Has global warming research misinterpreted cloud behavior?

Jun 09, 2008

Climate experts agree that the seriousness of manmade global warming depends greatly upon how clouds in the climate system respond to the small warming tendency from the extra carbon dioxide mankind produces.

To figure that out, climate researchers usually examine natural, year-to-year fluctuations in clouds and temperature to estimate how clouds will respond to humanity¹s production of greenhouse gases.

When researchers observe natural changes in clouds and temperature, they have traditionally assumed that the temperature change caused the clouds to change, and not the other way around. To the extent that the cloud changes actually cause temperature change, this can ultimately lead to overestimates of how sensitive Earth's climate is to our greenhouse gas emissions.

This seemingly simple mix-up between cause and effect is the basis of a new paper that will appear in the Journal of Climate. The paper's lead author, Dr. Roy W. Spencer, a principal research scientist at The University of Alabama in Huntsville, believes the work is the first step in demonstrating why climate models produce too much global warming.

Spencer and his co-author, principal research scientist William (Danny) Braswell, used a simple climate model to demonstrate that something as seemingly innocuous as daily random variations in cloud cover can cause year-to-year variation in ocean temperature that looks like -- but isn't -- "positive cloud feedback," a warmth-magnifying process that exists in all major climate models.

"Our paper is an important step toward validating a gut instinct that many meteorologists like myself have had over the years," said Spencer, "that the climate system is dominated by stabilizing processes, rather than destabilizing processes -- that is, negative feedback rather than positive feedback."

The paper doesn't disprove the theory that global warming is manmade.

Instead, it offers an alternative explanation for what we see in the climate system which has the potential for greatly reducing estimates of mankind's impact on Earth's climate.

"Since the cloud changes could conceivably be caused by known long-term modes of climate variability -- such as the Pacific Decadal Oscillation, or El Nino and La Nina -- some, or even most, of the global warming seen in the last century could simply be due to natural fluctuations in the climate system," Spencer said.

While the paper's two peer reviewers, both climate model experts, agreed that the issue is a legitimate one, Spencer knows the new paper will be controversial, with some claiming that the impact of the mix-up between cause and effect will be small.

"But we really won't know until much more work is done," Spencer said.

"Unfortunately, so far we have been unable to figure out a way to separate cause and effect when observing natural climate variability. That's why most climate experts don't like to think in terms of causality, and instead just examine how clouds and temperature vary together.

"Our work has convinced me that cause and effect really do matter. If we get the causation wrong, it can greatly impact our interpretation of what nature has been trying to tell us. Unfortunately, in the process it also makes the whole global warming problem much more difficult to figure out."

Source: University of Alabama

Explore further: Shell files new plan to drill in Arctic

add to favorites email to friend print save as pdf

Related Stories

Climate change: meteorologists preparing for the worst

Aug 21, 2014

Intense aerial turbulence, ice storms and scorching heatwaves, huge ocean waves—the world's climate experts forecast apocalyptic weather over the coming decades at a conference in Montreal that ended Thursday.

In-depth study examines air quality in metro Phoenix

Aug 07, 2014

Air can be considered a great equalizer – we all have to breathe it. Arizona State University faculty member Tom Cahill is interested in adding to our knowledge base of air quality in metropolitan Phoenix, ...

Study of aerosols stands to improve climate models

Aug 04, 2014

(Phys.org) —Aerosols, tiny particles in the atmosphere, play a significant role in Earth's climate, scattering and absorbing incoming sunlight and affecting the formation and properties of clouds. Currently, ...

Recommended for you

Shell files new plan to drill in Arctic

Aug 29, 2014

Royal Dutch Shell has submitted a new plan for drilling in the Arctic offshore Alaska, more than one year after halting its program following several embarrassing mishaps.

Reducing water scarcity possible by 2050

Aug 29, 2014

Water scarcity is not a problem just for the developing world. In California, legislators are currently proposing a $7.5 billion emergency water plan to their voters; and U.S. federal officials last year ...

User comments : 14

Adjust slider to filter visible comments by rank

Display comments: newest first

RAL
3.6 / 5 (13) Jun 10, 2008
"...the climate system is dominated by stabilizing processes, rather than destabilizing processes..."

Now this sounds like science. I salute the courage of those willing to speak out against the oppressive demands for conformity on AGW. Based on the flimsiest evidence and the advantage to certain groups we are about to stifle the US and global economy. It's time to step back and let cooler heads prevail.
gmurphy
2 / 5 (12) Jun 10, 2008
"Based on the flimsiest evidence". What planet have you been living on?. Glaciers the world over have receded while the level of solar output has diminished. We're heating up but getting less energy from the sun, please explain how this is flimsy?, let me guess, it sounds like science when it agrees with you own conclusions?, I cannot understand why people treat climate change with such suspicion, read this document : www.ipcc.ch/pdf/a...-spm.pdf
adam81
3.5 / 5 (13) Jun 10, 2008
"Based on the flimsiest evidence". What planet have you been living on?. Glaciers the world over have receded while the level of solar output has diminished. We're heating up but getting less energy from the sun, please explain how this is flimsy?, let me guess, it sounds like science when it agrees with you own conclusions?, I cannot understand why people treat climate change with such suspicion, read this document : www.ipcc.ch/pdf/a...-spm.pdf


Let me ask you something.

Has the world been baked to a crisp and risen dramatically in temperature every time a volcano has erupted?
gmurphy
3.3 / 5 (12) Jun 10, 2008
no, in fact volcanic eruptions are usually followed by global drops in temperature, 1816 was known as the year without a summer, caused by massive volcanic eruptions globally, read this wiki article : http://en.wikiped...a_Summer

Its not to hard to find out more information about these things on the web, try it some time.
adam81
3.2 / 5 (13) Jun 10, 2008
Exactly, and the amount of CO2 dumped into the atmospehre after a volcano eruption is in the order of a million times as much as all human activity since we began using fossil fuels, so how pray tell does our meagre contribution make a difference?
adam81
3.2 / 5 (13) Jun 10, 2008
Oops, it would appear I made that up!
ppnl
3.4 / 5 (10) Jun 10, 2008

"Exactly, and the amount of CO2 dumped into the atmospehre after a volcano eruption is in the order of a million times as much as all human activity since we began using fossil fuels,..."

Uh, no. CO2 produced by humans in a year is like 150 times all the CO2 produced by volcanoes in that year. You are a victim of a piece of viral nonsense.

adam81
3.1 / 5 (8) Jun 10, 2008
I beat you too it! lol
agg
2.8 / 5 (6) Jun 10, 2008
Turbulence is still one of the most highly intractable problems in physics. The lacking ability to treat this problem spells disaster for weather models. Any conclusion drawn from a weather model is likely flawed. But weather models is where the global warming seems to be championed. Then the "tiger in the woods" people run amok with their hands in the air because everywhere they look the sky is
falling.
x646d63
3.1 / 5 (9) Jun 10, 2008
Global warming is a hoax designed by industry and government to detract from real environmental concerns. The study of "global warming" is so incredibly complex that the cause simply won't ever be demonstrable either way. However, demonstrating that toxins and dangerous chemicals pollute our waterways and food supplies is easy and obvious, but industry and the government don't want any attention there.
Glis
1.6 / 5 (5) Jun 10, 2008
I think we've got much larger concerns than an abundance of plantfood in the atmosphere. Something about chemtrails... flame on.
DavidB_Benson
4.5 / 5 (2) Jun 14, 2008
Actual knowledge about climatology can be obtained by reading "The Discovery of Global Warming" by Spencer Weart:

http://www.aip.or...dex.html

The most importatn part of the main article is

"But we really won't know until much more work is done," Spencer said.

Which is in reference to the cause-effect relationship, ralated to the MJO, he claims to have found. Whichever way, the result for climatology is very small and cannot readjust know results from the palsoclimate record.
jerryd
not rated yet Jul 25, 2009

While you deniers can say what you want, the earth is warming as plants, animals move north and soon all the glaciers will have melted stopping the flows to many river systems which will seriously cut food production.

While I'm not fond of some of the science of GW, it is undeniably happening. While CO2 isn't as large a factor I believe we still need to tax fossil fuels, cut their use for health, national/economic security reasons.

To not tax them, especially oil to pay the costs of the Persian Gulf military and oil wars costs and giving our enemies like Iran, Russia, oil dictators and terrorist $1T in 2 yrs if we don't I think is treason. Better our gov tax it and give us tax breaks and help switching to more eff and alt energy sources than big oil, our enemies get it. Coal's costs are just as bad though from poisoning, destroying everything from land, water and air.

For instance I'd like to see a halt to jets flying above 28k' for a week or month to see what the lack of contrails does to the weather, GW.
jerryd
not rated yet Jul 25, 2009

I forgot to mention CO2 acidifying the oceans is a huge threat.