Study finds human-made aerosols exert strong influence on the geography of precipitation

Study finds human-made aerosols exert strong influence on the geography of precipitation
Aerosols can lower surface temperatures either directly, by reflecting sunlight skyward, or indirectly, by increasing the reflectivity of clouds. Credit: NASA

While the effects of power plant emissions, vehicle exhaust and other manmade aerosols on air quality and public health are well-known, their impact on the climate is not completely understood. Scientists have shown that aerosols can lower surface temperatures either directly, by reflecting sunlight skyward, or indirectly, by increasing the reflectivity of clouds, but until now have not figured out the role these airborne particles play in shaping the distribution of rain and snowfall around the world.

According to a new MIT study in Geophysical Research Letters, the effects of anthropogenic exert a strong influence in determining where precipitation increases and decreases take place across the globe. Running historical simulations with models that represent aerosol-cloud interactions with far greater precision than in previous analyses, the MIT study indicates that the distribution of precipitation in the second half of the 20th century is dominated by the effects of anthropogenic aerosols over the tropics, and also substantially influenced in non-tropical regions of the Northern Hemisphere.

"While it is true that total precipitation change is controlled by average global temperature change, which, in turn, is largely based on greenhouse gas emissions, our research shows that aerosols have significantly impacted the distribution of precipitation change around the world since preindustrial times," says Chien Wang, a senior research scientist at the MIT Joint Program on the Science and Policy of Global Change and the MIT Department of Earth, Atmospheric and Planetary Sciences.

Using historical simulations running from 1850 to 2005, the MIT study compared results of an ensemble of 10 models from the recent Coupled Model Intercomparison Project Phase 5 (CMIP5), which explicitly represent aerosol-cloud interactions, with those of a set of seven older models that oversimplified these interactions. The new models showed that aerosol-driven precipitation changes occurred not only where aerosol concentrations were high (e.g., the Indian summer monsoon region) but also in a number of far-off locations.

"We compared results with and without aerosols from preindustrial times to 2005, and found that aerosols alone can force a pattern change in precipitation," Wang says. "Because of the sophistication of the new, physically-based models, we can now see that aerosols have a larger impact on precipitation distribution than previously established."

Aerosol concentrations may rise or fall as nations grow their economies, implement clean air policies, or develop in other ways, leading to changes in the distribution of precipitation around the world that could adversely impact economic, agricultural, and other activities. These results suggest that anyone formulating a climate mitigation or adaptation strategy will be wise to consider the potential impact of aerosols on both local and global patterns.

Explore further

A warmer world will be a hazier one, study finds

More information: Chien Wang. Anthropogenic aerosols and the distribution of past large-scale precipitation change, Geophysical Research Letters (2015). DOI: 10.1002/2015GL066416
Journal information: Geophysical Research Letters

This story is republished courtesy of MIT News (, a popular site that covers news about MIT research, innovation and teaching.

Citation: Study finds human-made aerosols exert strong influence on the geography of precipitation (2016, January 22) retrieved 17 October 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Jan 22, 2016
So what? Some day we will all succumb to plastic fumes, when that mess reacts with the oceans' soup.

Jan 22, 2016
let us remember all past data has been altered. These so called scientist are working off false data. These pin heads are too stupid to realize it.

Jan 22, 2016
Collier's magazine from May of 1954.

61 year old magazine article is: "Weather Made To Order….. Man's Progress In Weather Control".

Global weather modification and weather warfare has been going on in plain sight and at a significant scale for over 70 years.

The article states, and with government and corporate authored prose:

"Over the last five years, our company has operated more than 150 separate projects in 18 states and six foreign countries. We had amassed more than 200,000 hours of seeding experience in varying latitudes. We don't think we can increase rainfall — we know it."

this was 61 years ago.

chemtrails are most definitely 100%, nay.... 1000% real. They are advanced weather control, that has gone far far beyond cloud seeding..... into population control and population debilitation.

They found a way to sneak it past most people's notice and they are using that avenue ----- big time. It's a dark war, a quiet war.

Jan 23, 2016
VINDOC, can you explain to me the superiority of your approach in which you disregard all available data as being false, dismiss the PhDs who use actual data as "pin heads" and offer absolutely no actionable ideas? If you don't mind I will accept the data and conclusions of the PhDs because I can repeat every one of the measurements they cite, design equivalent models and see if I get the same results. In other words, I understand this report and will search for supporting evidence whereas you simply dismiss it for some strange reason.

Jan 24, 2016

Is there a place where one can legally hunt cranks? I sure would like to bag a few.

Jan 24, 2016
VINDOC claims
let us remember all past data has been altered
"All" ? Really ? So it must then be a grand worldwide conspiracy shared effectively across millions of Physicists as AGW based upon proven Physics of Heat ?
never refuted for >100yrs and which leads to
illustrated graphically ie if you prefer pictures VINDOC

VINDOC, essential school Physics
1. All things move All the time
2. All atoms absorb & radiate light All the time

VINDOC rather than blurt inanities, where's Evidence please ?

These so called scientist are working off false data
Really ? So you claim they are uneducated & don't appreciate Provenance or Instrumentation, do you ?

These pin heads are too stupid to realize it
Ah so just you will educate "All' of them in Measurement Methodology re Sensor corrections ?

Physics !

Jan 24, 2016
I just found a few more users to ignore......

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more