Will 2005 Be the Warmest Year on Record?

Nicholas Bakalar
for National Geographic News

December 20, 2005

Two major meteorological organizations agree: 2005 was a very warm year,
and if it didn't set a new record for high average temperatures, it came
very close to doing so.

Last week the United Nations' World Meteorological Organization (WMO) based in Geneva, Switzerland, reported that the global mean surface temperature in 2005 is estimated to be 58.06°F (14.48°C). That figure is 0.86°F (0.48°C) warmer than the average between 1961 and 1990.

Although official figures will not be released until next February, 2005 is likely to be one of the hottest four years since record-keeping began in 1861. October and June of this year were the warmest those months have ever been.

The U.S. National Oceanic and Atmospheric Administration also issued a preliminary annual report on weather in 2005, reporting a warmer than average mean temperature for the United States.

Jay Lawrimore, chief of NOAA's Climate Monitoring Branch, thinks that 2005 will be very close to 1998, the warmest year on record for the nation.

"In fact it's likely to only be second warmest according to the data set we are currently using as our operational version," he said. "[But] an improved data set for global analyses currently undergoing final evaluation will likely show 2005 slightly warmer than 1998.

"These results are significant because the 1998 record was established under the influence of an extremely strong El Niño episode."

The El Niño phenomenon is a periodic warming of the Pacific Ocean that influences global weather patterns.

According to Lawrimore, the El Niño event of 2005 was weak and short-lived and had little effect on global temperature. This is what he finds so impressive about 2005's record highs.

"The lack of such a strong influence in 2005 but yet a global temperature very close to that remarkable year of 1998 makes this year's temperature very noteworthy," he said.

Floods and Droughts

The WMO acknowledges that there are gaps in the data record that lend some uncertainty to 2005's ranking. Still, the last ten years, with the exception of 1996, are the warmest years in the record book.

Overall temperatures in the Northern Hemisphere were more above average than the Southern, with an increase of 1.17°F (0.65°C) over the 30-year mean compared to the Southern Hemisphere's increase of 0.58°F (0.32°C).

Sea surface temperatures in the North Atlantic in 2005 will likely be the warmest ever, according to the WMO report, and air temperatures rose all over the globe.

These record temperatures have been driving extreme weather events across the world.

In Australia the hottest average temperatures since 1910 made dry conditions even more painful. During the first five months of the year temperatures averaged 3.15°F (1.75°C) above normal.

Drought also tormented Somalia, Kenya, Ethiopia, Tanzania, and much of western Europe.

In India people awaited the delayed arrival of the monsoon rains while enduring a heat wave that lasted into June. An estimated 400 deaths were attributed to the severe weather. When the monsoons arrived they led to massive flooding and 1,800 deaths.

On July 27 Mumbai (Bombay) recorded 37.2 inches (94.5 centimeters) of rain in a 24-hour period, a record for the city. As a comparison, New York City averages about 45 inches (114 centimeters) of rain in an entire year.

Eastern Europe also experienced flooding, with Bulgaria, Hungary, and Romania most heavily affected.

Human Causes?

In North America the Southwest had heavy rain and snow. Los Angeles had its second heaviest rainfall on record. And major flooding also caused huge economic losses in Canada.

A record 26 tropical storms formed during the Atlantic hurricane season, with seven of them categorized as Category Three or higher on the Saffir-Simpson scale.

The worst of these, Katrina, Wilma, and Rita, will be names to remember—according to NOAA, 2005 was the first time three Category Five storms have ever formed in the same season.

How much of this warming trend and the severe weather that has accompanied it can be attributed to human influences?

"We don't know whether this is down to human activity," said Mark Oliver, a WMO spokesperson. "Though we are naturally extremely concerned and are studying the issue very thoroughly."

NOAA's Lawrimore agrees. "We should not specifically link the severe weather this year with the global warming trend," he said.

"We don't know what aspect might have been worsened by global warming or if all of the hurricane activity, for instance, was entirely due to naturally occurring oscillations over longer periods of time."

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