World climate scientists are reaching a consensus based upon substantial scientific evidence that an increase of more than 2 degrees Celsius in global average temperature above pre-industrial levels (1860) would result in catastrophic climate change. A temperature increase above 2 degrees would result in species extinction and significant human suffering. Sea levels would rise between 12 and 40 feet due to melting of the land born Greenland and West Antarctic ice sheets. The Antarctica Peninsula is already experiencing the greatest increases in temperature on Earth. In fifty years the average ambient temperature has increased 0.5 degrees (C). The break up of the Wilkins Ice Shelf, thought to have been in place for a century, is an undeniable effect of the increase in local temperatures. This photo from space shows the 160 square mile piece of the shelf breaking off. The blue color is due to exposure of deep glacial ice.Policy makers in Europe have committed to a long-term goal of limiting warming to this critical two degree increase over pre-industrial levels. The United States has done little to address the growing crisis besides agreeing in principle to work within the UN Framework Convention on Climate Change. In the absence of federal action, several states in the west and northeast have entered into agreements or established policies to pursue global warming reduction targets. There are several bills pending in Congress, however there is little likelihood that any of these bills will pass during the current regime. Assuming the current political deadlock will change after the 2008 presidential election, the differences and relative effectiveness of these bills in reaching the needed temperate change limit should be evaluated. One objective measure suggested by the Union of Concerned Scientists is the amount of CO2 equivalent in parts per million removed or saved from the atmosphere. This measure, CO2eq/ppm, expresses the amount of all heat trapping gases in terms of carbon dioxide. Studies indicate that to have a 50% chance of reaching the two degree limit a policy measure must achieve 450ppm CO2eq or below. To achieve this concentration level world emissions of heat trapping gases must be limited to 1700 gigatons for the period 2000-2050. 330 gigatons have already been emitted. To stay within the world emissions budget, industrial nations like the US must be expected to achieve a70-80% reduction in their 2000 gas emission levels by 2050. The US has already emitted approximately 45 gigatons(Gt)CO2eq which means that it needs to reduce the level of polluting gas emission by at least 80%. A business as usual approach would mean the US would use 80% of its share of the world budget by 2030 according to the Energy Information Administration. Such a scenario would require drastic cuts that could not be realistically achieved without American returning to caves and eating raw meat.
Of the eight proposals on the table in Congress only two meet the criteria discussed here, S.309 introduced by Senators Boxer and Sanders, and H.R. 1590 introduced by Rep. Waxman, given a US emission budget of 160-265 GtCO2eq as the target range[1]. H.R. 1590 is the most aggressive proposal, while S.309 skirts the upper limit of the target range. Senator McCain's proposal (S.280) exceeds the target range substantially (over 300 GtCO2eq). According to Senator Obama's campaign material[2] he supports an auction cap and trade system to reduce CO2 emissions to the necessary level of an 80% reduction by 2050. He also promotes the use of economic incentives to reward stewards for protecting and expanding forest and grasslands as a means of carbon sequestration as well as a $150 billion investment in clean energy sources.
[1]Union of Concerned Scientists,http://www.ucsusa.org/ depending upon which allocation method is used to det ermine the US share of the world's total 700 GtCO2eq. Assumes the industrial nations' emissions peak in 2010 and the developing nations' emissions peak in 2020.
[2]Obama08, Blueprint for Change, p.25