Has climate change arrived?
More river water, extreme weather pointing to a trend
CAPITAL REGION When John McKeeby looks at the Schoharie Creek, he sees a very different waterway than the one that existed prior to tropical storms Irene and Lee.
In some places, the Schoharie is deeper, and in some places it’s more shallow. In the shallower channels, the water moves more quickly than it used to, because it has less space in which to flow. There are rock piles in the center of the river and on the edges, and a large, deep fishing hole that wasn’t there before.
Another big change, one that predates Irene and Lee, is the volume of water coursing through the streambed. This is something McKeeby keeps close tabs on, frequently checking the United States Geological Survey’s water gauge at the Schoharie Creek at Burtonsville for information about stream flow.
“We want to know what’s going on in the river,” said McKeeby, the executive director of the Schoharie River Center, which monitors the water quality of the creek and provides educational and cultural programming.
According to data from the United States Geological Survey’s New York Water Science Center in Troy, the past decade has been especially wet at the Burtonsville water gauge. During the 1940s, the gauge saw an average discharge of 855 cubic feet of water per second; during the 2000s, the average discharge was 1,407 cubic feet per second.
This greater volume of water might be part of a longer-term trend.
For years, scientists have warned that climate change would bring increased precipitation and more frequent flooding, and now a wealth of research suggests that the region is already experiencing those trends. According to a 2009 report from the U.S. Global Change Research Program, the Northeast experienced a 67 percent increase in very heavy precipitation between 1958 and 2007.
This has been a particularly wet spring in the Capital Region. According to the National Weather Service in Albany, May was the ninth wettest May on record, and June will likely make the top 10 as well. Last month also saw three tornadoes touch down in the Capital Region, an unusual occurrence.
Scientists cannot say for sure whether any particular storm or weather pattern is directly caused by climate change.
But they can describe the type of weather that will become more common in a world of rising global temperatures, where the air and oceans are warmer, sea levels are higher and there’s more moisture in the air.
“We expect more hot days in the summer and fewer colder days in the winter,” said Aiguo Dai, an associate professor in Department of Atmospheric & Environmental Sciences at the University at Albany. “Winter storms could be even more intense, more extreme. Tornadoes might become more extreme. Hurricanes might become more intense and could become more frequent. Summer heat waves and drought could become more frequent. We expect more extreme precipitation.”
A warmer atmosphere can hold more water vapor, and water vapor provides fuel for storms such as tornadoes, he said.
Dai said the weather this spring has been “consistent with model predictions” of what is in store for the Northeast as temperatures rise.
“It’s necessary for the public to know that climate change is a gradual process,” he said. “Over the long term, the next 30 to 50 years, we will see the impact of climate change on individual weather. The patterns will change.” The weather has a natural variability, he said, and climate change will make those shifts more extreme and more damaging.
“The tricky thing is making a direct connection to climate change,” said Stuart Findlay, an aquatic ecologist at the Cary Institute of Ecosystem Studies, an environmental research organization in the Dutchess County village of Millbrook. “But atmospheric scientists are becoming a little more blunt about saying, ‘Yes, this is climate change.’ ” He said it’s “pretty clear” that heavy precipitation events have become more common.
Findlay said that over the past 60 years, the Hudson River’s temperature has increased by about 1 degree. The amount of water moving through the river has increased by 30 percent over the past 30 years, he said.
“There’s more runoff,” he said. “There’s more water leaving the terrestrial system and entering the river.” More rain creates more problems: If the ground is already saturated with water, it can’t absorb rainfall, and the water flows into the rivers, causing them to rise.
Findlay said that a 1 degree temperature increase might not sound like much, but that even a seemingly slight change can have an impact on a river’s ecosystem. He said that the population of tomcod in the Hudson has declined as the river has gotten warmer; the fish is suited to colder water, and the southern limit of the tomcod’s range has long been the New York Harbor. Another species that has suffered is plankton — tiny organisms that serve as a crucial food source for fish. With more water moving through the Hudson, the plankton “get flushed out,” he said.
In 2011 the New York State Energy Research and Development Authority released a 600-page report that said that New York should begin planning for hotter summers, snowier winters, severe floods and other impacts stemming from climate change. The study predicts that average annual temperatures in New York will rise by 4 to 9 degrees by 2080, precipitation will rise by 5 percent to 15 percent, and that along the sea coast and tidal portion of the Hudson River the sea level will rise by one to five inches in the 2020s.
New York State Climatologist Mark Wysocki, who is based at Cornell University, said it’s possible that changes in the jet stream — the bands of strong wind in the upper atmosphere — are having an impact on weather patterns and weather events. Sometimes these bands move in short, choppy waves, which causes weather patterns to move through an area quickly. But sometimes they move in longer waves, which causes weather patterns to linger over an area for a longer period of time.
The question scientists are asking, Wysocki said, is whether longer waves are becoming more common, something that might be caused by larger temperature contrasts between land and water. These larger temperature contrasts, he said, are the result of the warming temperatures caused by climate change. Though both land and water are warming, “the land usually heats up and cools the most,” he said.
“If there are longer waves, a storm system might move through an area in five days, instead of three,” Wysocki said. He said the Oklahoma City area has always been prone to tornadoes, but “it’s unusual for the area to be under a tornado threat for three days in a row.” On May 13, a tornado struck Moore, Okla., killing 24 people and injuring more than 350; it was part of a bigger weather system that produced several other tornadoes that week.
‘On the edge’
“Our atmosphere lives on the edge,” Wysocki said. “It’s a very delicately balanced atmosphere. A slight change could set it off into a different climate scenario.”
According to the National Climatic Data Center, 2012 experienced 11 weather and climate disaster events, such as Hurricane Sandy and the yearlong drought that affected more than half the country, that cost more than $110 billion in damages throughout the year. It was the second costliest year since 1980, and second to 2011 in total number of billion-dollar weather and climate events. In 2011, there were 14 such events.
At the Schoharie River Center, McKeeby has noticed many changes since the contours of the river were dramatically altered by Irene and Lee and the subsequent flood. The turbidity of the river, he said, has increased. Turbidity refers to the muddiness that’s created when sediment or other foreign particles are stirred up; after a heavy storm event, such as Irene and Lee or the recent rains, water is much more likely to be turbid. McKeeby said that the tropical storms washed away much of the riverbank, leaving clay shelves with very little vegetation exposed. “The clay tends to liquidate and run into the Schoharie,” he said.
McKeeby said water levels in the Schoharie Creek vary.
“You have dry spells and you have wetter times,” he said.