This year, the world is expected to burn through some thirty-one billion barrels of oil, six billion tons of coal, and a hundred trillion cubic feet of natural gas. The combustion of these fossil fuels will produce, in aggregate, some four hundred quadrillion B.T.U.s of energy. It will also yield around thirty billion tons of carbon dioxide. Next year, global consumption of fossil fuels is expected to grow by about two per cent, meaning that emissions will rise by more than half a billion tons, and the following year consumption is expected to grow by yet another two per cent.
When carbon dioxide is released into the air, about a third ends up, in relatively short order, in the oceans. (CO2 dissolves in water to form a weak acid; this is the cause of the phenomenon known as “ocean acidification.”) A quarter is absorbed by terrestrial ecosystems—no one is quite sure exactly how or where—and the rest remains in the atmosphere. If current trends in emissions continue, then sometime within the next four or five decades the chemistry of the oceans will have been altered to such a degree that many marine organisms—including reef-building corals—will be pushed toward extinction. Meanwhile, atmospheric CO2 levels are projected to reach five hundred and fifty parts per million—twice pre-industrial levels—virtually guaranteeing an eventual global temperature increase of three or more degrees. The consequences of this warming are difficult to predict in detail, but even broad, conservative estimates are terrifying: at least fifteen and possibly as many as thirty per cent of the planet’s plant and animal species will be threatened; sea levels will rise by several feet; yields of crops like wheat and corn will decline significantly in a number of areas where they are now grown as staples; regions that depend on glacial runoff or seasonal snowmelt—currently home to more than a billion people—will face severe water shortages; and what now counts as a hundred-year drought will occur in some parts of the world as frequently as once a decade.
Elizabeth Kolbert summing up in a report on alternatives in the current New Yorker.