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Climate Change and the Imperative for Social Revolution Dr. Minqi Li, Assistant Professor Department of Economics, University of Utah E-mail: [email protected] Webpage: www.econ.utah.edu/~mli March 5, 2010, Salt Lake City Global Mean Temperature (1880-2009, Source: James Hansen) FIGURE 1. Change of climate forcings, in watts per square meter, between 1750 and 2000. Vertical bars show estimated uncertainty. Uncertainty for "other greenhouse gases" is similar to that for carbon dioxide. (Data from Hansen et al., "Efficacy of Climate Forcings." See sources.) Greenhouse Gases and Temperature (past 400,000 years, source: James Hansen) Paleoclimate Findings • At the depth of recent ice age, global temperature was about 5C lower than the pre-industrial time • Between two and three million years ago, global temperature was about 3C higher than the pre-industrial time. The northern hemisphere was nearly ice free, sea level was about 25 meters higher, and atmospheric CO2 was about 360-400 ppm • About 35 million years ago, when Antarctica started to be glaciated, global temperature was about 6C higher than the pre-industrial time. Sea level was about 70 meters higher and atmospheric CO2 was about 450 ppm Greenhouse Gases and Global Warming: the Present • The pre-industrial atmospheric CO2 was about 280ppm • Atmospheric CO2 is currently near 390ppm, rising at a rate of 2ppm/year • All long-lived greenhouse gases currently stand at about 470ppm of CO2-equivalent, rising at a rate of 3ppm/year • All greenhouse gases (including short-lived aerosols) currently stand at about 400ppm of CO2-equivalent, rising at a rate of 3ppm/year • Global surface temperature is currently about 0.8C higher than the pre-industrial time, rising at a rate of 0.2C/decade; current long-lived greenhouse gases imply long-term global warming of 2-4C Global Warming Scenarios • 2C: widespread drought and desertification; possible extinction of 15-40 percent species; initiation of dangerous climate feedbacks • 3C: global sea level rises by 25 meters; destruction of Amazon rainforests; climate feedbacks that could lead to another 1.5C warming • 4C and beyond: much of the earth’s surface becomes unsuitable for human inhabitation; end of human civilization as we know it Climate Safe Limit? • 450 ppm of CO2-equivalent: implying long-term warming between 2C (IPCC) and 4C (Hansen) • To keep CO2-equivalent at below 450ppm (requiring keeping CO2 below 350ppm), cumulative CO2 emissions from human activities need to stay below about 1,000 billion tons over the 21st century • But about 300 billion tons have already been emitted • Making about 200 billion tons of allowances for deforestations emissions, the remaining budget for fossil emissions is about 500 billion tons • Currently the global fossil emissions stand at about 30 billion tons a year Economic Growth and Carbon Dioxide Emissions • CO2 Emissions = GDP * Emission Intenisty • In recent years, world economy has grown at an annual rate of 4%, emission intensity has fallen at an annual rate of 1% • World emissions have grown at an annual rate of 3% • Assume an emission intensity reduction rate of 3%, to prevent 2-4C warming, world emissions need to fall at an annual rate of 5% and world economy needs to contract at an annual rate of 2% • Assume an emission intensity reduction rate of 3%, to prevent 3-6C warming, world emissions need to fall at an annual rate of 1.5% and world economy needs to grow no more rapidly than an annual rate of 1.5% Climate Stabilization and Limits to Growth • To have any chance of a reasonable climate stabilization, global economic growth must stop • But this is impossible under capitalism (production for profit market competition pressure for accumulation of capital growth) • Improvement of living standards for the world’s majority requires massive global redistribution • Climate stabilization can only be achieved through fundamental social change