New Study: Most of Arctic ice loss is due to natural processes, not man made global warming, CO2 levels
While there has been ice loss at the Arctic circle, the role of man, particularly carbon emissions, appears to be less than previously reported. In fact, “between 30-50 percent of the arctic melting is due to “unforced, or non-climate change caused variations.”
A new study in Nature Climate Change sheds new light on the conflict between theory and reality.
“There is a mismatch between the model’s output and the observation,” said lead author Qinghua Ding, a professor in the Geography Department at the University of California Santa Barbara. “Observation shows very fast, very abrupt sea ice melting, whereas the climate model cannot capture the fast melting.”
Ding and his team focused on the connection between September sea-ice extent (or how much of the Arctic sea had at least 15 percent sea ice) and the preceding summer’s (June-August) atmospheric circulation.
Ding’s previous work showed was that tropical air patterns from the Pacific can affect the North Atlantic Oscillation. The new study uses this knowledge to model how these natural patterns change the Arctic.
photo/ Darwin Laganzon
“In the model we turned off all CO2 forcing,” said Ding, or all climate changes that were “forced” by the addition of carbon dioxide into the atmosphere. “And we still got some sea ice melting, that was very similar to the observation.”
“If the circulation changes are caused by anthropogenic greenhouse warming (or other human or natural external forcings such as ozone depletion, aerosol emissions, or solar activity) this pattern of atmospheric change should emerge as a clear signature when averaging together many climate model simulations of this period,” Neil Swart, a Research Scientist with Environment and Climate Change Canada who wasn’t involved in the new study, wrote in an accompanying article.
Ding averaged the climate models together, the air circulation changes cancelled each other out—like a balanced equation. They only data that remained in the models was responding to external forcings, like greenhouse gas emissions. In other words, Ding found that between 30-50 percent of the arctic melting is due to these unforced, or non-climate change caused variations—and that with this factored in, the climate models were generally accurate. The increased rapidity of Arctic melting was due to natural variations outside of the scope of the climate change models.
Ding was quick to defend the climate change consensus, saying that this doesn’t mean that climate change isn’t real. Popular Science notes that Ding “equates these natural variations to putting a blanket on the sea ice, while climate change is turning up the thermostat. And as anyone who has huddled under a blanket in a toasty house knows, the end result is a whole lotta sweat.”
“Looking ahead, it is still a matter of when, rather than if, the Arctic will become ice-free in summer,” said Ed Hawkins, of the University of Reading.
Dr Nathanial Johnson, another member of the team, told The Independent that he hoped climate science deniers would not seize on their research in an attempt to suggest what is happening in the Arctic is purely natural.
“It would be unfortunate if this gets spun into a way that really sort of downplays the importance of anthropogenic forcing in this sea ice decline,” he said.
“There is internal, natural climate variability that can lead to these fluctuations about the long-term trend, but there’s nothing that really discounts the science behind the anthropogenic sea ice decline, nothing that really invalidates the models that are projecting this long-term decline.”
photo/ Fabio Piccini via pixabay.com
