Washington (AP): Major greenhouse gases are accumulating in the air faster than they had been despite efforts to curtail the growth.

Carbon dioxide concentration in the air increased by 2.4 parts per million last year, the National Oceanic and Atmospheric Administration (NOAA) reported on Wednesday.

At the same time methane concentrations also rose rapidly, the agency said.

Scientists have become more worried in recent years about the gases, with most atmospheric specialists concerned that the increasing accumulation is raising the earth's temperature in a potential disruption of climate through changing patterns of rainfall, drought and other storms.

The Intergovernmental Panel on Climate Change has worked to detail the scientific bases of this problem and the 1997 Kyoto protocol on climate change sought to encourage countries to act to reduce their greenhouse emissions. Some countries, particularly in Europe, have done so.

But carbon dioxide emissions, primarily from burning fossil fuels such as coal, oil and gasoline, have continued to increase.

Since 2000, annual increases of two parts per million or more have been common, compared with 1.5 ppm per year in the 1980s and less than one ppm per year during the 1960s, NOAA's Earth System Research Laboratory said.

Global concentration of carbon dioxide is now nearly 385 parts per million. Preindustrial carbon dioxide levels hovered around 280 ppm until 1850. Human activities pushed those levels up to 380 ppm by early 2006.