Uptick in carbon dioxide is recorded at Mauna Loa
A 50-year record of air measurements from Mauna Loa Observatory shows a steady increase in carbon dioxide, with faster growth since 2005, says station chief John Barnes.
But global warming has been slowed under an international agreement to reduce production and use of ozone-depleting chemicals, he said. "That's like the good story."
The National Oceanic and Atmospheric Administration's 11,140-foot observatory on Mauna Loa has the longest continuous measurements of atmospheric CO2 in the world.
During 800,000 years of history recorded in ice cores, including big ice ages every 100,000 years, carbon dioxide cycled from 180 to 280 parts per million molecules of air, Barnes said.
That changed around 2005, when atmospheric carbon dioxide hit 380 parts per million, he said.
"The de-seasonalized, postindustrial trend in added carbon dioxide has been increasing exponentially, with a doubling time of about 32 years," according to a NOAA report on global CO2 measurements.
The rising CO2 curve was slowed slightly by a strong growing season in Canada in 1995, but that was short term, Barnes said.
Other greenhouse gases measured are methane and nitrous oxide and ozone-depleting gases such as chlorofluorocarbon and CFC-12. Methane levels have stayed about the same, and chlorofluorocarbon gases have been declining in recent years, according to observatory records.
"The ozone layer is the other big issue our laboratory deals with," Barnes said.
In 1987, he said, nations around the world recognized that the compounds that destroy the ozone layer also act as greenhouse gases, and signed the Montreal Protocol agreeing to control the production and use of ozone-depleting substances.
Reporting results this month, NOAA's Earth System Research Lab said the agreement cut in half the amount of greenhouse warming caused by ozone-destroying chemicals that would have occurred by 2010 unabated.
"The amount of warming that was avoided is equivalent to seven to 12 years of rise in carbon-dioxide concentrations in the atmosphere," the scientists said.
Earth has lost probably about 6 percent of the ozone layer that protects the planet from harmful ultraviolet radiation, Barnes said. "In 20 years it should start to reverse and come back."
Montreal Protocol participants have been able to find replacements for ozone-depleting chemicals, such as fluids for car air conditioners, he said.
"But any time you burn fossil fuels, you always produce CO2. There is no way around that. Replacement in this case would be alternate energy or conservation."
The Mauna Loa Observatory is one of five base-line stations for the Earth System Research Laboratory. Scientists there are trying to get a global picture of greenhouse gases in the atmosphere for research and climate modeling, to see what will happen in 50 to 100 years, Barnes said.