Turn down the heat
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Coursera Final Project - Turn Down the Heat
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Turn down the heat
- 1. Turn Down the Heat Coursera Final Assignment Robert D. Cormia
- 2. Overview • Era of consequences – Climate change has arrived – At 0.8 deg C it’s significant • We don’t have 20 years to wait – Headed right at 450 ppm CO2 – 400 ppm today, adding 2+ ppm/yr • May not be ‘doable’ at 2 deg C – Rate of change may be too fast – Ecosystem and cryosphere failures
- 3. Assessing Dangerous Climate Change – James Hansen et al PLOS 2013
- 4. Era of Consequences • At just 0.8 deg C…. – Record droughts, fires, superstorms, and heat waves (frequency, intensity) – Pest migration, spring arrives two weeks earlier =>ecosystem stress – Crop stress, arid soil, desertification – Heat related disease, death, suffering – Insurance/property loss, sea level rise
- 5. Sochi Summer Winter Games Temperatures are soaring to 17 degrees Celsius in Sochi in the next couple of days and due to the warm weather, snow is melting in Krasnaya Polyana, the mountain cluster for the Winter Games, February 12, 2014. http://www.canada.com/olympics/columns/sochis-summer-winter-games
- 8. Temperature Anomaly NOAA Global Temperature Analysis - https://www.ncdc.noaa.gov/sotc/global/2011/13
- 9. Record Heat/Droughts • • • • • • USA – 2000 to 2009, esp. 2010 to 2012 Australia – Melbourne Europe – 2003/6 and esp. 2013 Russia – 100 deg F for over a month South Africa – 2013 Earth – warmest years on record – http://en.wikipedia.org/wiki/Instrumental_temperature_record
- 10. US Drought Zone 2000-2009 http://www.nrdc.org/health/climate/drought.asp
- 11. Record Drought in Europe
- 12. California Drought => Fires U.S. Forestry Service fire crews conduct a burnout operation as flames near homes in Azusa, California, in January. Over 500 firefighters, air tankers, helicopters and bulldozers worked to contain the fire which grew to over 1,700 acres. http://www.washingtonpost.com/blogs/govbeat/wp/2014/02/14/drought-stricken-california-other-states-prepare-for-landmark-year-in-fires/
- 13. Fires in Melbourne Australia http://www.cnn.com/2012/06/14/world/asia/melbourne-climate-change-c40/index.html
- 14. Heat Storms in the US Record heat across the US in summer, including an oppressive heat index
- 16. Don’t have 20 years to Wait • Trajectory to 450 ppm CO2 (2032-2035) – 450 ppm CO2 => 2 deg C committed/forcing – Amplifying feedbacks take us to 3+ deg C • Ocean acidity 450 ppm CO2 => pH 8 – concentration [CO2] = [HCO3] • Decisions made today impact 2030 – Still investing in carbon intensive energy – At 2+ ppm/year, for 20+ years, 450 ppm CO2
- 20. Why 450 ppm CO2 Limit? • 2 deg Celsius committed warming – Radiative forcing of ~ 2.5 Watts/M2 • Ocean acidification – pH 8 and under-saturation of bicarbonate ion – Less than 10% of coral will survive (~ 50 years) • Deglaciation of ice sheets – Rapid melting and instability, Greenland ice sheet • Sea level rise for centuries – Estimated 1 meter rise (or more) by 2100
- 22. Ocean Acidification CO2 dissolves in water to produce mild carbonic acid, which dissociates into bicarbonate and carbonate ion. Increasing acidity removes carbonate ion from solution. At pH 8 (450 ppm CO2) carbonate ion is under-saturated, shells will be difficult to form and stay stable . http://www.ocean-acidification.net/FAQacidity.html
- 23. May not be ‘Doable’ at 2 deg C • Secondary feedbacks to 3 deg C – Committed deglaciation of the ice sheets – Methane hydrates destabilize, release CH4 • Ocean warming AND acidification – Impacts to base of the food chain – Bleaching and degradation to coral • Open sea in the arctic alters ocean currents, albedo, and the jet stream – Rapid destabilization of climate system
- 24. Feedback Driven Warming • More radiative forcing, more warming – More warming, more water vapor => T – Warmer planet releases soil carbon (CO2/CH4) which leads to more warming • CO2/CH4 release amplifies warming – CO2 has a half-life of centuries – CH4 has a global warming potential of >20 • Loss of arctic ice/glaciers, lower albedo – Ground and oceans absorb more sun/energy
- 25. Effect of Climate Feedbacks Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming Margaret S. Torn and John Harte AGU GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L10703
- 26. Soil Feedbacks at 2 Deg C USDA-NRCS, http://soils.usda.gov/use/worldsoils/mapindex/soc.html
- 28. Arctic Sea Open Ice in 2015 http://arctic-news.blogspot.com/2012/11/arctic-sea-ice-set-to-collapse-in-2015.html
- 30. Ecosystems and Humanity – IPCC Assessment http://profmandia.wordpress.com/2010/07/25/climate-change-is-not-being-nice-to-mother-nature-overview/
- 31. Summary • We are at the front edge of climate consequences: storms & droughts • Trajectory towards 450 ppm CO2 – Ocean acidification, 2 deg C warming • Amplifying feedbacks may kick in – Deglaciation, albedo, methane hydrates • May not stop at 2 deg => 3 or 4 deg C – 4 deg C may not be ‘doable’ for biosphere
- 32. References/Attribution • Climate Change Index - http://www.igbp.net/4.56b5e28e137d8d8c09380002241.html • 350.org • CO2now.org • NOAA Climate Center • • https://www.ncdc.noaa.gov/sotc/global/2011/13 http://www.esrl.noaa.gov/gmd/ccgg/trends/ • Skeptical Science - https://www.skepticalscience.com/ • International Arctic Research Center • http://www.iarc.uaf.edu/ This presentation is intended solely for use/remix for educational purposes
Editor's Notes
- Turn down the heat final project for Robert Cormia, Foothill College, CormiaRobert@foothill.edu The notes field comments will help users of this material apply it to their various needs.
- Turn Down the Heat - Annotated Notes This final project for Coursera's 'Turn down the heat' summarizes the key learning outcomes for the class: 1. We are already experiencing significant impacts from ~0.6 to 0.8 deg Celsius warming, with at least another 0.6 to 0.8 deg in the pipeline 2. We are headed straight at 450 ppm CO2 (by 2035), potentially a 'tipping point' for climate change and widespread ecosystem damage 3. Warming of 2 degrees C may not be advisable (Hansen 2013) and further warming from amplifying feedbacks could take us to 3 deg C and even warmer Three looming factors include deglaciation of ice sheets, ocean acidification, and methane hydrate release, in addition to heat storms. Ocean acidification itself becomes an ever growing threat, within 20 years the ocean pH of 8 will lead to loss of 90% of all coral, and potentially the productivity of plankton, the base of the food chain. The course provided a wonderful foundation for understanding the integrated impacts of climate change, and why we MUST do everything possible to stay under 450 ppm CO2 and 2 deg of warming James Hansen Columbia University and formerly NASA GISS, published in PLoS: Assessing dangerous climate change (Nov 2013) making the following/similar points: 1. We are experiencing significant climate impacts from droughts, heat storms, floods, fires, pest migration at barely 1 deg Celsius warming 2. While scientists in the past have argued that 2 deg C is the edge of what might be considered safe (or barely sane) climate interference, recent data argues against that. 2 deg might not only be too much, we may not be able to stop warming there, and as amplifying feedbacks (albedo and methane hydrates) could take us to 3 deg C even without more fossil fuel combustion 3. The rate of warming may have already triggered irreversible deglaciation of Greenland ice sheets, and Arctic Ocean may be 'open sea' as early as 2015, triggering instability in methane hydrates on the sea floor The upshot of the Hansen article is that staying under 2 deg C would be better than reaching that level, and in order to do so, we should try to limit fossil fuel combustion to no more than 1,000 GT. From my calculations, and observing that we are at 400 ppm CO2 at 375Gton combustion, and adding 2+ ppm CO2 annually (at ~ 10GT carbon combustion), we don't have that much room, and need to stop at 625 to 700GT, and we will crash through 450 ppm by 2030 to 2035 at today’s rate of growth. After reading Hansen’s article, I no longer believe that we can avert disastrous climate impacts (storms, droughts, floods) and could be headed to catastrophic impacts (based in research published by the International Arctic Research Center, that has observed a doubling in arctic methane release from ocean (bed) methane hydrates (17 GT and 6 ppb atmospheric CH4). In my estimation, opening of sea ice in the arctic will destabilize sea floor permafrost, leading to increasing rates of methane release, leading to releases of 500 TG annually by 2030. An eventual release of 50GT methane (over decades) with a GWP (Global Warming Potential) would be equivalent to 1000GT carbon, the ENTIRE carbon budget that Hansen states we MUST NOT burn through.
- A key figure in Hansen’s article is a chart showing temperature anomaly and cumulative anthropogenic carbon emissions (GtC). The chart shows we have marched halfway up a path to 2 degrees Celsius. Having burned ~ 375 GtC, another 375 GtC might be burned in as little as 25 to 30 years.
- At just 0.8 deg C warming, we are already experiencing record heat storms, droughts, fires, superstorms, pest migration, crop and soil stress, heat related disease and death, and property and insurance loss. We are entering an era of consequences.
- As we participated in the Coursera MOOC, we also watched the Olympics in Sochi Russia, where sportscasters walked around in spring like conditions, people swam in the Black Sea, and athletes struggled with thawing (corn) snow in skiing and snowboarding events. How much longer will we be able to have winter Olympics?
- A sunflower wilts in the hot Midwest sun
- A farmer in the Midwest stands at the edge of a dry irrigation pond
- The mean temperature of earth has risen 0.5 deg C in just 35 years, and could rise another 0.5 deg C in 20 years. Even if carbon emissions stopped, warming would increase for 50 to 75 years or more, the time it takes for heat to reach and warm the deeper depths of the ocean.
- Record heat storms and droughts have occurred in nearly all areas of the globe (minus the poles) from the US (heat stress 2000-2009) and Midwest droughts in 2011-2012, to Europe (2003/6, and 2013, including 30,000 people who died in 2003, Russia in 2010 that killed 5,000 people, South Africa in 2013, and a link to earth temperatures and anomalies in Wikipedia
- Drought vulnerability in the US 2000-2009 - http://www.nrdc.org/health/climate/drought.asp
- A dry river bed during record drought in Europe
- California, in its worst drought in 200 years, experiences wild fires in January 2014
- Fires have plagued Australia for years as they experience an ongoing drought and record temperatures
- For a number of years since 2009 and especially 2011-2013, the US has experienced both severe drought and heats storms, that combined with high humidity (heat index) have caused extensive suffering.
- While it was a Category 2 storm off the coast of the Northeastern United States, the storm became the largest Atlantic hurricane on record (as measured by diameter, with winds spanning 1,100 miles (1,800 km)). Estimates as of June 2013 assess damage to have been over $68 billion (2013 USD), a total surpassed only by Hurricane Katrina. At least 286 people were killed along the path of the storm in seven countries (Wikipedia http://en.wikipedia.org/wiki/Hurricane_Sandy)
- While many people, including politicians and leaders, would wait until it was so painfully obvious that climate change was both real and a significant impact, we simply don’t have 20 years to ‘wait and see’. We have already seen significant impacts, (heat storms, drought, fires, and superstorms), at less than one degree Celsius of warming, and have been led to believe that 2 degrees is the edge of stability. On the contrary, other scientists have suggested that 450 ppm atmospheric CO2 is the threshold we should not cross, for both climate and ocean acidity (pH 8 and undersaturation of bicarbonate ion). Here are the facts: We are headed right at 450 ppm CO2, currently at ~400 ppm CO2, and rising at a little over 2 ppm CO2 per year (a rate that is also increasing), and will reach that level by 2035, if not sooner. There are two problems with 450 ppm CO2. First, the level of ‘committed warming’ will be ~ 2 degrees Celsius. Committed warming means the temperature of the ocean will eventually (~50 years) rise to that level. Second, as CO2 dissolves in the ocean (25% or more will end up there) the pH of the ocean decreases (from 8.15 to ~ 8.0) leading to undersaturation of bicarbonate ion, causing coral to dissolve (90% will be lost), and severely impacting plankton ability to form shells. Plankton are the base of the food chain. There is a possibility that amplifying feedbacks (albedo and methane hydrate destabilization) could cause us to warm even further, to 3 deg Celsius. Energy investments in infrastructure typically have a 25 to 40 year lifetime (physical and economic depreciation), so investments in carbon intensive infrastructure today will last at least to at least 2035 and possibly to 2040. Decisions we make today (and in the first decade of the 21st Century) will likely take us well over 450 ppm CO2, and some fear as much as 500 ppm CO2.
- The Keeling curve shows atmospheric CO2 measured at Mauna Loa in Hawaii from 1958 to 2013, rising from 315 to 395 ppm CO2, and showing the cycle in spring and fall when trees grow and then shed their leaves. The rate of increase, shown later in this presentation, has climbed from 1 ppm per year to 1.5 and now slightly over 2 ppm CO2 per year. At that rate, we will exceed 450 ppm CO2 by 2035, if not sooner.
- The rate of increase, shown later in this presentation, has climbed from 1 ppm per year to 1.5 and now slightly over 2 ppm CO2 per year. At that rate, we will exceed 450 ppm CO2 by 2035, if not sooner. This is a key metric, as it sets a time window in which we have to act, as once 450 ppm CO2 is reached, it is unlikely that disastrous if not catastrophic consequences of climate change will be felt worldwide.
- Estimates of future emissions are called ‘trajectories’ and in this slide represent three scenarios. One is a low emission strategy where we start a rapid reduction in carbon intensity beginning in 2020, and the ocean, atmosphere, and land begin to absorb carbon emissions, and atmospheric CO2 eventually stabilizes at ~400 ppm. In percentage terms, this has the highest probability of climate stabilization, but the least probability of actually happening. In the second scenario, carbon emissions also begin to decline in 2020, but not as fast, and the atmosphere rises in CO2 and then declines to ~ 450 ppm CO2. This has a 50% probability of success, but is probably not very likely, as most emission modeling shows an increase in energy intensity to ~2040 or later, and no decrease in carbon intensity until ~ 2035. As such, emissions rise as high as 500 ppm CO2, before stabilizing. This would be a climate disaster, but considering our nearly ineffectual governance, probably the most likely to occur.
- There are five reasons why 450 ppm CO2 is a threshold that shouldn’t be crossed, and probably not even approached. They involve a combination of temperature (heat), ocean acidification, ice sheet deglaciation and albedo, methane hydrate instability, and the combination of all four factors in an amplifying feedback network (Torn and Harte, 2006). The first factor is the radiative forcing that comes with 450 ppm CO2, which is ~ 2.5 watts/sq-meter, and equilibrium warming will reach ~1.9 degrees Celsius, close enough to 2 degrees warming to be a real concern. That much temperature (heat injection) in 50 years could easily destabilize the ice sheets, methane hydrates, and jet stream. Ice sheets will continue to degrade for centuries if not millennia, posing a risk of catastrophic sea level rise that is not adaptable. The albedo effects alone from rapid melting (witness the Greenland ice sheet and open arctic sea) could cause significant amplified warming as more energy is absorbed by the planet. Another related heat impact in the ocean is methane hydrate destabilization, and THIS is the most dangerous of all the climate impacts, as detailed later. This could lead to release of 50 Gtons of methane with a Global Warming Potential of 20 or more, a total release equal to 1,000 Gtons of carbon, more than human will have burned by 2040. Another equally catastrophic tipping point is ocean acidification. At 450 ppm CO2, the added CO2 in the ocean will add biocarbonate ion, but also lead to added protons (acidification) that remove isolated bicarbonate ion from solution (HCO3- and H+) leading to undersaturation of bicarbonate ion and difficulty for coral and plankton, the latter being the base of the food chain and itself a CO2 pump. The combination of amplifying feedbacks, including albedo and methane release, are significant drivers of increased temperature, while rapid deglaciation and ice sheet stability can lead to both rapid and sustained sea level rise. 2 deg Celsius committed warming Radiative forcing of ~ 2.5 Watts/M2 Ocean acidification pH 8 and under-saturation of bicarbonate ion Less than 10% of coral will survive (~ 50 years) Deglaciation of ice sheets Rapid melting and instability, Greenland ice sheet Sea level rise for centuries Estimated 1 meter rise (or more) by 2100 Methane hydrate destabilization Two degrees of warming and they are unstable
- Ocean acidification is one of two wild cards, the other being methane hydrates, that could spell real trouble for human civilization. As CO2 is added to the atmosphere, about 25% also dissolves in the ocean, leading to production of bicarbonate ion, a natural process, but too much adds extra protons, which remove CO2 from solution (undersaturation). The consumption of carbonate ions impedes calcification. CO2 + H2O => H2CO3 which becomes HCO3- + H+ (a weak acid) when too much CO2 dissolves, the added proton will seek out unprotonated CO32- bicarbonate ion. As atmospheric CO2 reaches 450 ppm, pH drops to ~8, and the concentration of CO2 exceeds bicarbonate ion, leading to undersaturation of the anion. That in turns will not only slow calcification, but can lead to dissolution of corals, and significant drop in phytoplankton, which may have already begun (Climos and Planktos) in the 20th Century. Losing the bottom of the food chain and a carbon dioxide pump in itself could lead to problems in both ocean productivity as well as future ability of the oceans to soak up CO2.
- When CO2 dissolves in seawater, carbonic acid is produced via the reaction: CO2 + H2O => H2CO3 This carbonic acid dissociates in the water, releasing hydrogen ions and bicarbonate: H2CO3 => H+ + HCO3 The increase in the hydrogen ion concentration causes an increase in acidity, since acidity is defined by the pH scale, where pH = -log [H+] (so as hydrogen increases, the pH decreases). This log scale means that for every unit decrease on the pH scale, the hydrogen ion concentration has increased 10-fold. One result of the release of hydrogen ions is that they combine with any carbonate ions in the water to form bicarbonate: H+ + CO32- <=> HCO3- This removes carbonate ions from the water, making it more difficult for organisms to form the CaCO3 they need for their shells.
- Building off Hansen’s paper, and assertions that 2 degrees Celsius and 450 ppm CO2 may be too much; there are three key factors to be concerned about with this amount of warming. First, are the secondary feedbacks of deglaciation (ice sheets) and methane release from hydrates and undersea permafrost. Ice sheet degradation, which could continue for centuries, could swamp low lying coastal cities, and either Greenland or Antarctica could add a meter or more of sea level. In this century alone, one meter of sea level rise is now expected, and it could be higher. Destabilization of methane hydrates could add one degree Celsius or more with a release of 50 Gtons. The second reason to avoid 2 degrees/450 ppm CO2 is ocean acidity, described earlier, and significant damage to ocean systems from coral to plankton. The third reason is related to the open sea ice in the Arctic, as well as heat injection to ocean currents, leading to destabilization of the jet stream and other ocean currents, which is partially seen in the highly bent jet stream in winter 2014. This, coupled with the thermohaline currents that move heat towards Europe, can be adversely affected, leading to extreme climate change, and conditions that are difficult to adapt to.
- The key to understanding both the science of climate change and the risks of changing any GHG or forcing factor, is understanding a feedback driven system. Torn and Harte (AGU 2006) describe a network of delayed and amplifying feedbacks that include CO2, CH4, H20 (water vapor and clouds) and albedo. In a feedback driven system each of these four factors increases temperature, as well as is driven by temperature. Furthermore, it is possible that the degree of amplification is a function of the rate of warming, as said in the quote “the hotter it gets, the faster it gets hotter” and likewise the faster it gets hotter, the warmer the system may eventually get. The two factors that can drive warming further (and fastest) are release of methane from soil and hydrates, and loss of albedo through surface melting.
- Feedback amplification can be quantified using the expressions shown in the figure taken from Torn and Harte’s paper (missing feedbacks) that shows the higher the feedback, the further a system will be driven by changes in temperature that both drive and are a consequence of feedbacks. Feedback amplification can be quantified using the expressions shown in the figure taken from Torn and Harte’s paper (missing feedbacks) that shows the higher the feedback, the further a system will be driven by changes in temperature that both drive and are a consequence of feedbacks. The key to this chart is the fraction of gain that comes from feedback, also known as climate sensitivity. If the feedback factor is 50%, then a forcing input of 1 deg Celsius translates to a final/equilibrium temperature gain of 2 degrees. The higher the feedback percentage, the greater the final equilibrium temperature will be. As Torn and Harte noted, not knowing the feedback amplification is very risky, as our predictions of future warming are based on previous climate sensitivities, and these factors may change (for the worse) with accelerated warming.
- The three examples given here are crucial processes in the ecosystem, shown in simplified form. a, Potential interactions between microbial metabolism and the physics of permafrost thawing and carbon release. b, The 'microbial priming effect'. An increase in carbon and energy sources easily utilized by microbes can stimulate the decomposition of 'old' soil carbon, especially in grassland soils. In the context of climate change this effect may have a positive-feedback effect on CO2 increase and global warming. c, Interactions between the carbon and nitrogen cycles shown here could alter expected ecosystem carbon responses to the prevailing trend of climate change. Pink arrows denote effects of terrestrial ecosystems on climate, orange arrows denote effects of climate change on terrestrial ecosystems, and black arrows denote interactions within ecosystems. The background image is a world map of soil organic carbon. (Map reproduced, with permission, from USDA-NRCS, http://soils.usda.gov/use/worldsoils/mapindex/soc.html.)
- http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ Sea Ice Volume is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) developed at APL/PSC. Anomalies for each day are calculated relative to the average over the 1979 -2011 period for that day of the year to remove the annual cycle. The model mean annual cycle of sea ice volume over this period ranges from 28,700 km3 in April to 12,300 km3 in September. The blue line represents the trend calculated from January 1 1979 to the most recent date indicated on the figure. Monthly averaged ice volume for September 2013 was 5,500 km3. This value is 52% lower than the mean over this period, 67% lower than the maximum in 1979, and 0.6 standard deviations below the 1979-2013 trend. September ice volume was about 1600 km3 larger than in September of 2012 and within 700 km3 of the 2010 September ice volume. While ice volume at the maximum during April was on par with the previous two years, reduction in ice volume during the summer months was less than in previous years. September ice volume showed the first increase since 2008 but is still below the long-term trend line (Fig 3).
- Arctic Sea Ice is diminishing at an accelerating rate, and the arctic may be ‘ice free’ in summer as early as 2015. This will have profound affects to albedo, adding energy to the arctic sea, destabilizing methane hydrates, and further adding to instability and/or erratic behavior of the jet stream and ocean currents. PIOMAS utilizes satellite tools for remote imaging of planet earth.
- Methane hydrates are a wild card in the climate system, as they contain thousands of gigatons of methane complexed with water in frozen slurry, and only stable at very high pressure, and very cold temperatures. The stability of methane hydrates, called the hydrate stability zone, requires very cold temperatures, and great depths (thousands of feet). As shown in the chart, the Eastern Siberian Ice Shelf (ESAS) is especially prone to methane release as hydrates on the sea floor are in relatively shallow waters (hundreds of meters deep or less) with less than one or two degrees Celsius of margin between stability and release of methane. Recent studies (Natalia Shakova) of the Arctic Research Center have shown a doubling of methane release since 2009, from 8 teragrams (mega tons) to 17 teragrams. This translates to 6 ppb methane release, significant to see in the atmosphere. Scientists at the arctic research center are concerned about two scenarios, one where a sudden release of methane occurs that can temporarily ‘swamp’ hydroxyl ion, leading to a longer half-life and consequently a much higher GWP (Green House Warming Potential), and second, a sustained release of up to 50 gigatons (3.4% of the estimated 1400 gigatons stored under permafrost in the ESAS) which when multiplied by the GWP of (at least 20) is equal to 1,000 gigatons of carbon, what Hansen and others have calculated to be the total carbon budget to keep us under 2 degrees Celsius.
- As discussed in the course, the interaction between human ecosystems and climate is especially important, as society is dependent on ecosystem services (whether it chooses to believe it or not) and human well-being, especially in developing nations, rests on having food, water, security, and lack of severe storms that have pummeled New Orleans, Philippines, New Jersey and many other areas. All too often humans have resorted to conflict as resources diminish, and it would be much better to resort to ‘collaboration’ which is actually the best thing for humanity.
- We are at the front edge of dangerous climate change, and beginning to feel serious impacts. We are on a trajectory to 450 ppm CO2, a point that we must not cross, as damage to the biosphere at that level will be even worse, and amplifying feedbacks may kick in, warming further, perhaps to even 3-4 degrees Celsius. Life at 4 degrees C warmer may not be possible for this biosphere, given the rate of change, and we really need to act now to avert this catastrophe. Ocean acidification at 450 ppm CO2, in itself, could threaten the base of the food chain, and lead to loss of ocean productivity. We have enough data now, and simply need to trust our climate models, and make the difficult decisions to decarbonize our energy infrastructure, for both our own long-term survival, as well as the optimum functioning of the biosphere.
- This presentation uses a Creative Commons copyright. This PowerPoint presentation was prepared for use by academic professionals, faculty and students to better understand and communicate climate change. It may be used as is, or remixed. Please use the references for images and other texts, and do not assume images are used with permission. If you wish to contact me, I can be reached at [email_address].