The Grimmest 21st Century Predictions from the Most Important Climate Report in 6 Years

"Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia."

With those words—unusually frank ones, considering they were written by scientists—so begins the document containing the fifth major international assessment of the world's climate change science. Those words were approved by 259 of the top scientists working in 39 countries after sorting through 55,000 comments critiquing their work, and were finally published today. Along with stating with newfangled certainty that humans are indeed frying the globe, the report also contains some seriously grim projections for the coming years.

The Intergovernmental Panel on Climate Change's conclusion this go round, as has been much remarked upon in the press, goes something like this: The world's scientists are 95 percent certain—more certain than ever before—that rising temperatures are our fault. It is "clear" and "extremely likely" that humans are the "dominant cause of the observed warming since the mid-20th century" and the primary reason are planet is heating up towards the point of no return.

"The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased," the report says.

But it's only going to get worse from here on out. And that's where things get interesting (if that's the right word). The report contains a number of predictions for the rest of the 21st century as to what will occur if we continue to burn through the world's coal, oil, and other fossil fuel stores. These predictions, which are endlessly getting adjusted and readjusted and calibrated with new models and data, are sobering.

First, here are some graphical representations of the expected changes to our world over the next hundred years. They are, to put it plainly, terrifying.

The world will be a lot hotter and a lot wetter. It will be a lot less icy, and much more acidic:

With those apocalyptic maps in mind, take a stroll through the IPCC's bleakest predictions for the future:

• "Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped," the authors write.
• "It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises." 
• "Global glacier volume will further decrease." That's worldwide, from Greenland to the Andes. 
• "Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900 … and more likely than not to exceed 2°C" for typical warming scenarios. That's a lowball, too.
• "The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase…" Read: Drier deserts and flooded wetlands.

• "Global mean sea level will continue to rise during the 21st century … the rate of sea level rise will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets," the paper notes. According to Stefan Rahmstorf of RealClimate, this means "a much more rapid sea-level rise is now projected (28-97 cm by 2100). This is more than 50% higher than the old projections (18-59 cm) when comparing the same emission scenarios and time periods.With unabated emissions (and not only for the highest scenario), the IPCC estimates that by the year 2300 global sea levels will rise by 1-3 meters."
• "It is virtually certain that near-surface permafrost extent at high northern latitudes will be reduced as global mean surface temperature increases. By the end of the 21st century, the area of permafrost near the surface (upper 3.5 m) is projected to decrease by between 37% to 81%." That means the icy ground that's currently locking methane underground is melting, releasing more global-warming gases.
• "Further uptake of carbon by the ocean will increase ocean acidification."
• "The global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation."

Sea levels will rise, dry places will get more arid while wet ones are inundated with floods, our glaciers will melt, the Arctic will dissipate, the oceans will heat and become laden with acid, and atmospheric temperature rise of 2˚C is all but guaranteed. Oh, and all of the above is probably irreversible unless we cut it all out right now. Which we won't.

This is why Al Gore is concerned that human civilization may not survive the next hundred years. Because even though scientists are more certain that we are causing global warming than almost anything, the concerted political action required to address it remains an abstraction hovering on the horizon.

Our best scientists are telling us that they're surer than ever that the world is about to get apocalyptic, and exactly how it will do so. But if we're not listening now, then when?