The 1,157 wildfires that occurred in Maine during 2020 included a fire at Baxter State Park that was controlled after 45 acres had burned. Since wind-driven fires tend to be most damaging,wind speeds are a major concern for firefighters. Courtesy of the Maine Forest Service/Forest Protection Division.
…Northwest winds between 10 to 20 mph with frequent gusts above 25 mph will continue to dry fuels and increase fire spread potential.
~ National Weather Service statement issued for 11 Maine counties on May 27, 2021
Through an “abnormally dry” spring, Maine had numerous fire weather watches due to some combination of wind speed, relative humidity and vegetative “fuel.” The threat of fire increases “anytime you see sustained winds over 10 mph,” said Joe Mints, a regional forest ranger who chairs the state’s fire weather team.
Historically, the state’s largest and most destructive fires have been wind-driven, Mints noted: “Here in Maine, wind is our nemesis.”
A 2019 study found that in the preceding nine years the global average wind speed increased nearly 6 percent, from 7.0 to 7.4 mph. Anecdotal observations in Maine support the premise that we’re experiencing more breezy and gusty conditions.
No one can say for sure how much everyday wind speeds and patterns have changed because the data have not been carefully analyzed. A 2009 study of wind speeds found “substantial discrepancies” in data sets, and a 2019 review noted “great uncertainties in long-term wind trends.”
Climate models and projections often ignore wind, despite its potential to signal and accelerate climate disruptions. Wind is a wild card we ignore at our peril, given its capacity to increase wildfire risks, aggravate drought and endanger boaters.
At state, national and international levels, climate research and forecasting should track and analyze wind data. Many scientists I contacted confirmed this need, acknowledging – as Maine State Climatologist Sean Birkel observed – “it’s a problem that requires a close look.”
Abundant data but little analysis
Storm-force winds, a known hazard, are being studied in relation to climate change. But breezes below the “high wind warning” threshold of 40 mph have largely fallen off the research radar.
Climatologists do extensive modeling of temperature and precipitation, given “they have such dominant influence on environmental systems,” said Birkel, who is also a research assistant professor at the University of Maine’s Climate Change Institute. The National Oceanic and Atmospheric Administration recently updated its U.S. Climate Normals for temperature and precipitation to better “reflect the impacts of the changing climate on our day-to-day weather experiences.” Wind affects daily “weather experiences” as well, but no one appears to be tracking whether its “climate normals” need updating.
What might it mean for those in fishing, aquaculture, agriculture and tourism if the region experiences more of what the Beaufort wind scale characterizes as strong (25-31 mph) or fresh (19-24 mph) breezes? Sustained surface winds can be a boon for wind power generation but a liability in many other spheres.
Fishermen are noticing rapid changes in wind, and are often “caught in something very different than the datasets (in short-term forecasts) would suggest,” said Ben Martens, executive director of the Maine Coast Fishermen’s Association. “It’s harder to find a calm day” for field research, noted marine scientist Susie Arnold of the nonprofit Island Institute.
Penobscot Bay buoy data tracking wind speeds show “pretty obvious trends of higher monthly means” starting around 2013 compared to the 20-year mean, Arnold said. Wind gust data from that buoy “suggests that the spring months are indeed gustier in recent years than earlier in the time series,” Jake Kritzer, executive director of the regional ocean-observing association NERACOOS, wrote in an email.
Of course, neither field observations nor quick reviews of a single dataset constitute definitive evidence of climate-driven changes in wind speeds or behavior. Efforts to discern climate impacts, Kritzer said, are complicated by the fact that winds can shift as part of natural cycles that span decades.
Maine has extensive data on near-surface wind measurements collected at least hourly from sites across the state. Some of those data go back several decades, and datasets from 1950 onward are available through climate reanalysis, according to Birkel.
Complex dynamics
Even with abundant data, the influence of the changing climate on wind patterns may be hard to discern. Winds respond to atmospheric forces at many geographic and time scales, driven in part by air temperature differentials over land and sea, as well as larger frontal systems.
The Gulf of Maine has experienced record-breaking warmth over the past 15 years — a trend expected to continue at least through 2050. Regional air temperatures are also on the rise, with further increases of 2 to 4 degrees likely in the coming three decades.
Warmer water temperatures would be expected to “decrease sea breezes during spring and summer, as the contrast in temperature between land and ocean during daytime would be reduced,” Jennifer Francis, senior scientist with the Woodwell Climate Research Center in Massachusetts, wrote in an email. So if winds are increasing, other factors are likely at play.
Warming oceanic and atmospheric temperatures could affect daily variations in wind, which historically have led to relative calm periods around sunrise and sunset. In the Northeast, night temperatures have seen a more pronounced increase than daytime temperatures, possibly disrupting that dynamic.
Rapid melting of the Arctic Ocean could also factor in, potentially by altering the jet stream – a fast-moving atmospheric ribbon that powers many weather systems. Some scientists, such as Francis, suggest that the jet stream is growing more wavy, leading to blocking patterns that hold weather systems in place longer – with extended high-pressure systems maintaining clear, dry weather, interspersed with more intense or persistent wet periods.
If blocking patterns produce longer stretches without precipitation, windier weather (particularly when humidity is low) could accelerate transpiration in plants and evaporation from soil – potentially causing both plant stress and warmer temperatures (since more solar energy gets converted to heat when soils dry).
Science starts in observation
Wind is undeniably one of the most complicated elements in the mass of interlinked climate variables scientists must consider. It’s not surprising it has been set aside in many assessments, often deemed too local and intermittent to be a significant factor in longer-term trends.
But as more people experience buffeting by stronger winds, there’s growing interest in further scientific analysis of the wind data already compiled. Many researchers I contacted were eager to have someone look into this topic, since they had observed changes themselves but seen few scientific references. “I’ve been wondering if others have been experiencing the same thing,” one noted.
“Anecdotal information can be extremely important,” Birkel said, in prompting in-depth research. He affirmed that as the state’s climatologist, he would very much like “to see a project that examined this (question of wind trends).”
That is welcome news to Mints as he heads into a fire season “shaping up to be as bad or worse” than last season, when Maine had 1,157 wildfires, more than it has seen in 35 years. “We’re very, very concerned about climate impacts,” he said.
For some time, Mints has wanted detailed data analysis to better understand how wind conditions are changing in a warming world: “Something is different. It would be interesting to know what it is.”
© Marina Schauffler, 2021. All Rights Reserved. Column reprints available upon request
