Featured Research

from universities, journals, and other organizations

Has Global Warming Research Misinterpreted Cloud Behavior?

Date:
June 12, 2008
Source:
University of Alabama Huntsville
Summary:
When researchers observe natural changes in clouds and temperature, they have assumed that temperature change caused the clouds to change, and not the other way around. This can lead to overestimates of how sensitive Earth's climate is to greenhouse gas emissions.

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. Researchers have traditionally assumed that temperature changes have caused clouds to change, but now there is reason to think that the cause-effect relationship is not so simple, and could even be reversed.
Credit: iStockphoto

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 paper¹s 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."


Story Source:

The above story is based on materials provided by University of Alabama Huntsville. Note: Materials may be edited for content and length.


Cite This Page:

University of Alabama Huntsville. "Has Global Warming Research Misinterpreted Cloud Behavior?." ScienceDaily. ScienceDaily, 12 June 2008. <www.sciencedaily.com/releases/2008/06/080611184722.htm>.
University of Alabama Huntsville. (2008, June 12). Has Global Warming Research Misinterpreted Cloud Behavior?. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/2008/06/080611184722.htm
University of Alabama Huntsville. "Has Global Warming Research Misinterpreted Cloud Behavior?." ScienceDaily. www.sciencedaily.com/releases/2008/06/080611184722.htm (accessed September 22, 2014).

Share This



More Earth & Climate News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Will Climate Rallies Spur Change?

Will Climate Rallies Spur Change?

Newsy (Sep. 21, 2014) — Organizers of the People's Climate March and other rallies taking place in 166 countries hope to move U.N. officials to action ahead of their summit. Video provided by Newsy
Powered by NewsLook.com
Thousands March in NYC Over Climate Change

Thousands March in NYC Over Climate Change

AP (Sep. 21, 2014) — Accompanied by drumbeats, wearing costumes and carrying signs, thousands of demonstrators filled the streets of Manhattan and other cities around the world on Sunday to urge policy makers to take action on climate change. (Sept. 21) Video provided by AP
Powered by NewsLook.com
Climate Change Rally Held in India Ahead of UN Summit

Climate Change Rally Held in India Ahead of UN Summit

AFP (Sep. 20, 2014) — Some 125 world leaders are expected to commit to action on climate change at a UN summit Tuesday called to inject momentum in struggling efforts to tackle global warming. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) — Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins