Climate Change Indicators in the United States: Fifth Edition

https://www.epa.gov/climate-indicators/climate-change-indicators-united-states-fifth-edition EPA Releases Updated Climate Indicators Report Showing How Climate Change is Impacting People’s Health and the Environment WASHINGTON — Today, July 2, the United States Environmental Protection Agency released the Fifth Edition of Climate Change Indicators in the United States. The report highlights new data showing the continuing and far-reaching impacts of climate change on the people and environment of the United States. New to the report this year are an indicator on Marine Heat Waves (showing trends related to multi-day high ocean temperatures) and a feature on Heat-Related Workplace Deaths. “EPA’s Climate Change Indicators report is an authoritative resource of how the climate crisis is affecting every American right now and with increasing intensity,” said EPA Administrator Michael S. Regan. “Extreme heat, flooding, and wildfires have become more common, harming human health, threatening livelihoods, and causing costly damage. Regular updates to the data in the Climate Indicators website and report help us track these unprecedented changes so we are better informed in our shared work to confront the crisis.” The Fifth Edition presents highlights from a subset of EPA’s total of 57 indicators, which include historical data and observed trends related to either the causes or effects of climate change. The report explores the interconnected nature of observed changes in climate with chapters thematically organized around Greenhouse Gases, Heat on the Rise, Extreme Events, Water Resources at Risk, Changing Seasons, Ocean Impacts, Rising Seas, and Alaska’s Warming Climate. Since publishing the first edition in 2010, EPA has maintained an up-to-date online resource of climate change indicators and regularly released updated publications that present the latest data. EPA partners with more than 50 data contributors from various U.S. and international government agencies, academic institutions, and other organizations to compile these key indicators of climate change. EPA’s indicators show multiple lines of compelling evidence that climate change is increasingly affecting people’s health, society, and ecosystems in numerous ways. For example: Global and U.S. Temperature – Worldwide, 2023 was the warmest year on record, 2016 was the second warmest, and 2014–2023 was the warmest decade on record since thermometer-based observations began. In the U.S., unusually hot summer days have become more common over the last few decades, and unusually hot summer nights have increased at an even faster rate, indicating less “cooling off” at night. Heat Waves in U.S. Cities – Heat waves are occurring more often in major cities across the United States. Their frequency has steadily increased, from an average of two heat waves per year during the 1960s to six per year during the 2010s and 2020s. The average length of the heat wave season across the U.S. cities is 46 days longer now than it was in the 1960s and, in recent years, the average heat wave in major U.S. urban areas has lasted about four days. A Closer Look – Heat-Related Workplace Deaths - From 1992 to 2022, a total of 986 workers across all industry sectors in the United States died from exposure to heat of which the construction sector accounted for about 34 percent of all occupational heat-related deaths. During this time frame, 334 construction workers died due to heat exposure on the job. Sea Surface Temperature – Over the past century, sea surface temperature has increased and continues to rise. Sea surface temperature has been consistently higher during the past three decades than at any other time since reliable observations began in 1880. Marine Heat Waves – Between 1982 and 2023, the annual cumulative intensity of marine heat waves has increased in most coastal U.S. waters, with the largest changes in waters off the Northeastern U.S. and Alaskan coasts. When a location experiences an increase in annual cumulative intensity over time, that means marine heat waves are becoming either more common, longer, more intense (hotter), or some combination of the three. Marine Species Distribution – In conjunction with warming ocean waters, many marine species off U.S. coasts are shifting northward and are moving to deeper waters. Since the 1980s, shifts have occurred among several economically important fish and shellfish species. For example, American lobster, black sea bass, and red hake in the Northeast have moved northward by an average of 145 miles. Coastal Flooding – Tidal flooding is becoming more frequent along the U.S. coastline. Most sites with long-term data experienced an increase in tidal flooding since the 1950s. At more than half of these sites, floods are now at least five times more common than they were in the 1950s. The rate of increase of flood events per year is largest at most locations in Hawai'i, and along the East and Gulf coasts. Wildfires – The extent of area burned by wildfires in the United States has increased since the 1980s, with the largest increases occurring in the West and Southwest. Of the 10 years with the largest acreage burned, all have occurred since 2004, including peak years in 2015 and 2020. This period coincides with many of the warmest years on record nationwide. Length of the Growing Season – The average length of the growing season in the contiguous 48 states has increased by more than two weeks since the beginning of the 20th century. A particularly large and steady increase has occurred since the 1970s. States in the West (like Washington and California) have seen the most dramatic increase. Snowpack – From 1982 to 2023, the snowpack season became shorter at 80% of the sites measured. Across all sites, the length of the snowpack season decreased by an average of about 15 days and peak snowpack has shifted earlier by an average of nearly seven days since 1982. Arctic Sea Ice – The September 2023 sea ice extent was the fifth smallest on record. It was about 789,000 square miles less than the historical 1981-2010 average for that month – a difference almost three times the size of Texas. Since 1979, the length of the melt season for Arctic sea ice has grown by 37 days. On average, Arctic sea ice now starts melting seven days earlier and starts refreezing 30 days later than it has historically. Understanding and addressing climate change is critical to EPA’s mission of protecting human health and the environment. Tracking observations over time reveals valuable information about what people are experiencing today and can help inform climate solutions. The Fifth Edition of the Climate Change Indicators in the United States report provides abundant evidence of how climate change is happening all around us. Taking action to fight the urgent threat of climate change is an opportunity to build more resilient infrastructure, protect public health, advance environmental justice, strengthen America's working communities, and spur American technological innovations.