Deluges in forecast

Climate change is expected to bring heavy rains, more floods, and more damage to communities.

By Mike Lynch

A few years ago, Paul Smith’s College scientist Curt Stager came across a rare find that he says helps tell the story of climate change in the Adirondacks: the journal of Bob Simon, a retired engineer and longtime resident of Cranberry Lake.

Simon, who died in 1991, kept a meticulous journal with entries for temperature, wind direction, barometric pressure, water level, ice cover, when loons arrived, and when thunderstorms occurred. He made entries twice a day, morning and night, for the last thirty-two years of his life. Stager received the journal from someone who found it in Simon’s former home, years after the man died.

Stager was particularly interested in the entries on thunderstorms because they are not recorded by automated weather stations. Thunderstorms are a form of extreme weather and one of the rain events that are expected to happen more often in the future, he said. Stager hasn’t found any other thunderstorm records in the Adirondacks. He gave the weather records to a group of his students, who analyzed the data for their senior project.

The students found that thunderstorms tended to increase in the period covered by the journal. For instance, from 1969 to 1979, there were between four and nine thunderstorms per year, except in 1973, when there were sixteen. From 1980 to 1989, there were between ten and seventeen, except in 1982, when there were eight.

“Climate modelers have proposed that thunderstorm activity should increase as the world warms, and Bob Simon’s data support that claim,” Stager said. As the frequency of thunderstorms increases, he added, people can expect to see heavier downpours and more flooding, lightning strikes, and destructive winds. Climate change is also creating more unstable weather patterns, so the temperatures are fluctuating to extreme highs and lows more than in the past. In addition, more drought periods are expected, not just extreme rainstorms. The moderate rainstorms are declining.

One of the main reasons that more extreme rainstorms are happening is that rising temperatures lead to more and heavier rainstorms. That’s because warm air can hold more water vapor than cold air can.

Northeast Regional Climate Center Director Arthur DeGaetano said his data have shown a discernable trend over the last fifty years in the frequency of heavy rainfalls —those with more than two inches of rain.

“That’s projected to continue through this current century,” said DeGaetano, who is based at Cornell University. National data, he said, have shown that “things like two-inch-rainfall events have been increasing across the country, but the Northeast really sticks out like a sore thumb in terms of having the greatest, the most pronounced trend.”

DeGaetano said scientists are still trying to figure out why the Northeast is experiencing more big rainstorms than other regions.

Scientists say climate change has been occurring for at least a century. Between 1895 and 2011, the average annual temperature in the Northeast increased nearly two degrees, while the average annual precipitation increased about five inches, according to the 2014 National Climate Assessment.

Temperatures are expected to go up faster this century. If carbon-dioxide emissions continue to rise, a warming of an additional four and a half to ten degrees is projected by the 2080s. If emission rates are reduced substantially, the temperature is still projected to increase three to six degrees.

DeGaetano’s work for the National Climate Assessment found that historic storms, known as hundred-year storms, appear to be happening on an average of once every sixty years in the Northeast. He also has researched storms that occurred just in New York State. He told the Explorer that projections across the state were consistent with the northeastern ones and that it didn’t vary much whether the region was Buffalo, Long Island, or the Adirondacks.

“I think a part of the increase in rainfall we see with climate change is that a warmer atmosphere can hold more water vapor,” he said. “Where the atmosphere is typically colder, it holds less vapor. So a little bit of warming in a cold atmosphere can have a bigger effect than a greater amount of warming in an atmosphere that is already warm. If I didn’t go across the State of New York but went from Florida to Vermont or something like that I would expect to see a bigger change in a place like Vermont than Florida.”

The Adirondacks has seen a number of major storms and floods in recent years. Floods often occur in spring when heavy rains combine with snowmelt. The amount of runoff into streams and rivers will be even greater if soils are saturated or frozen. Flooding also can be exacerbated by ice jams on waterways.

In April and May of 2011, there were many floods along the Hudson, Saranac, and Raquette rivers. The Raquette River near Piercefield reached five-hundred-year flood status. At North Creek, the Hudson peaked at 13.65 feet on April 28, breaking the record set in 1948 by about a foot and a half. Records for that gauge go back to 1907. Lake Champlain also hit historically high levels that spring and remained in flood stage for weeks.

The flooding occurred when it rained nearly three inches in forty-eight hours starting on April 26. During that period, temperature rose to seventy-eight degrees, triggering rapid snowmelt in the mountains.

Big storms can also occur in fall, often as a result of hurricanes or tropical storms. The most recent example is Tropical Storm Irene, which was downgraded from a hurricane before reaching the Adirondacks in August 2011. Irene caused a tremendous amount of damage to communities in the Ausable River watershed, including Keene, Keene Valley, and Jay. Not only did the river swell, but many small tributaries became raging rivers and jumped their banks. The storm destroyed thirty homes in Essex County and damaged eighty-six others.

The state Department of Transportation has begun making preparations for future storms. Last summer, it replaced seven bridges in the town of Keene with this in mind. The new bridges are wider and higher to allow more water to pass under. They also have stronger foundations. Meanwhile, local and county highway departments replaced culverts along the West Branch of the Ausable last summer with ones that allow for passage of more water.

These types of adaptation strategies for dealing with severe flooding are also outlined in the 2014 New York Rising Community Reconstruction Plan for the towns of Jay and Keene that came about because of Irene. This report also notes the type of ecological harm that flooding can do. Aquatic habitat and riparian corridors suffer damage. Significant bank and soil erosion occurs, including landslides. This causes more fine sediment to get into rivers, which can harm habitat for fish and other aquatic species. Invasive species spread through flooding and also from work that occurs later on by highway departments as soil is moved around.

In addition, wastewater-treatment plants are built near rivers and can be flooded during these storms, causing effluent to get into waterways. That happened in the spring of 2011 when Saranac Lake’s wastewater plant was overwhelmed by the Saranac River.

The National Climate Assessment also notes the Northeast is prone to extreme changes in temperature and heavy snowfall. Climate models have shown that these type of events are expected to increase, but scientists also say there is a great deal of uncertainty about what to expect.

“The old practice of looking at the past and using that as a guide to the future is clearly out the window,” DeGaetano said. “We’re in this period of time when the observed data and the projections for the future show kind of the climate evolving and changing and changing quite rapidly.”

 

Heavy rainstorms lead to landslides

One of the consequences of more severe rainstorms is the potential for more landslides, according to the 2014 New York State Hazard Mitigation Plan.

Landslides are a rare occurrence in the Adirondacks. They typically occur in the backcountry after the soil on steep slopes gets saturated after a heavy rain. The soil and vegetation slide down the mountain, leaving a bedrock scar, or slide.

During Tropical Storm Irene in August 2011, at least sixteen new slides were created, including ones that buried parts of the Orebed Brook Trail and Southside Trail in the High Peaks Wilderness. A landslide covered a section of the trail through Avalanche Pass in 1999 as a result of heavy rains associated with Hurricane Floyd.

Perhaps the slowest landslide in New York State was recorded on Little Porter Mountain in Keene Valley in May 2011. State geologists found that the eighty-two-acre mass of mud was moving downhill at a rate of six inches to two feet per day. The unusually slow-moving slide was triggered by excessive groundwater stemming from heavy rain and snow of that year. No one was injured, but a few homes were damaged.

One of the most serious situations involving landslides occurred in June 1963 when a localized storm caused landslides on Giant Mountain. The mud, trees, and debris from the storm covered cars, campsites, and a portion of Route 73.

The Hazard Mitigation Plan says the regions of eastern Essex and southern Franklin counties are among the most susceptible to landslides in the state. Only two areas are listed as more vulnerable: the Hudson River valley, from Saratoga County to Westchester County, and Niagara Falls.

 

December was a hot one

The month of December was the warmest on record in the Adirondacks, according to the National Oceanic and Atmospheric Administration. In Saranac Lake, the average temperature for the month was thirty-four degrees, which was fifteen degrees above normal.

The temperatures were so high this winter that Saranac Lake was unable to finish its ice palace by the first day of the annual Winter Carnival. For several days before the carnival, the structure was covered with a blue tarp to protect it from rain. In Wilmington, a World Cup freestyle skiing event was canceled because Whiteface Mountain didn’t have enough snow for the event.

National Weather Service meteorologist Brooke Taber attributed this winter’s warm weather in the Adirondacks to a shift in the polar jet stream and to climate change. Although this is an El Nino year and El Nino weather patterns can cause the polar jet stream to move north, Taber noted that not all El Nino winters in the Northeast are warm.

“Normally, the polar jet is down across our area … providing us with frequent bouts of arctic or modified artic air,” said Taber, who is based in Burlington. “This year, for the most part, it’s been well north up in central Canada, near Hudson’s Bay.”

The warm winter coincided with rising temperatures around the world. Average global temperatures in 2015 were the highest in modern history, according to NASA and the National Oceanic and Atmospheric Administration. The record temperatures in 2015 beat the previous mark set in 2014 by 0.23 degrees. Only once before, in 1998, has the new record been greater than the old record by this much. Records have been kept since 1880.

Most of the warming came about in the past thirty-five years. Fifteen of the sixteen warmest years on record occurred since 2000.

However, the warming trend didn’t hold true for the entire year in the Adirondacks, where the average temperature in the first few months of 2015 was lower than usual. “We had several really cold outbreaks in January and February,” Taber said. “We were sort of the exception, rather than the rule.”