Sep 27, 2013 9:35 PM by John Patrick
TUCSON - A panel concludes that it is extremely likely that human activity accounts for at least half of the global warming that has been observed since the 1950's, but some researchers still disagree.
The Intergovernmental Panel on Climate Change released its latest assessment on climate change claiming with a 95 percent certainty that the planet is warming at an accelerated pace and that humans are to blame.
Retired from the University of Arizona atmospheric sciences department, Dr. Benjamin Herman is one scientist who isn't ready to say that global warming is human caused.
"The climate is warming but there are many factors that maybe causing it and the CO2 solution has not been proven by any means," says Herman.
The IPCC holds high confidence in its findings due to the improvement of climate models that help scientists observe temperature trends.
Scientists like Herman question the validity of these models saying they still have a long way to go.
"If you lay your faith in the climate models I'll take a bet against you right now," says Herman.
Other UA researchers like Julie Cole from the geosciences department argue that models have improved greatly since the previous IPCC reports.
"Computer models are getting better and better on the various IPCC reports and the current report is no exception to that," says Cole.
She says climate models now include things like vegetation and carbon cycles which give us a clearer picture on how future climate may evolve.
"All of these things that we expected to see happen are now happening and that gives us greater confidence," explains Cole.
Nearly one-thousand researchers from around the world worked on the report which was reviewed by about as many scientists. The IPCC is appointed by the United Nation's and this is their fifth report in about 23 years.
The 2,000 page document will be made available on Monday September 30, 2013 but a summary can be found on the IPCC website by clicking here.