If we continue to burn fossil fuels without consequences, the global temperature will not only rise by 6 ° C before the industrial revolution, but 14 ° C! By then, most of the tropics will become so hot that warm-blooded animals, including humans, will not survive, and this extra warming is caused by a reduction in stratus.
The stratus cloud is disappearing?
The stratus cloud is a kind of loosely-structured large cloud suspended in low altitude. The height of the cloud bottom is usually below 2000 meters, which is common in marine and coastal areas. The thickness or shape is very different, and it has a strip shape, a sheet shape or a group shape, and the structure is loose. The stratus cloud looks like a cumulus cloud, and sometimes the scattered clouds merge into a single continuous cloud, sometimes with gaps between the clouds. Whether it is continuous or gapy, the color of the stratus cloud is very varied, and the cloud bottom generally has a very clear outline. Its color ranges from bright white to blue gray.
Recently, meteorologists at the California Institute of Technology used computer models to simulate stratus clouds over subtropical oceans. These stratus clouds cover nearly 7% of the world’s sky, and they keep the earth cool by reflecting sunlight back into space.
Meteorologists were surprised to find out whether the existence of stratus clouds is closely related to the concentration of carbon dioxide in the atmosphere: when the carbon dioxide concentration reaches 1200 ppm (1 ppm is 1 part per million), the stratus clouds over the subtropical ocean suddenly disappear.
The reason for the dissipation is that the stratus clouds are different from other cloud species in that they emit infrared rays on the top of the clouds to cool them and maintain their existence. When the carbon dioxide concentration is too high, the greenhouse gases are like a thick bed. More of the sun’s heat is trapped in the atmosphere, weakening the cooling effect of the stratus, and ultimately it cannot survive.
Losing the stratus will make the earth hotter
Once the stratus is lost, it will be catastrophic. The global temperature will increase by 8 °C on the basis of the original; considering that if the carbon dioxide concentration exceeds 1200 ppm, the temperature will have risen by more than 6 °C, which means the final temperature. The increase may exceed 14 °C. In addition, once the stratus clouds are dissipated, they must be re-formed only when the concentration of greenhouse gases is much lower.
The good news is that if countries increase their emissions, we should be able to avoid this outcome. In 2018, the average concentration of carbon dioxide in the world is 410ppm, and it is almost three times the current level to make the layered cloud “live”. However, this concentration is not easy to achieve, because even without any emission reduction measures, the greenhouse gas concentration will exceed 1200 ppm after more than 100 years. So, we don’t have to panic. But for the sake of future generations, we still need to take some measures to reduce emissions.
This discovery helps to unravel a long-standing mystery: Why did the Earth become so hot 50 million years ago that crocodiles that originally lived in the tropics could thrive in the Arctic? Although we know that the concentration of carbon dioxide was much higher than it is now, the greenhouse effect alone seems to be insufficient to explain the extreme temperatures of this period. It seems that it is likely that the concentration of carbon dioxide was too high at that time, causing the stratification of the cloud to disintegrate, thus bringing the “Matthew effect” – the temperature is higher.