Extreme Heat and Climate Change

Observed and projected changes (compared to the 1901–1960 average) in near-surface air temperature for Vermont. Projected changes for 2006–2100 are from global climate models for two possible futures: one in which greenhouse gas emissions continue to increase (higher emissions) and another in which greenhouse gas emissions increase at a slower rate (lower emissions). Sources: CISESS and NOAA NCEI.

Last week saw a seemingly endless string of days with heat advisories. Widespread heat index values (the measure of how hot it actually feels, factoring in temperature and humidity) soared up to 100 with localized heat index values up to 105 °F.

When we hear about death from natural disasters, we may picture floods, tornados, and hurricanes. In reality, the leading cause of weather-related deaths in the United States is extreme heat; an estimated 1,220 people are killed by extreme heat every year. In contrast, flooding causes about 98 deaths per year. Some experts refer to heat as the “silent killer” for this reason. The damage outside of the US is also severe– over 1,000 people died amid extreme heat at this year’s Hajj pilgrimage in Saudi Arabia. The difficulty in determining mortality numbers related to heat is that it can take a while to total up the “excess mortality,” or the number of deaths above what would normally be expected.  in 2003, when Europe experienced one of the first great 21st century heatwaves, it took months to calculate the true death toll: 70,000 people.

2023 was the earth’s hottest year since 1850, when record keeping began. It was also Vermont’s hottest year on record according to the National Weather Service Burlington office, which found that the average mean temperature in the northeast reached 50 degrees for the year– a first ever for the region. According to U.S Energy Department survey data, about one third of Vermont households do not use any air conditioning equipment. If you have memories of summers without air conditioning, it’s not just your imagination– Vermont summers used to be cooler. Vermont is, on average, about 3 degrees F warmer than it was in 1900. Since 1960 alone, Vermont’s average annual temperature has increased is 1.47 °F. We see 16 fewer days below freezing each year as we did in the early 1990s.

It is clear to scientists that this extreme heat will only continue to worsen as a result of global warming. In 2023, carbon dioxide (CO2) levels rose to 419 parts per million, around 50 percent more than before the Industrial Revolution. As we continue to burn fossil fuels, carbon dioxide levels rise. Some are absorbed by land and ocean, and the rest remain in the atmosphere. How much CO2 is absorbed varies depending on a number of factors and is predicted to go down in the future, meaning more CO2 in the atmosphere. In order to stop further warming, we would need to bring emissions essentially down to zero.

According to the National Oceanic and Atmospheric Administration (NOAA), under a high emissions scenario, Vermont could be 4 to 10 degrees warmer than the 20th century average by 2050. The implications of this warming trend are profound for Vermont and beyond. Hotter temperatures strain agriculture and exacerbate droughts and wildfires. Heat waves also threaten vulnerable populations, such older adults, the very young, and people with mental illness and chronic diseases, according to the CDC.

In the short term, focus on staying safe when a heat advisory is issued for your area. Visit www.heat.gov to view National Weather Service extreme heat advisories, watches, warnings, and forecasts, and follow advice of from the CDC on how to stay safe in extreme heat. Consider buying a heat pump, which efficiently cools and dehumidifies in the summer and heats in the winter.  You will receive a $350-$450 instant discount on qualifying heat pump models and a $200-$2,200 bonus rebate depending on income levels. Additionally, if you owe income taxes, you can receive a 30% tax credit (up to $2,000) for heat pumps.

In the long term, advocacy for climate policies and against fossil fuels will create meaningful change to slow global warming. Show up at town meetings, contact your representatives, and vote. The path forward demands collective action—a commitment to sustainable practices, advocacy for the climate, and resilience in the face of rising temperatures.


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