Summer of Extremes: Roundup of U.S. Records by Richard Somerville and Jeff Masters

Summer of Extremes: Roundup of U.S. Records

An Update from Climate Communication, September 25, 2012

Expert Reviewers:

• Richard Somerville, Scripps Institution of Oceanography, UC–San Diego
• Jeff Masters, Weather Underground

With oppressive heat waves, devastating droughts, ravaging wildfires, and hard-hitting rainstorms, the summer of 2012 has been one for the record books. Thousands of precipitation and temperature records were broken, plaguing almost all of the contiguous United States this season and underscoring the connection between climate change and increasingly frequent and intense extreme weather. With climate change, we’ve set the stage for precisely this kind of extreme weather, and unfortunately, our changing climate threatens to alter summers to come.

It is important to note that as the planet continues to warm, new high temperature records and some other types of extremes will increasingly occur, but where they occur in a given year will not be predictable due to natural modes of climate variability. Extreme weather pummeled the United States this summer, but the next few years might see the most dramatic extremes occurring elsewhere around the world. Regardless, record-breaking high temperatures, droughts, wildfires, and heavy downpours are all signs of new extreme weather patterns that we can expect to see more of in a warming world, both domestically and abroad.

Here’s a roundup of weather events during the record-breaking summer of 2012:

Heat

• From June to August 2012, nearly 10,000 daily high temperature records were broken compared to just over 1,400 daily low-temperature records throughout the same 3-month period.
• July 2012 was the hottest month in U.S. history.
• June–August 2012 was the 3rd hottest on record for the continental U.S., 2.3 degrees F above the 20th century average.
• Wyoming and Colorado each had their hottest summer on record; Nevada was record hot for August.
• Approximately 6% of the 300 largest U.S. cities set their all-time heat records in 2012. The only year with more all-time heat records than 2012 is 1936, when 20% of U.S. cities set their all-time heat records.
• Remarkably, 50% of the contiguous U.S. had maximum temperatures that were in the highest 10% historically during summer 2012. 
• More than 80 million people—about 10 million more than in 2011—experienced 100°F or higher temperatures. Oklahoma City had 18 straight days where temperatures reached 100° or greater, including three days in a row that were 112 °F, exacerbating wildfires and drought in the state. The only heat wave in Oklahoma history that compares to the August 2012 heat wave occurred during the great Dust Bowl summer of 1936, the hottest summer in U.S. history. Oklahoma City experienced a record streak of 22 straight days with a temperature of 100 °F or hotter that year.
• The unusually hot summer helped January–August be the warmest such period in U.S. history. Even if September–December temperatures rank in the coldest 1/3 of historical temperatures, 2012 will still set a record for the warmest year in U.S. history (since record-keeping began in 1895).

Drought

• More than 2/3 of the country experienced drought throughout the summer of 2012, much of it classified as “severe to extreme.”
• The percentage area of the U.S. experiencing top-10% drought conditions was 36%, which was second only to the summer of 1934 (57%).
• The U.S. Department of Agriculture (USDA) declared a federal disaster area in more than half of all the counties in the U.S., mostly caused by drought. It was the largest disaster declaration ever made by the USDA.
• The nation could face costs of up to $77 billion due to the 2012 drought, making it the 3rd costliest weather-related disaster since 1980, behind Hurricane Katrina and the drought of 1988.
• July 2012 ranked 4th for the greatest percent area of the contiguous U.S. covered by moderate or greater drought and was the worst drought since 1954. Drought records go back to 1895.

Wildfires

• January–August 2012 broke the year-to-date record for most acreage burned by wildfires (6,888,342).
• A total of 3 million acres burned from mid-July to the end of August 2012.
• Summer 2012 is setting a record pace for Missouri wildfires, with more than 50 fires and more than 4,000 acres of public and private lands burned in the 3-month period. 
• The Whitewater–Baldy Complex wildfire in southwestern New Mexico was the largest in state history. The previous record was set in 2011.
• The Waldo Canyon Fire in Colorado caused the evacuation of more than 32,000 residents during the summer of 2012 and caused more than $352.6 million in damage. It holds the record for most destructive and expensive fire in Colorado state history.
• The 8.5 million acres burned this year already puts 2012 in 5th place for biggest fire year since 1960, according to the National Interagency Fire Center. With over three months left in the year, 2012 will likely end as the 1st or 2nd biggest fire year in U.S. history for total acreage consumed.

Extreme Storms

• In June 2012, Tropical Cyclone Debby produced record-breaking rainfall across Florida, dropping more than 20 inches of rain in 24 hours in some locations. When Tropical Storm Debby formed on June 23, it was the first time since record keeping began in 1851 that 4 tropical storms formed before July.
• During Hurricane Isaac in August 2012, 7.86 inches of rain fell at New Orleans International Airport, setting a daily rainfall record and shattering the 4.5 inch mark established by Hurricane Katrina in 2005. New Orleans averages 5.98 inches of rain in an entire month. It is estimated that Hurricane Isaac could cause up to $2 billion in onshore economic damage to Louisiana and Mississippi.
• Fueled by extreme heat, the derecho event in late June slammed 700 miles of the U.S. with violent winds that left 22 dead and millions without power. Washington, D.C., one of the areas most affected by the derecho, set a June record-high temperature during that time, while Columbia, S.C., broke its all-time temperature record.

West Nile

• More than 2,100 cases of West Nile virus—including 92 deaths—were reported through early September of 2012, setting a record for highest human toll since the disease was first detected in the U.S. in 1999. The cases are projected to continue into the fall.

Summer of Extremes: Roundup of Global Records

Heat

• Summer 2012 was the 3rd hottest summer on record globally, and land temperatures were the hottest on record.
• The last time the world saw a cooler-than-average July was 1976.
• June 2012 was the 4th hottest June, July was the 4th hottest July, and August 2012 was the 4th hottest August ever recorded for the entire planet.
• August 2012 was the 330th consecutive month that the global temperature was above the 20th-century average.

Arctic Sea Ice Melt

• In September 2012, Arctic sea ice reached the lowest level since satellite monitoring began more than 30 years ago. Half of the Arctic sea ice has disappeared, compared to the 1979–2000 average.
• The new record is 18% below the earlier record set in 2007.
• In early August 2012, the Greenland ice sheet melted to a 30-year low.

Climate change has shifted the odds, altered the natural limits, and increased the severity of certain kinds of extreme weather. As a result, we are witnessing an increase in record-breaking extreme weather events.

http://climatecommunication.org/new/articles/summer-of-extremes/overview/