Norway Data Shows Earth’s Global Warming Less Severe Than Feared
Jan 27, 2013
New estimates from a Norwegian research project show meeting targets for minimizing global warming may be more achievable than previously thought.
After the planet’s average surface temperature rose through the 1990s, the increase has almost leveled off at the level of 2000, while ocean water temperature has also stabilized, the Research Council of Norway said in a statement on its website. After applying data from the past decade, the results showed temperatures may rise 1.9 degrees Celsius if Co2 levels double by 2050, below the 3 degrees predicted by the Intergovernmental Panel on Climate Change.
“The Earth’s mean temperature rose sharply during the 1990s,” said Terje Berntsen, a professor at the University of Oslo who worked on the study. “This may have caused us to overestimate climate sensitivity.”
The findings also show the effect of reduced airborne particulates from burning coal, which may decrease the cloud cover that cools the earth, probably has less of an impact on climate through indirect cooling than originally projected.
Study resets climate debate
A DECADE-LONG pause in global warming may have radically lowered the longer-term outlook for climate change, researchers have found.
A Norwegian team, using observations and powerful computer models, said the most likely outcome from a doubling of human carbon dioxide emissions was a 1.9C rise by 2100.
This compares with the Intergovernmental Panel on Climate Change's most likely scenario of a 3C temperature increase and is below the target that has been set to limit global temperature rise to 2C.
The lower temperature estimate follows research last week that said the Arctic ice may be much less sensitive to rising global temperatures than had previously been thought, and the acknowledgement this month by NASA climate scientist James Hansen that the five-year mean global temperature had been flat for a decade.
Dr Hansen said the temperature rise pause had been due to a combination of natural variability and "a slowdown in the growth rate of the net climate forcing". He said the 10 warmest years on record had all occurred since 1998 and global temperatures were expected to "rise significantly in the next few years" and in coming decades.
The Norwegian research does not reject the theory of climate change or downplay the need for action to reduce human carbon dioxide emissions, but it shows keeping the global temperature rise below 2C may not be as difficult as previously thought.
It is the inclusion of the pause in global temperature rises since 2000 that sets the Norwegian research apart.
Project manager Terje Berntsen said the sharp rise in global temperatures during the 1990s "may have caused us to overestimate climate sensitivity".
"We are most likely witnessing natural fluctuations in the climate system," Professor Berntsen said. "Changes that can occur over several decades and which are coming on top of a long-term warming.
"The natural changes resulted in a rapid global temperature rise in the 1990s, whereas the natural variations between 2000 and 2010 may have resulted in the levelling off we are observing now."