Tiny Aerosols Pose a Big Predicament in a Warming World

Fossil fuels are warming the planet and killing millions of people every year. We have to quickly decarbonize. Aerosols cool the atmosphere in an ironic twist. An odd climate contradiction is created by it. We will stop loading the sky with carbon dioxide if we burn less gas, oil, and coal.

Climate researchers don't know how much cooling aerosols will give us, and how strong that effect will be as the world gets rid of fossil fuels. The University of Oxford climate scientist said aerosols are important. There is a lot of uncertainty in climate science.

In a paper published last week in the journal Nature Climate Change, he played out a scenario for how aerosol concentrations will change through the end of the century. As we burn less fossil fuel, we'll produce less aerosols. He was able to adjust the amount of cooling aerosols that could be provided. One version of the model assumed that aerosols have a more intense cooling effect, which made it difficult to switch off the air conditioning. The Paris Agreement aims to keep global temperatures from rising more than 1.5 degrees Celsius. If we assume that aerosols have a 50 percent smaller cooling effect, we can keep warming below 1.5 degrees. The size of this effect is important for policymakers, who have spent the past two weeks at the COP 27 climate conference in Egypt haggling over how much more carbon countries should be allowed to emit.

It has been difficult to nail down that figure due to the complexity of aerosols. Clouds of sulfate produced by burning fossil fuels cool the climate in two ways. The particles act like mirrors and reflect sunlight back to space. It is similar to a parasol. The surface of the planet is protected from the sun's harmful rays.

They influence the formation of clouds which affect the local climate. Water vapor in the atmosphere condenses and forms cloud droplets with the help of aerosols.

Water condenses around dust when clouds are in the sky. If you load a given area with more aerosols, the droplets will be more numerous and smaller. The cloud bounces more of the sun's energy back into space when smaller droplets are brighter than bigger ones. The cloud can live longer if the droplets are made smaller. One of the larger contributors to this overall cooling is the lifetime effect.