The National Climatic Data Center’s (NCDC) latest “Billion Dollar U.S. Weather Disasters” report finds the U.S. has racked up more mega-expensive natural disasters in 2011 than ever before. So far we’ve suffered more than five times the huge disasters typical at this time of year. Already damage costs have reached nearly $32 billion. Compare that to the first half of the average year — prior to the onset of “big” hurricane season — between 1980 and 2010, where disaster costs typically run $6 billion.

Billion-dollar-plus natural disasters between 1980 and 2010, using a GNP inflation index.

All told, the U.S. has suffered 99 weather-related disasters over the past 31 years, where overall damages and economic costs reached or exceeded $1 billion. The normalized losses (that is, the numbers adjusted for the GNP inflation index) add up to more than $725 billion for those 99 disasters.

So far, nine natural disasters, each totaling more than a billion dollars in losses, have befallen the U.S. this year. Here’s the NCDC list:

• Groundhog Day blizzard, Jan. 29-Feb. 3: Insured losses were greater than $1.1 billion. Total losses (insurance, state and local snow removal, business interruption) were greater than $3.9 billion. Thirty-six deaths.

A picture of the EF3 tornado that struck Tushka, Okla., April 14, 2011. Photo: Gabe Garfield and Marc Austin/NOAA

• Midwest/Southeast tornadoes, April 4-5: An estimated 46 tornadoes caused more than $1.4 billion insured losses, total losses greater than $2 billion, nine deaths.
• Midwest/Southeast tornadoes, April 8-11: An estimated 59 tornadoes caused more than $1.5 billion insured losses, total losses greater than $2.2 billion, numerous injuries, no known deaths.
• Midwest/Southeast tornadoes, April 14-16: An estimated 160 tornadoes caused more than $1.7 billion insured losses, total losses greater than $2 billion, 38 deaths.
• Midwest/Southeast/Ohio Valley tornadoes, April 25-30: An estimated 305 tornadoes caused somewhere between $3.7 billion to $5.5 billion insured losses (the numbers are still being accounted), total losses approaching $10 billion, 320 deaths.
• Midwest/Southeast tornadoes, May 22-27: An estimated 180 tornadoes caused between $4 and $7 billion insured losses (the numbers are still being accounted), total losses may exceed $7 billion, 172 deaths — including the EF-5 tornado that struck Joplin, Mo., killing 141, the deadliest single tornado in the U.S. since record-keeping began.

Wildfires in Texas as of April 30, 2011. At this point more than 2 million acres had already burned. Image: Jesse Allen/NASA Earth Observatory

• Texas drought and wildfires, spring-summer 2011: Drought and wildfires across Texas, New Mexico, and western Oklahoma racked up fighting/suppression costs of about $1 million a day. Total losses to agriculture and cattle were estimated between $1.5 billion and $3 billion, as of June 16. Expenses are likely to rise as the drought continues.

This map depicts rainfall for the Midwest from April 19 to 25, when rainfall totals ranged from 5.9 inches to greater than 20.7 inches, prompting major flooding.Image: Jesse Allen/NASA Earth Observatory

• Mississippi River flooding, spring-summer 2011: Estimated economic loss ranges from $2 billion to $4 billion. Below are more detailed preliminary stats — the floods are still unfolding — as of June 16:
  • $500 million loss to agriculture in Arkansas
  • $320 million in damage to Memphis, Tenn.
  • $800 million loss to agriculture in Mississippi
  • $317 million loss to agriculture and property in Missouri’s Birds Point-New Madrid Spillway
  • $80 million loss for the first 30 days of flood-fighting efforts in Louisiana

The Missouri River floods have not made it onto this list, since their onset was near the end of the compilation period.

The technical report, “A Climatology of 1980-2003 Extreme Weather and Climate Events,” by Tom Ross and Neal Lott, is illuminating. Here are some highlights:

• In 20 of the past 24 years, the U.S. has experienced at least one weather-related billion-dollar disaster.
• The only years without at least one billion-dollar disaster were 1981, 1982, 1984, and 1987.
• Since 1988, at least one disaster occurred each year, with only one such event in 1988 and 1990, and seven billion-dollar events in 1998. Two of the 1998 disasters were caused by hurricanes.
• Overall, hurricanes and tropical storms account for 16 of the 58 events and 28 percent of the monetary losses (normalized to 2002).
• The 10 major droughts/heatwaves which have occurred since 1980 account for the largest percentage (42 percent) of weather-related monetary losses.

The report concludes:

Although some studies suggest that trends such as population increases, population shifts into higher risk areas, and increasing wealth have been the key factors in weather related disasters (as opposed to historical trends in the frequency or strength of such events), there is evidence that climate change may affect the frequency of certain extreme weather events. An increase in population and development in flood plains, along with an increase in heavy rain events in the U.S. during the past 50 years, have gradually increased the economic losses due to flooding. If the climate continues to warm, the increase in heavy rain events is likely to continue. While trends in extratropical cyclones are not clear, there are projections that the incidence of extreme droughts will increase if the climate warms throughout the 21st century.

Image: National Weather Service’s Climate Prediction Center

If you’re wondering what disasters might be delivered in the next quarter, check out the maps and the legend above for forecasts of temperature and precipitation anomalies through the end of October 2011. Hurricanes not included.

The National Oceanic and Atmospheric Administration (NOAA) just updated its Climate Normals for the United States. Per agreement of the World Meteorological Organization, “normals” are calculated per decade, rather than per year. NOAA’s latest update is crunched from weather data compiled from 1981 to 2010. 

The new annual normal temperatures for the U.S. strongly reflect a warming world:

July maximums, 1981-2010 compared with 1971-2000.Image: NOAA

January minimums, 1981-2010 compared with 1971-2000.Image: NOAA

In the two images above you can see the differences between the old normals (1971 to 2000) and the new normals. The top image shows changes in July maximum temperatures. The bottom shows changes in January minimum temperatures. Warmer temperature changes are orange and red. Cooler temperature changes are blue.

A few notables:

• On average, the contiguous U.S. experienced the lowest temperatures on January nights and the highest temperatures on July days.
• Both January minimum temperatures and July maximum temperatures changed in the past three decades — though not equally.
• Parts of the Great Plains, the Mississippi Valley, and the Northeast experienced slightly cooler July maximums from 1981-2010 compared to 1971-2000 (top map).
• Far more striking are the January minimums (bottom map). Nighttime January temps were higher everywhere except the Southeast. Warmer nights were most pronounced in the northern plains and northern Rocky Mountains.
• In some places the new normal is several degrees warmer than the old normal.

On a state-by-state basis, the annual average minimum (left) and maximum (right) temperatures across the United States are warmer in the 1981-2010 Climate Normals than in the 1971-2000 version.

Image: NOAA

As you can see in the maps above, based on average year-round temperatures, every state experienced warmer temperatures in 1981-2010 compared to 1971-2000.

A few pros and cons of a warming U.S.:

• Fire season is now longer due to warmer nights.
• Pollination patterns are changing, with flowering plants blooming an average of one day earlier each decade.
• Warmer nights and later onset of freezing days also mean plants are shifting farther north.
• Warmer temperatures pose hazards to plants by enabling pests (pine bark beetle and wooly adelgid) to thrive in places where cold winters previously froze them.