Michael MacCracken: The Achievable Path to Climate Protection

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Dr. Michael MacCracken spoke on December 3 in Washington, DC, outlining his proposal for building a bridge between developed and developing countries to forge an international climate agreement. He emphasized that without emissions reduction commitments from both developed and developing countries, the 2 degrees Celsius benchmark cannot be achieved.

Mike MacCracken is Chief Scientist for Climate Change Programs at the Climate Institute.

Speaking at the Heinz Center, he argued that an achievable and equitable agreement will require sharp emissions reductions in the developed world and near-term action in the developing world to sharply limit non-CO2 heat-trapping emissions (particularly methane, black carbon, and tropospheric ozone) while minimizing growth in CO2 emissions. In the longer-term, developing nations would join with the developed nations in reducing all emissions as cost-effective technologies are developed.

Dr. MacCracken emphasized that without emissions reduction commitments from both developed and developing countries, the 2 degrees Celsius benchmark cannot be achieved. He proposed that comparable and equitable commitments that consider per capita emissions, levels of economic development, and differentiated responsibilities could forestall the most catastrophic impacts of climate change.

His argument is elaborated in a 2008 paper, “Prospects for Future Climate Change and the Reasons for Early Action”

Part of the case for measures that can be taken by developing countries to reduce non-CO2 emissions in the near-term involves the role of black carbon in energy usage. Black carbon emissions are highest in the developing world, and represent both a waste of unburned fuel and a health risk. Technologies exist to mitigate these emissions, including improved-combustion stoves, fuel upgrades and engine retrofitting to reduce transportation emissions, and reducing industrial emissions by applying more modern production techniques.

An August 2009 article, “The Achievable Path to Climate Protection” appears in a publication from the Climate Institute that provides more detail on the role of black carbon.

Abstract from “Prospects for Future Climate Change and the Reasons for Early Action”

Combustion of coal, oil, and natural gas, and to a lesser extent deforestation, land-cover change, and emissions of halocarbons and other greenhouse gases, are rapidly increasing the atmospheric concentrations of climate-warming gases. The warming of approximately 0.1-0.2 degree C per decade that has resulted is very likely the primary cause of the increasing loss of snow cover and Arctic sea ice, of more frequent occurrence of very heavy precipitation, of rising sea level, and of shifts in the natural ranges of plants and animals. The global average temperature is already approximately 0.8 degree C above its preindustrial level, and present atmospheric levels of greenhouse gases will contribute to further warming of 0.5-1 degree C as equilibrium is re-established. Warming has been and will be greater in mid and high latitudes compared with low latitudes, over land compared with oceans, and at night compared with day.

As emissions continue to increase, both warming and the commitment to future warming are currently increasing at a rate of approximately 0.2 degree C per decade, with projections that the rate of warming will further increase if emission controls are not put in place. Such warming and the associated changes are likely to result in severe impacts on key societal and environmental support systems. Present estimates are that limiting the increase in global average surface temperature to no more than 2-2.5 degrees C above its 1750 value of approximately 15 degrees C will be required to avoid the most catastrophic, but certainly not all, consequences of climate change.

Accomplishing this will require reducing emissions sharply by 2050 and to near zero by 2100. This can only be achieved if: (1) developed nations move rapidly to demonstrate that a modern society can function without reliance on technologies that release carbon dioxide (CO2) and other non-CO2 greenhouse gases to the atmosphere; and (2) if developing nations act in the near-term to sharply limit their non-CO2 emissions while minimizing growth in CO2 emissions, and then in the long-term join with the developed nations to reduce all emissions as cost-effective technologies are developed.

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