January 27, 2017

Last week, the United States National Aeronautics and Space Administration (NASA) and the U.S. National Oceanic and Atmospheric Administration (NOAA) announced that 2016 was the hottest year on record, setting a new record for the third consecutive year. The average land and ocean surface temperature was 58.69 ˚F (14.83 ˚C), 1.69 Fahrenheit (0.94 Celsius) degrees warmer than the global average during the 1900’s. Sixteen out of the 17 warmest years on record have occurred since 2001, one of many clear indicators that the planet is warming.

This global heat map covering 2012 through 2016 shows areas with the sharpest temperature increases in red. White areas indicate Earth’s few remaining “cool” spots.  Credit: NASA

Global warming is an increase in the average temperature at Earth’s surface. People often use the term global warming to refer specifically to the warming observed since the mid-1800’s. Scientists estimate that Earth’s average surface temperature has risen by about 1.4 Fahrenheit (0.78 Celsius) degrees since 1880. Researchers have also found that most of the temperature increase occurred from the mid-1900’s to the 2000’s.

This chart clearly shows the sharp rise in global temperatures since 1980. Note the temperature spike coinciding with World War II (1939-1945). Credit: NOAA/NESDIS/NCEI

The record heat of 2014 topped the previous high by just 0.07 Fahrenheit (0.4 Celsius) degrees. Since then, however, record temperatures jumped by 0.29 Fahrenheit (0.16 Celsius) degrees in 2015 and 0.36 Fahrenheit (0.20 Celsius) degrees in 2016. The recent strong El Niño event, which began in mid-2014, contributed to the record-shattering heat. An El Niño is a part of the interaction between Earth’s atmosphere and the tropical waters of the Pacific Ocean. An El Niño occurs about every two to seven years, and it can affect the climate throughout the world.

El Niño was not the primary cause for the record heat, however. Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, estimated that the El Niño effect contributed just 0.09 Fahrenheit (0.05 Celsius) degrees to 2015′s record 1.62 Fahrenheit (0.90 Celsius) degrees increase and only 0.22 Fahrenheit (0.12 Celsius) degrees of 2016′s 1.69 Fahrenheit (0.94 Celsius) degrees record. Climate scientists agree that human activities, such as the release of carbon dioxide and other gases into the atmosphere, are responsible for the warming trend seen over the last several decades.

The recent El Niño ended in in the spring of 2016, and a La Niña cooling event emerged at the end of the year. Because of this development, almost all climate scientists agree that 2017 will not be as hot as 2016. But La Niña conditions are already declining, and some models predict another El Niño could begin as early as the middle of 2017.

The 2016 election of Donald Trump as president of the United States created new problems for climate scientists and environmentalists trying to slow global warming. Much of the momentum gained by last year’s Paris Climate Agreement has been halted by Trump, who has claimed that climate change is a hoax and has vowed to back out of the agreement. Working with Trump, the Republican-controlled U.S. Congress is preparing to dismantle many of the environmental regulations put in place or strengthened by former President Barack Obama. China and the other signatories of the Paris Agreement may have to act without the United States to try to prevent the direst effects of global warming. Trump’s administration has already removed climate change websites from numerous government agencies, and on Jan. 24, 2017, Trump banned government agencies from mentioning climate change on press releases and social media posts and from discussing the issue with other public officials.

December 28, 2015

During the Christmas weekend, weather patterns around the world produced a variety of extremes, from torrential rains and flooding in North America, South America, Europe, and Australia to fierce snowstorms in North America and raging wildfires in Australia.

Fire-damaged buildings are seen alongside a house that survived the Christmas Day bushfires at Separation Creek in the Otway Ranges south of Melbourne, Australia, on Dec. 27, 2015. Credit: © Julian Smith, EPA/Landov

Heavy storms pounded the Midwestern and Southern United States with rain and snow. Tornadoes with winds of up to 200 miles (320 kilometers) per hour tore through Texas, killing at least 11 people. Meanwhile, some areas of New Mexico received more than 1 foot (0.3 meter) of snow. At least 43 people died throughout the United States as a result of these storms and the flooding that followed. Meteorologists noted that higher-than-average temperatures contributed to the severity of the storms.

In Australia, a lightning strike in the southeastern state of Victoria on December 19 caused a series of wildfires known as bushfires. The fires grew in size and intensity and destroyed more than 100 homes on Christmas Day. Meanwhile, monsoon rains caused major flooding in the Northern Territory, forcing hundreds of people to evacuate their homes. At the same time, in South America, more than 100,000 people fled their homes in areas of Argentina, Brazil, Paraguay, and Uruguay to escape flooding caused by heavy rainfall. In northern England in the United Kingdom, downpours led to extensive flooding as dozens of rivers overflowed.

Authorities noted that El Niño conditions were to blame for much of the extreme weather. An El Niño is a part of the interaction between Earth’s atmosphere and the tropical waters of the Pacific Ocean. El Niños occur about every two to seven years, and can affect climate throughout the world. The term El Niño originally referred to a current of warm water that flows southward along the coast of Ecuador and Peru, in western South America, every winter. About every two to seven years, the warm current is abnormally strong, lasts for an unusually long time, and is accompanied by changes in the winds and precipitation across the entire tropical Pacific region. For this reason, El Niño came to refer to the entire interaction of the ocean and atmosphere during the period of the stronger-than-normal current. According to the World Meteorological Organization, a United Nations affiliate, this year’s El Niño is the strongest in more than 15 years.

Other World Book articles: 

• Christmas Eve Storms Hit United States (Dec. 25, 2015) – A Behind the Headlines article
• Meteorology
• Weather

March 19, 2012

A drought that began in Mexico in 2010 has turned into the worst that the country has experienced since official weather record keeping began in 1941, according to Mexican officials. At least two-thirds of Mexico’s 31 states are experiencing extremely dry conditions with below-normal rainfall. The north-central states of Coahuila, Durango, San Luis Potosi, and Zacatecas have been hardest hit. However, government officials are also concerned about drought in Guanajuato, one of the top food-producing states in the country. Mexican farmers produce large quantities of beans, corn, onions, and tomatoes, both for export and as food for their own people. Mexico is also the chief supplier of cattle to the United States. According to some estimates, food production across Mexico has fallen by 40 percent, raising food prices.

(World Book map; map data © MapQuest.com, Inc.)

Farmers who rely on rainfall to water their crops and livestock were the first to experience hardship. Rain has fallen in some states at only half the usual levels. As the dry conditions have continued, lakes and reservoirs have fallen to critically low levels. Many farmers are no longer able to irrigate their crops, and ranchers cannot supply their cattle with water. Several towns have run out of drinking water. The government has begun delivering emergency food and water supplies to thousands of people, and about 2 million others lack adequate food.

Some meteorologists expect the drought to continue for at least several more months. They believe the dry spell is the result of a La Nina. A La Nina is a weather phenomenon in which the waters of the eastern Pacific Ocean become colder and the climate becomes drier. A La Nina follows the better-known weather condition known as an El Nino. During an El Nino, waters of the eastern Pacific Ocean become warmer and the climate becomes wetter. One of the strongest La Nina’s in more than 10 years occurred from 2010 to 2011. Texas has also been experiencing a severe drought.

Additional World Book article:

• Food supply