Thousands of Americans lives can be saved if global warming is limited to 1.5°C: Study

Thousands of Americans lives can be saved if global warming is limited to 1.5°C: Study

Even as the US has decided to withdraw from the Paris Agreement, a new study shows that hundreds to thousands (110-2720) of heat-related deaths could be avoided per US city annually if the 1.5 degrees Celsius target of the Paris Agreement is achieved.

Climate change is projected to increase heat-related mortality in the US, Europe, the Americas, East, and Southeast Asia, Australia, the Middle East, and North Africa, said the paper.

“Achieving the 1.5°C threshold could avoid between 110 and 2,720 annual heat-related deaths. Population changes and adaptation investments would alter these numbers. Our results provide compelling evidence for the heat-related health benefits of limiting global warming to 1.5°C in the US,” said the paper, published in the journal Science Advances.

The findings are highly relevant to decisions about strengthening national climate actions in 2020, when the next round of climate pledges is due. The Paris Agreement aims at keeping the global average temperature to well below 2°C above pre-industrial levels, with an ambition of limiting warming to 1.5°C.


Nations in the agreement are required to submit their climate pledges every five years.

Lead author of the study, Dr. Eunice Lo from the University of Bristol’s Cabot Institute in the UK, told MEA WorldWide (MEAWW): “Nations’ current climate pledges imply 3 degrees Celcius warming. This means increasing nations’ climate actions would be substantially beneficial to public health in the US, as large numbers of human lives could be saved. Policymakers should focus on immediate and drastic emission cuts to avoid large increases in heat-related deaths in major cities in the US. They also have an obligation to help communities prepare for and adapt to rising temperatures, especially those who are most vulnerable to heat.”

This first-of-its-kind study, which involved climate scientists and epidemiologists from the UK and the US, observed temperature and mortality data with climate projections of different warmer worlds, to estimate changes in the number of heat-related deaths for 15 major US cities.


This included Atlanta, Boston, Chicago, Dallas, Detroit, Houston, Los Angeles, Miami, New York, Philadelphia, Phoenix, San Francisco, Seattle, St. Louis, and Washington D.C. Their findings showed that limiting warming to the lower Paris Climate Goal could avoid hundreds and thousand of annual heat-related deaths during extreme heat-events (defined as heat events that are expected to occur once every 30 years), depending on the city.

This is substantially more beneficial than limiting warming to the upper Paris Climate Goal, which could avoid 70 to 1,980 deaths per city, said the research team in a release by the University of Bristol.

New York City, the most populous city in the US could see 1,980 1-in-30-year heat-related deaths avoided in the 2°C warmer world relative to the 3°C warmer world under the assumption of constant population, said the paper.

If the 1.5°C world is realized, said the researchers, then 2,716 1-in-30-year heat-related deaths could be avoided, relative to 3°C.


The paper said Los Angeles, the second most populous US city, is projected to have 759 1-in-30-year avoided heat-related deaths under the 2°C threshold, relative to 3°C. Under the 1.5°C threshold, 1,085 1-in-30-year heat-related deaths could be avoided.

“Chicago could experience a statistically significant reduction in 1-in-30-year heat-related mortality relative to the 3°C warmer world under both Paris Agreement thresholds. Specifically, 636 and 8751-in-30-year heat-related deaths could be avoided in the 2° and 1.5°C warmer world, under an assumption of constant population. To put these numbers into context, the July 1995 Chicago heat wave led to 514 excess heat-related deaths in the city,” said the paper.

Dr. Kristie L. Ebi, Center for Health and the Global Environment, University of Washington, and one of the author’s of the study told MEAWW that under a scenario of an increase of 3 degrees Celsius in global mean surface temperature, a one-in-thirty-year extreme heat event would lead to nearly 1,350 heat-related deaths per city, on average, assuming today’s population.


“Chicago, Los Angeles, Miami, New York, and Philadelphia will be facing the highest number of fatalities. Miami and Detroit would face the highest rates of heat-related mortality because of older and more vulnerable populations,” she said.

Professor Ebi further said: “Our study adds to the evidence that accelerating ambition to reduce emissions and limit temperature rise to well below 2 degrees Celsius (3.6 degrees Fahrenheit) - the central goal of the Paris Agreement - could prevent thousands of extreme heat-related deaths in cities across the US Limiting global temperature rise to 2 degrees Celsius could mean nearly 740 fewer extreme heat-related deaths, on average, across these cities, and 1,980 fewer extreme heat-related deaths in New York City alone. Even more heat-related deaths can be avoided by limiting global temperature increase to 1.5 degrees Celsius (2.7 degrees Fahrenheit).”

The researcher said policymakers should focus on immediate and drastic emission cuts to avoid large increases in heat-related deaths in major cities in the US. (Getty Images)


The findings are critical in light of US President Donald Trump’s announcement in 2017, that the US would withdraw the participation in the 2015 Paris Agreement on climate change mitigation.

However, the effective withdrawal date is not until 2020, and states including New York and California are still committed to achieving the US climate goal within the agreement.

“The US should stay in the Paris Agreement and take ambitious climate actions to limit global warming to 1.5 degrees Celsius. The US has emitted the largest amount of heat-trapping carbon dioxide in the world since the 18th century, and it’s their very own citizens, and many others on the planet, whose livelihood and lives will be adversely affected by global warming. Pulling out of the Paris Agreement is threatening the well-being of thousands of people per US city, as our research shows,” Dr. Lo told MEAWW.

She said that adaptation measures such as developing heat wave early warning and response systems, increased access to air conditioning and affordable health care, and urban planning that reduces cities’ exposure to heat can be taken to prevent heat-related deaths.


Dr. Ebi said that the US cannot pull out of the Paris Agreement until after the next election, and therefore, there is still time for the country to reduce its emissions drastically to prevent additional heat-related mortality with warmer temperatures under climate change. Stating that one way to assess the risks of climate change is to understand the magnitude and pattern of risks to human health, Dr. Ebi suggested that policymakers should consider the risks to human, natural, and managed systems when developing adaptation and mitigation policies.

“Investments to better prepare for extreme heat can, in combination with emissions reductions, prevent nearly all heat-related deaths. Cities can expand municipal systems to provide early warning and response to heatwaves to protect the most vulnerable as temperatures rise, ensuring that residents are aware of heat-related health risks and that those with low or fixed incomes have access to air-conditioning supplied, increasingly, by carbon pollution-free sources of electricity. Cities can also begin designing expanded green spaces that provide cooling during hot weather, and buildings, roads and other urban infrastructure that reflect rather than absorb sunlight,” Dr Ebi said.


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