The world could be in for a devastating increase of some eight degrees Fahrenheit by 2100, resulting in drastically higher seas, disappearing coastlines and more severe droughts, floods and other destructive weather, according to climate scientists
Now, a study suggests the gloomier predictions may be closer to the mark
“Warming is likely to be on the high side of the projections,” John Fasullo of the National Center for Atmospheric Research in Boulder, Colorado, a co-author of the report, which was based on satellite measurements of the atmosphere, said
That means the world could be in for a devastating increase of about eight degrees Fahrenheit by 2100, resulting in drastically higher seas, disappearing coastlines and more severe droughts, floods and other destructive weather
Such an increase would substantially overshoot, what the world’s leaders have identified as the threshold for triggering catastrophic consequences.
In 2009, heads of state agreed to try to limit warming to 3.6 degrees, and many countries want a tighter limit
Climate scientists around the world use supercomputers to simulate the Earth’s atmosphere and oceans. Sophisticated programs attempt to predict how climate will change as society continues burning coal, oil and gas, the main sources of heat-trapping gases such as carbon dioxide
But these simulations spit out a wide range of warming estimates. All foresee an overheated planet in 2100, but some predict just three degrees of warming while others estimate eight or more degrees of extra heat
“This problem has been around for 30 years,” Fasullo said.
“As long as climate models have existed, there’s been this spread in projections of the future,” he added.
One source of uncertainty involves the impact of cloud cover, especially clouds that form in the tropical and subtropical regions between about 30 degrees north and south of the equator
“Tropical clouds are so important to climate,” Fasullo said.
“Small changes in clouds near the equator have a big effect on where you end up” for temperature predictions, he said
As sunlight pours onto the tropics, clouds bounce some of that heat back into space. Fewer clouds open up the atmosphere “like an iris,” Fasullo said, allowing more heat to beam onto Earth’s surface.