Most of the southwestern United States is having a very dry winter. The northern parts of Arizona and New Mexico were clipped by a few drenching storms exiting California in December, but dry conditions are more the norm.

Deep snow that fell across the Great Plains and the Northeast in late January and early February is the latest installment in the second very wintry winter in a row for the eastern U.S.

El Niño and La Niña can significantly alter seasonal climate conditions, such as temperature and rainfall patterns, in many parts of the world. Scientists Brad Lyon and Paul Block explain the potential impacts of La Niña in different parts of Africa.

Will climate change affect frequency or intensity of El Niño and La Niña? There is still little consensus among scientists on this, explains the International Research Institute for Climate and Society’s Lisa Goddard.  

Computer climate models help scientists such as Dave Dewitt predict the life cycles of individual El Niño or La Niña events and their effects on weather patterns throughout the world. While the accuracy of these models continues to improve, they still have limitations.  

More than half of the United States experienced heat, drought, or flooding during 2011, demonstrating the power and momentum of climate extremes.

Capping off the warmest decade on record, the average global temperature in 2010 tied 2005 as the warmest year since reliable records began in 1880.

On Hawaii’s Big Island, prevailing Pacific trade winds from the northeast bring more rainfall to northern & eastern slopes, leading to dramatic differences in vegetation on different sides of the island.

Few winter storms and El Niño conditions brought severe drought conditions to the Hawaiian Islands this past year.

The early wet season of 2010 was typical of La Niña, with rainfall in December 2010 between 200 and 400 percent above normal in much of Queensland, according to the Australian Bureau of Meteorology.