January 10, 2017

Last week, Australia’s Bureau of Meteorology (BOM) released its annual climate statement, and it was filled with bad news. Extreme weather lashed Australia throughout 2016, harming fragile landscapes and ecosystems both on land and in the sea. The BOM blamed the damaging weather extremes on climate change as well as an unusually strong El Niño, a periodic variation in ocean currents and temperatures that can affect climate throughout the world.

This photo taken on Feb. 12, 2016, shows the charred remains of rare alpine flora after bush fires raged through the Tasmanian Wilderness World Heritage Area. Credit: Rob Blakers (licensed under CC BY-SA 3.0)

The BOM listed a number of weather events that devastated parts of Australia in 2016. The cities of Darwin and Sydney saw their hottest years on record, while hot and dry conditions and large numbers of lightning strikes led to raging bushfires in Tasmania, Victoria, and Western Australia. Fires destroyed much of the unique alpine flora—including rare, 1,000-year-old cushion plants and King Billy pine trees—found in the Tasmanian Wilderness World Heritage Area. The seas around Australia also reached record high temperatures, causing unprecedented bleaching of the Great Barrier Reef and other coral systems. Around Tasmania, hot sea temperatures damaged fragile kelp forests as well as the abalone, oyster, and salmon populations.

This photo of Uluru, also known Ayers Rock, shows its typically hot and dry environment. Heavy rains in late 2016 caused waterfalls to cascade down the sides of the giant sandstone formation. Credit: © Steve Vidler, SuperStock

Australia’s extreme weather in 2016 included both drought and heavy rains that caused unprecedented flooding. The areas around Darwin and Brisbane saw significantly less rainfall during the year, while heavier than usual rains soaked Adelaide, Canberra, Hobart, and Sydney. In central Australia, dangerous flash floods took out roads, washed away cars, and forced the evacuations of several communities. At Christmastime, record rains and floods forced the closure of Uluru-Kata Tjuta National Park. Uluru itself, a giant sandstone formation among sand dune plains, was awash with waterfalls.

The BOM climate statement warned that such extreme weather events will become more common, even become normal, as global warming continues to reshape Earth’s climate.

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

February 12, 2014

Much of the southern United States, from East Texas to the Atlantic Coast, is being encased in ice. Moving west to east, the storm–which meteorologists characterize as possibly historic in scope–is blanketing large swaths of the South. “There is no doubt that this is one of Mother Nature’s worst kinds of storms . . .” Georgia Governor Nathan Deal stated in a public announcement. “We’re not kidding. We’re not crying wolf.”

The ice storm came in two waves. The first began yesterday, when snow and ice covered parts of Texas, Louisiana, Mississippi, Alabama, and Georgia. The second wave began early this morning. A mix of freezing rain and sleet, driven by high winds, quickly glazed roads, trees, and electric power lines.

Rain freezes into ice when the air temperature above the ground exceeds 32 °F (0 °C), the freezing point of water. At the same time, the ground and the thin layer of air above it must be colder than 32 °F. Under these conditions, precipitation from a winter storm can form as snow in the freezing temperatures high in the clouds. The snow falls into the warmer air layer below. There, it melts into rain. Upon reaching ground level, the rain refreezes into ice that coats all solid surfaces.

An ice storm can coat objects in heavy ice, often damaging trees and power lines. © Charles Bertram, MCT/Landov)

As the freezing rain continues throughout today, the ice will build up, to an estimated thickness of 1 inch (2.5 centimeters). The weight of an inch of ice encircling tree limbs and power lines is enormous. The weight pulls down branches and power lines, creating an extremely dangerous situation. The power lines, which remain live, fall into the street below, shooting sparks as they snap across the pavement like a cracking whip. Thousands of households are already without electric power across Georgia and South Carolina.

So far, six traffic-related deaths have been attributed to the storm–four in Texas and two in Mississippi–and the governors of eight states have declared states of emergency. More than 2,000 flights have been cancelled at Atlanta’s Hartsfield-Jackson International, the nation’s busiest airport. Amtrak has announced that southbound trains out of New York City and Washington, D.C., have been cancelled. Meteorologists predict that the storm will continue in the South through tomorrow. It will then head northward into the Northeast.

In January 2000, parts of the southeastern United States were engulfed by a similar ice storm. Areas of northern Georgia and western South Carolina had more than 2 inches (5 centimeters) of rain with temperatures below freezing. In the Atlanta area, more than 500,000 utility customers lost power because of the storm.