Back-to-back La Niñas cooled globe and influenced extreme weather in 2011

New NOAA-led report examines climate conditions experienced around the world

July 10, 2012

La Niña.

The lead character of the 2011 climate story was a double dip La Niña, which chilled the Pacific at the start and end of the year. Many of the 2011 seasonal climate patterns around the world were consistent with common side effects of La Niña. More information.

Download here. (Credit: NOAA Climate Portal).

Worldwide, 2011 was the coolest year on record since 2008, yet temperatures remained above the 30 year average, according to the 2011 State of the Climate report released online today by NOAA. The peer-reviewed report, issued in coordination with the American Meteorological Society (AMS), was compiled by 378 scientists from 48 countries around the world. It provides a detailed update on global climate indicators, notable weather events and other data collected by environmental monitoring stations and instruments on land, sea, ice and sky.

“2011 will be remembered as a year of extreme events, both in the United States and around the world,” said Deputy NOAA Administrator Kathryn D. Sullivan, Ph.D. “Every weather event that happens now takes place in the context of a changing global environment. This annual report provides scientists and citizens alike with an analysis of what has happened so we can all prepare for what is to come.”

Two back-to-back La Niñas, each characterized by cooler-than-average water temperatures in the eastern equatorial Pacific, affected regional climates and influenced many of the world’s significant weather events throughout the year. These included historic droughts in East Africa, the southern United States and northern Mexico. La Niña conditions contributed to an above-average tropical cyclone season in the North Atlantic hurricane basin and a below-average season in the Eastern North Pacific. It was also associated with the wettest two-year period (2010–2011) on record in Australia, which was particularly remarkable as the wet conditions followed a decade-long dry spell.

La Niña.

La Niña chilled the eastern tropical Pacific in 2011, but ocean heat content nearly everywhere else was above the long-term average. Maps and trend graphs of 8 additional are available from More information.

Download here. (Credit: NOAA Climate Portal).

The Arctic continued to show more rapid changes than the rest of the planet. Sea ice shrank to its second smallest “summer minimum” extent on record during 2011, as older ice (four to five years old) reached a new record minimum at more than 80 percent below average. Overall, glaciers around the world continued to lose mass. Loss from Canadian Arctic glaciers and ice caps were the greatest since measurements began in 2002.

The report used 43 climate indicators to track and identify changes and overall trends to the global climate system. These indicators include greenhouse gas concentrations, temperature of the lower and upper atmosphere, cloud cover, sea surface temperature, sea level rise, ocean salinity, sea ice extent and snow cover. Each indicator includes thousands of measurements from multiple independent datasets.


The report also provides details on a number of extreme events experienced all over the globe, including the worst flooding in Thailand in almost 70 years, drought and deadly tornado outbreaks in the United States, devastating flooding in Brazil and the worst summer heat wave in central and southern Europe since 2003.

The 2011 State of the Climate report is peer-reviewed and published annually as a special supplement to the Bulletin of the American Meteorological Society. The report is part of a suite of climate services NOAA provides government, business and community leaders so they can make informed decisions. It was edited by Jessica Blunden, Ph.D., and Deke Arndt of NOAA’s National Climatic Data Center. The full report can be viewed online. The report highlights are available online.

Additionally, for the first time a complementary article has been published by AMS today examining the linkages between climate change and extreme events of 2011. The paper looks at six global extreme weather and climate events from last year.


The paper, Explaining Extreme Events of 2011 from a Climate Perspective, was produced by NOAA and UK Met Offices scientists as well as numerous colleagues around the world. It was edited by Thomas Peterson, NOAA’s National Climatic Data Center; Peter Stott, UK Met Office-Hadley Center; and Stephanie Herring, NOAA’s Office of Program Planning and Integration. The study can be viewed online.

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