Since 1750, mankind has pumped some 150 billion tons of carbon dioxide into the atmosphere. Almost half that amount has been emitted since 2000, 9.9 billion tons of it in 2016 alone. U.S. President Donald Trump claims to think that links between carbon emissions and climate change are "a hoax," but if so, the hoax has taken in almost every scientist in the world. By burning fossil fuels, they believe, we have altered the chemistry of the air and the oceans. Last year was the first on record in which the atmosphere's carbon content never dropped below 400 parts per million, a level not seen for 800,000 years. The climate is warming and becoming more volatile, the ice caps are melting, and mass extinctions are underway. Another species of plant or animal disappears forever every 20 minutes or so....