Large future changes in climate variability
New computer model simulations identify widespread changes in climate variability under sustained anthropogenic forcing

Date:
December 9, 2021
Source:
Institute for Basic Science
Summary:
Large future changes in climate variability. New computer model
simulations identify widespread changes in climate variability
under sustained anthropogenic forcing.



FULL STORY ========================================================================== There is growing public awareness that climate change will impact
society not only through changes in mean temperatures and precipitation
over the 21st century, but also in the occurrence of more pronounced
extreme events, and more generally in natural variability in the Earth
system. Such changes could also have large impacts on vulnerable
ecosystems in both terrestrial and marine habitats. A scientific
exploration of projected future changes in climate and ecosystem
variability is described in a new study published in the journal Earth
System Dynamics, representing the result of a broad collaborative
partnership between the IBS Center for Climate Physics (ICCP) at Pusan
National University in South Korea and the Community Earth System Model
(CESM) project at the National Center for Atmospheric Research (NCAR)
in the US.


==========================================================================
The team conducted a set of 100 global Earth system model simulations over 1850-2100, working with a "business-as-usual" scenario for relatively
strong emissions of greenhouse gases over the 21st century. The runs
were given different initial conditions, and by virtue of the butterfly
effect they were able to represent a broad envelope of possible climate
states over 1850-2100, enabling sophisticated analyses of changes in
the variability of the Earth system over time. The nominally one-degree (~100km) resolution of the model, in conjunction with the 100-member set
of runs, represented an unprecedented set of technical challenges that
needed to be met before advancing to the goal of assessing how climate variability is impacted by sustained anthropogenic changes to the climate system. "We met these challenges by using the IBS/ICCP supercomputer
Aleph, one of Korea's fastest supercomputers" says Dr. Sun-Seon Lee from
the ICCP, a co-author of the study who ran the simulations together with
her NCAR colleague Dr. Nan Rosenbloom. For the project, approximately
80 million hours of supercomputer time were used, and approximately
5 Petabytes of disc space (approximately 5000 normal hard discs) were
required for storage of the model output.

The main finding of the study is that the impact of climate change is
apparent in nearly all aspects of climate variability, ranging from
temperature and precipitation extremes over land to increased number of
fires in California, to changes in bloom amplitude for phytoplankton in
the North Atlantic Ocean. Each of these changes has important impacts
for sustainable resource management. As an example, occurrences of
extreme precipitation events over the 21st century (between 2000-2009 and 2090-2099) indicate that extremes are expected to become more commonplace
over many regions. These projected changes in precipitation extremes
are in fact representative of the omnipresence of changes in extremes
in the future across a broad range of climate and ecosystem variables,
which has important implications for future adaptation strategies.

"In addition to large-scale changes in extreme events, our study also identified large-scale changes in the structure of the seasonal cycle
over the 21st century, showing an enhanced growing season length over
the continental regions north of 50DEGN," says Dr. Keith Rodgers from
the ICCP, first author of the study and a co-lead of the CESM2 Large
Ensemble Project. Largely due to mean state warming and ensuing changes
in the timing of the retreat and advance of winter snow cover, by the
end of the 21st century growing season length is projected to increase
by three weeks.

Taken together, the computer simulations reveal that across our
planet we can expect widespread changes in climate variability,
ranging in timescales from synoptic storms to seasons to that of El
Nin~o to decades. Dr. Gokhan Danabasoglu, a co-author of the study and a co-lead of the project, says "an important step moving forward will be to identify more fully the potential societal impacts and to communicate the implications for adaptation strategies." This broader study has already motivated a number of more specialized scientific investigations using
the tremendous volume of output from the simulations, spanning topics from marine ecosystem impacts to hydrological changes that affect water supply.

The National Center for Atmospheric Research is sponsored by the US
National Science Foundation and managed by the University Corporation
for Atmospheric Research.

========================================================================== Story Source: Materials provided by Institute_for_Basic_Science. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Keith B. Rodgers, Sun-Seon Lee, Nan Rosenbloom, Axel Timmermann,
Gokhan
Danabasoglu, Clara Deser, Jim Edwards, Ji-Eun Kim, Isla R. Simpson,
Karl Stein, Malte F. Stuecker, Ryohei Yamaguchi, Tama's Bo'dai,
Eui-Seok Chung, Lei Huang, Who M. Kim, Jean-Franc,ois Lamarque,
Danica L.

Lombardozzi, William R. Wieder, Stephen G. Yeager. Ubiquity
of human- induced changes in climate variability. Earth System
Dynamics, 2021; 12 (4): 1393 DOI: 10.5194/esd-12-1393-2021 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211209082609.htm

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