| Dear
EarthTalk: I‘ve noticed that wildflower
blooms in the mountains have been coming earlier and earlier
in recent years. Is this a sign of global warming? And what
does this mean for the long term survival of these hardy
yet rare plants?
-- Ashley J., via e-mail
| |
Aspen
sunflowers, like the one's pictured here, used to
first bloom in mid-May, but are now doing so in mid-April,
a full month earlier. University of Maryland ecologist
David Inouye thinks that smaller snow packs in the
mountains are melting earlier due to global warming,
in turn triggering early blooms.
© beautifulcataya, courtesy Flickr |
As
always, it‘s hard to pin specific year-to-year weather-variations
and related phenomena—including altered blooming schedules
for wildflowers—on global warming. But longer term
analysis of seasonal flowering patterns and other natural
events do indicate that global warming may be playing a
role in how early wildflowers begin popping up in the high
country.
University
of Maryland ecologist David Inouye has been studying wildflowers
in the Rocky Mountains near Crested Butte, Colorado for
four decades, and has noticed that blooms have indeed begun
earlier over the last decade. Aspen sunflowers, among other
charismatic high country wildflowers, used to first bloom
in mid-May, but are now are doing so in mid-April, a full
month earlier. Inouye thinks that smaller snow packs in
the mountains are melting earlier due to global warming,
in turn triggering early blooms.
Smaller
snow packs not only mean fewer flowers (since they have
less water to use in photosynthesis); they can also stress
wildflower populations not accustomed to exposure to late-spring
frost. According to Inouye‘s research, between 1992
and 1998 such frosts killed about a third of the Aspen sunflower
buds in some 30 different study plots; but more recently,
from 1999 through 2006, the typical mortality rate doubled,
with three-quarters of all buds killed by frost in an average
year thanks to earlier blooming.
Inouye‘s
worrisome conclusions are backed up by experiments conducted
by fellow researcher John Harte, who over a 15 year period
used overhead heaters in nearby wildflower study plots to
accelerate snow melt. The results were the same: Wildflowers
bloomed early and not as vigorously.
Several
studies in Europe have shown that some species of wildflowers
there may be able to migrate north and to higher elevations
as the climate warms, but Inouye fears his beloved Aspen
sunflowers and many other American wildflowers may be lost
forever as they are not able to migrate as quickly as needed
in order to survive widespread surface temperature increases
and escape extinction.
Harte
is also gloomy about the prospects for Colorado‘s
mountain wildflowers. He predicts that the wildflower fields
he and Inouye have been studying will give way to sagebrush
desert within the next 50
years, whether or not the governments of the world can get
a grip on greenhouse gas emissions.
As
a hedge against such dire predictions, the nonprofit Center
for Plant Conservation is spearheading seed collection efforts
on thousands of rare wildflower species across the U.S.
for inclusion in the Colorado-based National Center for
Genetic Resources Preservation, a repository for both common
and rare “prized” American plant seeds. The
“banked” seeds, useful if not solely for preserving
the genetic makeup of species that may go extinct in the
wild, can also be used for future restoration projects on
otherwise compromised landscapes.
CONTACTS:
David
W. Inouye; Center
for Plant Conservation; National
Center for Genetic Resources Preservation.
Dear
EarthTalk: What are the most important foods
to buy organic?
-- Rachel Klepping, Bronxville, NY
| |
The
Environmental Working Group's handy "Shopper's
Guide to Pesticides" makes it easy for consumer's
to know which foods they should definitely buy organic
("The Dirty Dozen") and they can eat safely
("The Clean 15") without paying a premium
for an organic variety.
© EWG |
Given the usual
higher prices of organic versus conventionally-grown foods,
it can be a challenge to get the biggest bang for our buck
while eating healthy and avoiding the ingestion of synthetic
chemicals along with our nutrients. One approach, say some
experts, is to only buy organic when the actual edible parts
of a non-organically grown food might come into direct contact
with toxic fertilizers and pesticides.
The nonprofit
Environmental Working Group (EWG) reports that consumers
can reduce their chemical exposure by some 80 percent by
either avoiding the most contaminated conventionally grown
fruits and vegetables altogether, or by eating only the
organic varieties. To help us sort through what and what
not to buy, the group offers a handy Shopper’s Guide
to Pesticides, which fits on a small piece of paper that
you can keep in your pocket and have handy on grocery trips.
You can print it out for free from EWG’s FoodNews.org
website, or you can download it as a free App for your iPhone.
To make it easy
to use, EWG has distilled its analysis into two lists. The
first, “Dirty Dozen: Buy These Organic,” lists
foods that when grown conventionally contain the largest
amounts of pesticide and fertilizer residues. These include
peaches, strawberries, apples, blueberries, nectarines,
bell peppers, spinach, cherries, kale/collard, greens, potatoes,
and (imported) grapes. Consumers should definitely spend
the extra money for organic versions of these foods.
On the other
side of the coin, EWG’s “Clean 15” list
includes foods that contain the least amount of chemical
residues when grown conventionally. These include onions,
avocados, sweet corn, pineapples, mangos, sweet peas, asparagus,
kiwi, cabbage, eggplant, cantaloupe, watermelon, grapefruit,
sweet potatoes and honeydew. It’s OK to eat conventionally
grown varieties of these foods.
EWG analysts
developed the “Clean 15” guide using data from
some 89,000 tests for pesticide residues in produce conducted
between 2000 and 2008 and collected by the U.S. Department
of Agriculture (USDA) and the U.S. Food and Drug Administration
(FDA). What’s the difference, you may ask? EWG found
that by eating five conventionally-grown fruits and vegetables
a day from the Dirty Dozen list, a consumer on average ingests
10 different pesticides; those who stick to the Clean 15
list ingest less than two.
Other foods you
and your family eat, such as meats, cereals, breads and
dairy products, might also be exposing you to unwanted chemicals.
According to EWG, the direct health benefits of organic
meat, eggs and milk are less clear, but you should play
it safe by sticking with all-natural, free-range, grass-fed
meats that are not fed antibiotics or growth hormones, and
by choosing only organic dairy products.
Thanks to increasing
demand, more and more food purveyors are putting extra emphasis
on organics. This will ultimately result in both lower prices
and larger selections. Natural foods market aisles are already
teeming with organic choices—and chances are your
local supermarket or big box store has introduced organic
versions of many popular items. Consequently, there has
never been a better time to take stock of what you are feeding
yourself and your family, and to make changes for better
health.
CONTACT:
EWG;
USDA/FDA. |
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