Clouds and Global Warming

Jul 29, 2016 | written by:

Made up by many small water particles, some condensed into ice crystals floating in the atmosphere above our heads. Clouds. They originate atmospheric phenomena, but also our children (and not only) games, watching the sky tring to find some resemblance to an object, a face or to our pet.

These soft and foamy clouds play also an important key role in Earth's climate system, helping to regulate the temperature of the planet, reducing global warming and the greenhouse effect. Yet, from a recent study by Joel Norris of the Scripps Institution of Oceanography and his colleagues published in the journal Nature, seems that the intensity of global warming has caused the displacement of some key groups of clouds. The research is still at an early stage of understanding of the relationship between climate change and clouds, and many question marks are waiting an answer due to the fact that not all changes will be negative.

The new positions acquired by certain clouds might be useful to tackle the greenhouse effect. The clouds have always been considered good for the climate system, but for researchers they’re also a terrible source of uncertainty. Their presence and their intrinsic function to mitigate global warming doesn’t allow to precisely estimate the actual levels of the latter, letting researchers resigned to having to make some approximations. In addition, their small size and the easy changes of shape make them difficult to accurately represent in climate models. Even with the use of satellites, the problem is the same: they are not scheduled to produce long-term information to be compared. That's not counting the substitutions or changes orbit of some.

Norris’ study tried to overtake these uncertainties by analyzing data in their possession since 1980, focusing on looking for those patterns that showed up in different climate models and that our physical understanding of the atmosphere supports. The observations showed that the main area of storm tracks in the middle latitudes of both hemispheres shifted poleward, expanding the area of dryness in the subtropics, and that the height of the highest cloud tops had increased. There is less solar radiation at the high latitudes near the poles, so as clouds shift that way, they have less radiation to reflect back to space. High cloud tops mean that more of the radiation that is absorbed and re-emitted by Earth’s surface is trapped by the clouds (akin to the greenhouse effect). Many points have yet to be studied, explored and established, such as the volcanic eruptions and their effects since even in post volcanic eruption, called "recovery", clouds move. Moreover, the study also doesn’t deal with some of the cloud changes that are expected to be most important, namely those to low clouds in the subtropics.Certainly, it’s a step toward better understanding how clouds will change along with the climate, and lays bare the limitations of the satellite record and the need for better long-term observations, reminding us how poorly prepared we are for detecting signals that might portend more extreme (both large and small) climate changes than are presently anticipated.

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