Malaria already kills a million people a year and now, researchers fear, climate change could make the problem even worse.
Working with the Kenya Meteorological Department, Madeleine Thomson, a senior research scientist for the International Research Institute for Climate and Society, has found that temperatures have increased significantly since the 1980s in the Kenyan Highlands.
Thomson, who has been working in Africa for the past 25 years, has looked at the possibility of increased risk of malaria from a rise in global temperatures for the past 10.
"Malaria is an appalling disease, particularly for those that don't have immunity, such as foreigners, young children and pregnant women, and also the people who live in the highlands who normally don't get malaria," Thomson said.
"When I visited Tigre, a mountainous region in Ethiopia, I met people with malaria in the highlands, and they were trying to understand what was going on," Thomson said. "We know that the rises in temperature that have been recorded at this site can significantly increase malaria. And it's the combination of climate change, drug resistant malaria and poor health conditions that can completely devastate an area."
Around the world, climate change is impacting human health -- from recent floods in India, Nepal and Bangladesh that have caused widespread waterborne disease that the U.N. attributes to global warming, to malaria-infected mosquitoes migrating to increasingly high elevations in the mountains of Africa.
"Climate change will touch the pillars of our health, food, water and shelter," Dr. Maria Neira, director of public health and environment for the World Health Organization, told ABC News. "In Asia, there are more people at risk of dengue fever due to global warming. In Mount Kenya, mosquitoes are being found at higher and higher elevations."
Besides studying the malaria problem, Thomson's knows about the disease from personal experience.
"I woke up feverish and hallucinating," she said. "Fortunately, I worked for the U.K. government's medical research council in Sierra Leone and was treated immediately with effective drugs."
Many are not so lucky -- and others agree with her that the malaria could become an even bigger problem as the climate changes.
"As temperatures have been increasing, the mosquitoes that are transmitting the disease have better conditions to breed, reproduce, and transmit the disease," Neira said. "Vector-borne diseases are expanding their reach and death tolls."
Climate Change Will Have Far-Reaching Impacts, Experts Warn
During this century, the Earth's average surface temperature likely will rise more than 2 degrees Celsius, scientists fear. According to the IPCC's 4th assessment released in 2007, as global temperatures continue to rise as a result of climate change, there will be increased risk of food and water shortages.
Already, every 21 seconds a child dies from lack of access to clean water. Could it get worse in a warming world?
As warming likely causes seawater level to rises, underground freshwater aquifers likely will get contaminated. Drought likely will continue to impact fresh water supplies for millions of people around the world, and more people will be forced to move.
Since 2008, Los Angeles, which gets a portion of its drinking water from the Colorado River, has faced long-term drought because of global warming. The river suffers from low volume and rising water temperatures. The shrinking river has raised health concerns for the 30 million people in seven states who depend on it for their water supply.
In Shanghai, China, 20 million people are at risk of facing a drinking water shortage because of rising sea levels combined with lowered water tables caused by pumping water for agricultural, public and commercial use.
For humans to survive, they need fresh water.
"The big issue with climate change is going to be population displacement," Gina Solomon, a senior scientist at NRDC, told ABC News. "We will see massive displacement on a global scale."
According to the U.N. high commissioner for refugees, Antonio Guterres, climate change could become the biggest driver of human displacement.
"Displacement causes conflict, creates a lot of health stress on the people who are displaced and the people taking in the refugees," Solomon said. "It can encourage the spread of disease from one part of the world to another. As people move, they can carry diseases with them."
Check out this interactive map by the NRDC, which highlights hotspots of climate change's effects on human health.
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