Subscribe free to our newsletters via your
. Earth Science News .




Subscribe free to our newsletters via your




















CLIMATE SCIENCE
Models, observations not so far apart on planet's response to greenhouse gas emissions
by Staff Writers
Seattle WA (SPX) Apr 18, 2017


File image.

How hot our planet will become for a given amount of greenhouse gases is a key number in climate change. As the calculation of how much warming is locked in by a given amount of emissions, it is crucial for global policies to curb global warming.

It is also one of the most hotly debated numbers in climate science. Observations in the past decade seem to suggest a value that is lower than predicted by models. But a University of Washington study shows that two leading methods for calculating how hot the planet will get are not as far apart as they have appeared.

In climate science, the climate sensitivity is how much the surface air temperature will increase if you double carbon dioxide from pre-Industrial levels and then wait a very long time for the Earth's temperature to fully adjust. Recent observations predicted that the climate sensitivity might be less than that suggested by models.

The new study, published April 17 in Nature Climate Change, focuses on the lag time in Earth's response. According to most models of climate change, during the early stages of global warming the sensitivity to greenhouse gas emissions is relatively small.

As the ocean catches up and feedbacks kick in, however, the sensitivity increases and the warming rate speeds up. The new study shows that when this difference is factored in, the observations and climate models are in agreement, with recent observations supporting a previously accepted long-term climate sensitivity of about 2.9 degrees Celsius.

"The key is that you have to compare the models to the observations in a consistent way," said author Kyle Armour, a UW assistant professor of oceanography and atmospheric sciences. "This apples-to-apples approach - where you factor in how long the planet has been adjusting to a change in its atmosphere - shows that climate sensitivity in the models is actually in line with what has been seen in the recent observations."

The planet's temperature takes thousands of years to fully adjust to a shift in the makeup of its atmosphere - the warming Earth has experienced to date is just a taste of what is in store. Early climate studies suggested that if the amount of carbon dioxide in the atmosphere doubled from pre-Industrial levels (we're now about 1.4 times) the planet would eventually warm by about 3 degrees C, with possible values as high as 5 or 6 degrees C.

But recent observations of warming so far and emissions to date have suggested that climate sensitivity may be just under 2 degrees Celsius, with a maximum possible value of 4 degrees C.

"If true, this really would be a shift in our understanding of the long-term climate sensitivity," Armour said.

For the new study, Armour looked at 21 leading global climate models run with increasing carbon dioxide. He focused on the warming rate compared to carbon dioxide levels, or climate sensitivity, in the early stages compared with in the late stages. The late-stage sensitivity across all the models was an average of 26 percent higher than the early-stage values. When factoring in that today's observations are for the early stages of warming, the recent observations support a climate sensitivity of 2.9 degrees Celsius.

"There have been a lot of other papers that looked at the reasons for the changes in climate sensitivity over time," Armour said. "This paper was the first attempt to quantify the effect across all the comprehensive models we use for climate prediction."

The situation can be likened to pressing the gas pedal on a car, but the mass of the vehicle takes a while to get rolling. If the driver floors the gas pedal, it can be tricky to calculate the car's final speed based on its initial reaction.

In the Earth system, the ocean temperatures around Antarctica and in the eastern Pacific Ocean have not risen in recent decades. Armour's previous research showed that deep, slow currents mean seawater touched by climate change will take centuries to reach the surface of the Southern Ocean. Similar but less extreme, currents reaching the eastern tropical Pacific from below the surface have also not seen daylight for decades.

Eventually, water touched by a warmer atmosphere will reach the eastern tropical Pacific and later the Southern Ocean. Warming in these regions will then activate feedbacks that will kick the planet's warming into a higher gear. "Currently we don't have any evidence that the models are too sensitive compared to the observations," Armour said. "The models appear to be in line with the observed range of warming."

The various climate models show a wide range of values between the early-stage and late-stage sensitivities. Armour and students are exploring why these differences between the models exist, in order to improve them and better model how climate sensitivity shifts over time.

Research paper

CLIMATE SCIENCE
Performance of the RegCM4 regional climate model over China
Beijing, China (SPX) Apr 10, 2017
The RegCM series of models are widely used throughout the world and in China. Applications range from paleo and present-day climate simulation, to mechanistic analyses, studies of atmospheric chemistry and aerosols, and climate change projections. The model is currently developed and maintained at the Abdus Salam International Centre for Theoretical Physics, with the latest version RegCM4. ... read more

Related Links
University of Washington
Climate Science News - Modeling, Mitigation Adaptation

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

CLIMATE SCIENCE
Glowing bacteria detect buried landmines

Mosul zoo lion and bear flown out of Iraq

World's oldest dental fillings found in Italy

US says ending UN mission in Haiti is a 'strong example'

CLIMATE SCIENCE
Despite EU fines, Greece struggling to promote recycling

New method for 3-D printing extraterrestrial materials

Ultra-thin multilayer film for next-generation data storage and processing

USC Viterbi researchers develop new class of optoelectronic materials

CLIMATE SCIENCE
Into the DNA of a coral reef predator

Guinea seizes shark fins from Chinese ships

New England's glacial upland soils provide major groundwater storage reservoir

Catch shares slow the 'race to fish'

CLIMATE SCIENCE
Researchers unravel the drivers of large iceberg movement

Polar glaciers may be home to previously undiscovered carbon cycle

Warm Atlantic waters contribute to sea ice decline

Permafrost more vulnerable than thought: scientists

CLIMATE SCIENCE
To save honey bees, human behavior must change

So sheep may safely graze

Fungus uses light to invade, attack wheat plants

Colombia forces struggle to root out coca

CLIMATE SCIENCE
Houses damaged as strong quake hits south Philippines

Antarctic penguin colony repeatedly decimated by volcanic eruptions

At least 35 dead in Iran floods; Quake rattles northern Chile

Developing a microinsurance plan for California earthquakes

CLIMATE SCIENCE
Four dead in army, police clashes in Nigeria: source

Three killed in Mogadishu army camp attack: military

El Nino can warn on cholera outbreaks in Africa: study

Five dead in jihadist attack in Mali

CLIMATE SCIENCE
Putting social science modeling through its paces

Study reveals 10,000 years of genetic continuity in northwest North America

Married couples with shared ancestry tend to have similar genes

Researchers uncover prehistoric art and ornaments from Indonesian 'Ice Age'




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement