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Q&A
Together, field and laboratory data and theoretical understanding are used to advance models of Earth's climate
system and to improve representation of key processes in them, especially those associated with clouds,
aerosols, and transport of heat into the oceans. This is critical for accurately simulating climate change and
associated changes in severe weather, especially at the regional and local scales important for policy decisions.
Simulating how clouds will change with warming and in turn may themselves affect warming, remains
one of the major challenges for global climate models, in part because many cloud processes occur on
scales smaller than the current models can resolve. Greater computer power may enable some of these
processes to be resolved in future-generation models.
Dozens of groups and research institutions work on climate models, and scientists are now able to analyse
results from essentially all of the world's major Earth-System Models and compare them with each other and
with observations. Such opportunities are of tremendous benefit in bringing out the strengths and weak-
nesses of various models and diagnosing the causes of differences among models, so that research can focus
on the relevant processes. The differences among models allow estimates to be made of the uncertainties in
projections of future climate change, and in understanding which aspects of these projections are robust.
Studying how climate responded to major changes in the past is another way of checking that we understand
how different processes work and that models are capable of performing under a wide range of conditions.
Why are computer models used to study climate change?The future evolution of Earth's climate as it responds to
the present rapid rate of increasing atmospheric CO2 has
no precise analogues in the past, nor can it be properly
understood through laboratory experiments. As we are also
unable to carry out deliberate controlled experiments on Earth
itself, computer models are among the most important tools
used to study Earth's climate system.
Climate models are based
on mathematical equations
that represent the best
understanding of the basic
laws of physics, chemistry,
and biology that govern the
behaviour of the atmosphere,
ocean, land surface, ice, and
other parts of the climate
system, as well as theinteractions among them. The most comprehensive climate
models, Earth-System Models, are designed to simulate
Earth's climate system with as much detail as is permitted by
our understanding and by available supercomputers.
The capability of climate models has improved steadily since
the 196os. Using physics-based equations, the models can
be tested and are successful in simulating a broad range of
weather and climate variations, for example from individual
storms, jet stream meanders, El Niio events, and the climate
of the last century. Their projections of the most prominent
features of the long-term human-induced climate change signal
have remained robust, as generations of increasingly complex
models yield richer details of the change. They are also used
to perform experiments to isolate specific causes of climate
change and to explore the consequences of different scenarios
of future greenhouse gas emissions and other influences on
climate.20 CLIMATE CHANGE
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National Academy of Sciences (U.S.). Climate Change Evidence & Causes, report, Date Unknown; (https://digital.library.unt.edu/ark:/67531/metadc949508/m1/22/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.