Double Threat

According to a Chinese proverb, the best time to plant an oak tree is twenty years ago. In the case of climate change, it was 127 years ago that a Swedish chemist determined that an increase in atmospheric carbon dioxide would lead to an increase in the global mean temperature. Of course, we didn’t plant an oak tree then, nor did we plant one sixty-six years ago when two American scientists asserted that, through the combustion of fossil fuels, we are conducting a “vast geophysical experiment.” Thirty-three years ago, the Intergovernmental Panel on Climate Change predicted a global mean temperature increase of 1 degree Celsius by 2025 and 3 degrees by 2100.

The last time the earth was 3 degrees warmer was three million years ago, when sea levels were seventeen to twenty metres higher and Lucy was teaching herself to walk upright in what is now Ethiopia. True, the IPCC’s First Assessment Report compelled us to plant a series of oak trees in the form of non-binding...