A global warming "hiatus," a pause in the rate our planet is heating up, never happened, and the evidence for it lacked sound statistical backup, U.S. researchers say.
The apparent pause in the warming, accepted by many both in and out of scientific circles, is an unreal artifact resulting from the use of faulty and inappropriate statistical methods, the scientists at Stanford University say.
Their study, "Debunking the Climate Hiatus," is appearing in the journal Climatic Change.
"We translated the various scientific claims and assertions that have been made about the hiatus and tested to see whether they stand up to rigorous statistical scrutiny," says lead author Bala Rajaratnam, a professor of Earth system science and statistics.
Climate change deniers and others who support the existence of a "hiatus" suggest the rate of warming has slowed and sometimes even stopped in the past 15 years.
The Stanford researchers looked at temperature data from the past 15 years compared with all the decades leading up to that point and examined the statistical tools used to analyze it.
They found the number of data points for the supposed hiatus was much smaller than most statistical tools needed to generate reliable results.
In addition, many of the statistical techniques used were not ideally suited to geophysical processes such as global temperature fluctuations, they determined.
When the researchers developed a new statistical framework designed specifically for taking into account the relevant geophysical processes, they found that the proposed hiatus statistically disappeared.
"Our results clearly show that, in terms of the statistics of the long-term global temperature data, there never was a hiatus, a pause or a slowdown in global warming," says study co-author Noah Diffenbaugh, a climate scientist in Stanford's School of Earth, Energy and Environmental Sciences.
The findings support another recent study published in Science, which found that ocean buoys used to record sea surface temperatures in recent decades were turning in cooler readings than those recorded by ships at sea.
When the buoy measures were corrected, the data no longer supported the idea of a warming pause, the authors of the Science study said.
"I think it further enhances the robustness of the notion that we really do not have strong evidence for a slowdown or a stoppage of global warming," says lead author Thomas Karl, director of NOAA's National Centers for Environmental Information.
Not that this will end the debate; a recent paper issued by Britain's Met Office said the hiatus – if it existed, mind you – is ending.
And another recent study reported that the Southern Ocean has been taking up increased amounts of carbon dioxide greenhouse gases, acting as a carbon sink, with the suggestion that could ameliorate global warming a bit and limit climate change. Oceans have filled that carbon sink role for years, but scientists are concerned if too much carbon dioxide is absorbed, it could make the water too acidic, which could prevent sea animals such as crabs and lobsters from being able to properly grow their shells, making them more vulnerable to predators.
When it comes to climate science, only one thing is sure – more studies supporting both sides of the argument are surely in store.
