Global warming effects worse than previously thought

by Jim Lobe

Washington, Jun 30 -- Global warming over the next century is likely to be worse than previously estimated and the United States, which has yet to ratify an international climate change treaty, can ill afford to ignore the problem, say two new studies.

The first study, by a key contributor to the 1995 report by the Intergovernmental Panel on Climate Change (IPCC), projects an increase in the global mean temperature of between 1.3 and 4.0 degrees Centigrade and a rise in sea level of between 17 and 99 centimetres by the year 2100.

That compares with the IPCC's 1995 estimates of 0.8-3.5 degrees Centigrade and 13-94 cms, respectively, according to the report by the Pew Centre on Global Climate Change, a year-old research group here which supports international initiatives to address global warming.

Tom Wigley, a senior scientist at the National Center for Atmospheric Research in Boulder, USA and author of the report, also predicts that the United States - particularly the northern states in the eastern half of the country - will experience noticeably faster warming than the global mean rate.

A second report, from the non-governmental Environmental Defence Fund (EDF), says that New York City is likely to experience a major increase in extremely hot days - and predicts repeated flooding of its roads, subways and airports - as a result of global warming.

The new studies, released Tuesday, come amid growing consensus among scientists that human activity - notably emissions into the atmosphere of 'greenhouse gases' such as carbon dioxide, methane, nitrous oxide, and ozone - is indeed warming Earth's surface. Of these, carbon dioxide, which is produced from the burning of fossil fuels like oil and gas, is the most important.

In 1990, the IPCC - considered the most authoritative international body on global warming - found that it could not reach a definitive conclusion as to whether warming experienced over the previous century of about 0.6 degrees Centigrade was induced naturally or by human activity.

By 1995, following the development of new and more sophisticated research models, the panel revised its opinion, finding a "discernible human influence" in the warming of the globe.

The IPCC is preparing a new assessment which is supposed to be completed in about 18 months. Wigley, the main author of the section of the IPCC's 1995 report on detecting the human contribution to climate change, remains a key participant, and his latest study has been reviewed by a number of other IPCC members.

While the IPCC refines its models, other scientists report extensive empirical evidence of warming and its effects. Earlier this year, one team reconstructed surface temperatures in the northern hemisphere over the past millennium and found that the 20th century has been the warmest by far.

Other studies have found the 1990s to be the warmest decade and 1998 the warmest year on record.

Still more evidence of warming has been found in the receding of snow at higher mountain elevations, the thinning of the polar ice caps, the bleaching of coral reefs in the tropics, and the migration of butterflies, sea birds and even crustacea, from temperate areas toward the poles.

Despite all of the evidence of warming - and the potentially disruptive impacts it could have - governments, and especially the United States, have been slow to react.

In December 1997, industrialised countries, which have been responsible for most greenhouse gas emissions, agreed to reduce emissions to five percent below their 1990 levels by the year 2012. Some scientists consider that step to be extremely modest, bordering on insignificant.

But the administration of President Bill Clinton, which signed on to that target, has declined to send it to the US Senate for ratification because it knows that the measure faces certain defeat there.

Many lawmakers, especially those who receive substantial contributions from oil, gas and coal interests, insist that global warming is only a theory and that Washington should wait until it receives positive proof before taking preventive measures that could adversely affect the US economy.

The Pew Centre is taking out advertisements based on its latest study in The New York Times, Washington Post, Newsweek and two publications widely read in Congress, Roll Call and National Journal. The group was set up precisely to provide more information about the accumulating evidence of climate change and its impact on the United States.

The Pew study differs from the earlier IPCC estimates mainly because it assumes that sulphur dioxide emissions will not be as great as previously anticipated, due to efforts by national governments to reduce air pollution and acid rain.

The reduction in sulphur dioxide emissions - which actually cool the atmosphere - in turn will mean that global temperatures and sea level will be slightly higher than previously projected.

The study says that warm temperature extremes will almost certainly become more frequent and cold temperature extremes, more rare.

In addition, the frequency of rainfall associated with hurricanes and other extreme weather events will likely increase, according to the report.

These phenomena could have huge and potentially disastrous impacts, particularly in low-lying coastal areas, according to the EDF report, which lawmakers from the New York area have quickly endorsed.

"The New York of tomorrow must be protected by prudent action today," says Sen. Charles Schumer of New York. "The US Senate should begin to take action addressing this problem, which will impact on New Yorkers and all Americans." (IPS)

The above article by the Inter Press Service appeared in the South-North Development Monitor (SUNS).