Climate variability

UMD researcher sorts climate variability from climate change – Duluth News Tribune

Research by a UMD professor that separates the Earth’s natural climate variability from external factors indicates that these external factors – in particular greenhouse gas-induced climate change – are the probable cause of global warming of the planet.
The study found that natural climate variability has likely helped keep things cooler in recent years than they otherwise would have been due to outside factors.
The research, published today in Science Magazine, was led by Byron Steinman of the University of Minnesota Duluth, assistant professor of geological sciences at the Great Lakes Observatory and the Department of Earth and Environmental Sciences.
By analyzing computer models that simulate Earth’s climate over time, Steinman and his fellow researchers have described an approach to identify this internal variability.
The paper, “Atlantic-Pacific Multidecadal Oscillations and Northern Hemisphere Temperatures,” is the latest in a series of peer-reviewed research that points to greenhouse gas impacts as driving of climate change.
The study looked at how weather patterns stimulated by the North Atlantic and North Pacific oceans – called oscillations – affect climate patterns.
The natural cooling trend in recent years has not been enough to offset global warming, but it likely helped slow the rate of global warming in recent years, Steinman said.
But when the current negative oscillation period turns positive and naturally variable factors begin to raise temperatures, “it will only accelerate” the global warming trend, Steinman told the News Tribune.
With a model of this internal variability in place, scientists were able to expand understanding of how external forces such as greenhouse gases, solar fluctuations and volcanic eruptions affect climate events such as rising drought in Africa and an increase in hurricanes in the Atlantic.
“Are these trends driven by natural, internal oscillations? Are they pushed by outside forces?” Steinman said. “Based on our research, it appears that these changes are strongly influenced by external forces and, in particular, the increase in greenhouse gases from the burning of fossil fuels.”
Steinman, formerly of Penn State University, started with UMD’s Swenson College of Science and Engineering last fall. Prior to joining UMD, he worked closely with renowned climatologist Michael Mann, a distinguished professor of meteorology at Penn State, and Sonya Miller, a Penn State weather coder and analyst.
Steinman said he expects the paper’s findings to spur further work.
“We’re moving forward with ideas, concepts and questions that people have been thinking about for years,” he said. “Over the next few years, I would expect some of our findings to be challenged in the same way that all good science is challenged. This is how science works; it’s a healthy exchange and I welcome it.
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