Clouds have been known to cool down the Earth’s surface. Their white surfaces reflect the sun’s rays away from the Earth’s surface, creating a cooling effect. Without clouds, the Earth could be five times hotter.
The stratocumulus clouds, those fluffier ones closer to the surface, reflect more sunlight and cool the Earth.
However, another type of cloud, the cirrus cloud – the high and wispy ones can trap heat from the sun.
The effect of climate change on clouds and how clouds will respond to climate change has remained a mystery to climate scientists and models until recently.
Not until in the last few years that they nailed down the answer exactly how clouds will change shape and location in the rapidly warming world, and what they found out is good news for science but not suitable for humanity.
The Washington Post article presents three studies on how climate change will affect cloud formation and their cooling or heating effect on the Earth and other factors that encourage cloud formation, which creates a temporary cooling effect on the Earth’s surface.
A study in Nature Climate Change, “Observational constraints on low cloud feedback reduce uncertainty of climate sensitivity“, uses a satellite observation to discover how cloud formation is affected by ocean temperatures, wind speed, humidity and other factors and how these factors will change as temperatures continue to rise— and then analysed how these factors will change as the world warms.
One of the study authors says that low-level clouds over the oceans tend to disappear as the ocean warms. The dissipation of stratocumulus clouds because of warm ocean water means fewer clouds reflect the sun’s rays and heat – hence more warming.
The study in the Proceedings of the National Academy of Sciences, “Observational evidence that cloud feedback amplifies global warming“, also showed that clouds would magnify global warming. It used high-resolution models that can better model cloud formation. The study also revealed other factors that can affect cloud formation. It shows that artificial aerosols caused by air pollution have encouraged the formation of low-level clouds.
Another study, “Assessing effective radiative forcing from aerosol-cloud interactions over the global ocean“, showed similar findings. It indicates that low-level clouds formed with the help of sulphate aerosols in the atmosphere have masked the impacts of global warming. Casey Wall, a postdoctoral researcher at the University of Oslo, notes, “There’s potential that as we clean up air pollution, we unmask global warming”.
With the findings from the studies above revealing that clouds will amplify global warming, scientists can now calculate how much the world will warm when carbon dioxide emissions double. Before the industrial revolution, CO2 concentration was around 280 parts per million; now has reached 412 ppm and continues to increase.
Before, scientists estimated that when CO2 emissions reached 560 ppm, the temperature would increase between 1.5 and 4°C. However, with the recent findings on climate change’s effect on cloud formation, scientists calculate that with 560 ppm CO2 emissions, the temperature rise will reach at least 3 or 3.5°C unless countries will continue to shift to clean energy, and we won’t be seeing those levels of emissions.
Click the links on the study above to learn more about changes in cloud formation as a response to climate change.