In 1990, Yale economist William Nordhaus wrote an article titled “Count Before You Leap” in which he warned of the consequences of doing too much to prevent climate change given the uncertainties regarding both the effects of climate change and the likelihood that such effects will actually occur. Nordhaus argued for a careful cost-benefit analysis based on more certain information about climate change rather than a knee-jerk reaction to grim prophecies about the end of the world as we know it. He argued that very little economic activity in industrialized societies depends on climate and that significant GNP losses are likely to be incurred in trying to mitigate climate change. In his words: “A vague premonition of some potential future disaster is not sufficient reason to plunge the world into depression. But if scientists can identify the likelihood of catastrophic risks, people and governments can rationally decide how much 'climate insurance' to buy." Thus, according to Nordhaus, what was known about climate change merited further research, but hardly justified aggressive action to prevent the possibility of climate change. There is a lot of pressure for climate scientists to be certain of their theories because of the way politics is done (Norgaard). Policymakers must allocate funds in such a way that the costs of a given policy are justified by the benefits, and climate change mitigation is one item on an agenda of hundreds of different issues. Estimates of the cost of reducing CO2 to neutralize the effects of climate change range from $10/tonne of CO2 reduced to $250/tonne (Norgaard). Considering such a wide range of estimates, it is understandable that politicians declare... mid-paper ......h certain CO2 levels because by then it will already be too late to avoid certain unacceptable consequences. Because the consequences of waiting could cause serious or irreversible harm to the public, in the absence of clear scientific data on exactly what will happen, the burden of proof is on those who support waiting. Let them prove that we have to wait. In the meantime, we must act on what we already know and move aggressively towards climate change mitigation and prevention. Works Cited1. Hansen, James et al. “Atmospheric CO2 Target: Where Should Humanity Aim?” Washington DC: NASA, 2007. Hansen, James. “Because we can't wait.” The nation. May 7, 2007.3. Nordhaus, William D. “Count Before You Leap.” The Economist 7 July 1990.4. Norgard, Richard. Lesson. ERG 280. Cory Hall, UC Berkeley, Berkeley, CA. March 11th 2008.