Global climate models both agree and disagree with actual Antarctic data

May 7, 2008

Scientists who compared recorded Antarctic temperatures and snowfall accumulation to predictions by major computer models of global climate change offer both good and bad news.

The models’ predictions covering the last 50 years broadly follow the actual observed temperatures and snowfall for the southernmost continent, although the observations are very variable.
That’s the good news.

The bad news, however, is that a similar comparison that includes the entire last century is a poor match Projections of temperatures and snowfall ranged from 2.5 to five times what they actually were during that period.

The findings, reported last month in the journal Geophysical Research Letters, suggest that current computer models of the effects of global warming may not work as well for the remote Antarctic regions.

“This doesn’t say that global warming from a planetary perspective is wrong,” argues David Bromwich, professor of geography at Ohio State. “It says nothing about the tropics or the subtropics!

“It does imply that with the ocean north of Antarctica and the continent itself, there are some significant issues with the current climate models.”

Bromwich’s emphasis can be traced back to a preliminary report he gave a year ago at a major national science meeting.

He announced then that an apparent conflict existed between the models’ Antarctic predictions and the actual recorded data. People who deny climate change flocked to the report as evidence that the planet wasn’t at risk, in spite of overwhelming evidence that it is.

“I think the reaction to this new work may be pretty much what it was the last time,” Bromwich said sadly.

In their latest work, Bromwich, Andrew Monaghan, formerly a researcher at Ohio State’s Byrd Polar Research Center, and David Schneider from the National Center for Atmospheric Research, relied on two sets of data. Monaghan has since joined the staff at NCAR.

One set came from observations of snowfall and temperature recorded from Antarctica since the International Geophysical Year a half-century ago. The other consisted of temperature data derived from short ice cores recovered from the continent.

This information was compared to an average taken from five of the major climate change models used by the Intergovernmental Panel on Climate Change (IPCC) for that period. While there are 23 global climate models (GCMs) available, the average of these five provided the best combination for this research.

Most worrisome is the finding that the century-long data set shows temperatures that vary from 2.5 to five times higher than actually occurred, based on the data. The models show a warming of the continent at the global rate, whereas the actual warming is much more muted.

Bromwich and his colleagues think they may know why the predictions vary so much from the records. They’re blaming the errors on water vapor in the atmosphere over the ice.

They suggest that long-wave radiation emitted by water vapor may be heating the ice surface and raising the temperature projected by the models.

“The models predict the water vapor,” Bromwich says, “but we don’t have anything to actually measure the amount of water vapor over the Antarctic continent.

“Regarding water vapor over mainland Antarctica, the models just have to be wrong,” he said.

Bromwich says that the Antarctic climate has not warmed like the rest of the globe due, in part, to the strengthening of winds around the continent. That strengthening is driven by a combination of the Antarctic ozone hole in the stratosphere, greenhouse gas increases and internal climate variability across the continent, he says.

“We don’t know how any of these factors will evolve during the coming century and therefore, there is still considerable uncertainty as to how much warming will occur in Antarctica,” he says.

“Most people are convinced that the warming along the Antarctic Peninsula is due to human influences, but the question is how far south that warming will go, and what effect it will have,” Bromwich says.

Key to this is that if melted, the ice stacked atop the Antarctic continent is enough to raise sea levels 200 feet worldwide. “That question of global sea level rise should be one that is relevant to almost everybody,” he said.

Source: Ohio State University

Explore further: A new primer on climate change

Related Stories

A new primer on climate change

November 15, 2018

Jason Smerdon is coauthor of the newly revised Climate Change: The Science of Global Warming and Our Energy Future. The book is a succinct, non-ideological reference for anyone who wants to understand what we know (and don't) ...

An ice age lasting 115,000 years in two minutes

November 6, 2018

An international research team used a computer model to reconstruct the history of glaciation in the Alps, visualising it in a two-minute computer animation. The simulation aims to enable a better understanding of the mechanisms ...

The secret behind coral reef diversity? Lots of time.

November 6, 2018

Strap on a diving mask and fins and slip under the crystal-clear water near a coral reef in Indonesia, Papua-New Guinea or the Philippines, and you'll immediately see why divers and snorkelers from across the world flock ...

Recommended for you

'True polar wander' may have caused ice age

November 19, 2018

Earth's latest ice age may have been caused by changes deep inside the planet. Based on evidence from the Pacific Ocean, including the position of the Hawaiian Islands, Rice University geophysicists have determined Earth ...

Greenhouse gasses triggering more changes than we can handle

November 19, 2018

A new study published in Nature Climate Change provides one of the most comprehensive assessments yet of how humanity is being impacted by the simultaneous occurrence of multiple climate hazards strengthened by increasing ...

Major natural carbon sink may soon become carbon source

November 19, 2018

Until humans can find a way to geoengineer ourselves out of the climate disaster we've created, we must rely on natural carbon sinks, such as oceans and forests, to suck carbon dioxide out of the atmosphere. These ecosystems ...

Local drivers of amplified Arctic warming

November 19, 2018

Long-term observations of surface temperatures show an intensified surface warming in Canada, Siberia, Alaska and in the Arctic Ocean relative to global mean temperature rise. This warming pattern, commonly referred to as ...


Adjust slider to filter visible comments by rank

Display comments: newest first

3.4 / 5 (7) May 07, 2008
"People who deny climate change flocked to the report as evidence that the planet wasn't at risk, in spite of overwhelming evidence that it is."

I've studied both sides of this issue for school and I'm still skeptical about global warming. I don't think the statement "overwhelming evidence that it is" is very accurate. At least if you're going to make such a claim include some links to solid research or reasons for this "overwhelming evidence."
2.6 / 5 (5) May 07, 2008
Reader411: You want more evidence? The Intergovernmental Panel on Climate Change (IPCC) state "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations" via the greenhouse effect. These basic conclusions have been endorsed by at least thirty scientific societies and academies of science,including all of the national academies of science of the major industrialized countries.While individual scientists have voiced disagreement with some findings of the IPCC, the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.
3.4 / 5 (5) May 07, 2008
I agree Reader411--this very article suggests the the 'evidence' is somewhat vauge. Another article here on Physorg says that cleaner air is no good for the Rain forests! And i read a week or two back that the closing of the ozone hole may cause the arctic to melt faster!Again here on Physorg. I guess the hole was actually good for the ice sheet! So what are we to believe?
Ive said in previous posts, that i dont mind if we investigate other energy sources and move away from fossil fuels...i consider it a normal progression of technology. but im just so tired of the constant cries that the sky is falling!
2.9 / 5 (8) May 07, 2008
Man mad global warming is starting to seem more and more like a scam..... Temps have not risen in the last 10 years.... Temps are suppose to go down in the next 10.... Cimate change models are falling apart... Water vapor seems to be the major contributor to global warming.... I think that we should listen to the quote..... Regarding water vapor over mainland Antarctica, the models just have to be wrong
1.9 / 5 (7) May 07, 2008
Global warming is a self-fulfilling prophecy. The warmer it gets, the more people shout out about it thus releasing more CO2 and hot air.
2.3 / 5 (9) May 07, 2008
What other field publishes reports indicating that other reports contradicting the "preferred finding" may not actually be as contradictory as they appear? Seems like a lot of money must be tied up in the Global Warming Scam - ethanol industry, carbon credit snake oil salesmen, etc...
3.2 / 5 (6) May 07, 2008
So, as many of the AGW deniers have claimed all along, water vapor plays a much bigger role in climate than CO2 does and the importance of CO2 has been overstated!
3 / 5 (8) May 07, 2008
What is apparent is that naysayers are ever hopeful that climate change isn't due to overwhelming air pollution, so they don't have to alter their energy and material consumptive habits.

Newsflash! It doesn't matter a Tinkers Damn whether you believe in climate change or not.

There is undeniable evidence that the global air pollution base level is rising rather quickly. Add to that the steady climb in local air pollutant loading and resultant increase in ground-level oxidants, such as ozone, nitric and sulfuric acids and carbon black particulates that bind and carry these oxidants into your lungs...

Voila! Cumulative respiratory, cardiovascular and neurological damage, neatly coupled to damaged immune system response. The latter results in (a) piss poor infection control barriers at the cell surface in both upper and lower respiratory tract and (b) abnormal inflammatory response.

Climate change may not kill you, but air pollution induced disease will definitely do so. That statistic has been recently reported here, too.
2.7 / 5 (9) May 07, 2008
Not one person has died because of man made global warming... thats a fact. How much money has been spent just talking combating Global warming? How much money has been spent just flying to global warming conferences? If that money would have been spent on infrastructure, or food, or medicine.... how many people could have been saved....

Actually.... I take it back... a lot of people are now facing starvation because of the man made none existant global warming crisis... all the food gone to make ethanol... to solve a problem that didn't exist...

Dont get me wrong.... I am for getting rid of the internal combustion engine... it does pollute real pollution like NO, CO, Ozone, and the like.... but Co2 is normal...
3.4 / 5 (5) May 07, 2008

Actually.... I take it back... a lot of people are now facing starvation because of the man made none existant global warming crisis... all the food gone to make ethanol... to solve a problem that didn't exist...

If you believe that the US ethanol mandate originated from or is politically supported because of global warming fears then you are quite mistaken. Suggest you research the origins of the US ethanol effort - and if you do so you will realize that the policy is based on Agriculture policy, and then to a lesser extent on "energy independence" policy.
3 / 5 (6) May 07, 2008
I think we can all agree that humans do influence the Earth's atmosphere. Releasing countless tons of carbon dioxide combined with some other pollutants does change its chemical composition. Its also pretty obvious that chemical composition influences physical properties like heat capacity etc, those physical properties in term influence climate. Science is 100% certain about the above.

It is also obvious that the climate is changing, what science doesn't known is to what extent human activities are responsible for those climate changes.
Although more evidence seem to indicate that we are responsible for large part of current changes those results are not conclusive.
What we should do is to take acknowledge that we are not sure and work from there.
If global warming IS real and we wont prevent it then we will destabilize Earth's climate and the consequences might be very drastic. Humanity is very susceptible to nature's wrath. Of course its impossible to predict how bad it could be but consequences could be extremely costly both economically and in terms of human lives. it could theoretically lead to another mass extinction.
There are only 4 possibilities:

1. We decide to fight global warming and it proves to be real. This means we are doing the right thing and even though it costs a lot we might prevent much higher losses.

2. We decide to fight global warming and it proves fake. We waste a lot of money.

3. We decide to ignore global warming and it proves to be real. This is the worst case, it could lead to irreperable damage to the environment and future generations would rightly view as as greedy fks who ruined the Earth due to their pervasive greed.

4. We decide to ignore global warming and it proves fake. This is the best scenario as there are no losses and no danger.

If we compare the worst cases in assuming global warming IS and ISN'T real its rather obvious that assuming IT ISN'T real and being wrong carries much higher potential costs then assuming that global warming IS real and being wrong. Thats why I do believe that we should attempt to limit our impact on the environment at least until we know more about the issue.
2.5 / 5 (8) May 08, 2008
"I think we can all agree that humans do influence the Earth's atmosphere."

Classic sophist opening. Also a classically misleading characterisation of the situation, another sophist predilection in ancient times.

Carbon Dioxide levels since the beginning of the Cenozoic some 65 million years ago have varied between about 160 ppm and 4000 ppm. Right now we are running at 380.

When we were up around 4000 ppm the world was covered with forests and there were crocodiles in the arctic ocean. When we're at 160 ppm, which we have been dozens of times in the past few millions of years, you get ice a mile thick down to about 50 degrees north latitude and every mountain range above a mile high glacier locked regardless of where it is.

The real question is where do you want us to be between those two extremes. Biodiversity was in little danger at 4000 ppm. I'll let you decide for yourself if it was in danger at 160 ppm.
3 / 5 (4) May 08, 2008
plaasjaapie- 65 million years ago, when the CO2 levels were in the 4000 ppm range, there was NO ice on the planet! In the last 25 mil years, CO2 levels have never been above 400 ppm. So the 4000 ppm figure is hardly a reliable figure to argue against man-made climate change. Remember: NO ICE!
2.8 / 5 (4) May 09, 2008
>"I think we can all agree that humans do influence the Earth's atmosphere."
>Classic sophist opening. Also a classically misleading characterisation of the situation, another sophist predilection in ancient times.

Even if humanity converts a single atom of free carbon to CO2 and releases it to atmosphere then humanity is "influencing the Earth's atmosphere".
This is extreme case of course but maybe it will help you understand that this statement is not really debatable.
We are influencing the atmosphere cause we release gasses, their atmospheric concentration has NOTHING to do with it since our influence combines with natural shifts.
1 / 5 (1) Sep 25, 2008
Sound pretty sophist to try to teach people raising CO2 level 35% is without consequences.

Its inconsistent with the scientific knowledge we have so far.

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

Click here to reset your password.
Sign in to get notified via email when new comments are made.