Comment on this storyCommentGift ArticleFor over a decade, the largest scientific uncertainty about how the planet will respond to warming temperatures hasn’t come from how much carbon dioxide will be soaked up by the ocean or absorbed by the trees. It’s come, instead, from clouds.The fluffy, whimsical collections of water droplets floating in the air have, for some time, confounded climate scientists and models alike. Scientist have long known that depending on how clouds respond to warming temperatures, the world could become even warmer or a little bit cooler. They just haven’t known which.But in the past few years, scientists have begun to nail down exactly how clouds will change shape and location in the rapidly warming world. The result is good news for science — but not good news for humanity.“We’ve found evidence of the amplifying impact of clouds on global warming,” said Paulo Ceppi, a climate scientist at Imperial College London.AdvertisementScientists have long known that clouds have two primary influences on the global climate. First, clouds are reflective — their white surfaces reflect the sun’s rays away from Earth, creating a cooling effect. (If the planet were suddenly devoid of these fluffy parasols, the planet would be roughly five times hotter than even the most disastrous global warming projections.) But clouds also create a warming effect — certain types of clouds insulate the Earth’s radiation, keeping the planet warm much like carbon dioxide released from the burning of fossil fuels.Which effect is stronger depends on the type of cloud. Cirrus clouds — high, wispy clouds visible in the distant atmosphere on relatively clear days — absorb and trap more radiation, warming the Earth. Stratus or stratocumulus clouds — plump, fluffy clouds that often hover over the ocean on overcast days — reflect more sunlight, cooling the Earth.How exactly those two factors will balance out as the world warms has been uncertain. That’s mostly because, even though clouds can look gigantic — when you are flying through them in a plane or looking up at them from the ground — they form at microscopic levels, when water vapor condenses around a particle of dust or a droplet. As a result, they are essentially impossible to model in the standard big climate models. (Clouds form at the micrometer level, while the models that most climate scientists use separate the world into blocks hundreds of kilometers in width.)Advertisement“We have a really tough time simulating with any f …
