If the air tastes different these days, it’s because no humans until now have ever breathed air with 400 parts per million of carbon dioxide. By passing that number in January, we have created an atmosphere last seen on this planet some 2.5 million years ago, before modern humans evolved.
We have, however, experienced the results of earlier temporary warming, created naturally rather than by pumping CO2 into the air. And we may well again within young Canadians’ lifetimes.
The scientific media have been rumbling lately about an unwelcome new report finding: the drought in California, now in its third or fourth year, could be a “megadrought” — a dry spell lasting 20 to 35 years, something not seen in North America since an 11th-century drought that caused the collapse of the Anasazi civilization in Arizona and New Mexico.