, and a 20% increase in Polar Regions due to the melt water from ice by 2070. To help control this feedback, the biological pump mentioned earlier takes excess bicarbonate and carbonate and stores it as biological matter. Forams an d other phytoplankton store carbon in their calcium carbonate shells which eventually comes to rest on the ocean floor. This carbon pump was discussed earlier in context of the carbon thermostat where it plays a major role in returning carbon to the earth and has propagated the Ocean as a large carbon sink. Unfortunately, because the atmospheric levels of CO 2 have increased along with its partial pressure an excess amount CO 2 is being dissolved in the oceans. The dissolving reaction above produces a n et positive charge in the form of an acidic proton. Thus, the oceans, because of anthropogenic CO 2 are slowly acidifying ( figure 24 ). Some areas in extreme latitudes posted changes as high as .12 (cold water can dissolve more CO 2 ) while the global mean changed somewhere around 0.075, 8.179 to 8.104. (Orr et al. 2005) Likewise, a new report, by Wootton et al. published in 2008 looked specifically at the pH of coastal regions around Tatoosh, Washington and found that after taking 24,159 measurements fr om 2000 2008 the pH had dropped nearly on average 0.045 units a year as demonstrated by figure 25. Overall, the pH in the region dropped from around 8.45 to around 8.25. This annual drop is 10 times greater then what was predicted by the IPCC models. Wh ile Wootton et al. does suggest the possibility that an alkaline buffer was breached they find it more reasonable that some other form of CO 2 bubbling was the
30 | Page culprit. Also, most scientist s contend that eight years is too short of a time period to measur e pH because its variation for short term change can be high, while long term trends are slower. Despite this, most research does show a strong trend of acidification but even more research is necessary in the coming years to see the whole severity (W ootton et al. 2008) The forams and phytoplankton mentioned earlier and animal corals require a slightly basic ocean in order to construct and deposit their calcium carbonate shells. Under normal conditions, the standards for calcium carbonate production are stable in surface waters since the carbonate ion is at supersaturating concentrations. However, as ocean pH falls, so does the concentration of this ion, and when carbonate becomes under saturated, structures made of calcium carbonate are vulnerable t o dissolution. Therefore there is some fear among researchers that as CO 2 levels continue to climb Ocean pH levels will continue to drop. This acidification has to potential to stall or stop the biological pump phytoplankton shell production (Orr et al. 2005) It is unclear how fast the ocean will acidify or what extremes the plankton can handle although some research has already shown that marine species experience reduced shell growth in the presence of high CO 2 ( Gattuso, 1998 ) Also, many scientist s agree that acidification has potential to contribute to warming by hinderin g this large carbon sequester (Orr et al. 2005) Warmer oceans as a whole, because of decreased solubility and the potential for acidification which can stall the biological pump tend to act as a viable part of a strong positive feedback loop that can potentially further warm the planet. Figure 24 This depiction shows the estimated change in pH of the earth's oceans from 1700's until the present. This chart uses a combination of data from Orr et al. 2005 for newer pH numbers while the preindustrial were mainly estimated in the same paper.
31 | Page 4 How Bad Will it Get? A Future Projection If anything is clear at this point it is that the climate system is extremely complicated. Different systems of forcing and feedback interact to produce res ults that further interact and a ffect other results until an interwoven system is made that has been conveniently labeled climate. In the 1960's, when James Lovelock first publ ished the Gaia hypothesis it was mocked and scorned but even Lovelock likely misjudged its later implications. Highlighting the relationship between the biosphere and the physical earth this hypotheses presented an interconnected world where not only one climate could affect another but even humans or organisms could influence the climate. This means for example that anthropogenic CO 2 emissions can affect temperature which in turn can affect decomposition rates of biomatter in tundra bogs by saprophy tes which in turn can further warm the environment through their own emissions. Because of some truancy in this relationship it is thus necessary to approach possible future climate projections with a Gaia style, big picture, holistic mindset in order to ascertain with any accuracy. The researchers behind the IPCC fourth assessment report attempted this processes by including some of the forcings and feedbacks highlighted above (water vapor, uptake in warmer oceans, some albedo, aerosols, and clouds) whi le neglecting others (methane clathrate, permafrost decomposition, ocean currents, soil warming, and the effects of an acidic ocean). Because of this omission there is a strong possibility that the IPCC 3 o C Figure 25 This is the average result of 24,149 pH measurements on the Tatoosh, Washington coas tline during the period of 2000 2008. (Wootton et al. 2008)
32 | Page temperature increase projection is too conservat ive. Furthermore, the IPCC report was released nearly three years ago and climate science is progressing at an incredible rate. While this does not make the report obsolete it does promote the possibility that the data requires necessary modification. I t is in this frame that I will try to answer the question "How bad will it Get". All negative and positive feedback and forcing mechanisms discussed will be integrated to present a possible climate outcome. It is important to note, aside from the IPCC, t he greatest researchers and scientists have failed to answer this question with a high degree of confidence nor do they claim to completely understand the depth of the situation. This assessment will be broken into three related sections emphasize the mor e probable occurrences. This hierarchy will be based on the overall attitude and acceptance of climate scientists for a given study or theory. The first part, "This Probably Will Happen", will integrate theories that most scientists agree are not only lik ely to happen but already occurring. Next, "This Might Happen" will look at feedbacks and climate forcings that are well documented and have a moderate probability of occurrence. The final section, titled "Lets Hope this Doesn't Happen" will look at pos sible climate occurrences and tipping points that are still documented but fail to have the same empirical evidence as other scenarios. The interconnectedness of the entire climate system will be stressed along with the fact that temperature change will b e the predominate indicator of measuring climate progression. 4.1 This Probably Will Happen The se Mechanisms Will Likely Effect Future Climate Considering the global temperature mean has already warmed nearly 0.75 o C in the last 100 years from m ainly anthropogenic emissions many temperature influenced feedback mechanisms have already been activated or are in danger of doing so. The oceans, because they are directly connected to the atmosphere have already warmed over the past 100 years. As m entioned above, because of the solubility of gas law s, the warmer the oceans become the smaller the percentage of CO 2 is sequestered. Current experiments have already shown that CO 2 uptake has already decreased as demonstrated by the Sea of Japan me asurements taken from 1992 2007 where uptake was halved furing this short period ( Lee, 2009) Furthermore, as stated above, the Max Planck climate model predicts uptake drops in globa l oceans as high as 45% by 2070 (Crueger et al. 2008) The less CO 2 s equestered by the ocean, the more in the atmosphere which reinforces a warming trend that further diminishes CO 2 uptake in the earth's oceans. In extreme latitudes, warming continues to melt age old snow and ice, which in the Arctic has diminished by ne arly 35% since 1960. As previously stated, when the ice and snow melt it is replaced by soil, water, or vegetation that according to figure 13 have considerably lower albedo. Forest lines are also moving north as demonstrated b y Euskirchen ( 2007 ) beca use of a more favorable growth environment which also decreases albedo. Thus, the earth surface will absorb more energy from the sun and more heat will be release d into the atmosphere via conduction and convection Current extreme estimates using satelli te data predict the complete loss of ice in as early as 10 years while more conservative estimate 40 years, which could increase nort hern albedo by as much as 40% (Scharien et al. 2007) This will not only warm local climates but also promote more melti ng as indicative of a feedback loop and can also promote global warming as
33 | Page the Arctic is heavily connected to wind currents in the northern hemisphere. Deposits of methane clathrate, locked under the ocean in undersea permafrost and pressure are particul arly vulnerable to a warming climate because of the stability properties of methane hydrate. On the Eastern Siberian Arctic Shelf methane concentrations have been measured as high as 4 ,400% above normal saturation (Shakhova 2006) Furthermore, as Figure 22 suggests, methane release from year to year is increasi ng and was recorded as high as 13.7 # 10^4 g CH4 /km 2 per year in 2004. The methane clathrate requires either high pressure or cold temperatures to remain stable and thus the combination of melting permafrost and a shallow ocean created the situation in the ESAS where 50% of the world's oceanic methane release occurs (Scharien et al. 2007) Considering methane's GHG potential, this situation makes for a powerful feedback mechanism. Furthermore, the re is always the danger of other similar occurrences in northern oceans or even tundra lakes. Warming has also started to cause permafrost to melt in northern latitudes which can potentially further cause CO 2 and methane release by biological decompositio n. Figure 19 and 20 show the relative amount of biomatter stored deep below different styles of permafrost. When frozen, saprophytic bacteria cannot access the plant matter but can when thawed. The saprophytes produce CO 2 in aerobic conditions and metha ne in anaerobic conditions as metabolic waste. Subsequently, when the permafrost thaws and saprophytes thrive a powerful f eedback mechanism is realized. Current evidence suggests that decay activity in Alaskan tundra has increased by as much as 5% in 5 de cades and scientist predict an increase of atmospheric C of 100 Pg in the next 100 years from decay alone. Atmospheric water vapor, another common GHG, has increased linearly with temperature as demonstrated by figure 23 over the past 25 years and is e xpected to continue. Vapor is responsible for 66 85% of the entire greenhouse effect on earth. Therefore while the earth warms so does the amount of water vapor in the air which further contributes to warming and water evaporation. There are also a f ew negative feedback mechanisms that are currently active to help counter some of the occurrences described above. The Max Planck Cl imate Model, described repeatedly above, predicted the Arctic Ocean to have a 20% increase in CO 2 uptake despite a warming climate. This occurs because as ice and snow melt water is added to the ocean providing more solvent to dissolve CO 2 Furthermore, this works by negative feedback because the warmer it gets the more ice melts and the more CO 2 can be dissolved. It was m entioned above that water vapor can promote a powerful positive feedback loop. While this is true, water vapor can also act in a negative sense by promoting cloud formation which propagates a cooling trend because of a high albedo. Unfortunately, the und erstanding of cloud growth under the influence of a warmer climate is still relatively unpredictable. Most scientists agree, however, that in a warmer earth there is more cloud coverage because of increased vapor extenuating a cooling feedback. Industri alizat ion does not only produce green house gases but also atmospheric aerosols which can help cool the earth because of their strong albedo. As developing nations progress they are expected to increase energy demands and in the process release more aeroso ls. Additionally, aerosols are a primary constituent of clouds and thus promote their formation. Finally, the carbon thermostat described earlier is continually expressed as long rocks are weathered and oceanic phytoplankton are thriving. CO 2 a reacta nt necessary for the weathering of rocks is sequestered and later added to the shell of a foram or other phytoplankton and stored at the bottom of the ocean. Because
34 | Page weathering increases in a warmer environment this mechanisms can help cool the earth by removing CO 2 These negative feedback mechanisms are continually active even as the earth continues to warm. In lieu of these feedback mechanisms and the current warming trend, one of the most common predictions researchers have made is that the future climate will be much dryer and have a higher propensity for droughts then the present. Shifting weather patterns (changing air currents, refer to section on "Ocean Currents" for reason to why this happens) and the physical fact that a warm atmosphere ca n hold more moisture is the root cause ( Warren, 2009). Likewise, as the ground heats up, stationary water will evaporate quicker leading to deficient aquifers and strained agriculture (the water evaporates before plants can use it ) Specifically, clima te models show southern Europe, the Amazon in South America, and south east Asia suffering from drought in the near future (Jones, 2009)(Warren, 2009). Furthermore, some locations, like China and Australia, are already experiencing their worst droughts in history. While most of this report has analyzed climate relations, it is important to note that all of these mechanisms discussed can have anthropogenic effects. These droughts can ultimately cause a cascade of problems for human populations. Water sho rtage not only affects thirst but also food and agriculture supplies. Food shortages can lead to famine, malnutrition, death, and even in some cases war, for resources. Ultimately, if the earth does become as dry as some scientist s predict, the Earth's h uman carry ing capacity would be reduced and like any natural population would necessitate a large die off. While it was minimized in this report, this likely example shows that climate change does not just affect the physical environment but also every be ing on this planet. 4.2 This Might Happen Moderate Possibility of Effect Current research shows that the earth's oceans sequester as much as 1/3 of all anthropogenic CO 2 released into the atmosphere. Likewise, with the atmospheric CO 2 leve ls nearing 390 ppm the oceans are forced to uptake even more CO 2 too accommodate the increase, in atmospheric partial pressure. According to the equation above on page 10, for every molecule of CO 2 dissolved there is the potential to produce an acidic pr oton which is slowly causing the acidification of the earth's oceans. The pH of the ocean has droppe d 0.5 since industrialization (Orr et al. 2005) Furthermore, the results from the Wootton et al. experiment shows that the acidification might be increas ing at a faster rate than expected. The carbon thermostat mentioned above depends on the calcium carbonate shell production of phytoplankton and benthic marine organisms in order to store the carbon on the ocean floor. As atmospheric CO 2 continues to ris e from anthropogenic and other feedback the ocean will likely continue to acidify which could potentially adversely affect the shell formation of marine phytoplankton. If this formation is stalled or stopped one of the planets largest negative feedback mechanisms would be greatly affected in a negative way. This would not only slow CO 2 sequester but could also prolong any natural climate recovery. Most of the feedback mechanisms discussed in this report involve a loop that effected temperature. It is important to note that this feedback loop is independently based solely on CO 2
35 | Page While the effects of warming on ocean currents is somewhat unclear, most research suggest an overall weakening caused by a similar weakening in air currents. This relatio nship comes from the fact that most surficial ocean currents are driven by air currents. The Walker equatorial circulation, which was discussed above, has weakened over the past 100 years because of a change in pressure which drove the circulation. The p ressure disparity has slowly been diminishing as the earth has warmed, likely due to a larger temperature uniformity (Vecchi et al., 2006) Because surface currents are largely driven by wind currents they slow down. Weakening currents can cause cooling as less heat is transferred around the globe. Likewise, northern regions have higher odds of being climatically isolated with weaker currents. A modern example of this is Antarctica, which is virtually disconnected from air and water currents. The Gulf Stream, which is largely responsible for warming Europe, can also be weakened or even potentially stopped as a result of a warmer earth. As explained above, a quick melting of ice in Greenland can disrupt the thermohaline pump that drives the Gulf Stream causing it to stall or potentially stop. Without the warming effects of the Caribbean water in Europe, temperatures would likely drop as much as 10 o C. This occurrence, including the large scale temperature drop, would have massive global impacts and pro mote a very large cooling trend similar to wh at was seen 12,700 years ago (Bunyard 1999) Some scientist also believe that if Greenland continues to melt at a slow pace the Gulf Stream could actually be strengthened however other evidence largely con tradicts this as the Gulf Stream weakened by nearly 30% in the time period from 1993 2005 as reported by The American Meteorological Society in 2006. In conclusion, most evidence suggests that warming could potentially create a negative feedback loop by s lowing currents which tend to produce a cooling effect. 4.3 Lets Hope This Doesn't Happen A look at Tipping Points All of the feedback and forcing mechanisms outlined in this report have been described as completely legitimate side eff ects to the earth's continued warming ca used by anthropogenic emissions. A major concern for many climatologists comes in the form of evidence in the paleoclimate record of "tipping points" or brief threshold s where the climate transiently changed from one state to another. Famous examples, which were described earlier, are; the Paleocene Eocene Thermal Maximum, where a greenhouse earth quickly warmed by 6 o C in a short time period, the Permian Triassic extinction, where the earth quickly warmed by 10 o C, and th e start of the Ediacaran period, where some scientist say that a snowball earth underwent mass melting due to climate change. All of these time periods were marked by mass extinctions followed by a renewed earth that scantly resembled the old. The impetu s for these events is the fact that most of the climate mechanisms highlighted in this report act by positive feedback. Likewise, the secondary control (primary control is anthropogenic emissions which causes a temperature response that becomes the contro l for other feedback loops) in nearly every mechanism is temperature. Therefore, the severity of these mechanisms, along with crossing "tipping point" boun daries, is based almost exclusively on how high the temperature rises. Too summarize, the warmer an thropogenic emissions make the earth, the more powerful the feedback loops, which further warm the earth and greatly increase
36 | Page the likelihood of a threshold crossing, which once crossed a permanent environmental change will be enacted. It is important to n ote that when scientist s use the term threshold or tipping point they are referring to any climate event which produces a irreversible result. This could be the temperature threshold when reached causes the poles or Greenland to melt and initiate sea lev el rise, or it could be the temperature boundary that causes a permanent change to a dryer earth, or in worst cases, a tipping point could represent the threshold where any or all the positive feedback mechanisms are too powerful to stall leading to runawa y warming. Even though the situation today is somewhat dissimilar to the past, experts have stated that the climate is in danger if crossing various thresholds. One particular possible tipping point that has been recently documented and has great potent ial for calamity is a quick surge of continental ice movement into the Ocean caused by softening ice aprons. This concerns three large ice shelves, one in Greenland and two in Antarctica, that contain 99% of the world's terrestrial ice. The scenario inv olves ice aprons that traditionally block or stall the movement of terrestrial glaciers into the ocean. These aprons are "appendages" of the mainland glaciers that are floating in the ocean and act as a stop cock that prevents net glacial movement (by eit her melting and falling off or creeping) into the ocean (Bell, 2008) These aprons are generally regrown by winter snow but recent warming has caused a trend of decreased snow and increased melting. Robin E. Bell of Columbia University contends that if t hese ice aprons fail there is a chance that the glacial flow towards the ocean could increase. Furthermore, he contends that surficial snow melt on thick glaciers is causing water to trickle down to the continental rock bed. This water can then meander b etween the glacier and rock and act as a lubricant to further speed up ocean bound movement. The Greenland glacier has potential to cause a 7.2 m sea level rise, while the western and eastern Antarctic shelves could cause 6 m and 52 M sea level rise respe ctively (Bell, 2008) If anyone of these glaciers "lurched" into the ocean the consequences would be catastrophic. This example shows that there are many possibilities and potentials (some more extreme than others, but still possible) for a future climat e and tipping points make future projections much more complicated. In a recent study published by the Europe Intelligence Wire with the Financial Times in 2009, "43 of the world's leading climate experts, scientists have for the first time worked out th e likelihood of one of the major climate thresholds being breached. They concluded there is a one in six chance of at least one threshold being passed with a rise of just 2 4 o C in global average temperature. If the average increase in temperature is higher than this, then the probability becomes one in two" (Europe Intelligence Wire, 2009) In more extreme cases some scientists, like NASA's James Hansen, believe that thresholds could be breached in just a 1 o C temperature rise. Thus, the research and scien ce is still uncertain on the exact location of the thresholds, but most experts agree that they not only exist but are likely to occur if warming continues.
37 | Page 5. Conclusion Since the essence of positive feedback involves a system where input amplifie s expulsion which in turn amplifies input, the determining factor to the success of the system is amount of input. In nearly all cases of described feedback the input was defined as an increase in temperature. Thus, the question "How bad is it going to get", is predominated by the amplitude of the initial rise in temperature compelled by anthropogenic emissions. Considering emissions have already generated a 0.75 o C increase in temperature, most of the mechanisms described above, according to this logic, have been activated to at least some extent. Recent research further reiterates this by presenting evidence for declining surface albedo through ice reduction and vegetative expansion, rises in oceanic methane bubbling, increases in permafrost thawing fo llowed by proliferation of saprophytes with metabolic CO 2 and methane emissions, and amplification of atmospheric water vapor. The positive mechanisms are fortunately only half the picture as negative feedback strives for climate equilibrium through chem ical weathering in the carbon thermostat, raising albedo with both aerosols and cloud formation, and slowing ocean and air currents. While these feedback loops exist in opposition, the anthropogenic forcing of CO 2 induced warming has empowered many of t he positive feedback loops. Likewise, the research presented throughout this report bolsters this claim as nearly all positive feedback loops present evidence of a strengthening trend form year to year. Despite having this affirmation, many unknowns incl uding thresholds and tipping points still exist that can have minor or major impacts on climate outcome. For example, if a warming threshold is crossed that swiftly melts Greenland and the gulf stream stops then the entire climate could shift to a cooler state or if oceanic dissolved CO 2 lowers pH levels beyond those necessary for calcium carbonate shell formation then the carbon thermostat could stall. In more extreme cases, the earth could warm to a point where positive feedback loops strengthen to an unstoppable state leading to runaway warming and swift climate change as the record showed in the PETM and the Precambrian extinction with methane clathrate release. Likewise, if the Bell "Ice Apron" theory came to prosper as a tipping point then the ear th could witness sea leavel rise above 50 m. These unknowns and all of this presented information illustrate the notable complexity of the climate system. Furthermore, this system and all of its components, according to human and paleoclimate records, has never been predictable or linear. Tipping points, unknown feedbacks, abrupt climate change can all cause quick shifts in climate. For these reasons, very rarely, do climate scientists publish climate projections. The IPCC and their models have rel eased four assessments reports since 1990 and the only thing greater than the amount of peer reviewed research and science increased in each subsequent report is the grimness of its message. The most recent, AR4, released in 2007, contained the most accu rate projection to date but failed to include many of the feedback mechanisms highlighted in this report. AR4's models foresaw a medial 3 o C rise on average across the entire globe. Based on their report, along with the many research articles presented ab ove that showed increasing activity of positive feedback with nearly every indicator, and very little indication of industrial slow down it must be assumed that the AR4's projection leaned on the side of too conservative. Therefore, the future projection would most likely fall at the upper extreme of Ar4 around 3 6.5 o C which
38 | Page accounted for more unknowns. Likewise, in March 2009, the United Nations held a Framework Convention on Climate Change in Copenhagne, which seemed to reiterate this belief. The gene ral consensus from the meeting saw that the IPCC Ar4 was far too optimistic and too conservative. The meeting highlighted unpublished reports by Brahic (2009) that forwards evidence for a larger increase in sea level than the IPCC projected, and research by Jones (2009) and Warren (2009) who predicted a much dryer Amazon and Europe than previously estimated. C urrently, the IPCC is outlining their fifth assessment report which is set for release in 2014 and will likely include all of the mechanisms highlig hted in this report. Furthermore, the IPCC should assess their use of linear climate projection as both feedback and tipping points(IE large glacial melt) could cause nonlinear or exponential shifts. It will be interesting to see what numbers the new comp uter models create. With a 3 6.5 o C increase, most scientists contend, according to the results of the European Intelligent Wire poll, that there is a greater then $ chance of crossing at least one climate tipping point. This substantial rise and the pot ential for tipping points paint a grim picture for the earth's future. Furthermore, most research now asserts that the future earth will be much dryer then the present This can lead to a cascade of events that has the possibility to cause mass loss of h uman life. Considering the human produced CO 2 emissions are forcing the initial warming that promotes deadly positive loops and amplifies the situation, the best solution is to greatly curb and sequester CO 2 While the negative feedback mechanisms are a ctive, history and research have shown that none of them are powerful enough to prevent warming in the short term as demonstrated by Zeebe et al. ( 2000 ) statistical analysis of the carbon thermostat. Likewise, a report in 2008 by Hanson et al. suggests t hat if CO 2 levels must return around at least 350 p.p.m.v. to avoid most of the scenarios laid out in this report. Thus, quick human action is necessary and the only hope of preventing an unpredictable and costly future. The real answer of "How Bad Will it get" should really be "I hope we don't have to find out."
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