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Additional Deaths, Health Disparities Forecast in Pair of Climate Change Studies

Allison Inserro

A pair of articles published this month paint a devastating picture of the effects of climate change on human health. One paper cited increased air pollution spurred by air conditioning and another paper said that the decreased nutritional quality of staple crops will increase diseases like anemia and diarrhea.

The papers were published in a special climate change issue of the journal PLOS Medicine.

In one study, researchers at the University of Wisconsin-Madison predicted as many as 1000 additional deaths a year in the eastern United States alone, due to elevated levels of air pollution driven by the increased use of fossil fuels, such as coal-fired plants, for air conditioning.1

"What we found is that air pollution will get worse," said David Abel, the lead author of the report, in a statement. "There are consequences for adapting to future climate change."

The analysis combines projections from 5 different models to forecast increased summer energy use and how that would affect power consumption from fossil fuels, air quality, and, consequently, human health just a few decades into the future.

Their modelling study considers different climate increases with or without adaptation. The scientists predict increases of 4.8% and 8.7% for particulate- and ozone-associated deaths, respectively, above climate change impacts alone. The study forecasts an additional 13,000 human deaths annually caused by higher summer levels of fine particulate matter and 3000 caused by ozone in the eastern United States by mid-century.

Most of those deaths will be attributable to natural processes like atmospheric chemistry and natural emissions, which are affected by rising temperatures. However, about 1000 of those deaths each year would occur because of increased air conditioning use as temperatures continue to get hotter, essentially creating a vicious cycle.

Air pollution is a known factor for respiratory diseases like asthma, pneumonia, and others. It has also been linked to lung infections, especially in small children.

Air conditioning does and will save lives, said Jonathan Patz, MD, MPH, a senior author of the study and a UW-Madison professor of environmental studies and population health sciences. However, he said that there will be a trade-off in air quality and human health, he said, if the increased use of air conditioning due to climate change depends on power derived from fossil fuels.

"We're trading problems," said Patz, an expert on climate change and human health. "Heat waves are increasing and increasing in intensity. We will have more cooling demand requiring more electricity. But if our nation continues to rely on coal-fired power plants for some of our electricity, each time we turn on the air conditioning we'll be fouling the air, causing more sickness and even deaths."

Air quality expert Tracey Holloway, PhD, a UW-Madison professor of environmental studies as well as atmospheric and oceanic sciences, said the study adds to our understanding of the effects of adapting to climate change by simulating the scope of fossil fuel use to cool buildings under future climate change scenarios.

Buildings are responsible for more than 60% of power demand in the eastern United States, the geographic scope of the study.

"Air quality is a big issue for public health," she said, noting that the increased use of fossil fuel will increase ground-level ozone and fine particulate matter in the air, which worsen respiratory conditions.

Policy makers and planners need to consider energy conservation, building design, and other measures, like investing in wind and solar power, to tackle future dependence on buildings' cooling systems, the researchers said.

In another article, scientists predict reduced crop nutritional content and subsequent health disparities due to increased carbon dioxide levels associated with climate change.2 In their study looking at 137 countries, the researchers incorporated estimates of climate change, crop nutrient concentrations, dietary patterns and disease risk into a model of iron and zinc deficiency.

Their estimates predict a disease burden of approximately 125.8 million disability-adjusted life-years globally over the period from 2015 to 2050, disproportionately affecting southeast Asian and sub-Saharan African countries, because of a greater burden of infectious diseases, diarrhea, and anemia.

These regions already have high existing disease burdens from zinc and iron deficiencies.

Climate mitigation strategies, such as the Paris Agreement, may be more effective than traditional public health interventions in averting this disparity, they wrote. They tested strategies consistent with the Paris agreement, which the United States has withdrawn from, with 5 public health interventions.

Of the traditional public health interventions, zinc supplementation would be expected to avert 5.5%, iron supplementation 15.7%, malaria mitigation 3.2%, pneumonia mitigation 1.6%, and diarrhea mitigation 0.5% of the disease burden.

By contrast, interventions consistent with the Paris Agreement, which was previously anticipated to feasibly prevent approximately 47% of the increase in carbon dioxide concentrations by 2050, would be expected to avert 48.2% of global carbon dioxide–attributable zinc and iron deficiency burden of disease (95% credible interval: 47.8% ± 48.5%).

References
1. Abel DW, Holloway T, Harkey M, et al. Air-quality-related health impacts from climate change and from adaptation of cooling demand for buildings in the eastern United States: an interdisciplinary modeling study. PLoS Med. 2018;15(7):e1002599. doi: 10.1371/journal.pmed.1002599.

2. Weyant C, Brandeau ML, Burke M, Lobell DB, Bendavid E, Basu J. Anticipated burden and mitigation of carbondioxide-induced nutritional deficiencies and related diseases: a simulation modeling study. PLoS Med. 2018;15(7):e1002586. doi: 10.1371/journal.pmed.1002586.
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