The effects of Antarctic water vapor have been overestimated.

===

Climate Models Overheat Antarctica

WASHINGTON--Computer analyses of global climate have consistently
overstated warming in Antarctica, concludes a new study. The findings
can help scientists improve computer models and determine if the
southernmost continent will warm significantly this century, a major
research question because of Antarctica's potential impact on global
sea-level rise.

"We can now compare computer simulations with observations of actual
climate trends in Antarctica," says Andrew Monaghan of the National
Center for Atmospheric Research (NCAR) in Boulder, Colo., lead author of
the study. "This is showing us that, over the past century, most of
Antarctica has not undergone the fairly dramatic warming that has
affected the rest of the globe. The challenges of studying climate in
this remote environment make it difficult to say what the future holds
for Antarctica's climate."

The study marks the first time that scientists have been able to compare
the past 50 to 100 years of Antarctic climate with simulations run on
computer models. The models are a primary method for researchers to
project future climate. Scientists have used atmospheric observations to
confirm that computer models are accurately simulating climate for the
other six continents.

Antarctica's climate is of worldwide interest, in part because of the
enormous water locked up in its ice sheets. If those vast ice sheets
were to begin to melt, sea level could rise across the globe and
inundate low-lying coastal areas. Yet, whereas climate models accurately
simulate the last century of warming for the rest of the world, they
have unique challenges simulating Antarctic climate because of limited
information about the continent's harsh weather patterns.

Monaghan and his colleagues at NCAR and Ohio State University, in Columbus,
published their findings last month in Geophysical Research Letters, a
journal of the American Geophysical Union (AGU).

The authors compared recently constructed temperature data sets from
Antarctica, based on data from ice cores and ground weather stations, to
twentieth century simulations from computer models used by scientists to
simulate global climate. While the observed Antarctic temperatures rose
by about 0.2 degrees Celsius (0.4 degrees Fahrenheit) over the past
century, the climate models simulated increases in Antarctic
temperatures during the same period of 0.75 degrees C (1.4 degrees F).
The error appeared to be caused by models overestimating the amount of
water vapor in the Antarctic atmosphere, the new study concludes.

The models, however, have correctly captured trends in Antarctic snowfall,
including increases in snowfall in the late twentieth century, prior to
a decrease over the last decade.

Part of the reason that Antarctica has barely warmed has to do with the
ozone hole over the continent. The lack of ozone is chilling the middle
and upper atmosphere, altering wind patterns in a way that keeps
comparatively warm air from reaching the surface. Unlike the rest of the
continent, the Antarctic Peninsula has warmed by several degrees, in
part because the winds there are drawing in warmer air from the north.

The study delivered a mixed verdict on Antarctica's potential impact on
sea-level rise. The Intergovernmental Panel on Climate Change, which
operates under the auspices of the United Nations, has estimated that
sea-level rise could amount to 18 to 59 centimeters (7 to 23 inches)
this century, in part because of melting glaciers worldwide. The new
findings suggest that other effects of warming in Antarctica over the
next century could reduce that by about 5 centimeter (2 inches) if the
continent warms by 3 degrees C (5.4 degrees F) as computer models have
indicated. The reason is that the warmer air over Antarctica would hold
more moisture and generate more snowfall, thereby locking up additional
water in the continent's ice sheets.

But the authors caution that model projections of future Antarctic
climate may be unreliable.

"The research clearly shows that you can actually slow down sea-level
rise when you increase temperatures over Antarctica because snowfall
increases, but warmer temperatures also have the potential to speed up
sea-level rise due to enhanced melting along the edges of Antarctica,"
says Monaghan, who did some of his research at Ohio State University
before going to NCAR. "Over the next century, whether the ice sheet
grows from increased snowfall or shrinks due to more melt will depend on
how much temperatures increase in Antarctica, and potentially on erosion
at the ice sheet edge by the warmer ocean and rising sea level."

"The current generation of climate models has improved over previous
generations, but still leaves Antarctic surface temperature projections
for the twenty-first century with a high degree of uncertainty," adds
co-author and NCAR scientist David Schneider. "On a positive note, this
study points out that water vapor appears to be the key cause of the
problematic Antarctic temperature trends in the models, which will guide
scientists as they work to improve the climate simulations."

This study was funded by National Science Foundation and by the
Department of Energy.

**********

Images:
Available for download at
http://www.ucar.edu/news/releases/2008/antarctica.jsp
are a color map of Antarctica showing warming and cooling trends and a
photo of researcher Andrew Monaghan.

Title:
"Twentieth century Antarctic air temperature and snowfall simulations by
IPCC climate models"

Authors:
Andrew J. Monaghan and David H. Bromwich: Polar Meteorology Group, Byrd
Polar Research Center, Ohio State University, Columbus, Ohio, USA.; Bromwich
also with Atmospheric Sciences Program, Department of Geography, Ohio State
University, Columbus, Ohio, USA;

David P. Schneider: Climate and Global Dynamics Division, National
Center for Atmospheric Research, Boulder, Colorado, USA.

Citation:
Monaghan, A. J., D. H. Bromwich, and D. P. Schneider (2008), Twentieth
century Antarctic air temperature and snowfall simulations by IPCC climate
models, Geophys. Res. Lett., 35, L07502, doi:10.1029/2007GL032630.

On Thu, 08 May 2008 09:14:01 -0500, pseudomodo
wrote:

The effects of Antarctic water vapor have been overestimated.

===

Climate Models Overheat Antarctica

WASHINGTON--Computer analyses of global climate have consistently
overstated warming in Antarctica, concludes a new study. The findings
can help scientists improve computer models and determine if the
southernmost continent will warm significantly this century, a major
research question because of Antarctica's potential impact on global
sea-level rise.

"We can now compare computer simulations with observations of actual
climate trends in Antarctica," says Andrew Monaghan of the National
Center for Atmospheric Research (NCAR) in Boulder, Colo., lead author of
the study. "This is showing us that, over the past century, most of
Antarctica has not undergone the fairly dramatic warming that has
affected the rest of the globe. The challenges of studying climate in
this remote environment make it difficult to say what the future holds
for Antarctica's climate."

The study marks the first time that scientists have been able to compare
the past 50 to 100 years of Antarctic climate with simulations run on
computer models. The models are a primary method for researchers to
project future climate. Scientists have used atmospheric observations to
confirm that computer models are accurately simulating climate for the
other six continents.

Antarctica's climate is of worldwide interest, in part because of the
enormous water locked up in its ice sheets. If those vast ice sheets
were to begin to melt, sea level could rise across the globe and
inundate low-lying coastal areas. Yet, whereas climate models accurately
simulate the last century of warming for the rest of the world, they
have unique challenges simulating Antarctic climate because of limited
information about the continent's harsh weather patterns.

Monaghan and his colleagues at NCAR and Ohio State University, in Columbus,
published their findings last month in Geophysical Research Letters, a
journal of the American Geophysical Union (AGU).

The authors compared recently constructed temperature data sets from
Antarctica, based on data from ice cores and ground weather stations, to
twentieth century simulations from computer models used by scientists to
simulate global climate. While the observed Antarctic temperatures rose
by about 0.2 degrees Celsius (0.4 degrees Fahrenheit) over the past
century, the climate models simulated increases in Antarctic
temperatures during the same period of 0.75 degrees C (1.4 degrees F).
The error appeared to be caused by models overestimating the amount of
water vapor in the Antarctic atmosphere, the new study concludes.

The models, however, have correctly captured trends in Antarctic snowfall,
including increases in snowfall in the late twentieth century, prior to
a decrease over the last decade.

Part of the reason that Antarctica has barely warmed has to do with the
ozone hole over the continent. The lack of ozone is chilling the middle
and upper atmosphere, altering wind patterns in a way that keeps
comparatively warm air from reaching the surface. Unlike the rest of the
continent, the Antarctic Peninsula has warmed by several degrees, in
part because the winds there are drawing in warmer air from the north.

The study delivered a mixed verdict on Antarctica's potential impact on
sea-level rise. The Intergovernmental Panel on Climate Change, which
operates under the auspices of the United Nations, has estimated that
sea-level rise could amount to 18 to 59 centimeters (7 to 23 inches)
this century, in part because of melting glaciers worldwide. The new
findings suggest that other effects of warming in Antarctica over the
next century could reduce that by about 5 centimeter (2 inches) if the
continent warms by 3 degrees C (5.4 degrees F) as computer models have
indicated. The reason is that the warmer air over Antarctica would hold
more moisture and generate more snowfall, thereby locking up additional
water in the continent's ice sheets.

But the authors caution that model projections of future Antarctic
climate may be unreliable.

"The research clearly shows that you can actually slow down sea-level
rise when you increase temperatures over Antarctica because snowfall
increases, but warmer temperatures also have the potential to speed up
sea-level rise due to enhanced melting along the edges of Antarctica,"
says Monaghan, who did some of his research at Ohio State University
before going to NCAR. "Over the next century, whether the ice sheet
grows from increased snowfall or shrinks due to more melt will depend on
how much temperatures increase in Antarctica, and potentially on erosion
at the ice sheet edge by the warmer ocean and rising sea level."

"The current generation of climate models has improved over previous
generations, but still leaves Antarctic surface temperature projections
for the twenty-first century with a high degree of uncertainty," adds
co-author and NCAR scientist David Schneider. "On a positive note, this
study points out that water vapor appears to be the key cause of the
problematic Antarctic temperature trends in the models, which will guide
scientists as they work to improve the climate simulations."

This study was funded by National Science Foundation and by the
Department of Energy.

**********

Images:
Available for download at
http://www.ucar.edu/news/releases/2008/antarctica.jsp
are a color map of Antarctica showing warming and cooling trends and a
photo of researcher Andrew Monaghan.

Title:
"Twentieth century Antarctic air temperature and snowfall simulations by
IPCC climate models"

Authors:
Andrew J. Monaghan and David H. Bromwich: Polar Meteorology Group, Byrd
Polar Research Center, Ohio State University, Columbus, Ohio, USA.; Bromwich
also with Atmospheric Sciences Program, Department of Geography, Ohio State
University, Columbus, Ohio, USA;

David P. Schneider: Climate and Global Dynamics Division, National
Center for Atmospheric Research, Boulder, Colorado, USA.

Citation:
Monaghan, A. J., D. H. Bromwich, and D. P. Schneider (2008), Twentieth
century Antarctic air temperature and snowfall simulations by IPCC climate
models, Geophys. Res. Lett., 35, L07502, doi:10.1029/2007GL032630.

AFAIK a sizable chunk of antarctica has floated away
recently. What does the computer say about that?
(Won't raise sea level of course, but won't reflect
sunlight anymore either.)

Also the alaskan tundra is melting, so native villages
are sinking into the mud. Glaciers are receeding at
an increasing rate. The snow pack in the rockies that
supports the south western desert is at record low
levels. What says the computer?

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.

It's a blessing we have computer models to explain
everything both ways and in the middle. In the 50's
at the dawn of the computer age, folks feared that
computers were smarter than people and would
take over everything. They were damn right.

Is it raining?
Hell, don't ask me. Ask your computer.

Keynes wrote:

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.

Good point, Keynes. I knew I could count on ya....

And, perhaps almost predictably, my answer (verified by the simplest of
empirical evidence that's so clear that even a kid - or even DharmaTroll
- can't miss it) is:

Soot, baby. Soot.

It's messing up the Boreal north - the subArctic, the pole & Greenland,
pouring out of diesel motors & coal-burning power plants.

http://www.sciam.com/article.cfm?id=...he-driven-snow

Look at the iceberg. It's black!

http://www.scienceagogo.com/news/200...runc_sys.shtml

It's the 800 lb gorilla sitting in the middle of the climatology
profession, and they're researching it like mad while the media is
keeping mostly mum about it. It's the most bizarre thing I've ever seen.

When NYT readers found out about the effects of soot on the Arctic, they
started hammering the journalist to cut the CO2 bull**** out and come
straight with them. No response.

Here's something to ponder: If a methane tipping point is a risk, then
the sootfall on the Siberian tundra could get us there FAST. Wasting
money on CO2 solutions that don't work won't fix our most pressing
problem. So either it's a feigned risk, or CO2 politics is wildly
misdirecting the science and public policies in a stupid and dangerous way.

/leebert

On Thu, 08 May 2008 12:22:50 -0500, pseudomodo
wrote:

Keynes wrote:

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.

Good point, Keynes. I knew I could count on ya....

And, perhaps almost predictably, my answer (verified by the simplest of
empirical evidence that's so clear that even a kid - or even DharmaTroll
- can't miss it) is:

Soot, baby. Soot.

It's messing up the Boreal north - the subArctic, the pole & Greenland,
pouring out of diesel motors & coal-burning power plants.

http://www.sciam.com/article.cfm?id=...he-driven-snow

Look at the iceberg. It's black!

http://www.scienceagogo.com/news/200...runc_sys.shtml

It's the 800 lb gorilla sitting in the middle of the climatology
profession, and they're researching it like mad while the media is
keeping mostly mum about it. It's the most bizarre thing I've ever seen.

When NYT readers found out about the effects of soot on the Arctic, they
started hammering the journalist to cut the CO2 bull**** out and come
straight with them. No response.

Here's something to ponder: If a methane tipping point is a risk, then
the sootfall on the Siberian tundra could get us there FAST. Wasting
money on CO2 solutions that don't work won't fix our most pressing
problem. So either it's a feigned risk, or CO2 politics is wildly
misdirecting the science and public policies in a stupid and dangerous way.

/leebert

Dirty river ice isn't the cause of early thaws.
Soot isn't the cause of a dwindling rocky mt snowpack.
The receeding glaciers are not black. In fact, apart from
that picture, I haven't seen the arctic painted black at all.

This winter careless snow removers left a pile that
turned to ice in my mom's driveway, keeping her
from moving her car. We had no tools, but I
blackened the ice to make it melt. It didn't
do much good in the seven days I was there.

The article says soot in the air causes cooling?
And then it falls on the snow causing warming?
What is the net effect? Ask your favorite computer
modeler. (I think they're like an accountant I hired.
I asked him how much was 2 times 2. He locked the
door and pulled down the shades and whispered,
"How much do you want it to be?")

Things are happening that haven't happened before.
Serious things. More severe storms in unlikely places,
more drought, northern migration of tropical species.
Inertia is not a good strategy IMO.

And as far as I know, fire is not a new technology
that is suddenly turning the climate upside down.

Ya can't baffle me with numbers.
I can't understand numbers anyway. 8-P

Keynes wrote:
On Thu, 08 May 2008 12:22:50 -0500, pseudomodo
wrote:

Keynes wrote:

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.
Good point, Keynes. I knew I could count on ya....

And, perhaps almost predictably, my answer (verified by the simplest of
empirical evidence that's so clear that even a kid - or even DharmaTroll
- can't miss it) is:

Soot, baby. Soot.

It's messing up the Boreal north - the subArctic, the pole & Greenland,
pouring out of diesel motors & coal-burning power plants.

http://www.sciam.com/article.cfm?id=...he-driven-snow

Look at the iceberg. It's black!

http://www.scienceagogo.com/news/200...runc_sys.shtml

It's the 800 lb gorilla sitting in the middle of the climatology
profession, and they're researching it like mad while the media is
keeping mostly mum about it. It's the most bizarre thing I've ever seen.

When NYT readers found out about the effects of soot on the Arctic, they
started hammering the journalist to cut the CO2 bull**** out and come
straight with them. No response.

Here's something to ponder: If a methane tipping point is a risk, then
the sootfall on the Siberian tundra could get us there FAST. Wasting
money on CO2 solutions that don't work won't fix our most pressing
problem. So either it's a feigned risk, or CO2 politics is wildly
misdirecting the science and public policies in a stupid and dangerous way.

/leebert

Dirty river ice isn't the cause of early thaws.
Soot isn't the cause of a dwindling rocky mt snowpack.
The receeding glaciers are not black. In fact, apart from
that picture, I haven't seen the arctic painted black at all.

This winter careless snow removers left a pile that
turned to ice in my mom's driveway, keeping her
from moving her car. We had no tools, but I
blackened the ice to make it melt. It didn't
do much good in the seven days I was there.

The article says soot in the air causes cooling?
And then it falls on the snow causing warming?
What is the net effect? Ask your favorite computer
modeler. (I think they're like an accountant I hired.
I asked him how much was 2 times 2. He locked the
door and pulled down the shades and whispered,
"How much do you want it to be?")

Things are happening that haven't happened before.
Serious things. More severe storms in unlikely places,
more drought, northern migration of tropical species.
Inertia is not a good strategy IMO.

And as far as I know, fire is not a new technology
that is suddenly turning the climate upside down.

Ya can't baffle me with numbers.
I can't understand numbers anyway. 8-P



I understand. CO2-driven warming alone can't do all that. Some of that
is, well, just weather. The rest is a trend & I've heard it from other
people.

Large amts. of airborne soot can cause weird winter mega-storms, as well
as many of the things you describe. The soot-driven Arctic thaw plays a
huge role, b/c the ice is not longer there to reflect sunlight back into
space.

The soot studies are getting around, in a quiet way. The research teams
are field-validating testimonies made before Congress. They know they're
working against some big politics.

China just announced their next 10-year plan, work rules, minimum wages
and environmental cleanup.

/leebert

"pseudomodo" wrote in message
news:kPadnVKqWeZ0q77VnZ2dnUVZ_r-vnZ2d@grandecom...
Keynes wrote:

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.

Good point, Keynes. I knew I could count on ya....

And, perhaps almost predictably, my answer (verified by the simplest of
empirical evidence that's so clear that even a kid - or even DharmaTroll -
can't miss it) is:

Soot, baby. Soot.

It's messing up the Boreal north - the subArctic, the pole & Greenland,
pouring out of diesel motors & coal-burning power plants.

http://www.sciam.com/article.cfm?id=...he-driven-snow

Look at the iceberg. It's black!

http://www.scienceagogo.com/news/200...runc_sys.shtml

It's the 800 lb gorilla sitting in the middle of the climatology
profession, and they're researching it like mad while the media is keeping
mostly mum about it. It's the most bizarre thing I've ever seen.

When NYT readers found out about the effects of soot on the Arctic, they
started hammering the journalist to cut the CO2 bull**** out and come
straight with them. No response.

Here's something to ponder: If a methane tipping point is a risk, then the
sootfall on the Siberian tundra could get us there FAST. Wasting money on
CO2 solutions that don't work won't fix our most pressing problem. So
either it's a feigned risk, or CO2 politics is wildly misdirecting the
science and public policies in a stupid and dangerous way.

/leebert

It is a brain plasticity theory that neurons that wire together fire
together in the brain. It only takes about three weeks for new neurons to
grow. After months of being inundated with the soot theory - I now associate
global warming and soot if I think about either one. It would be OK, but I'm
not absolutely and completely sure that lee is well - either incredibly
intelligent and insightful, or insane. Kitty

KittyP wrote:
"pseudomodo" wrote in message
news:kPadnVKqWeZ0q77VnZ2dnUVZ_r-vnZ2d@grandecom...
Keynes wrote:

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.
Good point, Keynes. I knew I could count on ya....

And, perhaps almost predictably, my answer (verified by the simplest of
empirical evidence that's so clear that even a kid - or even DharmaTroll -
can't miss it) is:

Soot, baby. Soot.

It's messing up the Boreal north - the subArctic, the pole & Greenland,
pouring out of diesel motors & coal-burning power plants.

http://www.sciam.com/article.cfm?id=...he-driven-snow

Look at the iceberg. It's black!

http://www.scienceagogo.com/news/200...runc_sys.shtml

It's the 800 lb gorilla sitting in the middle of the climatology
profession, and they're researching it like mad while the media is keeping
mostly mum about it. It's the most bizarre thing I've ever seen.

When NYT readers found out about the effects of soot on the Arctic, they
started hammering the journalist to cut the CO2 bull**** out and come
straight with them. No response.

Here's something to ponder: If a methane tipping point is a risk, then the
sootfall on the Siberian tundra could get us there FAST. Wasting money on
CO2 solutions that don't work won't fix our most pressing problem. So
either it's a feigned risk, or CO2 politics is wildly misdirecting the
science and public policies in a stupid and dangerous way.

/leebert

It is a brain plasticity theory that neurons that wire together fire
together in the brain. It only takes about three weeks for new neurons to
grow. After months of being inundated with the soot theory - I now associate
global warming and soot if I think about either one. It would be OK, but I'm
not absolutely and completely sure that lee is well - either incredibly
intelligent and insightful, or insane. Kitty



Those go together too. and/or.

I've got science on my side. ;-)

/leebert

"pseudomodo" wrote in message
news
KittyP wrote:
"pseudomodo" wrote in message
news:kPadnVKqWeZ0q77VnZ2dnUVZ_r-vnZ2d@grandecom...
Keynes wrote:

Also the spring thaw in northern rivers is coming
earlier and earlier. Maybe it's the calendar's fault.
Good point, Keynes. I knew I could count on ya....

And, perhaps almost predictably, my answer (verified by the simplest of
empirical evidence that's so clear that even a kid - or even
DharmaTroll - can't miss it) is:

Soot, baby. Soot.

It's messing up the Boreal north - the subArctic, the pole & Greenland,
pouring out of diesel motors & coal-burning power plants.

http://www.sciam.com/article.cfm?id=...he-driven-snow

Look at the iceberg. It's black!

http://www.scienceagogo.com/news/200...runc_sys.shtml

It's the 800 lb gorilla sitting in the middle of the climatology
profession, and they're researching it like mad while the media is
keeping mostly mum about it. It's the most bizarre thing I've ever seen.

When NYT readers found out about the effects of soot on the Arctic, they
started hammering the journalist to cut the CO2 bull**** out and come
straight with them. No response.

Here's something to ponder: If a methane tipping point is a risk, then
the sootfall on the Siberian tundra could get us there FAST. Wasting
money on CO2 solutions that don't work won't fix our most pressing
problem. So either it's a feigned risk, or CO2 politics is wildly
misdirecting the science and public policies in a stupid and dangerous
way.

/leebert

It is a brain plasticity theory that neurons that wire together fire
together in the brain. It only takes about three weeks for new neurons to
grow. After months of being inundated with the soot theory - I now
associate global warming and soot if I think about either one. It would
be OK, but I'm not absolutely and completely sure that lee is well -
either incredibly intelligent and insightful, or insane. Kitty

Those go together too. and/or.

I've got science on my side. ;-)

/leebert

I once knew a fella who thought Napoleon was the second coming of Jesus
Christ and even wrote a pamphlet about it. He said he had God on his side.
heh
Kitty

You need to read the articles you post, then you might actually know
what they are saying. This article does not say that Antarctica has not
warmed over the past 100 years.

pseudomodo wrote:
The effects of Antarctic water vapor have been overestimated.

===

Climate Models Overheat Antarctica

WASHINGTON--Computer analyses of global climate have consistently
overstated warming in Antarctica, concludes a new study. The findings
can help scientists improve computer models and determine if the
southernmost continent will warm significantly this century, a major
research question because of Antarctica's potential impact on global
sea-level rise.

"We can now compare computer simulations with observations of actual
climate trends in Antarctica," says Andrew Monaghan of the National
Center for Atmospheric Research (NCAR) in Boulder, Colo., lead author of
the study. "This is showing us that, over the past century, most of
Antarctica has not undergone the fairly dramatic warming that has
affected the rest of the globe. The challenges of studying climate in
this remote environment make it difficult to say what the future holds
for Antarctica's climate."

The study marks the first time that scientists have been able to compare
the past 50 to 100 years of Antarctic climate with simulations run on
computer models. The models are a primary method for researchers to
project future climate. Scientists have used atmospheric observations to
confirm that computer models are accurately simulating climate for the
other six continents.

Antarctica's climate is of worldwide interest, in part because of the
enormous water locked up in its ice sheets. If those vast ice sheets
were to begin to melt, sea level could rise across the globe and
inundate low-lying coastal areas. Yet, whereas climate models accurately
simulate the last century of warming for the rest of the world, they
have unique challenges simulating Antarctic climate because of limited
information about the continent's harsh weather patterns.

Monaghan and his colleagues at NCAR and Ohio State University, in Columbus,
published their findings last month in Geophysical Research Letters, a
journal of the American Geophysical Union (AGU).

The authors compared recently constructed temperature data sets from
Antarctica, based on data from ice cores and ground weather stations, to
twentieth century simulations from computer models used by scientists to
simulate global climate. While the observed Antarctic temperatures rose
by about 0.2 degrees Celsius (0.4 degrees Fahrenheit) over the past
century, the climate models simulated increases in Antarctic
temperatures during the same period of 0.75 degrees C (1.4 degrees F).
The error appeared to be caused by models overestimating the amount of
water vapor in the Antarctic atmosphere, the new study concludes.

The models, however, have correctly captured trends in Antarctic snowfall,
including increases in snowfall in the late twentieth century, prior to
a decrease over the last decade.

Part of the reason that Antarctica has barely warmed has to do with the
ozone hole over the continent. The lack of ozone is chilling the middle
and upper atmosphere, altering wind patterns in a way that keeps
comparatively warm air from reaching the surface. Unlike the rest of the
continent, the Antarctic Peninsula has warmed by several degrees, in
part because the winds there are drawing in warmer air from the north.

The study delivered a mixed verdict on Antarctica's potential impact on
sea-level rise. The Intergovernmental Panel on Climate Change, which
operates under the auspices of the United Nations, has estimated that
sea-level rise could amount to 18 to 59 centimeters (7 to 23 inches)
this century, in part because of melting glaciers worldwide. The new
findings suggest that other effects of warming in Antarctica over the
next century could reduce that by about 5 centimeter (2 inches) if the
continent warms by 3 degrees C (5.4 degrees F) as computer models have
indicated. The reason is that the warmer air over Antarctica would hold
more moisture and generate more snowfall, thereby locking up additional
water in the continent's ice sheets.

But the authors caution that model projections of future Antarctic
climate may be unreliable.

"The research clearly shows that you can actually slow down sea-level
rise when you increase temperatures over Antarctica because snowfall
increases, but warmer temperatures also have the potential to speed up
sea-level rise due to enhanced melting along the edges of Antarctica,"
says Monaghan, who did some of his research at Ohio State University
before going to NCAR. "Over the next century, whether the ice sheet
grows from increased snowfall or shrinks due to more melt will depend on
how much temperatures increase in Antarctica, and potentially on erosion
at the ice sheet edge by the warmer ocean and rising sea level."

"The current generation of climate models has improved over previous
generations, but still leaves Antarctic surface temperature projections
for the twenty-first century with a high degree of uncertainty," adds
co-author and NCAR scientist David Schneider. "On a positive note, this
study points out that water vapor appears to be the key cause of the
problematic Antarctic temperature trends in the models, which will guide
scientists as they work to improve the climate simulations."

This study was funded by National Science Foundation and by the
Department of Energy.

**********

Images:
Available for download at
http://www.ucar.edu/news/releases/2008/antarctica.jsp
are a color map of Antarctica showing warming and cooling trends and a
photo of researcher Andrew Monaghan.

Title:
"Twentieth century Antarctic air temperature and snowfall simulations by
IPCC climate models"

Authors:
Andrew J. Monaghan and David H. Bromwich: Polar Meteorology Group, Byrd
Polar Research Center, Ohio State University, Columbus, Ohio, USA.;
Bromwich
also with Atmospheric Sciences Program, Department of Geography, Ohio State
University, Columbus, Ohio, USA;

David P. Schneider: Climate and Global Dynamics Division, National
Center for Atmospheric Research, Boulder, Colorado, USA.

Citation:
Monaghan, A. J., D. H. Bromwich, and D. P. Schneider (2008), Twentieth
century Antarctic air temperature and snowfall simulations by IPCC climate
models, Geophys. Res. Lett., 35, L07502, doi:10.1029/2007GL032630.