Sustainability Climate Change

Climate change could cause more global deaths than all infectious diseases combined: study

climate change crisis national bureau of economic research report daily deaths elderly per 100,000 people gdp global warming temperatures rising poor hot cold
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Story at a glance

  • Older generations are particularly at risk, especially in poorer, tropical countries.
  • Richer countries will be able to pay to avoid the worst ramifications, but it will affect them economically.

The devastation of climate change is often measured as environmental tolls: rising waters, melting ice caps, record-breaking temperatures and air pollution. These common metrics gauge how severe humans’ effect on the environment is now — and can or will be in the future.

But data from a new report published by the National Bureau of Economic Research takes a different approach. 

Researchers are now asking, as temperatures warm and our planet changes in unprecedented ways, who will live and who will die — and when?

For starters, researchers say, older generations are particularly at risk. But as we inch closer to a tipping point and if no action is taken, climate change could claim more lives than all infectious diseases combined around the world.

In the first globally comprehensive estimate on mortality and a warming climate, researchers looked at 40 countries’ data, covering about 55 percent of the world’s population, to create multivariate models relating mortality rates to temperature, climate and income. Their analysis found an age-specific relationship between mortality and global temperatures, where elderly people are projected to suffer disproportionately with rising temperatures. 

“These results demonstrate that the elderly are disproportionately harmed by additional hot days and disproportionately benefit from reductions in cold days,” the report reads. 

Researchers also analyzed the economics of adapting to climate change, particularly the actions one might take in response to warmer climates. They found that not only are elderly populations vulnerable, but poorer communities are as well when it comes to the cost of living on a warming planet. 

“The data show that poor communities don’t have the means to adapt, so they end up dying from warming at much higher rates,” co-author Tamma Carleton, an assistant professor at the Bren School of Environmental Science and Management at the University of California, Santa Barbara said. “Rich communities are likely to spend a lot of money to protect themselves, resources that they would be able to spend elsewhere if they didn’t have to spend it coping with the heat.”

Using a scenario where carbon emissions are high and few adaptations are taken, researchers found that climate change projections could raise global mortality rates to 73 deaths per 100,000 people in 2100. This is conditional on humans adapting to prevent climate change. Should no action be taken, data projects that there would be 221 deaths per 100,000 people globally by 2100. 

This would be the rough equivalent to the sum of all global deaths from cardiovascular disease today, and surpass the total number of deaths from infectious diseases such as HIV, tuberculosis, and yellow fever (about 75 deaths per 100,000).

Among the populations expected to shoulder the greatest burden of climate change and its adverse effects on human health are the elderly. In the sample collected within the report, data suggests that people over the age of 64 will experience about 4.7 extra deaths per 100,000 people with a day at 35 degrees C (95 degrees F) versus a 20 C day (68 F).

“A lot of older people die due to indirect heat affects,” Amir Jina, an environmental economist at the University of Chicago and a co-author of the study said to The Guardian. “It’s eerily similar to Covid – vulnerable people are those who have pre-existing or underlying conditions. If you have a heart problem and are hammered for days by the heat, you are going to be pushed towards collapse.”

While poor communities in warmer parts of the world bear a disproportionately high fraction of the global mortality of climate change, the report also finds that those living in colder climates will not suffer as much, although older people are also threatened by unusually cold days — another effect of climate change.

The negative effects of climate change do not stop at human life. When monetizing the projected mortality toll, the authors found that fatalities associated with climate change will result in a decline of approximately 3.2 percent of global GDP in 2100. Using the same high emissions scenario, each ton of carbon dioxide emissions will cost $36.60 in damages. For a lower emissions hypothetical, the cost shrinks to $17.10 in adaptation costs. 

Should action be taken early to mitigate the effects of climate change, with only 0.6 percent of the global economic output accompanying the mortality risk damages when hypothetical carbon emissions are reduced from high to moderate.

The authors also acknowledge the discrepancy between colder and warmer climates, noting that under their models, “damages being especially large in today’s poor and/or hot locations.”

“Just as countries are impacted in different ways by extreme temperatures today, we find that the trend will continue and perhaps even intensify into the future as adaptation becomes more and more critical to people’s survival. Indeed, some will need to choose between paying a high cost to adapt and death,”  Jina said in a prepared interview.