CAMBRIDGE – While George W. Bush has begun to acknowledge the risks of global climate change, his administration failed to lead on the issue for eight years. That may change after the 2008 American election. Both presidential candidates, Barack Obama and John McCain, promise to take climate change more seriously.
Emissions of carbon dioxide, a greenhouse gas that accumulates in the atmosphere and is a major cause of rising temperatures, is a byproduct of a wide range of normal economic activities. And, because CO2 emissions are what economists call a “negative externality” – emitters do not bear the full cost of the damage that they cause – there is little incentive to reduce them.
Smoking is a similar example: non-smokers must bear part of the increased healthcare costs that smoking imposes. But, unlike smoking, which can be discouraged through taxes and regulations, there is no global government to regulate excessive CO2 emissions, and countries are tempted to leave remedies to others. Moreover, some countries, such as Russia, which could benefit economically from a warmer Siberia, have different incentives from countries like Bangladesh, a poor country that is likely to be flooded by rising sea levels that will accompany global warming.
Some scientists predict that climate change will cause severe disruptions, such as weather-related natural disasters, droughts, and famines, which may lead to enormous loss of life. Global warming between 1.6 and 2.8 degrees Celsius over the next three decades would raise sea levels by half a meter.