Dust plays larger than expected role in determining Atlantic temperature

Dust plays larger than expected role in determining Atlantic temperature
A dust storm off the coast of Morocco was imaged by NASA’s MODIS Aqua meteorological satellite on March 12, 2009. A new study by UW-Madison researcher Amato Evan shows that variability of African dust storms and tropical volcanic eruptions can account for 70 percent of the warming North Atlantic Ocean temperatures observed during the past three decades. Since warmer water is a key ingredient in hurricane formation and intensity, dust and other airborne particles will play a critical role in developing a better understanding of these storms in a changing climate. Photo: courtesy Amato Evan

(PhysOrg.com) -- The recent warming trend in the Atlantic Ocean is largely due to reductions in airborne dust and volcanic emissions during the past 30 years, according to a new study.

Since 1980, the tropical North Atlantic has been warming by an average of a quarter-degree Celsius (a half-degree Fahrenheit) per decade. Though this number sounds small, it can translate to big impacts on hurricanes, which thrive on warmer water, says Amato Evan, a researcher with the University of Wisconsin-Madison's Cooperative Institute for Meteorological Satellite Studies and lead author of the new study. For example, the difference between 1994, a quiet hurricane year, and 2005's record-breaking year of storms, was just one degree Fahrenheit.

More than two-thirds of this upward trend in recent decades can be attributed to changes in African storm and tropical during that time, report Evan and his colleagues at UW-Madison and the National Oceanic and Atmospheric Administration in a new paper. Their findings will appear in an upcoming issue of the journal Science and publish online March 26.

Evan and his colleagues have previously shown that African dust and other airborne particles can suppress hurricane activity by reducing how much sunlight reaches the ocean and keeping the sea surface cool. Dusty years predict mild hurricane seasons, while years with low dust activity — including 2004 and 2005 — have been linked to stronger and more frequent storms.

In the new study, they combined satellite data of dust and other particles with existing to evaluate the effect on ocean temperature. They calculated how much of the Atlantic warming observed during the last 26 years can be accounted for by concurrent changes in African and tropical volcanic activity, primarily the eruptions of El Chichón in Mexico in 1982 and Mount Pinatubo in the Philippines in 1991.

In fact, it is a surprisingly large amount, Evan says. "A lot of this upward trend in the long-term pattern can be explained just by dust storms and volcanoes," he says. "About 70 percent of it is just being forced by the combination of dust and volcanoes, and about a quarter of it is just from the dust storms themselves."

The result suggests that only about 30 percent of the observed Atlantic temperature increases are due to other factors, such as a warming climate. While not discounting the importance of , Evan says this adjustment brings the estimate of global warming impact on Atlantic more into line with the smaller degree of ocean warming seen elsewhere, such as the Pacific.

"This makes sense, because we don't really expect global warming to make the ocean [temperature] increase that fast," he says.

Volcanoes are naturally unpredictable and thus difficult to include in climate models, Evan says, but newer climate models will need to include dust storms as a factor to accurately predict how ocean temperatures will change.

"We don't really understand how dust is going to change in these climate projections, and changes in dust could have a really good effect or a really bad effect," he says.

Satellite research of dust-storm activity is relatively young, and no one yet understands what drives dust variability from year to year. However, the fundamental role of the temperature of the tropical North Atlantic in hurricane formation and intensity means that this element will be critical to developing a better understanding of how the climate and storm patterns may change.

"Volcanoes and dust storms are really important if you want to understand changes over long periods of time," Evan says. "If they have a huge effect on ocean temperature, they're likely going to have a huge effect on hurricane variability as well."

Source: University of Wisconsin-Madison (news : web)

Explore further

African dust forecast may help hurricane season predictions

Citation: Dust plays larger than expected role in determining Atlantic temperature (2009, March 26) retrieved 19 September 2019 from https://phys.org/news/2009-03-larger-role-atlantic-temperature.html
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

Mar 26, 2009
But...but...it's global warming isn't it...

Mar 26, 2009
Does this mean that the ban on nuclear testing is a contributing factor to global warming???

Mar 26, 2009
WHEW! another incredible coincidence has saved us from explaining the total lack of global warming ... but we cant rely on these reprieves people, this only makes it more important that we make algore richer faster so that he will save us by making us live in huts and caves ... to save the planet of course.

Mar 27, 2009
Luckybrandon, I believe the earth has cooled off quite a bit lately by comparison.. Other than the heated air from dust and volcanos.. and Al Gores mansion I mean.

The earth axis idea seems a bit more solid than Al Gore's money making scheme claiming that emissions and CO2 from USA automobiles and factories (for the whopping 50 years of unregulated CO2 emissions that is). Compare 50 years of man made CO2 to how many millions of years of life on this muddy rock?

The oceans are not recending and what water that is changing locations/elevations/sea level is from simple land erosion.. all natural of course.

Mar 27, 2009
"Since 1980, the tropical North Atlantic has been..."

Does this region interact with the arctic equatorial systems??

Mar 27, 2009
It must I say must be caused by co2. Dont tell me all the indoctratnation Ive been receiving for the last 10 years is false. It just cant be. Last 10 years were in a cooling trend.... No it cant be.... sun causing warming trends.... no it cant be.... our profit Al Gore would of told us.... and not make profit out of our belief that he inspired...

Mar 27, 2009
global warming is fake, its a normal weather variation. to believe otherwise requires you to completely disregard the evidence. not 1 , ... none of the GW alarmist predictions have come true. none. ever not once ... at all. so why should we continue to support these people when they are wrong? wrong every time.

Mar 27, 2009
It's interesting that the effects of natural events (dust, volcanic eruptions, PDO, La Nina, etc) seem to be able to override the devastating effects of CO2 caused AGW.

Back to the drawing board?

Apr 01, 2009
"You can't disregard their hypothesis because the framework in which they are operating is incomplete. You can disregard their hypothesis because they refuse to refine their framework to the point of theory"

I can disregard their hypothesis, ... because it is demonstrably wrong. these people are wrong. Its obvious. Just the fact that water vapor masks the effect of CO2 is enough to prove them fools or charlatans. thats just one problem with AGW. Ignoring the sun variations should be evidence for insanity.

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