[RegCNET] Exciting new paper!

[moetasim]

HI ALL,

I am forwarding this email to you with a small note of inormation:

Noah is my supervisor and Jeff is my instructor in two courses at Purdue..n I think you know rest of 
the guys very well.

MOet

 

Hi, All,

An exciting new paper by our very own Noah Diffenbaugh and Jeff Trapp
and their collaborators Jeremy Pal and Filippo Giorgi is just out today
in PNAS!

Please see press release below:

 

October 17, 2005


Climate model predicts dramatic changes over next 100 years


WEST LAFAYETTE, Ind. - The most comprehensive climate model to date of
the continental United States predicts more extreme temperatures
throughout the country and more extreme precipitation along the Gulf
Coast, in the Pacific Northwest and east of the Mississippi. 

 

Changes in climate 
Download graphic
<http://news.uns.purdue.edu/images/+2005/diffenbaugh-climate.jpg>  
caption below

The climate model, run on supercomputers at Purdue University, takes
into account a large number of factors that have been incompletely
incorporated in past studies, such as the effects of snow reflecting
solar energy back into space and of high mountain ranges blocking
weather fronts from traveling across them, said Noah S. Diffenbaugh
<http://www.purdue.edu/eas/people/faculty/diffenbaugh.html> , the team's
lead scientist. Diffenbaugh said a better understanding of these factors
- coupled with a more powerful computer system on which to run the
analysis - allowed the team to generate a far more coherent image of
what weather we can expect to encounter in the continental United States
for the next century. Those expectations, he said, paint a very
different climate picture for most parts of the country. 

"This is the most detailed projection of climate change that we have for
the U.S.," said Diffenbaugh, an assistant professor of earth and
atmospheric sciences in Purdue's College of Science and a member of the 
Purdue Climate Change Research Center <http://www.purdue.edu/climate> .
"And the changes our model predicts are large enough to substantially
disrupt our economy and infrastructure." 

The research team also includes Diffenbaugh's Purdue colleague Robert J.
Trapp, as well as Jeremy S. Pal and Filippo Giorgi of the Abdus Salam
International Centre for Theoretical Physics in Trieste, Italy. Their
paper appears in today's (Monday, Oct. 17) online edition of the journal
Proceedings of the National Academy of Sciences.

Climate models are sophisticated computer codes that attempt to
incorporate as many details about the complex workings of our
environment as possible. Hundreds of dynamic processes, such as ocean
currents, cloud formations, vegetation cover and - of particular import
- the increase in atmospheric greenhouse gases, are programmed into the
computers, which then attempt to discern the net effects on
square-shaped plots of land that represent small pieces of the Earth's
surface. The smaller these squares are, the better the resolution the
model can provide.

"Just as a digital camera that creates images with more pixels can
result in a better photograph, we want to make those squares as small as
possible," Diffenbaugh said. "We'd also like to incorporate as much of
the climate system as we can so the analysis will be realistic." 

Despite the number-crunching power of the linked computers used for
these simulations, a model must factor in so many changing variables
that a full analysis can require months of nonstop computational effort.
Diffenbaugh's team required five months to run their model on a cluster
of Sun computers at the Rosen Center for Advanced Computing on Purdue's
campus. 

"The results were worth it, though, because this model allows us to
project changes in climate with unprecedented resolution," Diffenbaugh
said. 

Until now, the fastest computers have been used to resolve squares 50
kilometers to a side, which can return a reasonably accurate but rather
grainy "photograph" of climate change. 

"We can now analyze areas that are only 25 kilometers to a side, which,
for example, allows us to discern more clearly where California's
central valley stops and the Sierra Nevada mountain range begins."

With their improvements over previous models, the team has been able to
make several observations about the change in climate over the next
century, particularly for the late century when greenhouse gas
accumulation could have greater effect than, say, a decade from now.

"These projections are not necessarily about specific weather events,"
Diffenbaugh said. "But they do give us a good idea about what kind of
weather to expect over the long run in a particular part of the
country." 

Some of these expectations include: 

* The desert Southwest will experience more heat waves of greater
intensity, combined with less summer precipitation. Water is already at
a premium in the four-corners states and southern Nevada and, as years
pass, even less water will be available for the region's burgeoning
populations, with extreme hot events increasing in frequency by as much
as 500 percent. 

* The Gulf Coast will be hotter and will receive its precipitation in
greater volumes over shorter time periods. "The region actually will get
more rainfall than it does now, but it will not be steady," Diffenbaugh
said. "We project more dry spells punctuated by heavier rainfalls. We
need to perform further analyses to understand how much of this is
related to tropical cyclone activity." 

* In the northeastern United States - roughly the region east of
Illinois and north of Kentucky - summers will be longer and hotter.
"Imagine the weather during the hottest two weeks of the year,"
Diffenbaugh said. "The area could experience temperatures in that range
lasting for periods of up to two months by century's end." 

*Similarly, the continental United States will experience an overall
warming trend: Temperatures now experienced during the coldest two weeks
of the year will be a past memory, and winter's length will diminish as
well, according to the model.

The model, Diffenbaugh said, assumes that greenhouse gases will attain a
concentration more than twice their current levels, but he said he is
confident that the model's performance gives as accurate a picture of
the future as we can hope for at the moment.

"We checked our model's performance by analyzing the period from 1961 to
1985 for which, of course, we do not need a prediction," Diffenbaugh
said. "The model performed admirably, which tells us we've got a good
understanding of how to represent the physical world in terms of
computer code. It's certainly not perfect, but we'll need a computer at
least 100 times as powerful as the cluster we used to really improve the
accuracy. We would like to have access to such computing power in the
future." 

Diffenbaugh emphasized that, while the model was in no way designed to
return an alarmist image of our climate's future, the picture it painted
should be considered.  

"The more detail we look at with these models, the more dramatic the
climate's response is," he said. "Critics have complained that climate
models lack sufficient spatial detail to be trusted. In terms of looking
at the whole contiguous United States, we've quadrupled the spatial
detail and, as a result, it appears that climate change is going to be
even more dramatic than we previously thought. Of course, we can never
be completely certain of the future, but it's clear that as we consider
more and more detail, the picture of future climate change becomes more
and more severe." 

Commenting on the study, Stanford University's Stephen H. Schneider said
the results confirm scientists' suspicions about the future of climate
change. 

"This study is the latest and most detailed simulation of climatic
change in the United States," said Schneider, who is Stanford's Melvin
and Joan Lane Professor for Interdisciplinary Environmental Studies.
"Critics have asserted that the coarse resolution of previous studies
made their sometimes dire predictions suspect, but this new result with
a very high resolution grid over the United States shows potential
climatic impacts at least as significant as previous results with lower
resolution model. As the authors wisely note, such potential impacts
certainly should not be glibly dismissed."

This research was funded in part by a grant from the National Science
Foundation.

The Rosen Center for Advanced Computing is a research computing center
named in memory of Saul Rosen, who served as director of Purdue's
Computing Center from 1968-87 and who helped to establish Purdue as a
pioneering academic institution in high-performance computing. The Rosen
Center is a part of Information Technology at Purdue, which is
responsible for planning and coordinating the central computing and
telecommunications systems on the West Lafayette campus. 

Writer: Chad Boutin, (765) 494-2081, cboutin at purdue.edu

Source: Noah S. Diffenbaugh, (765) 494-0754, diffenbaugh at purdue.edu

Purdue News Service: (765) 494-2096; purduenews at purdue.edu

 

Related Web site: 
Previous news release on Diffenbaugh's research
<http://news.uns.purdue.edu/html4ever/2005/050509.Diffenbaugh.veg.html> 

 

GRAPHIC CAPTION: 
These graphics illustrate some of the changes in climate predicted for
the 21st century by Purdue University's Noah Diffenbaugh and his team of
scientists using a computer simulation they recently completed. The
simulation indicates that the entire continental United States will
experience more intense heat waves, most dramatically in the desert
Southwest (top figure). It also indicates that several areas, notably
the Gulf Coast, will experience more storms that bring heavy
precipitation (bottom figure). The computer model, which incorporates
many climatic factors in unprecedented detail, suggests that these
changes will be significant enough to disrupt our national economy and
infrastructure. (Purdue graphic/Diffenbaugh Lab)

A publication-quality graphic is available at 
http://news.uns.purdue.edu/images/+2005/diffenbaugh-climate.jpg
<http://news.uns.purdue.edu/images/%2B2005/diffenbaugh-climate.jpg> 

 

 

_________________________________

Rose Filley

Purdue Climate Change Research Center

512 Third Street

West Lafayette, IN 47907

Tel: 765-496-3211; Fax: 765-496-3210

Email: rfilley at purdue.edu <mailto:rfilley at purdue.edu> 

Web: http://www.purdue.edu/climate <http://www.purdue.edu/climate>