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Global Sea Levels and Temperatures On The Rise

Posted on: Thursday, 19 June 2008, 15:05 CDT

According to new scientific research, ocean temperatures are warming and sea levels rising faster than previously believed. Apparently, data from previous studies was misinterpreted.

The scientists reported their findings on Thursday in the journal Nature. They looked at millions of ship-based measurements taken since 1950. The data from 1960 revealed an error from a common probe called XBT.

The team came up with a global estimate of ocean warming in the top layers down to 700 meters (2,300 feet), as well as how fast ocean levels are rising, after correcting the error in data running over decades, as well as applying a complex statistical analysis to sea temperature data.

"We show that the rate of ocean warming from 1961 to 2003 is about 50 percent larger than previously reported," said team member Catia Domingues, from the Centre for Australian Weather and Climate Research. 

John Church, a senior research scientist with the climate centre, said he had long been suspicious about the historical data because it did not match results from computer models of the world's climate and oceans.

"We've realigned the observations and as a result the models agree with the observations much better than previously," said Church.

"And so by comparing many XBT observations with research ship observations in a statistical way, you can estimate what the errors associated with the XBTs are."

Domingues said that this was crucial because the ocean stores more than 90 percent of the heat in the planet's climate system and can act as a buffer against the effects of climate change.

As water gets warmer, it expands, pushing the sea levels up, in addition to the melting glaciers and ice sheets in Greenland and parts of Antarctica

The global average surface warming between 1961 to 2003 was about 0.4 degrees Celsius according to the team's estimates.  That rose sea level on average 1.6 millimeters a year during this period.

Church said that since 1993, sea levels had been rising more than 3 millimeters a year as the world consumes even greater amounts of fossil fuels. 

XBT's, which were disposable, were thrown over the side of a boat with a wire attached to measure temperatures as it sank.  Now they have been largely replaced by satellites and permanent probes in the ocean.

"if you miscalculate how quickly the instruments falls through the water column, you miscalculate the depth and therefore the temperature at that depth and that's the prime source of error," said Church.

A mathematical formula was figured out to correct the error by colleague Susan Wijffels and other associates. 

"Now we see a more steady rate of warming and an increased trend in that warming," Church told Reuters.

"It builds confidence in the models that we use for projecting the future," adding that observations also indicated that the actual sea level rise was tracking on the upper end of those projections.

Last year, the U.N. Climate Panel's latest global assessment estimated sea levels could rise by up to 80 cm by the end of 2100 unless carbon dioxide levels were retained.

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On the Net:

Nature

Centre for Australian Weather and Climate Research

Source: redOrbit Staff & Wire Reports

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