Long term North Atlantic surface temperature fluctuations linked to aerosols

Apr 05, 2012 by Bob Yirka report
Atlantic Multidecadal Oscillation Timeseries with a 12 month moving average (black), 1856-2009. Image: NOAA

(PhysOrg.com) -- Manmade pollution doesn’t always cause atmospheric warming, a group of researchers from Britain’s Met Office Hadley Centre, write in their paper published in the journal Nature, sometimes it causes cooling. That’s because, they say, manmade aerosols injected into the atmosphere can cause heat from the sun to be reflected back into space. The team has made this observation after studying the impact of aerosols on the temperature of the air just above the surface of the North Atlantic over the past century and a half, which has a decades-long cycle of rising and lowering.

The cycle, which researchers refer to as the Multidecadal Atlantic Oscillation (MAO), is not due to natural causes the team asserts, as has been the common consensus, but to , both manmade and natural. They found this out by creating a climate model that included the effects of aerosols on air temperatures. In so doing, they were able to show that aerosols could be linked to seventy six percent of variations found for the period 1850 to 2005. To demonstrate that their model was accurate, the team reduced the amount of aerosols in the simulation by roughly the same amount that has occurred in the real world due to legislation in most of the industrialized world since the 1970’s, and found that the temperature rise predicted by their model matched those that actually occurred. Thus, they say, the up and down temperature fluctuations over the surface of the North Atlantic over the past hundred and fifty five years, can be at least partially attributable to manmade .

The team got the idea to look into the MAO after noting that it didn’t occur in other oceans, leading them to believe the source was manmade pollutants, because the time frame coincided with the industrial revolution. Subsequent analysis of surface temperatures over the Indian Ocean in more recent years indicates the same situation might be occurring there as has happened over the Atlantic due to increased aerosols from newly industrializing nations. Thus far, the Pacific seems unaffected by such aerosols, though the researches cannot explain why, as aerosols from China should be having an impact.

In a corollary to their studies the team suggests that the fluctuations in temperatures over the Atlantic likely have had an impact on weather related phenomenon, such as causing draughts in Africa, and more lately, giving rise to more severe hurricanes moving easterly towards the Americas.

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More information: Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability, Nature (2012) doi:10.1038/nature10946

Systematic climate shifts have been linked to multidecadal variability in observed sea surface temperatures in the North Atlantic Ocean. These links are extensive, influencing a range of climate processes such as hurricane activity and African Sahel and Amazonian droughts. The variability is distinct from historical global-mean temperature changes and is commonly attributed to natural ocean oscillations. A number of studies have provided evidence that aerosols can influence long-term changes in sea surface temperatures, but climate models have so far failed to reproduce these interactions and the role of aerosols in decadal variability remains unclear. Here we use a state-of-the-art Earth system climate model to show that aerosol emissions and periods of volcanic activity explain 76 per cent of the simulated multidecadal variance in detrended 1860–2005 North Atlantic sea surface temperatures. After 1950, simulated variability is within observational estimates; our estimates for 1910–1940 capture twice the warming of previous generation models but do not explain the entire observed trend. Other processes, such as ocean circulation, may also have contributed to variability in the early twentieth century. Mechanistically, we find that inclusion of aerosol–cloud microphysical effects, which were included in few previous multimodel ensembles, dominates the magnitude (80 per cent) and the spatial pattern of the total surface aerosol forcing in the North Atlantic. Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol–cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions.

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User comments : 26

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TS1
2 / 5 (3) Apr 05, 2012
So the wild weather we have is not necessarily because of "global warming" but because of the pollutants in the atmosphere?
Modernmystic
Apr 05, 2012
This comment has been removed by a moderator.
ryggesogn2
2 / 5 (8) Apr 05, 2012
WHATEVER it is it's man made....

So banning something that is NOT the cause is a good idea?
Modernmystic
3.2 / 5 (5) Apr 05, 2012
WHATEVER it is it's man made....

So banning something that is NOT the cause is a good idea?


I'm sorry, but what in the HELL are you talking about now?
ryggesogn2
1.4 / 5 (9) Apr 05, 2012
WHATEVER it is it's man made....

So banning something that is NOT the cause is a good idea?


I'm sorry, but what in the HELL are you talking about now?

Is CO2 an aerosol?
rubberman
Apr 05, 2012
This comment has been removed by a moderator.
joefarah
1.8 / 5 (5) Apr 05, 2012
So, there you have it. The CC "scientific" community asked us to ban aerosols in the 1980s, and as a result, there are warmer temperatures. Now they ask to reduce carbon emissions. Frankly, I wouldn't trust them.
jet
4.3 / 5 (3) Apr 05, 2012
To Joefarh I think you are recalling the CFC (chlorofluorocarbon) from the Montreal Protocol etc.

In this article aerosol would be any particulate matter in the atmosphere "Technically, an aerosol is a colloid suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke." wiki

oh the Montreal protocol made the developed nations switch to HFC from CFC.. which now the environmental movement wishes to remove also.
Vendicar_Decarian
0.8 / 5 (44) Apr 05, 2012
"Is CO2 an aerosol?" - RyggTard

Nope
Vendicar_Decarian
0.9 / 5 (44) Apr 05, 2012
What does Tard Boy think is bannd?

"So banning something that is NOT the cause is a good idea?" - RyggTard

Idiot
julianpenrod
2 / 5 (7) Apr 05, 2012
An important point that not even believers in climate change seem to have noticed.
There is not an Atlantic Multidecadal Oscillation!
From about 1855 to 1900, there were a majority of warm years, but, interspersed among them, a number of cooler ones, as well. From 1900 to about 1925 almost every year except one was below "average" temperature. From about 1925 to about 1963, there was an admixture of years, most warmer than "
average", but a few lower. From about 1963 to about 1995, again, most years were cool, with five slightly above "average". From 1995 to 2012, there have been absolutely no years below "average"! Initially, "warm" and "cool" periods had years at the opposite temperature. The trend is for more warm years in the cool periods and no cool years in the warm periods!
Paulw789
3.7 / 5 (3) Apr 05, 2012

It would be different if the aerosols cycled up and down like the AMO does but since they haven't --> we have to call a fail for this study.

rubberman
5 / 5 (2) Apr 05, 2012

It would be different if the aerosols cycled up and down like the AMO does but since they haven't --> we have to call a fail for this study.



This is a valid point. Also considering that aerosol atmospheric residency is on the order of days to weeks, it would have to be a sustained source both in qty. and duration to have a sustained effect. Add to this the fact that not all aerosols cause cooling...
Modernmystic
3 / 5 (2) Apr 05, 2012
WHATEVER it is it's man made....

So banning something that is NOT the cause is a good idea?


I'm sorry, but what in the HELL are you talking about now?

Is CO2 an aerosol?

Uh no...

I was being sarcastic.....*sigh*.....
axemaster
4.6 / 5 (10) Apr 05, 2012
So, there you have it. The CC "scientific" community asked us to ban aerosols in the 1980s, and as a result, there are warmer temperatures. Now they ask to reduce carbon emissions. Frankly, I wouldn't trust them.

Hey, have you ever heard of the ozone layer? It prevents you from roasting in an oven of ultraviolet solar radiation. CFCs, a major component of (now banned) aerosols, destroy ozone. So unless you like cancer, those aerosols should stay banned. Forever.

So the wild weather we have is not necessarily because of "global warming" but because of the pollutants in the atmosphere?

I just love how you say "global warming" like there's some legitimate question of whether or not it's happening.
NotParker
1.9 / 5 (9) Apr 05, 2012
"The team got the idea to look into the MAO after noting that it didnt occur in other oceans"

Why not just wear a sign around their neck with an arrow point upward that says "I'm With Stupid"?

The PDO only occurs in the Pacific.
The AO in the arctic.
ENSO in the Southern Ocean,

The oscillations are named for where they are. It hardly suggests the amazing stupidity they are suggesting.

ryggesogn2
1 / 5 (5) Apr 06, 2012
How do you plan to ban volcanoes and deserts?

"Three types of aerosols significantly affect the Earth's climate. The first is the volcanic aerosol layer which forms in the stratosphere after major volcanic eruptions like Mt. Pinatubo. The dominant aerosol layer is actually formed by sulfur dioxide gas which is converted to droplets of sulfuric acid in the stratosphere over the course of a week to several months after the eruption"
"The second type of aerosol that may have a significant effect on climate is desert dust."

http://www.nasa.g...ols.html
NotParker
1 / 5 (3) Apr 06, 2012
"The second type of aerosol that may have a significant effect on climate is desert dust."


Mongolia to Phoenix ...

"The storm had occurred in the Gobi Desert of Mongolia and China. That's right folks the Gobi Desert.

Six-Day Journey

The dust had been carried to high altitude by winds so fierce that airports had to be closed, and then transported 7,000 miles across the Gulf of Alaska, down through British Columbia and over the vast expanse of open land in this country known as the Colorado Plateau."

http://abcnews.go...biS_i_EE
NotParker
1 / 5 (3) Apr 06, 2012
Where does particulate matter come from ....

75% of PM10 particles are from dust.

http://www.epa.go...hoice=PM
StarGazer2011
2 / 5 (4) Apr 07, 2012
Interesting, I have wondered how much of the warming 1978-1998 was caused by clean air legislation.
The idea that the AMO is caused by aerosols seems weak unless the magnitude has been increasing in line with aerosol emissions. The amount of aerosols released in 1850 would be miniscule compared to 1950, orders of magnitude apart.
In other climate news, new peer reviewed paper by physicists (who I hope we can agree outrank climate postnormalists) cant find any evidence of man made warming: www.eike-klima-en...ural.pdf
Maybe the science was just waiting for some real scientists to get involved?
StarGazer2011
1 / 5 (2) Apr 07, 2012

It would be different if the aerosols cycled up and down like the AMO does but since they haven't --> we have to call a fail for this study.



This is a valid point. Also considering that aerosol atmospheric residency is on the order of days to weeks, it would have to be a sustained source both in qty. and duration to have a sustained effect. Add to this the fact that not all aerosols cause cooling...


Agreed.
Interesting if the 1978-1998 warming was caused by clean air legislation though, anyone know if thats been looked into?
ubavontuba
1 / 5 (3) Apr 07, 2012
Agreed.
Interesting if the 1978-1998 warming was caused by clean air legislation though, anyone know if thats been looked into?
Less "smog" = warming? Fascinating concept, and it makes sense from a purely mechanical "more sunshine getting through the atmosphere" context. But I doubt its significance.

physicists cant find any evidence of man made warming:


From the paper:

From 1998 on, the global temperatures begin again to drop. This also conforms to [71] and the data recorded by HADCRUT 3GL, RSS, GISS, and UAH, which at the least show temperature series as remaining flat.
Exactly what I've been saying!

http://www.woodfo...12/trend

NotParker
1.8 / 5 (5) Apr 07, 2012

Interesting if the 1978-1998 warming was caused by clean air legislation though, anyone know if thats been looked into?


Look for papers by Martin Wild that reference global dimming/brightening.

There was an anomalous increase in sunshine during the warming 1910 to 1944 phase (early global brightening), dimming until about 1980 and then brightening again until around 1998.

You can see it in this graph of sunshine at Potsdam.

http://i51.tinypi...3pmb.jpg

UK Sunshine: http://i40.tinypi...fyok.jpg
gregor1
1.7 / 5 (6) Apr 09, 2012
@Stargazer There was an article in New Scientist a few years back that suggested that the scrubbers applied to coal fired power stations and the catalytic converters to car exhausts to reduce acid rain had reduced the aerosols sufficiently to account for the warming in the later part of last century. Being predominantly in the Northern Hemisphere global warming has never been global and this was thought to support this. Maybe someone else has a reference for this. New Scientist has a pretty shoddy reputation these days
Vendicar_Decarian
0.4 / 5 (38) Apr 09, 2012
Given that ConservaTards believe they can ban reality though simple disbelief, it is hardly surprising that they would ask how a Liberal plans to ban such things.

"How do you plan to ban volcanoes and deserts?" - RyggTard

But here in the reality based community we know it isn't possible - yet - to do so.

Provided that ConservaTards don't get their wish to ban science, then mankind will probably advance enough to avert volcanoes and transform deserts.
gregor1
1.7 / 5 (6) Apr 09, 2012
Perhaps, someday, Vendicar Decarian will climb out of the gutter and advance beyond the need to resort to name calling and belligerence.
gregor1
1 / 5 (3) Apr 09, 2012
Any one with an interest in climate science should definitely watch this
http://notrickszo...ia-laws/
rubberman
not rated yet Apr 09, 2012
@ Gregor:
I can't beleive the pure genius behind the AGW skeptics, how could they have seen through the green energy consortiums plan so easily. Does this mean that the secret address on the back of my GEC membership card that tells me the secure location where we are all going to hide after we have thrown the world into chaos with our expensive clean energy....isn't safe anymore? And after decades of pain staking work altering satelite data and temperature records to dupe the world into thinking pollution causes bad s**t to happen to the environment. In one fell swoop you have undermined our entire effort! Kudos to you and your army of righteousness who know that there truly is an unlimited supply of harmless fossil fuel for us to use as we wish. I'm gonna go take the lincoln Navigator for a spin to pick up some organic beer and take a leak on my neighbours solar array....