Greenhouse gases make high temps hotter in China

China, the world`s largest producer of carbon dioxide, is directly feeling the man-made heat of global warming, scientists conclude in the first study to link the burning of fossil fuels to one country`s rise in its daily temperature spikes.

China emits more of the greenhouse gas than the next two biggest carbon polluters — the U.S. and India — combined. And its emissions keep soaring by about 10 percent per year.

While other studies have linked averaged-out temperature increases in China and other countries to greenhouse gases, this research is the first to link the warmer daily hottest and coldest readings, or spikes.

Those spikes, which often occur in late afternoon and the early morning, are what scientists say most affect people`s health, plants and animals. People don`t notice changes in averages, but they feel it when the daily high is hotter or when it doesn`t cool off at night to let them recover from a sweltering day.

The study by Chinese and Canadian researchers found that just because of greenhouse gases, daytime highs rose 0.9 degree Celsius (1.7 degrees Fahrenheit) in the 46 years up to 2007. At night it was even worse: Because of greenhouse gases, the daily lows went up about 1.7 degrees Celsius (3 degrees Fahrenheit).

China is the world`s biggest producer and consumer of coal, which is the largest source of man-made carbon dioxide emissions. While the country has made huge investments in alternative energy such as wind, solar and nuclear in recent years, its heavy reliance on coal is unlikely to change any time soon.

About 90 percent of the temperature rise seen by the researchers could be traced directly to man-made greenhouse gases, the study said. Man-made greenhouse gases also include methane and nitrous oxide, but carbon dioxide is considered by far the biggest factor.

The study appeared online in late March in the peer-reviewed journal Geophysical Research Letters.

The study uses the accepted and traditional method that climate scientists employ to attribute a specific trend to man-made global warming or to rule it out as a cause.