I admit it. I used to be a climate-change skeptic. I was one of those conservatives who thought that the science was inconclusive, that fears of global warming were as overblown as fears of a new ice age in the 1970s, that climate change was natural and cyclical, and that there was no need to incur any economic costs to deal with this speculative threat. I no longer think any of that, because the scientific consensus is so clear and convincing.
The Fourth National Climate Assessment, released Friday by the U.S. government, puts it starkly: “Observations collected around the world provide significant, clear, and compelling evidence that global average temperature is much higher, and is rising more rapidly, than anything modern civilization has experienced, with widespread and growing impacts.