People around the world are feeling the effects of extreme heat this summer. More than 100 million people in the United States lived under heat alerts during this month’s heat waves. In the UK and China, infrastructure buckled under record-breaking heat that also has contributed to wildfires across Europe and elsewhere. Shanghai, China, hit an all-time record high of 105 degrees F (40.9 C) this week, and other regions of the country are expected to reach temperatures of 104 F or higher in the next week.

No longer limited to historically warm places, extreme heat has become a new reality across the globe as human-caused greenhouse gas emissions increase. As the concentration of greenhouse gases in the Earth’s atmosphere grows, more heat gets trapped, and both average and extreme temperatures rise. Other factors, such as jet streams shifting northward and slowing (also linked to climate change), are also dialing up extreme heat.

These climate effects have caused daily high temperatures to occur twice as often as record daily lows across the continental United States in the past ten years. The National Climate Assessment estimates 20–30 more days hotter than 90 F in most areas of the United States by mid-century. Globally, temperatures have already increased by 1 C above pre-industrial levels and are continuing to rise. These higher baseline temperatures are driving up mean daily highs during periods of extreme heat. They become even more dangerous when combined with high humidity (i.e., high dew points), causing heat stress, when the human body is less easily able to cool itself through perspiration (which can lead to heat stroke and death). Extreme heat also increases the risk of other types of disasters, such as wildfires, droughts, and crop failures.

Rising temperatures across the globe pose a threat to people, ecosystems, and the economy. After hurricanes, extreme heat kills more people each year than any other weather-related disaster, and six of the ten deadliest U.S. disasters since 1980 have been heat waves (defined as periods of extreme heat that last two or more days and differ from historic temperature averages). Extreme heat impacts are especially acute in cities, where the urban heat island effect can make air temperatures up to 7 F hotter than outlying areas. Older adults, infants and children, people with chronic health conditions, and outdoor workers are the most susceptible to heat stress.

Extreme heat also takes its toll on the global economy. The European Environmental Agency estimates that extreme heat cost Europe $71 billion between 1980 and 2000. Heat-related productivity losses in the United States are estimated to be around $100 billion a year at current temperatures but are projected to increase to $200 billion, or 0.5 percent of GDP, by 2030. Additionally, extreme heat can stress or kill livestock, burn crops, and damage infrastructure that is vital to industry, commerce, and energy production.

Even as temperatures rise, there are near-term local policy actions that can help mitigate heat or help people prepare:

• Green Infrastructure and nature-based solutions: Trees and vegetation can reduce heat by shading buildings, pavement, and other surfaces to prevent solar radiation from reaching surfaces that absorb heat and then transmit it to buildings and surrounding air. Increased tree canopy cover has been shown to reduce temperatures up to 4.3 degrees.
• Cooling Infrastructure: Cool roofing and pavement materials increase the solar reflectance of traditional materials that absorb and transfer heat to buildings and sidewalks, resulting in cooler buildings and a reduction in the urban heat island effect. Both green and cooling infrastructure have the added benefit of creating jobs for installation and maintenance.
• Emergency Preparedness & Awareness Measures: Emergency planning and warning systems can help cities and states prepare for emergencies before they occur. Heat vulnerability should be considered in community planning to understand access to cooling, energy system load capacity, and local resilience hubs and cooling centers that support emergency needs. Warning systems can also be used to communicate information and services available during periods of extreme heat.

As explored in a recent C2ES report, resilience solutions for extreme heat and other hazards can be integrated with and build off strategies for economic development, yielding additional benefits for local economies. For example, workforce development programs can be tailored to green infrastructure construction and maintenance. Cooling infrastructure can be built into brownfield redevelopment projects, and new businesses can be created that offer local extreme heat solutions and technologies.

At the national level, the Biden administration has increased the focus on extreme heat by creating the first-ever national heat-specific safety standard for workers, stepping up enforcement, building inter-agency coordination, and launching Heat.gov to educate the public. The bipartisan infrastructure law passed in 2021 also devotes significant funding to extreme heat resilience, including through programs like the Low Income Home Energy Assistance Program.

Congress can also pass the National Climate Adaptation and Resilience Strategy Act, which would require the development of a national resilience strategy and the creation of a Chief Resilience Officer for the nation. If enacted, it would streamline the federal response to extreme heat and other hazards, unlocking new resources for cities and towns to better prepare.

Tools such as the recently released Climate Shift Index are visualizing and quantifying the effects of climate change on daily temperatures. For instance, the tool shows that the current high temperatures in the Pacific Northwest are four times more likely in our global warming environment. The current heat wave is driving temperatures up to 17 F higher than expected seasonal temperatures.

Increasing atmospheric greenhouse gas concentrations are making it harder to escape higher temperatures; but, with the right policies and priorities, people and property can be more resilient, and local economies can better absorb the impacts.