TOKYO — Japan on Friday launched the first satellite to monitor greenhouse gases worldwide, a tool to help scientists better judge where global warming emissions are coming from, and how much is being absorbed by the oceans and forests.
The orbiter, together with a similar U.S. satellite to be launched next month, will represent an enormous leap in available data on carbon dioxide and methane in the atmosphere, now drawn from scattered ground stations.
"I'm saying Christmas is here," said an enthusiastic Inez Fung, an atmospheric scientist at the University of California, Berkeley. "Now we get about 100 observations every two weeks. With the satellite we'll get a million."
The satellite _ named "Ibuki," which means "breath" _ was sent into orbit along with seven other piggyback probes on a Japanese H2A rocket. Japan's space agency, JAXA, said the launch was a success, and officials said they were monitoring the satellites to ensure they entered orbit properly.
Ibuki, which will circle the globe every 100 minutes, is equipped with optical sensors that measure reflected light from the Earth to determine the density of the two gases.
Carbon dioxide, the biggest contributor to global warming, is emitted by the burning of fossil fuels by power plants, motor vehicles and other sources. Methane has a variety of sources, including livestock manure and rice cultivation.
International science agencies report that carbon dioxide emissions rose 3 percent worldwide from 2006 to 2007. If emissions are not reined in, a U.N. scientific panel says, average global temperatures will increase by 4 to 11 degrees Fahrenheit (2.4 to 6.3 degrees Celsius) by the year 2100, causing damaging disruptions to the climate.
"Global warming is one of the most pressing issues facing the international community, and Japan is fully committed to reducing CO2," said Yasushi Tadami, an official working on the project for Japan's Environment Ministry. "The advantage of Ibuki is that it can monitor the density of CO2 and methane gas anywhere in the world."
Scientists currently depend on 282 land-based stations _ and scattered instrumented aircraft flights _ to monitor carbon dioxide at low altitudes. Ibuki, orbiting at an altitude of about 415 miles (670 kilometers), will be able to check gas levels in entire columns of atmosphere at 56,000 locations.
With the current ground-level network, "due to the relatively small number of locations, only large-scale regional averages could be determined" for greenhouse-gas emissions, said Swiss climatologist Fortunat Joos, of the University of Bern.
With satellite readings, he said, "one would perhaps be able to discriminate carbon emissions from different countries."
Such data could help negotiators in ongoing global climate talks to determine more precisely who would need to reduce emissions by how much to protect the climate.
"Basically, we're sort of doing detective work," said Fung. "We may be able to see fossil fuel emission hotspots."
The scientists said readings from space should also enable them to better understand carbon's movement through the atmosphere, and its inadequately understood absorption by oceans and forests, crucial to keeping warming from growing even worse than predicted.
The upcoming NASA satellite, the Orbiting Carbon Observatory, will have more precise measurements because it will check only one gas, carbon dioxide, said David Crisp, that project's chief scientist. And its smaller observational target area will mean less chance of clouds contaminating sample results.
Having two satellites will allow researchers to double-check results, Crisp said.
"We need to understand what processes are controlling the amount of carbon dioxide today so that we can understand how fast CO2 will build up in the future," he said.
The launch of the piggyback satellites, from Tanegashima, a remote island about 600 miles (970 kilometers) southwest of Tokyo, was also seen as crucial to Japan's efforts to demonstrate that its domestically developed H2A rocket can compete in the global commercial launching business.
Japan has long been a leading space-faring nation, having launched its first satellite in 1970, but in recent years it has struggled to get out from under China's shadow and gain a hold in the global rocket-launching industry, which is dominated by Russia, the U.S. and Europe's Arianespace.
Earlier this month, Japan got its first commercial order, from South Korea, to launch a satellite on an H2A. Liftoff is scheduled after April 2011.
Associated Press writers Charles J. Hanley in New York and Shino Yuasa in Tokyo contributed to this report.