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Spring did not come for the oaks of Martha's Vineyard. For three years, the residents here watched a stunning outbreak of caterpillars that stripped an oak tree bare in a week, then wafted on gossamer threads to another.  In the denuded branches, scientists see a fingerprint of climate change - and a pattern of things to come. The islanders fought through clouds of drifting filaments with brooms, brushed off the showers of excrement after they walked under trees, and tiptoed through a maze of half-inch worms on the sidewalks. The local newspapers ran pictures of building sides covered with caterpillars, looking like horror-movie outtakes. 

Spring did not come for the oaks of Martha's Vineyard. For three years, the residents here watched a stunning outbreak of caterpillars that stripped an oak tree bare in a week, then wafted on gossamer threads to another. 

In the denuded branches, scientists see a fingerprint of climate change - and a pattern of things to come.

Climate Change Is Beginning to Disrupt Agriculture

Climate variability has already affected rains, droughts and temperatures in several parts of the United States, said Cynthia Rosenzweig, a senior research scientist with NASA's Goddard Institute for Space Studies. "We are already seeing climate change." "We are seeing the expansion of drying," said Rosenzweig, as she brought up a slide showing precipitation measurements across the United States. The measurements, comparing values from 1958 through 2008, showed significant reductions in rainfall across large portions of the Northwest and Southeast. Idaho, Washington, Montana, Georgia and Florida had some of the most drastic changes in rainfall on the map. However, the opposite is not good either, she said, adding that increased soil moisture in some areas could potentially harbor insects and other pests. And, in general, "crops do not like to have their feet wet." Aside from concerns about rainfall, local temperature is also extremely important for crop performance. The reproductive development in many important grains is a process sensitive to temperature, said Paul Gepts, a professor of agronomy at the University of California, Davis. Some plants need cold winters One of the potential side effects of climate change is a trend toward milder winters in some regions. Vital plants, Gepts said, require a cold winter in order to properly develop their seeds for the next season. Rosenzweig agreed. Heat waves, at odd times of the year, affect the proper development of proteins within corn kernels, she said. "It is like scrambling eggs." Gepts also presented a number of well-known strategies for mitigating some of the possible economic effects of climate change on agriculture. Aside from breeding plants to be more drought-, heat- and pest-resistant, he also suggested varying the types of crops maintained on a particular site on the basis of environmental suitability.

Bolstered by mild winters and heavy spring rains, the poison ivy creeping across the Chicago landscape this summer is at bumper crop levels.The abundance of poison ivy and other invasive plants proliferating in Illinois and across much of the nation this year is a symptom of a scenario more serious than an itchy red rash, experts say.Elevated CO2 levels in the atmosphere, although destructive to many plant species, are proving a boon for adaptive weeds such as poison ivy, said Lewis Ziska, a federal plant physiologist.

"We are up to our arms in poison ivy this summer," said Ziska, with the USDA's Agricultural Research Service in Beltsville, Md. The higher CO2 levels, he said, also are contributing to an increasing abundance of kudzu, the legendary vine once limited to the South but was discovered lurking in central Illinois and as far north as Canada. Dr. Paul Epstein, associate director for the Center for Health and the Global Environment at Harvard Medical School, said recent studies show that poison ivy is not only more prevalent across the U.S. but more toxic, too. The rise in CO2 levels strengthens an oil in the plant that triggers itchy havoc when it touches the skin, he said. The heavy rains, warmer temperatures and rising CO2 levels that have disturbed plant chemistry also have increased pollen counts, leading to higher rates of asthma and allergies. "It's not an accident we're having this perfect storm," said Epstein. "Pests and pathogens thrive in extreme events, like floods or droughts. We need to stabilize the climate by reducing fossil fuel emissions dramatically." John Masiunas, an associate professor in the Department of Crop Sciences at the University of Illinois Urbana- Champaign, said he is unaware of any quantitative data tracking an increase in poison ivy taking root across the state. But, he said, "it makes perfect sense that higher CO2 levels will make these plants more efficient." The plant has "a survivor's ability" to grow in a variety of environments, Masiunas said, adding that climate change is also detrimental to endangered species such as native thistles and orchids that require specific soils and pollinators to thrive. "When climate change occurs … it is poor for these plants and contributes to the extinction of the species," Masiunas said. "When endangered plants are competing in an agricultural ecosystem, they start losing, and plants like poison ivy start doing better."

The new report shows that over 80% of the whitebark pine forests of Wyoming, Idaho, and Montana are already dead or dying.

“The red and grey trees littering the western landscape are a testament to the fact that North America’s forests are under assault,” said Louisa Willcox, senior wildlife advocate for NRDC and one of the minds behind a new report on whitebark pine mortality in the Greater Yellowstone Ecosystem. “Climate change is hitting the whitebark pine hard by allowing mountain pine beetles access to previously inhospitable forests at higher elevations.  Whitebark, which grows from roughly 8500 feet up to treeline, has never had to fight off a threat like this, and if we don’t act quickly, we could lose this essential tree species.”

Unfortunately for those dependent wildlife species, such as squirrels, chipmunks, grosbeaks, crossbills, and grizzlies (especially in Yellowstone) as well as other creatures, whitebark pine forests are being decimated throughout their range by an array of threats that have emerged in high-elevation environments, as a result of climate change, particularly now swarming mountain pine beetles, as well as an invasive nonnative disease, blister rust.