19 May 2013
from NewsMax Website
Extreme global warming is less likely in coming decades after a slowdown in the pace of temperature rises so far this century, an international team of scientists said on Sunday.
Warming is still on track, however, to breach a goal set by governments around the world of limiting the increase in temperatures to below 2 degrees Celsius (3.6 Fahrenheit) above pre-industrial times, unless tough action is taken to limit rising greenhouse gas emissions.
The rate of global warming has slowed after strong rises in the 1980s and 1990s, even though all the 10 warmest years since reliable records began in the 1850s have been since 1998.
The slowdown has been a puzzle because emissions of heat-trapping greenhouse gases have continued to rise, led by strong industrial growth in China.
Examining recent temperatures, the experts said that a doubling of carbon dioxide concentrations in the atmosphere above pre-industrial times - possible by mid-century on current trends - would push up temperatures by between 0.9 and 2.0 degrees Celsius (1.6 and 3.6F).
That is below estimates made by the U.N. panel of climate scientists in 2007, of a rise of between 1 and 3 degrees Celsius (1.8-5.4F) as the immediate response to a doubling of carbon concentrations, known as the transient climate response.
The U.N. panel also estimated that a doubling of carbon dioxide, after accounting for melting of ice and absorption by the oceans that it would cause over hundreds of years, would eventually lead to a temperature rise of between 2 and 4.5 C (3.6-8.1F).
Findings in the new study, by experts in,
...broadly matched that range for the long-term response.
But for government policy makers,
The oceans appear to be taking up more heat in recent years, masking a build-up of carbon dioxide in the atmosphere that passed 400 parts per million this month for the first time in human history, up 40 percent from pre-industrial levels.
Professor Reto Knutti of ETH Zurich, one of the authors, said that the lower numbers for coming decades were welcome.
Temperatures have already risen by about 0.8 Celsius (1.4F) since the Industrial Revolution and two degrees C is widely viewed as a threshold to dangerous changes such as more floods, heat-waves and rising sea levels.
He said findings,