From lakes to ocean, N.H. climate is changing



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If you wanted to study climate change in New Hampshire, where would you go?Maybe Mount Washington, to see how long snow lingers in Tuckerman Ravine. Or Hampton Beach, to see if the ocean is rising.Or how about First Connecticut Lake, the largest of the three ponds that form a necklace along the state's northernmost tip, way above Plymouth, Berlin and even Colebrook.That beautiful but unheralded water body wouldn't have occurred to me, but takes center stage in a new report from the University of New Hampshire's Carsey Institute that does a terrific job distilling how the state's climate has changed in recent decades, how we know it has changed, and why the matter can't be waved off by vague comments that climate is always variable and it's OK because there was lots of snow in Washington, D.C., this winter."We gave examples with an idea of looking at areas where there is public confusion," said Lawrence Hamilton, a professor of sociology at UNH who is co-author of the report with two names familiar to New Hampshire climate-watchers: UNH Professor Cameron Wake, who has been gathering data about climate for decades, and former state climatologist Barry Keim."You meet people who will tell you that it seems warmer because weather stations are all in cities ... due to the urban heat-island effect," Hamilton said. "This is the most un-urban station I can find in New Hampshire."Alas, for those of us who love traditional New Hampshire weather, the First Connecticut weather station shows that annual temperatures at the lake rose an average of one-third of a degree per decade from 1895 through 1969, and slightly more than half a degree per decade since 1970, which is faster than the worldwide rise in average temperatures.If you had any doubts - and you shouldn't have if you're paying attention to things like ever-earlier Lake Winnipesaukee "ice out" dates and the way maple syrup season has crept forward to the edge of January - they're put to rest by the report, "Is New Hampshire's Climate Warming?"Despite that question mark, it's clear we are warming, and are warming faster than many of us realize.The report, one of a number of so-called "policy briefs" from the Carsey Institute, presents this information in a relatively brisk, six-page format aimed at "the interested, engaged general public" rather than researchers."We tried to avoid using jargon or strange-looking symbols," Hamilton said. "We put all the references into the endnotes, where you can ignore them."A subtle message in the report, Hamilton adds, is that climatologists aren't idiots - that the obvious objections you and I think of upon encountering a climate-change study have occurred to them, too.We can't, for example, ignore bad news about the rise in ocean levels by saying "ice age glaciers changed continental levels" and then wandering away."They've thought of things like that, they really have," said Hamilton. "Tide gauges, satellites, they're all telling the same story."That part of the story startled me, since I'm not a beach person and don't think much about oceans: The tidal level at Portland, Maine, has already risen 5 inches in the past half-century. 'Temperature anomalies'Hamilton became interested in climate change when he realized he could no longer cross-country ski to work at UNH because the Oyster River wasn't freezing up the way it did when he first moved here decades ago.From my way of thinking, the report's most valuable section is a half-page discussion of "temperature anomalies" and the role they play in climate analysis. It's a bit on the geeky side, but not unreadably so.Anomalies are simply the difference between one year's temperature and the average over a long period of time, or baseline temperature. They help reflect how temperatures are changing, regardless of whether they're near the coast or in the White Mountains."A lot of people think that if you have more (weather) stations in a warm place that will bias the trend toward global warming. That's simply wrong, because climatologists use temperature anomalies, not temperatures themselves, for their trends," Hamilton said.To underline this point, the report includes a comparison of temperature anomalies at Durham and atop Mount Washington. They proceed almost in lockstep from 1950 to today.The report doesn't spend much time on the contentious issue of whether this change is man-made - there's only so much you can tackle in six pages - but it's clear that the authors know human activity is a major factor: "New Hampshire temperature trends are consistent with results from climate models, which have shown that natural forces alone (such as the effects of volcanoes, solar variation, or climate oscillations like El Nino) cannot explain recent global changes in climate. ... A large body of scientific evidence shows that climate change has been influenced by human activities, including deforestation, land use or urbanization, and the 26 billion tons of carbon dioxide we are adding to the atmosphere each year."How to change behavior is another matter. The report's only contribution to that discussion is a negative one: It points to a recent survey that shows that people really, really hate the idea of raising the gasoline tax to provide a "market incentive" for our driving less.The report, "Is New Hampshire's Climate Changing?" can be read online at carseyinstitute.unh.edu.

 

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