Context: A study by California Institute of Technology has found that Marine clouds that protect us from hothouse Earth conditions by reflecting sunlight back into space could break up and vanish if CO2 in the atmosphere triples. Computer modeling shows that marine stratus clouds could disappear if atmospheric CO2 levels climb high enough, raising global temperatures.

Concerns highlighted by the study:

• Stratocumulus clouds cover about 20% of subtropical oceans, mostly near western seaboards such as the coasts of California, Mexico and Peru. When they disappear, Earth warms dramatically, by about eight degrees Celsius — in addition to the global warming that comes from enhanced greenhouse concentrations alone.
• A temperature increase of that magnitude would melt polar ice and lift sea levels tens of metres.
• The last time the planet was that hot, some 50 million years ago during the Eocene Epoch, crocodiles roamed the Arctic. Even half that much warming would overwhelm humanity’s capacity to adapt.

What are stratocumulus clouds?

Stratocumulus clouds are low-level clumps or patches of cloud varying in colour from bright white to dark grey. They are the most common clouds on earth recognised by their well-defined bases with some parts often darker than others. They usually have gaps between them, but they can also be joined together.

How do stratocumulus clouds form?

Stratocumulus clouds usually form from a layer of stratus cloud breaking up. They are indicators of a change in the weather and are usually present near a warm, cold or occluded front.

What weather is associated with stratocumulus clouds?

Stratocumulus clouds can be present in all types of weather conditions, from dry settled weather to more rainy conditions, but they themselves are often not the culprit. Stratocumulus are often mistaken for rain clouds, when in reality it is quite rare to get anything more than the lightest drizzle from them, if anything at all.