U.S. health agencies have been monitoring climate change for some time. So have researchers at universities across the country. What they've found might help people protect their health as weather conditions change.

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Climate change is not just a change in the global temperature; it is also a change in the weather. George Luber, the chief of the climate and health program at the U.S. Centers for Disease Control and Prevention, told VOA, "Climate change has a broad impact on health, both through the direct effect that climate change has on extreme weather – heat waves to heavy rainfall events and associated flooding, coastal storms, hurricanes -- but also indirectly, in the way that it alters disease ecology, or ecosystems that are important in maintaining a healthy environment."

One example is Lyme disease, which is caused by a particular type of bacterium spread through the bite of infected blacklegged ticks, also known as deer ticks. A warming climate and changing seasonal temperatures have expanded the tick's range.

"We're seeing more cases. We're seeing shifts northward and to the midwest, and that's linked to changing seasonal patterns," Luber said. In the past 20 years, blacklegged ticks have increased their range from the southeastern U.S., north to Canada and west to Minnesota, which is known for very cold winters.

Scientists are seeing more heavy rains in some regions, drought in others. The rain can create flood plains where mosquitoes breed, and storms, floods and droughts can create conditions conducive to clusters of water-, mosquito- and rodent-borne diseases. Scientists expect storms and floods to increase the spread of cholera in developing countries as flooding creates contaminated water.

Other research concerns the spread of malaria. A larger portion of Africa than previously predicted is now at high risk for malaria transmission, according to a new University of Florida mapping study. Malaria will arrive in new areas, the research suggests, posing a risk to new populations and will require changes in managing public health. The study also shows that some parts of Africa will become too hot for malaria.

Part of Luber's job involves preparing the public for the threat of climate change, bringing in the latest science and help the various states integrate climate change into their planning. For example, CDC's research shows that the state of Oregon will soon experience heatwaves. Oregon is known for its temperate weather.

"We work with them (state health officials) to assess their weather or climate-related risks, and through the use of climate models discovered that while they don't experience heatwaves now, the future projections is that they will start experiencing heatwaves in the future," said Luber.

Oregon actually experienced two unusual heat waves last summer. The CDC advised health authorities to set up cooling shelters and help people who are especially vulnerable to heat. Luber said the southeastern states will be more prone to inland flooding as the climate changes, which will mean people there will have to find a source of clean water.

Vocabulary

ecosystem：生態(tài)系統(tǒng)

tick：扁虱

cholera：霍亂

malaria：瘧疾

來(lái)源：VOA

編輯：丁一