What Connecticut’s drought can teach about a warming climate
Experts across Connecticut spoke about the state’s ongoing drought, the implications of last week’s heavy rain and the need for current infrastructure to evolve with a changing climate.
Zoe Berg, Photography Editor
Amid an ongoing drought across the state, last week’s heavy rain was a welcome gift for Connecticut’s soil and rivers. But the resulting flooding that occurred in New Haven and across the state raised concerns over the inability of current infrastructure to survive a warming climate.
On Jul. 14, Gov. Ned Lamont declared most regions of Connecticut, including New Haven, in a Stage 2 drought, and two counties as experiencing a Stage 3 drought. Despite receiving well over a month’s worth of rain from Tuesday night into Wednesday, these drought advisories still remain in effect.
“[While] it’s difficult to say how closely related to climate change this [particular drought] is, it’s certainly something we would expect from the effects of climate change,” assistant professor of earth and planetary sciences Juan Lora said. “One of the things we expect from climate change is an intensification of the water cycle, so that means both dry and wet extremes become more extreme.”
There may be more extremes — more days of extreme rain and more days of no rain — as well as less days of moderate precipitation. Additionally, the frequency of extreme precipitation in Connecticut may double for every degree of local warming of the climate.
“So if you think about projections for change in temperature over Connecticut through the end of the century, if we continue to emit at our present rate, it’s going to be more than one degree Celsius warming,” said Robert Nazarian, assistant professor of physics at Fairfield University. “We’re going to see the strongest storms more often, and they’re going to be stronger.”
During droughts, torrential rain is not beneficial in the long term as it does not infiltrate deeper levels of the soil, said Diego Cerrai, program manager and associate director for storm preparedness and emergency response at the Eversource Energy Center and assistant professor at University of Connecticut. Normally, roots can access water stored in deeper levels of the soil, but are otherwise unable to during a drought.
According to Cerrai, last week, although flooding still occurred in the state, the steadiness and timeframe of the downpour should have enabled some of the rain to be absorbed by the soil.
According to Alexey Fedorov, professor of ocean and atmospheric sciences, the ongoing drought in Connecticut forms part of a larger trend of aridity in the Northeast. In an Aug. 18 press release, Gov. Lamont attributed the “exceptionally dry summer” to an effect of climate change.
“That [several] inches of water [of rain] over a very short period of time is not enough to get us out of a drought, but we’re going into a rainy season so hopefully we’ll get more,” Fedorov said.
Waters in the North Atlantic have been 4 to 5 degrees Celsius higher than normal this time of year, Fedorov said, and is likely caused by a combination of global warming enhancing and maintaining warmer temperatures brought upon by a seasonal weather pattern known as “La Niña.”
Warmer climates allow for more water to be evaporated into the atmosphere, thus leaving less for rivers and groundwater, according to James O’Donnell, executive director of the Connecticut Institute for Resilience and Climate Adaptation (CIRCA). This can also dry out the ground and may factor into stronger droughts.
“If you had a puddle of water on the ground and you put warm air over it, it would evaporate into the atmosphere faster,” O’Donnell said. “So that’s why climate change models can predict more precipitation in Connecticut, but also more droughts.”
Warm temperatures can also result in stronger downpours, Lora said, as higher volumes of water vapor can condense out of the atmosphere as rain. However, this means that more rain will be distributed over shorter periods of time, with most of that water not being absorbed by the environment and being flushed out through flooding and runoff.
According to O’Donnell, CIRCA seeks to help the state adapt infrastructure to the effects of climate change. Culverts, tunnels that carry streams under roadways, were designed for storms in the latter half of the 20th century. Future storm events may overwhelm culverts, which may flood streets and houses.
“Rainfall is only one metric that the Interagency Drought Working [Group] looks at when determining drought status for the state,” Chris Collibee, director of communications for the Connecticut Office of Policy and Management, said. “Other factors include groundwater levels, stream flow, drinking water reservoir levels … and fire danger. While recent rainfalls could help, we need to allow for additional data to be reviewed and collected in the coming weeks before making further recommendations to Gov. Lamont.”
Yale School of Public Health Assistant Professor of Epidemiology Kai Chen said that drought “is of great concern” because it can worsen water quality and increase water-borne diseases, while also leading to poor air quality by intensifying heat, wildfires and dust storms.
Since 2000, the longest duration of drought in Connecticut lasted 46 weeks from summer of 2016 to spring of 2017.