a climate change model of Earth with a quasi-uniform but nonorthogonal quadrilateral grid.

 

Science Foundation to apply petascale computing capacity—10¹⁵ floating point operations per second—to the analysis of ocean-atmosphere interactions. He cites the example of tropical instability waves in the eastern Pacific Ocean as a medium-scale marine phenomenon that climate scientists “originally thought the atmosphere didn’t care about.” Higher-resolution calculations show, however, that these instability waves, along with mesoscale ocean eddies measuring 10 kilometers or so across, profoundly influence not only how heat mixes both horizontally and vertically within the ocean, but also how heat is exchanged between ocean and atmosphere. The eastern Pacific Ocean-atmosphere interaction, Kirtman explains, in turn feeds into the year-to-year evolution of the well-known El Nino-Southern Oscillation, demonstrating that regional calculations on the kilometer scale are crucial to a better understanding of globally significant phenomena.

atmospheric challenges

The atmosphere presents more difficult

problems. Different GCMs are often compared in terms of the average global temperature increase they predict for a doubling of atmospheric carbon dioxide. That figure ranges from approximately 1. 5° C to 4. 5° C, and much of the variation between models stems from the different ways they parameterize fine-scaled atmospheric features such as convection and cloud cover. Higher-resolution calculations will do much to clarify convective and turbulent flows, says Jerry Meehl of the Climate and Global Dynamics Division at the National Center for Atmospheric Research (NCAR) in Boulder, CO, but clouds are more complicated. Clouds reflect sunlight from above but trap heat rising from below, so their net effect on climate depends on details of cloud composition and structure that current models struggle to depict. Typically, models allocate some percentage of various cloud types to each grid cell, and allow some randomized overlap of cloud layers at different altitudes. But the biggest obstacle to more accurate modeling, says Meehl, has been a lack of detailed observations of the way clouds literally stack up in the atmosphere. In this case, increased computer power will only be useful if it is coupled to better physical data on cloud structure and properties that can be used to refine cloud simulations. “The cloud community now is as excited as I’ve ever seen them,” Meehl says, because satellites are beginning to provide just the type of detailed 3D data that modelers need.

The steadily increasing resolution of GCMs is blurring the already fuzzy distinction between weather and climate. Researchers are beginning to calculate models with 50-kilometer resolution

Education
Students Flock to Game Design

as governments and universities worldwide develop strategies to reverse a dizzying downturn in computer science students, a hot field of study is getting even hotter and helping to rekindle interest in computer science.

game design has become a popular new major at more than 200 schools across the u. S., according to a report

from the entertainment Software association. Because game creation crosses several disciplines, the diversity of programs that offer such courses is stunning: Fine arts colleges, engineering schools, film schools, music schools, and even drama programs are sending graduates into the burgeoning industry.

game companies literally

over periods of decades, enabling them to see how climate change might affect the frequency and intensity of extreme storms or the statistics of droughts. Such information, rather than the more abstract concept of global average temperature, starkly conveys the tangible consequences of global warming.

In addition to using computing pow-
er to calculate on an ever-finer scale,
climate researchers can always think of
more science to put into their simula-
tions. Historically, the growth of com-
putational capacity allowed researchers
to integrate previously separate models
of ocean, atmosphere, sea ice, and land,
and that trend continues on a number
of fronts. At the moment, for example,
atmospheric carbon dioxide concentra-
tion is applied to climate models as an
external parameter, derived from the
work of scientists who add up emissions
from tailpipes and smokestacks and,
taking into account the natural process-
es that absorb and release the gas, try to
estimate how much CO will be in the
2
atmosphere 10, 20, or more years from
now. But this approach misses all types
of crucial feedbacks. Changing tempera-
tures of the oceans affects how well they
hold dissolved CO , while changes in the
2
world’s vegetation cover, due to a warm-
ing climate, influence the amount of
carbon that ends up in the atmosphere
rather than being taken up by biomass.
Climate modelers are beginning to inte-
grate parts of this complex network of
feedbacks into GCMs, so that ultimately
they will be able to input human CO
2
emissions directly into the models, and
allow the computer to figure out where
it all ends up—and how that disposition
changes in a changing climate.

Climate researchers, then, are forced

image courtesy of m.a. taylor, J. eDwarDs, a. st.cyr, “Petascale atmosPheric moDels for the community climate system moDel: new DeVeloPments anD eValuation of scalable Dynamical cores”, J. Phys. conf. ser. 125 (2008) 012023

recruit “armies” to work in studios
around the world, according to
the Los Angeles Times. the jobs
vary from inventing characters,
to writing dialogue, composing
music, creating digital scenes,
and writing the software that
rules these fantasy worlds. a
blockbuster game can take
more than 100 developers, each
working for two or more years to

complete one product.

colleges began noticing the game industry about six years ago when its sales started to compete with movie box-office receipts, says Jessie Schell, who teaches game design at carnegie Mellon university. Since then, computer science schools have experienced a boom in the number of programs to train future developers.