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We need to rethink everything we know about global warming

New research shows that the degree to which aerosols cool the earth has been grossly underestimated, necessitating a recalculation of climate change models to more accurately predict the pace of global warming.

For a while now, the scientific community has known that global warming is caused by humanmade emissions in the form of greenhouse gases and global cooling by air pollution in the form of aerosols.

However, new research published in Science by Hebrew University of Jerusalem Professor Daniel Rosenfeld shows that the degree to which aerosols cool the earth has been grossly underestimated, necessitating a recalculation of climate change models to more accurately predict the pace of global warming.

Aerosols are tiny particles that float in the air. They can form naturally (e.g., desert dust) or artificially (e.g., smoke from coal, car exhaust). Aerosols cool our environment by enhancing cloud cover that reflect the sunlight (heat) back to space.

As for the first, clouds form when wind rises and cools. However, cloud composition is largely determined by aerosols. The more aerosol particles a shallow cloud contains, the more small water droplets it will hold. Rain happens when these droplets bind together. Since it takes longer for small droplets to bind together than it does for large droplets, aerosol-filled or "polluted" clouds contain more water, live in the sky longer (while they wait for droplets to bind and rain to fall, after which the clouds will dissipate) and cover a greater area. All the while, the aerosol-laden clouds reflect more solar energy back into space, thereby cooling the Earth's overall temperature.

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