Climate Change Is Increasing the Spread of Disease and Pandemics

The jury is out on whether coronavirus has spread more widely than it may have if the world were not undergoing climate change. It is not, however, when it comes to a rise in infectious diseases overall.

“As the planet heats up, animals big and small, on land and in the sea, are headed to the poles to get out of the heat,” writes the Harvard T.H. Chan School of Public Health. “That means animals are coming into contact with other animals they normally wouldn’t, and that creates an opportunity for pathogens to get into new hosts.”

And one of the world’s largest carriers of disease — the mosquito, which transports malaria, dengue and the West Nile virus to name a few — has been migrating. While mosquitos generally live in the warm equatorial region and in the Global South, a Stanford University biologist named Erin Mordecai has predicted that as the world heats up, the wrath of mosquitos and other biting insects will travel into historically colder countries, including wealthy northern ones.

“It’s coming for you,” Mordecai said. “If the climate is becoming more optimal for transmission, it’s going to become harder and harder to do mosquito control.”

In general, studies have found that there is “a close correlation with human health” as the world heats up. It is estimated that “global death rates will increase by 73 per 100,000 by 2100 due to changes in temperature,” according to a 2021 study published by the National Library of Medicine. The researchers’ work concluded that “a prevalently increasing trend in climate change factors corresponds to an increase in victims.”

An August study published in the journal Nature Climate Change said that 58 percent — 218 out of 375 infectious diseases worldwide — have been “at some point aggravated by climatic hazards; 16 percent were at times diminished.”

When it comes to the coronavirus, while it’s not clear that climate change has affected the spread of the disease, studies have shown that pollution is “positively associated with higher county-level COVID-19 mortality rates,” Harvard reports. The results, the university’s study found, are statistically significant.

The predicted change in disease-carriers’ migration patterns is already happening, some scientists say. Studies have shown that climate change has already made the conditions for infectious disease outbreaks more favorable than in the past. Harvard cites Lyme disease, waterborne diseases, and mosquito-borne diseases as already on the rise in unexpected places:

“Future risks are not easy to foretell, but climate change hits hard on several fronts that matter to when and where pathogens appear, including temperature and rainfall patterns.”

Also, as humans gravitate to particular cities — and away from drought-stricken farms and other no longer viable kinds of agriculture — animals, and insects travel with us.

All of this collides with the drop in available health care when a climate-related emergency hits. And countries with weak health infrastructure are likely to be most affected in natural disasters — which includes impoverished areas of the United States.

“The climate crisis threatens to undo the last 50 years of progress in development, global health, and poverty reduction, and to further widen existing health inequalities between and within populations,” the World Health Organization reports. “It severely jeopardizes the realization of universal health coverage in various ways — including by compounding the existing burden of disease and by exacerbating existing barriers to accessing health services, often at the times when they are most needed.”

One of the Harvard studies offers a solution, as unreachable and known, unfortunately, as it already is: “To help limit the risk of infectious diseases, we should do all we can to vastly reduce greenhouse gas emissions and limit global warming to 1.5 degrees.”