Nature & Environment
Manmade Pollutants Cool Our Planet: Brighter Clouds Means Less Sunlight
Catherine Griffin
First Posted: May 06, 2013 10:38 AM EDT
It may seem counterintuitive, but pollutants could be cooling our planet slightly. New research has found that natural emissions and human created pollutants could have a cooling effect on Earth by making clouds brighter.
Clouds can keep our planet warm by trapping heat, keeping it close to our surface. By that same token, though, they also have the ability to reflect heat. Made of tiny water droplets condensed onto tiny particles suspended in the air, clouds form when the air is humid enough. For years, scientists have known that these particles and their size can control exactly how bright clouds appear from the top. This, in turn, determines how efficiently clouds scatter sunlight and reflect it back into space, consequently cooling the planet. Yet it's only now that scientists have examined this phenomenon a bit more closely.
The tiny seed particles that water droplets cling to can either be natural or manmade. They often contain a large amount of organic material. Usually volatile, these particles exist as vapor in warm conditions.
In order to understand how these different particles may cause different warming or cooling effects, researchers developed a model and made predictions of a substantially enhanced number of cloud droplets from an atmospherically reasonable amount of organic gases. They found that volatile organic compounds from pollution evaporate and give off characteristic aromas (think of when you spray perfume). These particles enter the atmosphere and under moist, cooler conditions where clouds form, turn into liquid. These particles, acting as the nuclei, actually encouraging the formation of larger cloud droplets.
"More cloud droplets lead to brighter cloud when viewed from above, reflecting more incoming sunlight," said study author Gordon McFiggans in a news release. "We did some calculations of the effects on climate and found that the cooling effect on global climate of the increase in cloud seed effectiveness is at least as great as the previously found entire uncertainty in the effect of pollution on clouds."
That's not to say that the entire Earth is cooling because of this phenomenon, though. It's doubtful that these droplets can cause an overall cooling effect to offset the current warming trend. However, the findings may have implications for climate models and local weather patterns.
The findings are published in the journal Nature Geoscience.
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First Posted: May 06, 2013 10:38 AM EDT
It may seem counterintuitive, but pollutants could be cooling our planet slightly. New research has found that natural emissions and human created pollutants could have a cooling effect on Earth by making clouds brighter.
Clouds can keep our planet warm by trapping heat, keeping it close to our surface. By that same token, though, they also have the ability to reflect heat. Made of tiny water droplets condensed onto tiny particles suspended in the air, clouds form when the air is humid enough. For years, scientists have known that these particles and their size can control exactly how bright clouds appear from the top. This, in turn, determines how efficiently clouds scatter sunlight and reflect it back into space, consequently cooling the planet. Yet it's only now that scientists have examined this phenomenon a bit more closely.
The tiny seed particles that water droplets cling to can either be natural or manmade. They often contain a large amount of organic material. Usually volatile, these particles exist as vapor in warm conditions.
In order to understand how these different particles may cause different warming or cooling effects, researchers developed a model and made predictions of a substantially enhanced number of cloud droplets from an atmospherically reasonable amount of organic gases. They found that volatile organic compounds from pollution evaporate and give off characteristic aromas (think of when you spray perfume). These particles enter the atmosphere and under moist, cooler conditions where clouds form, turn into liquid. These particles, acting as the nuclei, actually encouraging the formation of larger cloud droplets.
"More cloud droplets lead to brighter cloud when viewed from above, reflecting more incoming sunlight," said study author Gordon McFiggans in a news release. "We did some calculations of the effects on climate and found that the cooling effect on global climate of the increase in cloud seed effectiveness is at least as great as the previously found entire uncertainty in the effect of pollution on clouds."
That's not to say that the entire Earth is cooling because of this phenomenon, though. It's doubtful that these droplets can cause an overall cooling effect to offset the current warming trend. However, the findings may have implications for climate models and local weather patterns.
The findings are published in the journal Nature Geoscience.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone