Greenhouse gases play an important role in North American climate, but differences in regional ocean temperatures may hold a key to predicting future U.S. regional climate changes, according to a new NOAA-led scientific assessment. The assessment is one in a series of synthesis and assessment reports coordinated by the U.S. Climate Change Science Program.

Credit: U.S. Climate Change Science Program
U.S. Climate Change Science Program Synthesis and Assessment 1.3 Report
This latest assessment, Reanalysis of Historical Climate Data for Key Atmospheric Features: Implications for Attribution of Causes of Observed Change, describes what has changed—and why—in North America’s climate over the past half century. The assessment addresses the likelihood and extent to which human activity or natural variations have driven surface warming, precipitation, droughts, and floods.
“A major implication of this assessment is that improving predictions of regional sea-surface temperatures will be crucial to predicting climate variability across the U.S. from years to decades, as well as projecting long-term regional climate changes,” said Randall Dole, lead author and a scientist at NOAA’s Earth System Research Laboratory in Boulder, Colo.
Some regional temperatures rose sharply, while others held steady; drought impacts worsened; and precipitation swung widely—all within the continent’s gradually warming climate.
Changes in sea-surface temperature patterns likely played an important role in determining differences in U.S. regional temperature trends. They also contributed to large precipitation swings from year to year or decade to decade during the past 50 years.
While a general trend toward warmer ocean conditions is expected with increasing greenhouse gases, regional differences in sea surface temperature trends can be either natural or human-caused, according to Dole.
The assessment found that an increase in greenhouse gases is likely responsible for more than half of the average continental warming of 1.6° Fahrenheit observed during the past 50 years. Greenhouse gases, emitted by fossil fuel burning and natural sources, trap heat in Earth’s atmosphere and warm the surface.
Drought impacts have likely become more severe as surface temperatures warmed, increasing evaporation, reducing soil moisture, and causing other water stresses. The scientists found no long-term trends in where or how often droughts occur or in how much rain or snow has fallen on average each year.
The assessment also describes in detail how climate scientists use enormous amounts of data in a powerful method for examining past climate, called “reanalysis.” Another section illustrates how they systematically probe cause-and-effect relationships to find the most likely cause of a

The year 2008 is on track to be one of the 10 warmest years on record for the globe, based on the combined average of worldwide land and ocean surface temperatures, according to a preliminary analysis by NOAA’s National Climatic Data Center in Asheville, N.C. For November alone, the month is fourth warmest all-time globally, for the combined land and ocean surface temperature. The early assessment is based on records dating back to 1880.

Global Temperature Highlights – 2008 The combined global land and ocean surface temperature from January – November was 0.86 degree F (0.48 degree C) above the 20th century mean of 57.2 degrees F (14.0 degrees C). Separately, the global land surface temperature for 2008 was the fifth warmest, with an average temperature 1.44 degrees F (0.80 degree C) above the 20th century mean of 48.1 degrees F (9.0 degrees C).

Also separately, the global ocean surface temperature for 2008 was 0.67 degrees F (0.37 degrees C) above the 20th century mean of 61.0 degrees F (16.1 degrees C).

Global Temperature Highlights – November 2008 The November combined global land and ocean surface temperature was 1.06 degrees F (0.59 degree C) above the 20th century mean of 55.2 degrees F (12.9 degrees C).

Separately, the November 2008 global land surface temperature was fourth warmest on record and was 2.11 degrees F (1.17 degrees C) above the 20th century mean of 42.6 degrees F (5.9 degrees C).

For November, the global ocean surface temperature was 0.68 degrees F (0.38 degree C) above the 20th century mean of 60.4 degrees F (15.8 degrees C).

Other Global Highlights for 2008

In the tropical Pacific, 2008 was dominated by El Niño-Southern Oscillation neutral conditions. La Niña conditions that began the year had dissipated by June.

Arctic sea ice extent in 2008 reached its second lowest melt season extent on record in September. The minimum of 1.74 million square miles (4.52 million square kilometers) reached on September 12 was 0.86 million square miles (2.24 million square kilometers) below the 1979-2000 average minimum extent.

The 2008 Atlantic hurricane season was the third most costly on record in current dollars, after 2005 and 2004, and the fourth most active year since 1944. This was the first season with a major hurricane (Category 3 or above) each month from July through November. With the exception of the South Indian Ocean, all other tropical cyclone regions recorded near to below-average activity during 2008. Globally, there were 89 named tropical cyclones, with 41 reaching the equivalent of hurricane strength (74 mph), and 20 achieving the equivalent of major hurricane status (111 mph or greater) based on the Saffir-Simpson scale.

The United States recorded a preliminary total of just under 1,700 tornadoes from January - November. This ranks 2008 second behind 2004 for the most tornadoes in a

(inan.info)-By VOA News
U.S. weather forecasters say Hurricane Dolly is moving slowly through the Gulf of Mexico toward the the U.S. - Mexico border.

The National Hurricane Center in Miami upgraded the storm to a Category One hurricane Tuesday. Maximum sustained winds are 130-kilometers-per-hour with higher gusts.

Dolly is east-southeast of Brownsville, Texas and is expected to strengthen before making landfall later Wednesday.

But while forecasters do not anticipate that Dolly will become a major hurricane, they are concerned that the storm could drop as much as 38 centimeters of rain as it moves

(inan.info)-The U.S. Climate Change Science Program and the Subcommittee on Global Change Research today released a scientific assessment that provides the first comprehensive analysis of observed and projected changes in weather and climate extremes in North America and U.S. territories. The Intergovernmental Panel on Climate Change previously evaluated extreme weather and climate events on a global basis in this same context. However, there has not been a specific assessment across North America prior to this report.

Among the major findings reported in this assessment are that droughts, heavy downpours, excessive heat, and intense hurricanes are likely to become more commonplace as humans continue to increase the atmospheric concentrations of heat-trapping greenhouse gases.

The report is based on scientific evidence that a warming world will be accompanied by changes in the intensity, duration, frequency, and geographic extent of weather and climate extremes.

"This report addresses one of the most frequently asked questions about global warming: what will happen to weather and climate extremes? This synthesis and assessment product examines this question across North America and concludes that we are now witnessing and will increasingly experience more extreme weather and climate events," said report co-chair Tom Karl, Ph.D., director of NOAA’s National Climatic Data Center in Asheville, N.C.


"We will continue to see some of the biggest impacts of global warming coming from changes in weather and climate extremes,” said report co-chair Gerry Meehl, Ph.D., of the National Center for Atmospheric Research in Boulder, Colo. "This report focuses for the first time on changes of extremes specifically over North America."

The full CCSP 3.3 report, Weather and Climate Extremes in a Changing Climate, and a summary FAQ brochure are available online.

Global warming of the past 50 years is due primarily to human-induced increases in heat-trapping gases, according to the report. Many types of extreme weather and climate event changes have been observed during this time period and continued changes are projected for this century. Specific future projections include:

* Abnormally hot days and nights, along with heat waves, are very likely to become more common. Cold nights are very likely to become less common.
* Sea ice extent is expected to continue to decrease and may even disappear in the Arctic Ocean in summer in coming decades.
* Precipitation, on average, is likely to be less frequent but more intense.
* Droughts are likely to become more

(inan.info)-NOAA deployed the final two tsunami detection buoys in the South Pacific this week, completing the buoy network and bolstering the U.S. tsunami warning system. This vast network of 39 stations provides coastal communities in the Pacific, Atlantic, Caribbean and the Gulf of Mexico with faster and more accurate tsunami warnings.

These final two deep-ocean assessment and reporting of tsunami (DART) stations, deployed off the Solomon Islands, will give NOAA forecasters real-time data about tsunamis that could potentially impact the U.S. Pacific coast, Hawaii and U.S. Pacific territories. Tsunami sensors are now positioned between Hawaii and every seismic zone that could generate a tsunami that would impact the state and beyond, including the U.S. West Coast. Buoys already in the western Atlantic, Gulf of Mexico and Caribbean have been keeping watch over the U.S East and Gulf coasts.


“Completing the U.S. Tsunami Warning System is truly a monumental triumph that includes the advancement of the science, the development and testing of cutting edge technology, and the large scale project management skills that brought it all together on a global scale,” said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. “As a young scientist who researched tsunamis and built early models of their effects, I never imagined that we could come so far in our ability to understand, to detect, to model and to warn on such a scale as we have just achieved.”

DART stations consist of a bottom

(inan.info)-By Greg Flakus
Council Bluffs, Iowa

Surging water is moving down the Mississippi river devastating towns and farmland along the way. The river has topped close to a dozen levees flooding towns in Iowa, Illinois and Missouri and residents farther downstream are bracing for the surge as it heads their way. VOA's Greg Flakus has more from Council Bluffs, Iowa.

Residents are returning to their homes in some parts of Iowa and farmers are trying to determine if they can salvage fields that were flooded soon after being planted. President Bush toured the disaster area Friday as did presidential candidates, Senator John McCain, the presumptive Republican candidate, and Senator Barack Obama, the likely Democratic candidate.

But even as citizens began the clean up

(inan.info)-By Scott Stearns
White House

U.S. President George Bush is in the Midwest state of Iowa surveying flood damage from heavy rains that have washed out millions of hectares of grazing and farmlands. VOA White House Correspondent Scott Stearns has the story.

President Bush went to Iowa's second-largest city of Cedar Rapids for a briefing from local and federal officials at an emergency command center where relief efforts are being coordinated.

"Obviously to the extent that we can help immediately, we want to help and then plan for recovery," he said.

Much of Cedar Rapids was submerged by the Cedar River, which crested nearly seven meters above flood levels. The Federal

(inan.info)-By VOA News

People across the central and southern United States are starting to clean up Monday after a severe weather system tore through the region, spawning more than 70 tornadoes.

Officials blame the tornadoes for 22 deaths in three states on Saturday and Sunday.

Some of the worst damage was reported in the central state of Missouri. The storms also claimed lives in the southern state of Georgia and the central state of Oklahoma, where

(inan.info)-By VOA News
In the U.S. state of Arkansas, six people have died in a wave of violent storms.

The weather system that hit Arkansas early Friday has been sweeping across parts of the central and midwestern United States. Powerful storms with winds of up to 130 kilometers per hour have been accompanied by heavy rains and hail.

The National Weather Service issued tornado warnings along a line of storms stretching from Texas through Arkansas, Missouri, Kansas, Oklahoma and Tennessee.

Strong winds, possibly a tornado, that whipped through an area of Kansas City, Missouri, ripped apart some homes and damaged at

(inan.info)-Shirley Murillo is a research meteorologist at the National Oceanic and Atmospheric Administration's (NOAA) Hurricane Research Division in Miami, Fla., and she is an expert on the behavior of hurricanes when they reach landfall. Murillo specializes in examining how hurricane wind fields change as