Bolder efforts to limit emissions would reduce these risks, or at least slow the effects, but it is already too late to eliminate the risks entirely. Scientists fear climate effects so severe that they might destabilize governments, produce waves of refugees, precipitate the sixth mass extinction of plants and animals in the EarthРІР‚в„ўs history, and melt the polar ice caps, causing the seas to rise high enough to flood most of the worldРІР‚в„ўs coastal cities.Р”Р„ll of this could take hundreds or even thousands of years to play out, but experts cannot rule out abrupt changes, such as a collapse of agriculture, that would throw civilization into chaos much sooner. Longer term, if emissions continue to rise unchecked, the risks are profound. Coastal flooding will grow more frequent and damaging, as isР’В already happening. The number of hurricanes and typhoons may actually fall, but the ones that do occur will draw energy from a hotter ocean surface, and therefore may be more intense. Rainfall will be heavier in many parts of the world, but the periods between rains will most likely grow hotter and drier. Over the coming 25 or 30 years, scientists say, the climate is likely to resemble that of today, although gradually getting warmer, with more of the extreme heat waves that can kill vulnerable people. This means the current generation of people is dooming future generations to a more difficult future. The risks are much greater over the long run than over the next few decades, but the emissions that create those risks are happening now.

If emissions continue unchecked, they say the global warming could ultimately exceed 8 degrees Fahrenheit, which would transform the planet and undermine its capacity to support a large human population. Scientists believe most and probably all of the warming since 1950 was caused by the human release of greenhouse gases. The heat accumulating in the Earth because of human emissions is roughly equal to the heat that would be released by 400,000 Hiroshima atomic bombs exploding across the planet every day.

The substantial warming that has already occurred explains why much of the worldРІР‚в„ўs land ice is starting to melt and the oceans are rising at an accelerating pace. So a rise of 2 degrees Fahrenheit since the 19th century is actually high. But when you average across the entire planet and over months or years, the temperature differences get far smaller РІР‚вЂњ the variation at the surface of the Earth from one year to the next is measured in fractions of a degree. We experience much larger temperature swings in our day-to-day lives from weather systems and from the changing of seasons. The warming is greater over land, and greater still in the Arctic and parts of Antarctica. That figure includes the surface of the ocean. As of early 2017, the Earth had warmed by roughly 2 degrees Fahrenheit, or more than 1 degree Celsius, since 1880, when records began at a global scale.

Atomic society cheat table