On Monday, the Intergovernmental Panel on Climate Change released a stark warning that time is running out to adapt to climate change. Climate change is already having “widespread, pervasive impacts” on people everywhere in the world, a new report from the scientific panel says, due to the warming that has occurred so far — roughly 1.09 degrees Celsius (1.96 degrees Fahrenheit) above pre-industrial levels.
Global warming doesn’t only affect humans by changing the weather and melting the ice caps, the report warns. It also has resounding implications for how insects and other organisms move through the world, intermingle, and spread disease to human populations. “Climate-sensitive food-borne, water-borne, and vector-borne disease risks are projected to increase under all levels of warming,” the report says. (Vector-borne diseases are those spread by blood-sucking bugs like ticks and mosquitoes.) What’s more, the warming that has already taken place has already caused unprecedented disease impacts across the globe. Climate change is no longer a future prospect; it’s making people sick right now.
“One of the most striking conclusions in our report is that we’re seeing adverse impacts being much more widespread and being much more negative than expected in prior reports within the current 1.09 degrees that we have,” Camille Parmesan, a coordinating lead author of the report, told reporters on Sunday. “Some of the things that we’re seeing that were not expected at 1.09 degrees are diseases emerging into new areas.”
Insects and other organisms that carry disease spend much of their lives in the same place, which is why certain diseases are endemic to specific areas. Lyme disease, for example, is an illness spread by black-legged ticks — tiny, eight-legged, blood-sucking creatures that live in the Northeastern United States and other parts of the Northern Hemisphere. But climate change is messing with the environmental factors that geographically constrain these ticks. Warming temperatures and shifting weather patterns across the U.S. are making it easier for ticks to proliferate and move into new areas, where people and the doctors who treat them are unaccustomed to Lyme disease. It’s a double whammy, the report shows: Ticks are preying on bigger swaths of the population and growing more common where they already live. “Climate change can be expected to continue to contribute to the geographical spread of the Lyme disease vector,” the report says.
Similar stories are playing out in every corner of the globe, as diseases are emerging in places they have never been found before. Dengue fever, a mosquito-borne tropical illness that causes fever, headache, and vomiting and has a 20 percent death rate if it progresses and goes untreated, is projected to become an increasingly big risk for people in Asia, Europe, Central and South America, and sub-Saharan Africa as warm seasons grow longer and aedes aegypti mosquitoes expand their geographic range. “There are estimates of billions of additional people at risk of dengue fever later in the century,” Kristie Ebi, an epidemiologist at the University of Washington and a co-author of the report, said on Sunday.
Other mosquito-borne illnesses such as Zika virus, Chikungunya disease, and West Nile virus are at risk of becoming more common as climate change accelerates. So are serious water-borne diseases such as vibriosis and cholera, which cause nausea, diarrhea, and vomiting. Diarrheal diseases have decreased globally thanks to better distribution of medicines and low-tech medical interventions like treating patients orally with a mixture of water, glucose, and salts, but the report notes that increased rainfall and flooding in many regions has driven up the occurrence of diarrheal diseases such as cholera and other gastrointestinal infections.
And if existing diseases aren’t scary enough, melting permafrost and coastal erosion could surface prehistoric cemeteries, campsites, and reindeer burial grounds in the Arctic, unleashing ancient diseases that modern humans have no immunity to.
The report’s authors said that putting a number on future climate-related fatalities is extremely difficult, but they predict 250,000 extra deaths per year from heat, undernutrition, malaria, and diarrheal disease combined by 2050. Hundreds of existing diseases and more that will emerge in the coming years will add to the death toll.
Reducing the burden of disease on people is possible, but the clock is ticking to make those necessary adjustments, the report says. Developing surveillance systems for vector-borne diseases, implementing early warning systems to alert communities to those diseases and the prevalence of new vectors, and developing vaccines to inoculate people against vector-borne illnesses are all essential additions to the preparedness toolbox. To adapt to water-borne and food-borne illnesses, the report recommends governments improve access to potable water and protect water and sanitation systems from flooding. And protecting and preserving wild spaces such as wetlands, peatlands, and forests from human development has the two-pronged effect of sequestering carbon dioxide and preventing the spread of disease to humans by limiting contact between wild animals and people.
Zak Smith, director of the Natural Resources Defense Council’s wildlife division, who was not involved in the IPCC’s report, told Grist that governments largely aren’t prepared to take the necessary steps to protect public health from the increased risk of disease due to climate change. “What happened with COVID doesn’t raise my confidence level that people are ready to make the kinds of investments we need,” he said. “I think COVID is a warning. We don’t have this.”