Still more from James Hansen’s email:
Ed Wilson explains that the 21st century is a "bottleneck" for species, because of extreme stresses they will experience, most of all from climate change. He foresees a potentially brighter future beyond the fossil fuel era, beyond the peak human population will occur if developing countries follow the path of the developed world to lower fertility rates. Air and water can be clean and we will learn to live with other species in a sustainable way, using renewable energy. The question he asks is how many species will survive the tremendous pressure of the 21st century bottleneck. It is the question that I asked Sophie, how many of the animals?
We have had only three decades of rapid global warming so far, but animals are already on the run. If we continue down the "business-as-usual" path, the cumulative shifting of climate zones will become the major factor in species extinctions. Global warming before the end of the century already would be at least half as large as global warmings that caused mass extinctions earlier in the Earth’s history. Human-made warming, if we continue to put in the air fossil fuels stored in the ground over many millions of years, will be far more rapid than the earlier events. And it occurs at a time of other human-induced stresses on species. Interdependencies among species, some less mobile than others, can lead to collapse of ecosystems and rapid nonlinear loss of species, if climate change continues to increase.
Coal will determine whether we continue to increase climate change or slow the human impact. Increased fossil fuel CO2 in the air today, compared to the pre-industrial atmosphere, is due 50% to coal, 35% to oil and 15% to gas. As oil resources peak, coal will determine future CO2 levels. Recently, after giving a high school commencement talk in my hometown, Denison, Iowa, I drove from Denison to Dunlap, where my parents are buried. For most of 20 miles there were trains parked, engine to caboose, half of the cars being filled with coal.
If we cannot stop the building of more coal-fired power plants, those coal trains will be death trains — no less gruesome than if they were boxcars headed to crematoria, loaded with uncountable irreplaceable species.