Climate Change: A Boon for Pests, A Bane for Us
Earlier this week, the U.S. Global Change Research Program (USGCRP) released its third national climate assessment, Climate Change Impacts in the United States. Its results, which, although U.S.-focused, echo the results found in a report from late last year by the globally-focused Intergovernmental Panel on Climate Change (IPCC), are a boon to post-apocalyptic storytellers and a downer for just about everyone else.
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Climate change is real, it's human made, and we're already experiencing its negative effects.
What's worse — for farmers, people who like eating, and entomophobes — is that even while climate change is disrupting maple syrup supplies and leaving cities like Sacramento, California so arid that restaurants are encouraged to only serve water at patron request, the one group benefitting from climate change are pests.
Insect pests already have a significant, negative impact on agricultural production. We lose 18 percent of our global crop production to these chitinous shelled creatures. Under climate change their populations are likely to expand. More bugs can potentially lead to more crop loss.
The reason is fairly straightforward. Insects are temperature sensitive. When it gets too cold, they either lay dormant, incapable of reproduction, or die off while their winter tolerant eggs wait for warmer weather. The warmer winters we experience under climate change — even while the U.S. shivered under a Polar Freeze during the winter of 2013-2014, it was still the eighth warmest winter on record, globally — means that fewer insects die off. Come spring time, there are more insects around to wreak havoc on our human systems, like agriculture. Even worse, warmer winters in conjunction with hotter summers means that there are more reproductive cycles in a year. In short, climate change lets more bugs survive, and allows them to reproduce more frequently, creating still more pests.
It's not just crops that stand to suffer. More pests can lead to more pest-borne diseases like dengue and malaria. A study released earlier this year posits that climate change will hasten the spread of the West Nile Virus. It's helpful to remember that prior to 1999 West Nile was a disease that was on almost no one's radar — it's now present worldwide. And this boon in pest comes at the same time that the U.S. has lost at least seven million bats due to white nose syndrome, a fungus thought to have come from Europe. Bats not only pollinate crops, they eat more than 3,000 insects in an evening, including mosquitoes.
Insects aren't the only pests that stand to benefit under climate change. Weeds, which, according to the USGCRP currently account for 34 percent of current crop loss and $11 billion dollars spent on weed control — mostly on herbicides, are also projected to become more of a nuisance. Remember in elementary school, learning that plants breathe in carbon dioxide? Weeds, especially pasture weeds, really like carbon dioxide, the very chemical that we're pumping into the atmosphere that's causing climate change. The most popular herbicide, glyphosate also known as RoundUp, doesn't work as well on weeds grown at the carbon dioxide levels projected to occur in the coming decades. Glyphosate is popular both because of its efficacy and because certain crops, like corn, had been genetically modified to withstand its application. Farmers can apply it to their fields and kill only weeds. However, in recent years, weeds have grown increasingly immune to it, and a number of other herbicides earning the nickname "superweeds." As carbon dioxide levels rise, glyphosate and other herbicides will become even less effective.
In the coming years, if we don't work to stem the flow of climate change we'll have more weeds and pest, and fewer weapons in our arsenal to combat them.
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