The deadliest weather disasters are droughts followed by famines, particularly in Africa. From October 2010 to September 2011, a severe drought in the Horn of Africa caused widespread famine and large-scale migratory movements, particularly in Somalia and Kenya. Around 80 percent of the livestock of Somalia's nomadic population died, some 13 million people required humanitarian aid, and an estimated 50,000 people lost their lives. But because human agency played a large role in this catastrophe, it was not included in the analysis of 2011 natural disasters.

The monetary losses from 2011's natural catastrophes reached a record $380 billion, surpassing the previous record of $220 billion set in 2005. The year's three costliest natural catastrophes were the March earthquake and tsunami in Japan (costing $210 billion), the August-November floods in Thailand ($40 billion), and the February earthquake in New Zealand ($16 billion).

The report notes that Asia experienced 70 percent, or $265 billion, of the total monetary losses from natural disasters around the world----up from an average share of 38 percent between 1980 and 2010. This can be attributed to the earthquake and tsunami in Japan, as well as the devastating floods in Thailand: Thailand's summer monsoons, probably influenced by a very intensive La Niña situation, created the costliest flooding to date, with $40 billion in losses.

Further highlights from the report:

The last decade was dominated by a series of devastating earthquakes and tsunamis, with an enormous human impact. These included geophysical events in Haiti in 2010 (222,570 deaths); in Southeast Asia in 2004 (220,000 deaths); in Pakistan in 2005 (88,000 deaths); and in China in 2008 (84,000 deaths).

The costliest weather-related disasters are tropical cyclones, floods, winter storms, and thunderstorms. Hurricane Katrina, which occurred in 2005 and caused $125 billion in overall losses, was the most expensive weather catastrophe ever.

Ninety-five percent of Europe's 150 disasters in 2011 were weather-related. The continent's overall economic loss of $2.5 billion is one of the lowest annual figures since 1980.

With 551 fatalities, the 2011 U.S. tornado season was the deadliest in more than 85 years. The Atlantic Ocean hurricane season was the third-strongest since record-keeping began, with 19 named storms. And in May and June 2011, the worst floods in decades occurred along the Mississippi and Missouri rivers, causing more than $5 billion in overall losses.