During 2011, 820 natural catastrophes were documented around the world, resulting in 27,000 deaths and $380 billion in economic losses, according to data compiled by Munich Reinsurance Company and analyzed in the Worldwatch Institute's Vital Signs series. The number of natural catastrophes was down 15 percent from 2010 but was above the annual average of 790 events between 2001 and 2010, and considerably above the annual average of 630 events between 1981 and 2010.

"The influence of La Niña from January to May and August to December was a major cause of many of the extreme weather events in 2011," said report author Petra Löw, a geographer and Munich Re consultant who focuses on natural catastrophe losses. "In 2011, 91 percent of natural disasters were weather-related."

(For more, see: La Nina predictions a high-wire act)

The report found that only 9 percent of natural disasters were geophysical events, but these events, which include the earthquake and tsunami in Japan, accounted for 62 percent of overall fatalities. Japan suffered 15,840 fatalities from the earthquake and tsunami in March 2011.

"The steady increase in losses from natural catastrophes around the world demonstrates the need for preventative measures to the world's poorest and most vulnerable communities protect themselves," said Worldwatch President Robert Engelman. "These communities often have little beyond their own wits and meager resources to help them recover from a crop failure, the destruction of a home, or the tragic loss of a family's breadwinner."

The report analyzes natural catastrophes by their geographic location, type (geophysical, meteorological, hydrological, or climatological), deadliness, and costliness. Most natural disasters in 2011 occurred in the Americas (290) and Asia (240), while fewer occurred in Europe (150), Africa (80), and Australia (60). Of the weather-related natural catastrophes, 37 percent were caused by storms (meteorological), 37 percent by floods (hydrological), and 17 percent by climatological events such as heat waves, cold waves, wildfire, and droughts.

In 2011, 27,000 people died in sudden-onset natural catastrophes----63 percent below the annual average of 73,000 fatalities between 1980 and 2010. (These figures exclude slow-onset famine victims, discussed below.) In contrast, in 2010, the deadliest year recorded in the 30-year period, 296,000 people died from natural catastrophes. The report found that 38 percent of all victims of such catastrophes died from weather-related events, the rest being caused by geophysical events.