Atmosphere also has a profound impact on climate

An Aug. 4 letter writer is correct in that the sun does power a planet’s climate system. However, its atmosphere also has a profound impact. For example, although Mercury is closer to the sun, Venus is hotter because its atmosphere is mostly carbon dioxide.

In its report “America’s Climate Choices,” the National Academy of Sciences states that climate change “is very likely caused primarily by the emission of greenhouse gases from human activities,” and it calls for strong national action and international cooperation to address it.

The NAS contends that this is wise risk management, because climate impacts will last for hundreds to thousands of years, but climate action can be scaled back if it is shown to be more stringent than what is needed.

Climate change poses great threats, such as sea level rise, extreme weather and the ravaging of the world’s coral reefs. Conservatives would be unlikely to tolerate this level of risk with regard to national defense or financial markets. Prudence dictates that we also hedge against the risk of disastrous climate change.

Terry Hansen

Oak Creek, Wis.