Climate Debate Heats Up

Well, since we're going through some days with sub-freezing temperatures this week, it must be time to bring up the topic of climate change. The United Nations has released the first volume of the latest assessment of the Intergovernmental Panel on Climate Change. The policy summary (PDF file) states

Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years (see Figure SPM-1). The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change, while those of methane and nitrous oxide are primarily due to agriculture. {2.3, 6.4, 7.3}

Meanwhile, the editors at National Review Online comment that the IPCC has pulled back from some of the more dire conclusions of their 2001 assessment.

Gone from the latest summary is the infamous “hockey stick” of the 2001 report. This was a graphic purporting to show that the planet is warmer today than at any time in the last thousand years, a demonstration which required erasing the inconvenient medieval warm period and the little ice age. The new IPCC report has also reduced its estimate of the human influence on warming by one-third (though this change was not flagged for the media, so few if any news accounts took notice of it). That reduction is one reason the IPCC narrowed the range of predicted future warming, and lowered the new midpoint — i.e., the most likely prediction of temperature increase — by a half degree, from 3.5 degrees Celsius in 2001 to 3 degrees in this report. The new assessment also cuts in half the range of predicted sea-level rise over the next century.

So an appropriate response to the question is somewhere between complacency with the status quo and a panic induced push toward economic restrictions and social engineering. Certainly, climate does change (warmer and cooler) over time, and the natural and human factors involved are not yet fully understood. Scientific efforts to monitor and analyze the situation must be sufficiently funded. And regardless of the actual impact of human activity on the global climate, practical measures to develop alternative energy sources and use the energy efficiently make sense from national security, economic, and general environmental grounds.