How do aerosols influence climate

Although absorption, like reflection, tends to reduce sunlight at the ground level, the enhanced atmospheric heating eventually warms up the surface, and counteracts the cooling caused by reflection. The resulting brightening of clouds renders them more potent at shielding the surface from sunlight, causing the first indirect effect or cloud albedo effect. More aerosols may also enable clouds to last longer by suppressing rainfall — the second indirect effect or cloud lifetime effect.

Despite many years of active research, aerosols are still the least certain of all known climate forcings. This seriously hinders our ability to separate the roles of aerosols and greenhouse gases in driving the past climate change, thereby precluding one from reliably projecting the future climate. Air pollution has been linked to increased risk of heart disease, stroke, lung disease, asthma, and more.

By some recent estimates fine particles in the air contributed to over four million premature deaths globally in , hitting children and the elderly the hardest. The health risks from fine-particle exposure are highest in China and India, particularly in urban areas.

Aerosols influence climate in two primary ways: by changing the amount of heat that gets in or out of the atmosphere, or by affecting the way clouds form. Some aerosols, like many kinds of dust from ground-up rocks, are light-colored and even a little bit reflective. The effect can be dramatic: The Mt. Pinatubo volcanic eruption in , in the Philippines, spewed the equivalent of 1. But other aerosols, like little flecks of black carbon from burned coal or wood, do the opposite, absorbing heat from the sun as it beats down.

That ends up warming the atmosphere, though it cools the surface of the Earth by preventing the heat from escaping. Aerosols also influence how clouds form and grow.

Water droplets coalesce readily around particles, so a particle-rich atmosphere promotes cloud formation. White clouds reflect incoming sun, preventing it from getting to the surface and warming land or water—but they also absorb the heat that the planet is constantly emitting back outward, trapping it in the lower atmosphere.

Depending on the cloud type and location, they can either warm their surroundings or cool them. Aerosols have a complicated suite of different effects on the planet, but humans have directly impacted their presence, abundance, and distribution. And while the climate effects are complex, the health impacts are clear: More fine material in the air hurts human health. All rights reserved. What are aerosols? Share Tweet Email. Why it's so hard to treat pain in infants.

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India bets its energy future on solar—in ways both small and big. In the US, diesel vehicles are the major source of soot, and filters on exhaust pipes can help reduce the amount that they pump into the air. In terms of sulfate aerosols, which are created by sulfur dioxide given off by power plants, the US and Europe have very successfully used sulfur dioxide scrubbers in power plants to reduce these emissions over the past 20 years or so.

But we can definitely do more. By reducing aerosol soot emissions, we can buy ourselves some climate time — about 5 to 10 years — while we work on reducing emissions of greenhouse gases such as carbon dioxide CO2 in parallel.

CO2, you see, hangs around in the atmosphere for an extremely long time, from decades to centuries, so even if we implement cuts today, it will take years for them to take effect. Aerosols, on the other hand, have much shorter lifetimes. If we work to reduce soot emissions now, which can enhance the global warming effect of CO2 by percent, the climate impacts will be felt more rapidly.

I have a paper in review at the moment that is quite exciting; we're looking at the future total climate impacts of current emissions from different industries, taking into account the effects of both greenhouse gases such as CO2, ozone and methane, and the impacts of aerosols.

What we've found is that for the next 40 years, emissions from road vehicles will have the largest global warming impacts of all human activities — because of the air pollutant effects that enhance greenhouse gas warming. After , however, power sector emissions are by far the largest global warmer because of the build up of CO2 in the atmosphere from that activity.