Climate change to profoundly affect the Midwest in coming decades
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| A flooded urban street. (Credit: Don Becker, USGS) |
In the
coming decades, climate change will lead to more frequent and more intense
Midwest heat waves while degrading air and water quality and threatening public
health. Intense rainstorms and floods will become more common, and existing
risks to the Great Lakes will be exacerbated. Those are some of the conclusions
contained in the Midwest chapter of a draft report released last week by the
federal government that assesses the key impacts of climate change on every
region in the country and analyzes its likely effects on human health, water,
energy, transportation, agriculture, forests, ecosystems and biodiversity.
Three
University of Michigan researchers were lead convening authors of chapters in
the 1,100-plus-page National Climate Assessment, which was written by a team of
more than 240 scientists.
University
of Michigan aquatic ecologist Donald Scavia was a lead convening author of the
Midwest chapter. Dan Brown of the School of Natural Resources and Environment
was a lead convening author of the chapter on changes in land use and land
cover. Rosina Bierbaum of SNRE and the School of Public Health was a lead
convening author of the chapter on climate change adaptation. Missy Stults, a
research assistant with Bierbaum and a doctoral student at the A. Alfred
Taubman College of Architecture and Urban Planning, was a contributing author
on the adaptation chapter.
In
addition, Bierbaum and Marie O'Neill of the School of Public Health serve on
the 60-person advisory committee that oversaw development of the draft report,
which is the third federal climate assessment report since 2000. The report
stresses that climate change is already affecting Americans, that many of its
impacts are expected to intensify in coming decades, and that the changes are
primarily driven by human activity.
"Climate
change impacts in the Midwest are expected to be as diverse as the landscape
itself. Impacts are already being felt in the forests, in agriculture, in the
Great Lakes and in our urban centers," said Scavia, director of the Graham
Sustainability Institute and special counsel to the U-M president on
sustainability issues.
In the
Midwest, extreme rainfall events and floods have become more common over the
last century, and those trends are expected to continue, causing erosion,
declining water quality and negative impacts on transportation, agriculture,
human health and infrastructure, according to the report.
Climate
change will likely worsen a host of existing problems in the Great Lakes,
including changes in the range and distribution of important commercial and
recreational fish species, increases in invasive species, declining beach
health, and more frequent harmful algae blooms. However, declines in ice cover
on the Great Lakes may lengthen the commercial shipping season.
In
agriculture, longer growing seasons and rising carbon dioxide levels are likely
to increase the yields of some Midwest crops over the next few decades,
according to the report, though those gains will be increasingly offset by the
more frequent occurrence of heat waves, droughts and floods. In the long term,
combined stresses associated with climate change are expected to decrease
agricultural productivity in the Midwest.
The
composition of the region's forests is expected to change as rising
temperatures drive habitats for many tree species northward. Many iconic tree
species such as paper birch, quaking aspen, balsam fir and black spruce are
projected to shift out of the United States into Canada.
The
rate of warming in the Midwest has accelerated over the past few decades,
according to the report. Between 1900 and 2010, the average Midwest air
temperature increased by more than 1 degree Fahrenheit. However, between 1950
and 2010, the average temperature increased twice as quickly, and between 1980
and 2010 it increased three times as quickly.
The
warming has been more rapid at night and during the winter. The trends are
consistent with the projected effects of increased concentrations of
heat-trapping greenhouse gases, such as carbon dioxide released by the burning
of fossil fuels.
Projections
for regionally averaged temperature increases by the middle of the century,
relative to 1979-2000, are approximately 3.8 degrees Fahrenheit for a scenario
with substantial emissions reductions and 4.9 degrees for the current
high-emissions scenario. Projections for the end of the century in the Midwest
are about 5.6 degrees for the low-emissions scenario and 8.5 degrees for the
high-emissions scenario, according to the report.
Source: University
of Michigan
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