TRAVERSE CITY, Mich. (AP) — A report by the National Climate Assessment
says a warming planet will worsen a series of weather trends already
showing up across the Midwest. Look for more extremes: searing heat,
late-spring freezes, floods and droughts across a region that includes
Ohio, Michigan, Indiana, Illinois, Wisconsin, Minnesota, Iowa and
FORESTS: The growing season, already two weeks longer than in 1950, will
continue lengthening. But the gains will be offset by smaller yields for
some crops, including corn. Soybean yields will improve for a while, but
the gains will eventually be offset by heat stress. Sensitive fruits such
as tart cherries in Michigan and Wisconsin will be increasingly vulnerable
to early budding followed by killing freezes as in 2012, when the crop was
devastated. Wetter springs could delay planting.
prairies and other ecosystems will change profoundly, none more so than
the northern forests. Familiar tree species such as paper birch, quaking
aspen, balsam fir and black spruce will probably migrate even farther
north, giving way to oak and pine varieties now common farther south.
WHEN IT RAINS, IT
POURS: The report acknowledges it's harder to project long-range changes
in precipitation than temperature. But the Midwest generally has gotten
wetter in the past century, mostly because of increasingly intense storms,
and that's likely to continue in the next century. Just how much will
depend on how successfully people cut back on carbon emissions.
patterns may become increasing erratic — wet in some parts of the region,
dry in others. Snowfall may decline in much of the Midwest but increase in
areas that get lake-effect snow. More flooding is likely, which
intensifies sewer overflows, soil erosion and water pollution from runoff.
SUMMER IN THE
CITY: Heat and humidity will raise the misery index in cities, with one
study predicting up to 2,217 additional heat-related deaths per year in
Chicago toward the end of the 21st century, although cutbacks in
greenhouse gas emissions could reduce the number significantly. Higher
temperatures should lengthen the pollen season and worsen the effects of
degraded air quality.
THE GREAT LAKES:
More than 90 percent of the Great Lakes' surface froze this winter, but
don't be fooled. Ice cover has retreated steadily for decades, and the
trend will probably continue, despite the occasional blip. Expect warmer
surface waters and more nuisance algae blobs that harm fish and water
quality. Reduced ice cover could lengthen the cargo shipping season,
although the benefit could be offset if water levels decline. The effect
of climate change on water levels is uncertain.
KNOCKS: The Midwest is well-positioned to soften the blow of climate
change. Its energy-intensive economy cranks out greenhouse gases at a rate
20 percent above the national average, primarily because of heavy reliance
on coal. Greater reliance on natural gas is a step in the right direction,
the report says. In some parts of the region, solar power's potential
matches that of Florida. In cloudier states, there is great opportunity to
expand use of wind, biodiesel and ethanol.