New Study: Eat Your Strawberries Before Climate Change Wipes
Them Out
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Avocados, almonds, peaches, and many
other California crops are also threatened. |
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By Tom Philpott |
MotherJones |
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danny4stockphoto/Getty Images |
With its year-round sunshine and vast tracts
of fertile land, California is one of the jewels of US food
production, providing a third of the nation’s vegetables and
two-thirds of our fruits and nuts. As the climate warms, can we
continue to take this $50.5 billion bounty for granted?
That’s the question posed by a team of University of California
researchers in an eye-opening new paper published in the journal
Agronomy, in which they digest recent research to “document the
most current understanding on California’s climate change trends
in terms of temperature, precipitation, snowpack, and extreme
events such as heat waves, drought, and flooding, and their
relative impacts” on the state’s agriculture.
They address these topics one by one, and the results are hardly
comforting to US eaters.
For one thing, the scientists found, a temperature change of
just a few degrees is “closely related to yield reductions” in
some of the most cherished California crops: almonds, wine
grapes, strawberries, walnuts, freestone peaches, and cherries.
Avocado production could plummet by the middle of the century.
Because of fewer winter chill hours, by the end of the century,
the paper suggests, only 10 percent of the Central Valley will
remain viable to grow fruits like apricots, kiwis, peaches, and
nectarines.
Then there’s the Sierra Nevada snowpack, the horde of frozen
water that gathers in the mountains on California’s eastern
fringe over winter, before melting in the spring and irrigating
farmland in the Central Valley, the state’s most productive
farming region. California’s devastating recent drought
(2012-2016) was largely driven by paltry winter mountain snows,
which provide “almost 80 percent of the state’s precipitation in
an average year,” the report notes.
"Under an optimistic
scenario, the snowpack is projected to be 48 percent lower in
coming decades."
And those dry times may already be back. As I reported in early
February, a winter had left the snowpack at just 24 percent of
its long-term average for the time of year. This past weekend, a
big snowstorm raised it to 37 percent of average—still not
great. Such levels may soon be considered the new normal.
California’s snowpack has already “reduced considerably” in
recent decades and is “projected to shrink further in the future
climate,” the authors report.
Under an optimistic scenario, the snowpack is projected to be 48
percent lower in coming decades than it was in the 1961-1990
period. Under a more dire but realistic scenario, the pack will
undergo a 65 percent loss. |
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Graphics from “Climate Change
Trends and Impacts on California Agriculture: A Detailed
Review,” by Pathak, et al. |
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Of course, when Central Valley farmers lack
access to irrigation water that comes from melted snow, they
revert to pumping it from underground aquifers. As we learned in
the last drought, such massive withdrawals of a finite resource
cannot go on long without causing severe problems, including dry
wells, infrastructure-destroying land subsidence, and soil
that’s too salty to grow most crops.
On top of the shrinking snowpack, the authors also note that
“daytime and nighttime heat waves are expected to become more
frequent and intense.” And as temperatures rise, the “impact of
pests, diseases, and weeds is increasing substantially, with
their altered growth cycles possibly becoming concentrated and
impacting crop harvests,” they note.
"The time has probably
come to de-Californify the nation’s produce supply."
In short, California’s climate has already “changed
significantly” since the first half of the 20th century, when
the state emerged as a linchpin of our food system. And “this
change can be expected to continue in the future.” As I put it
in a 2015 New York Times piece, the time has probably come to
de-Californify the nation’s produce supply—that is, increase
fruit and vegetable production in less water-stressed areas. |
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