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    August 17, 2018 | 9:05 AM

    Climate Change and Health: Heatwaves

    This is a part of a new series from Climate Reality on the many ways that climate change is impacting human health. This is the first blog in the series, but check back for content on topics like hurricanes, wildfires, asthma, and more.

    What Exactly Is a Heatwave?

    Generally speaking, “extreme heat conditions are defined as weather that is much hotter than average for a particular time and place—and sometimes more humid, too.” Temperature isn’t the only part of the equation: to qualify as a heatwave, extreme heat usually needs to last at least two or three consecutive days.

    The humidity component is also important here. Take a look at the heat index graph below. For example, it may be 96°F (36°C) outside but if the relative humidity is 65 percent, it feels like 121°F to the human body -- while in the shade. Exposure to full sunshine can increase heat index values by up to 15°F! And that’s dangerous. Very dangerous.

    Source: Center for Disease Control, Climate Change and Extreme Heat: What You Can Do to Prepare

    Some quick facts:

    Number of fatalities by hazard (2006-2015) in the US. Source: Center for Disease Control, Climate Change and Extreme Heat: What You Can Do to Prepare

     

    How Do Heatwaves Impact Our Health?

    Plain and simple, exposure to a heatwave can overwhelm the human body. Our bodies are designed to keep our temperatures at about 98.6°F, but exposure to a heatwave makes it very difficult to maintain a healthy temperature. That’s because one of the best mechanisms the body has to keep itself cool is sweating. But if it’s both very hot and humid, sweat isn’t able to evaporate on our skin and we can’t cool down.

    We see people especially impacted by heatwaves when it doesn’t cool down overnight. As one expert explained, “If the temperature remains elevated overnight, that's when we see the increase in deaths. The body becomes overwhelmed because it doesn't get the respite that it needs… When a person is exposed to heat for a very long time, the first thing that shuts down is the ability to sweat.”

    According to the CDC, there are three main phases that the body goes through after prolonged exposure to extreme heat:

    • Heat cramps: “Muscle spasms, often in the abdomen, arms, or calves, caused by a large loss of salt and water in the body. Heat cramps can occur from prolonged exposure to extreme heat combined with dehydration, and they commonly happen while participating in strenuous outdoor activities such as physical labor or sports.”
    • Heat exhaustion: “A severe illness requiring emergency medical treatment. It can occur from exposure to extreme heat over an extended period of time (usually several days), especially when combined with dehydration.” Symptoms include heavy sweating, weakness, nausea or vomiting, and fainting. 
    • Heat stroke: “The most serious medical condition caused by extreme heat, requiring emergency treatment. Heat stroke (or hyperthermia) occurs when the body can no longer regulate its temperature, and its temperature rises rapidly—up to 106°F or higher…. It can result in death without immediate medical attention.”

    It’s important to remember that, like most climate impacts, heatwaves don’t affect all people the same way. Young children, the elderly, the poor, and people with preexisting conditions (like respiratory disease or diabetes) are the most at risk when exposed to extreme heat.

    So, Exactly How Are Heatwaves Related to Climate Change?

    Of all the types of extreme weather, heatwaves may be the most obvious one to connect to climate change and, well, a warming world. As humans burn more and more fossil fuels, we’re releasing heat-trapping gases like carbon dioxide into our atmosphere. As a result, we’re seeing more and more warmer-than-average years and more frequent extreme heat events. And if we don’t stop burning fossil fuels, we’ll keep setting heat records and keep experiencing more heatwaves.

    Source: Center for Disease Control, Climate Change and Extreme Heat: What You Can Do to Prepare

    Yes, extreme heat and heatwaves have happened since the beginning of time. But across the board, climate change is making heatwaves more common, more severe, and more long-lasting.

    Luckily, solutions to the climate crisis (and its health impacts) are available today. Clean, reliable energy like solar, wind, and geothermal don’t release heat-trapping greenhouse gases like oil, coal, and natural gas. That’s why we have to make the shift. Renewable energy, at the end of the day, just makes sense for the health of our families.

    How Are Other Types of Extreme Weather Related to Climate Change?

    It’s not just heatwaves. Droughts. Wildfire. Hurricanes. Flooding. All these types of extreme weather have been linked to our changing climate. In our free e-book, Extreme Weather and the Climate Crisis: What You Need to Know, we dive into the details — and also outline what you can do to stop climate change and work for a healthier future. Download the free e-book today.

    The Climate Reality Project