November 11, 2013
Global Warming Standstill Attributed To Montreal Protocol
Lee Rannals for redOrbit.com - Your Universe Online
Researchers writing in the journal Nature Geoscience say CFC gases have had an impact on the rise in global temperatures. Scientists believe CFC gases are responsible for a massive hole in the ozone layer, but the latest study links the ban of these gases to a slowdown in temperature increases since the mid 1990s.The standstill of global temperature rises since 1998 has been used as a key argument by some to show the impacts of global warming have been exaggerated. However, this new study brings this debate back to life, offering up evidence the standstill may simply be because international climate talks resulted in the Montreal Protocol.
Researchers from the National Autonomous University of Mexico and Vrije Universiteit in Amsterdam carried out a statistical analysis on the connection between rising temperature and rates of increase in concentrations of greenhouse gases in the atmosphere between 1880 and 2010. The team analyzed radiative forcing and temperature time series with state-of-the-art statistical methods to figure out what to attribute the slowdown in warming to. They found changes in the warming rate can be attributed to human actions that affected greenhouse gas concentrations.
According to the findings, long-term trends in total radiative forcing and temperatures have been determined by atmospheric greenhouse gas concentrations, modulated by other radiative factors. The study identified a pronounced increase in the growth rate of both temperatures and radiative forcing around 1960, which marks the onset of sustained global warming.
The team says the standstill in global temperature rises coincides with the introduction of the Montreal Protocol, which was originally signed by 46 countries in 1987. This international treaty was designed to protect the ozone layer by phasing out the production of substances believed to be responsible for ozone depletion.
"Our statistical analysis suggests that the reduction in the emissions of ozone-depleting substances under the Montreal Protocol, as well as a reduction in methane emissions, contributed to the lower rate of warming since the 1990s," the authors wrote in the journal.
The researchers also said they identified a contribution from the two world wars and the Great Depression to the documented cooling in the mid-twentieth century. They said cooling experienced during this period was due to lower carbon dioxide emissions.
“We conclude that reductions in greenhouse gas emissions are effective in slowing the rate of warming in the short term,” the researchers wrote.