LEVELS of carbon dioxide, the greenhouse gas chiefly responsible for global warming, have risen to a new high, according to measurements taken at the world’s leading climate science laboratory.
Concentrations of CO2 in the atmosphere have increased to 378 parts per million (ppm), according to results gathered at Hawaii’s Mauna Loa observatory.
Although the rise from an average of 375.64 ppm in 2003 is smaller than in the previous two years, experts say it again fits the pattern of increases in emissions driving the warming of the Earth’s atmosphere and oceans.
The research was carried out by the US government’s climate monitoring diagnostics laboratory, part of the National Oceanic and Atmospheric Administration.
The new figures are likely to be a powerful tool in the battle to convince the United States, the world’s biggest polluter, that it urgently needs to join efforts to slow down emissions of carbon dioxide, which are created through the burning of fossil fuels such as oil.
Dr Pieter Tans, the laboratory’s director, said: "The most striking thing about the data is that we’ve seen an increase in carbon dioxide levels every single year since 1958."
Greenhouse gases that cause climate change have a delayed effect, like a "disease" with a long incubation period.
This inertia means that the consequences of the emissions that have already been released into the environment will not be felt for some years. Even if emissions of CO2 were stopped immediately tomorrow, certain changes to the global climate over the next 50 years would still take place.
According to Dr Tans, one significant finding is that the annual rate at which CO2 is rising is increasing, and the growth rate over the past decade has been about twice as fast as that found in the 1960s.
He believes that variations in this growth rate year by year can be explained by natural factors, such as changes in the rate at which plants and the oceans absorb CO2. However, Dr Tans and fellow researchers have concluded that the steady rise overall can be attributed to manmade, or anthropogenic, emissions of carbon.
Measurements began in 1957, at the observatory on top of the Mauna Loa volcano, which at an altitude of 11,500ft ranks amongst the most remote scientific outposts in the world.
Since then the station has grown to become the premier long-term atmospheric monitoring facility on Earth, largely because its altitude means the air it samples is stable, and free from the traffic pollution present round the Hawaiian coast.
Pacific air is also well-mixed, meaning there is no immediate source of pollution such as heavy industry, and there is no natural "carbon sink" nearby, such as a forest which would absorb CO2.
Tony Blair, the Prime Minister, has already revealed that he intends to use his presidency of the G8 group meeting at Gleneagles to bring Mr Bush back into negotiations on ways of preventing global warming.