ME 432 Fundamentals of Modern Photovoltaics. Discussion 29: IPCC Special Climate Report 5 November 2018

Transcription

1 ME 432 Fundamentals of Modern Photovoltaics Discussion 29: IPCC Special Climate Report 5 November 2018

2 Topics 1. Brief History of Climate Science up to the formation of the IPCC 2. IPCC Findings, Common Terminology, and the Paris Agreement 3. Findings of the latest report

3 Brief History Who is believed to be the first to have raised the possibility that human burning of fossil fuels could raise the planet s average temperature?

4 1896 Swedish We ve mentioned him before in class Answer: Svante Arrhenius He referred to it as the greenhouse effect

5 We often hear lamentations that the coal stored up in the earth is wasted by the present generation without any thought of the future, and we are terrified by the awful destruction of life and property which has followed the volcanic eruptions of our days. We may find a kind of consolation in the consideration that here, as in every other case, there is good mixed with the evil. By the influence of the increasing percentage of carbonic acid in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind. - Arrhenius

6 Brief History Did anyone pay attention? Should they have paid attention? The greenhouse effect was just one of several speculations about climate change, and not the most plausible one.

7 1930 s Scientists realized that the United States and North Atlantic region had warmed significantly during the last 50 years Most people assumed it to be a phase of some natural cycle, cause unknown. Most people thought this could be a good thing. One lone dissenting voice: G. S. Callendar linked this to global warming

8 1950 s Scientists begin looking at the question of climate change using improved techniques and calculations Lots of government funding for this, especially from military agencies with Cold War concerns about the weather and the seas First systematic measurements of CO 2 in the atomosphere by C. D. Keeling showed that the level of gas in the environment was rising year by year

9 1960 s Earliest computer models of atmospheric circulation Most results showed that average temperatures would rise a few degrees in the next century But models were preliminary, and no one saw any need for policy action or concern, aside from putting effort into research to really understand what was happening

10 1970 s Rise of modern environmentalism Alongside the greenhouse effect, scientists pointed out that human activity was putting dust and smog into the atmosphere which could block sunlight and cool the world Analysis of Northern Hemisphere weather statistics showed a cooling trend had begun in the 1940 s. (followed up by further analysis suggesting a cooling in the Southern hemisphere) Confusion and contradictory articles in the media about potential warming and potential cooling

11 1970 s Scientists agreed that they didn t understand the competing effects and that more research was needed. Lots of efforts to gather data, fleets of oceanographic ships and satellite measurements. After a few years, the warnings of a new ice age (which, contrary to current conventional wisdom, were never widely accepted in the first place) were dropped and attention focused on global warming and CO 2 as the dominant source of climate forcing

12 1970 s Idea of the climate as being chaotic emerges. Highly (non-linearly) sensitive to multiple influences. Naturally questions arose about whether its possible to predict the climate at all. Changes based on volcanic eruptions and solar variations, subtle changes in the earth s orbit all affect climate. The climate is so delicately balanced that almost any small perturbation could cause a great shift. We finally started to understand where ice ages come from

13 1980 s By the late 1970 s global temperatures began to rise again. Improved computer models began to explain and reproduce previously unexplained sudden jumps in temperature in history 1988 hottest summer on record. Lots of public attention. Most summers since then have been hotter. Probably the beginnings of the politicization of climate science. Corporations who opposed regulation began to spend millions on lobbying, advertising, and reports. Environmental groups lacked funding but had passion and made alarming warnings. Scientists largely acknowledged the uncertainties and the sheer complexity of climate. The uncertainty left room for debate about what actions should be taken.

14 Sources of uncertainty: Warmer atmospheres hold more water vapor, which could then cause even more warming (positive feedback, still often cited as a source of uncertainty) Cloudiness can change in ways that could either enhance or diminish the warming The increasing amounts of pollutants emitted and their effect on climate

15 1990 s The first programs to study climate were organized on an international scale, establishment of the IPCC Started to answer the most pressing questions: Is the global temperature rise due to an increase in the Sun s activity? No, the solar activity was declining but the temperature was rising faster than ever Modelers could successfully reproduce in detail patterns of warming, changes in rainfall, actually observed in different parts of the world over the last century Predictive vs. Descriptive models. Did computer models reproduce the present climate because they were fitted/tweaked, making them worthless for predicting a future climate change? No, the models successfully predicted temporary cooling due to the 1991 eruption of Mt. Pinatubo in the Phillipines and other effects Nobody could produce a model that matched the historical record that did not show significant warmings when greenhouse gasesdue to human activity were included.

16 Antarctic ice cores 1990 s

17 2000 s By 2001 the IPCC established a consensus, phrased so cautiously that no expert or government representative could legitimately dissent. Although the climate system is so complex that scientists would never reach complete certainty, it is much more likely than not that our civilization faces severe global warming. At this point, the discovery of global warming was effectively complete. Most important elements of how the climate would change in response to actions taken in the 21 st century were largely understood. How the climate would actually change would now depend on policies that would be adopted.

18 Topics 1. Brief History of Climate Science up to the formation of the IPCC 2. IPCC Findings, Common Terminology, and the Paris Agreement 3. Findings of the latest report

19 IPCC Intergovernmental body of the United Nations. Stated mission is to provide the world with an objective, scientific view of climate change and its political and economic impacts. Established in 1988 by the World Meteorological Organization (WMO) and the United National Environmental Programme (UNEP) Produces reports that support the United Nations Framework Convention on Climate Change, whose objective is to stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system The IPCC does not carry out original research, and does not monitor climate. It assess published literature, including peer-reviewed and non-peer reviewed sources. Scientists and other experts contribute on a voluntary basis to write reports Reports are then reviewed by governments Reports contain a Summary for Policymakers subject to line-by-line approval by delegates from all participating governments Principles governing their work states that the IPCC will assess the risk of human induced climate change, its potential impacts, and possible options for prevention

20 Reports published Five so far: 1990, 1995, 2001, 2007, 2014, next one coming in 2022 First assessment: the summary for policymakers says the IPCC is certain that emissions resulting from human activities are substantially increasing the atmospheric concentrations of greenhouse gases, resulting on average in an additional warming of the earth s surface. They predict that under a BAU scenario, global mean temperatures will increase by about 0.3 C per decade in the 21 st century. Note that this estimate has held up (not changed substantially since then). Since the third report, most of the conclusions are given quantitative estimates of how probable it is that they are correct (Bayesian probabilities) Fifth report started showing RCPs (Representative Concentration Pathways) that make predictions based on a wide range of possible changes to anthropogenic greenhouse gas emissions based on policy decisions etc.

21 Hockey stick controversy - How do we reconstruct the mean average temperature going back in history? No one ever measured it. - We use proxy indicators : fossil record, isotopic measurements of oxygen contained in sediments from land and the ocean - This plot featured prominently in the 2001IPCC Third Assessment Report - Some aspects of the statistical methods were criticized by a few scientists. Most acknowledge that their criticism has a small impact on the overall plot and uncertainty values. - This didn t stop politicians from jumping in, i.e. Congressman James Inhofe: global warming is the greatest hoax ever perpetrated on the American people and said that scientists are cooking the science.

22 Topics 1. Brief History of Climate Science up to the formation of the IPCC 2. IPCC Findings, Common Terminology, and the Paris Agreement 3. Findings of the latest report

23 Special Report on Global Warming of 1.5 C Where did this report come from? Paris Agreement choose 2 C as a target temperature in 2015 This was not acceptable to all nation members of the UN. Compromise: take action to limit global warming to 2 C, while striving for target of 1.5 C New report assesses what it would take to get to the 1.5 C target. The report cites over 6000 peer-reviewed articles

24 Special Report on Global Warming of 1.5 C Findings: We are on the path to hit 1.5 C by 2040: food shortages, wild fires, massive die-offs of the coral reefs. Est $54 trillion in damages. To limit total warming to 1.5 C, requires cutting greenhouse gas emissions by 45% below 2010 levels by 2040 and reaching net zero emissions by 2050 (i.e. cutting coal consumption by 1/3) Some of the plans they propose involve an overshoot, meaning that the scenario allows emissions amounts that would exceed a warming of 1.5 C and then rely on using technologies to take CO 2 out of the air. Needed because its really hard to decarbonize some sectors of the economy (air travel, agriculture) Avoiding the worst outcomes requires massive changes to economies Carbon tax, changes to our food supply, huge worldwide coordinate program of re-industrialization

25 Can it be done? One thing the report did not aspire to do is answer the question of feasibility. We said it was possible within the laws of physics and chemistry. Jim Skea, co-chair of IPCC Working Group III

26 Can it be done?

27 Shell BECCS (there is currently no commercial BECCS industry do we bank on it to develop?)

28 Special Report on Global Warming of 1.5 C vs. 2 C But also: the damage is non-linear. 2 C is worse than 1.5 C, which is worse than the current 1 C Currently we are experiencing: fastest decline in Arctic sea ice in 1,500 years, 8 of sea level rise since 1880, more damaging extreme weather Difference between 1.5 C and 2 C: fisheries would face double the decline, maize harvests would decrease by double, insects (esp. pollinators) would see their habitable range drop threefold. Sea levels would rise by another 2 putting an extra 10 millions people at risk of coastal flooding (note -- my conclusion): Everything we do to mitigate warming will have some benefit, and it s worth fighting to control every fraction of a degree

29 random speculations (not science J ) Human nature: when we don t believe we can solve a problem, we tend to ignore it. Example: Climate change doesn t poll as a top priority amongst voters of either major party in the US Climate change is not an invincible, unbeatable amorphous monster. Solving this is an engineering design problem. Need to admit the scale of the problem, but identify actionable ways to address it. By talking about the problem as solvable, we actually make it more solvable What is needed: Conventional methods like energy efficiency measures replacing fossil fuel generators with renewables Electrification of everything that can be electrified Some negative emissions still (it seems hard to eliminate this strategy completely) Interesting to note that some of the best models for hitting the 1.5 C target are actually coming from the oil industry. Exxon Mobil came out in favor of a carbon tax. Shell came out with a CCS model to hit 1.5 C.

30 Useful References Summary of historically important climate change papers: The Discovery of Global Warming by Spencer R. Wearth (Harvard University Press, 2008). See an excerpt from this book at All previous IPCC reports can be found at