Allergies Soar as Temperature Rises
Report: Allergy Season to Get Worse with
Climate Change
Time Magazine,
April 14, 2010
Allergy sufferers
like to claim - in between sniffles - that each spring's allergy season
is worse than the last. But this year, they might actually be right.
Thanks to an
unusually cold and snowy winter, followed by an early and warm spring,
pollen counts are through the roof in much of the U.S., especially in
the Southeast, which is already home to some of the most allergenic
cities in the country. A pollen count - the number of grains of pollen
in a cubic meter of air - of 120 is considered high, but in Atlanta last
week the number hit 5,733, the second highest level ever recorded in
the city.
The bad news is
that in a warmer world, allergies are likely to get worse - and that's
going to cost sufferers and the rest of us. A new report released on
Wednesday by the National Wildlife Federation (NWF) found that global
warming will likely increase pollen counts in the heavily populated
eastern section of the country and that the effect of climate change
could push the economic cost of allergies and asthma well above the
current $32 billion price tag. "The latest climate science makes it
clear that allergies could get much worse," says Amanda Staudt, a
climate scientist at NWF and the author of the report. "I really think
this should be a wake-up call."
Here's how it
works: higher concentrations of CO2 in the atmosphere
generally speed plant growth, while warmer temperatures mean that spring
- and with it, allergy season - arrives earlier. Spring-like conditions
in the East are already arriving on average 14 days earlier than just
20 years ago.
Pollen from
ragweed, which triggers most cases of spring hay fever, is projected to
increase up to 100% between now and 2085 if fossil-fuel emissions
continue to rise unabated. And more CO2 could make the
ragweed pollen that exists more potent: if CO2 concentrations
rise from current levels (385 parts per million) to 600 parts p.p.m.,
which could happen as soon as mid-century, ragweed pollen could become
up to 70% more allergenic. An earlier, longer spring will just give
ragweed more time to grow and give off pollen.
As the climate
warms, it is likely to favor trees that give off pollen - like oaks and
hickories - over pines, spruces and fir trees, which don't. By 2100,
once relatively cool states in the Northeast - including Vermont, New
Hampshire and New York - could have the sort of highly allergenic trees
now seen in the hotter Southeast, as species migrate north to adjust to
the heat.
Asthmatics will
suffer as well - about 10 million Americans have allergic asthma, which
is triggered by allergens. The condition tends to make people unusually
sensitive to air pollution, and some studies indicate that pollution
will worsen over time if fossil-fuel emissions aren't curbed.
Ground-level ozone pollution from auto emissions, for instance, can
trigger allergic asthma attacks, and it's likely to get worse as
temperatures warm. One study found that climate change could increase
the daily maximum concentration of ozone from 3 parts per billion to 5
parts per billion by 2050 in the Midwest and Northeast. During bad heat
waves - which will also become more frequent on a hotter planet - those
levels can double. "We've already seen an overall doubling of asthma in
the U.S. since 1980," says Paul Epstein of Harvard's Center for Global
Health and the Environment. "We can't afford it to get worse."
There are ways to
fight rising allergies even in a warmer world: for example, by
replacing trees that emit high levels of pollen in densely populated
areas - like the Norway maples found on New York City streets - with
species that produce less, like mountain ash or golden rain. "We can get
better allergy management and help people reduce their exposure to
triggers," says Mike Triangle of the Asthma and Allergy Foundation of
America. But absent a concerted effort to reduce carbon emissions, get
ready for a sniffly future.
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