All the rain, snow, heat ... Is it global warming?
Plenty of people are skeptical about the idea of global warming.
But in Minnesota, some minds are being changed by this past winter's record snowfall, this summer's record heat, recent torrential rains and flooding, and the unusual number and ferocity of tornadoes.
Earlier in his career, University of Minnesota climatologist Mark Seeley might have ignored climate change as a cause for these events.
"For many years I was a global warming skeptic — I'm a measurements guy, not a (climate) modeler," he said. "But when the measurements I saw showed so much change, that's what convinced me."
So in assessing the recent weather extremes, he often mentions climate change. He notes disparities — "amplified variabilities" — in rainfall around the region.
This summer, for example, nearly all of Minnesota's counties have gotten more rainfall than average (as much as 10 inches of rain in July alone in some places). But Cook and Lake counties in northeastern Minnesota, have gotten very little rain.
Likewise, in August 2007, five counties in southeastern Minnesota got huge amounts of rain that caused major flooding, yet 24 counties got very little rain. It was the first time in the state's history, he said, when some counties were declared disaster areas because of flooding, while others were declared disaster areas because of drought.
In fact, this summer is the seventh straight in which there's been amplified variability.
"It might be a sign of the future," Seeley said.
He also noted that all of the major river basins in the Midwest — the Ohio, the Mississippi and the Missouri — experienced major flooding this spring. It's unusual to have more than one that's flooded during a spring, he said.
And as for July, "we're not even beginning to analyze all the records that were set," he said, mentioning heat indices and dew points.
But Lee Frelich, director of the Center for Forest Ecology at the University of Minnesota, speaks more starkly about the region's future.
"More heat waves is a given, and they will last longer," he said.
Also, Frelich said, more variability in rainfall and drought can be expected. And the main cause of climate change is emissions of carbon dioxide, he said.
The weather variabilities are the result of increased energy in the atmosphere caused by the warming climate, he said. Among factors are higher levels of moisture in the atmosphere from increased evaporation from ocean water, including the Gulf of Mexico.
Doubts about danger
Richard Muller, a physics professor at the University of California, Berkeley, and longtime critic of government-led climate studies, isn't ready to draw conclusions about the potential impact of increased surface temperatures in the United States.
"We need to be cautious about (predicting) danger," he said. "Any time there is weather that people don't like, they will blame it on global warming,"
Muller, however, recently made unexpected statements to Congress in which he backed up surface temperature data that's been collected by groups including NASA and the National Oceanic and Atmospheric Administration.
Muller is directing the Berkeley Earth Surface Temperature project , whose biggest private backer is the Charles G. Koch Charitable Foundation, named after oil billionaire Charles Koch, a prominent funder of efforts to prevent curbs on the burning of fossil fuels.
Muller told the Post-Bulletin that while he doesn't consider current climate variability to be a significant danger, "What I'm deeply concerned about is that it's on track to become very large."
"I do know that we're putting enough carbon dioxide into the atmosphere to worry about it," he said.