New beginning of 'natural spring' announced by UNH scientist, group

Climate change cited

You could say the first day of spring came a week earlier this year: Monday, March 13th.

That's what's indicated by a new report, Evidence of an Early Spring, that draws on research by University of New Hampshire (UNH) climate scientist Cameron Wake. The report, released by the group Clean Air-Cool Planet (CA-CP), finds that over the last 150 years, scientific measurements show that events signifying the beginning of spring - including when plants bud, sap flows, ice breaks up, and the last frost and final 32-degree day occur - have all shifted. These events now happen a week earlier on average.

These trends are consistent with what computer models have predicted would happen with global warming.

"Climate researchers had known for some time that various trends were emerging in the long-term data sets for things like temperature, precipitation, day with snow on the ground, length of growing season, as well as bloom dates," said Wake, a research associate professor at the Climate Change Research Center in UNH's Institute for the Study of Earth, Oceans and Space. "Working with researchers from Cornell, US Geological Survey, and others, we've been able to bring this data together in one place for the first time, and analyze it for consistent trends."

Wake released Indicators of the Climate Change in the Northeast, a comprehensive look at 11 different physical and biological markers of the changing climate in the region.

"Biological spring has changed due to global warming and that's threatening to put ecosystems badly out of synch," said Adam Markham, executive director at CA-CP. "What matters to us is when we can shed the winter clothes, when we see the crocuses and daffodils and smell the lilacs, when spring actually arrives. That time is coming earlier and earlier much earlier than it did a century ago."

All of the major indicators of climate in the Northeast, from temperature and length of growing season, to lake ice-out and lilac bloom and apple blossom time, are showing that spring is at least a week earlier now than it was in1850.

The following indicators show average changes as indicated: Growing season: 8 days longer
Spring bloom: 4 8 days earlier
High-volume spring river flow: 7 14 days earlier
Lake ice-out: 9 16 days earlier
Days with snow on ground: 16 fewer days

One of the contributors to the indicators report, Dr. David Wolfe from the Horticulture Department at Cornell University, collected biological data on bloom dates for apples, grapes, and lilacs.

"Collectively, analyses for the northeastern U.S. indicate that, on average, lilacs are blooming about four days earlier, and apple and grapes are blooming about eight days earlier than they were half a century ago," Wolfe noted in his report, while cautioning that the earlier start to the growing season indicated by the data may not be a good thing.

"Farmers may tend to look at this and say that it's good, because they will get an earlier yield. But earlier bloom dates make these species more susceptible to damage from frost," he said, "and analysis of data on apple yields indicates that warmer temperatures from January 1 to bud break correlated with lower yields, not higher."

Wolfe also reported that the magnitude of the impact of earlier bloom dates on woody perennials in the Northeast "is similar to that reported for bloom of other plant species, and for bird and insect spring migration arrivals, by researchers in other parts of the U.S. and Europe." He said findings are also "qualitatively in agreement with reports of earlier spring 'green wave' advancement in the northern hemisphere based on satellite imagery of vegetative cover," both observations supporting the findings.

Markham noted that we don't know "where this kind of interference with the climate system will lead us. But we have already begun to see disruptions in traditional economies like maple sugaring and ski tourism, and it's likely these are harbingers of major disruptions to come."

The remarkable thing about the findings, according to Wake, is the consistency. "Despite the fact that this evidence comes from a wide range of environments the atmosphere, the biosphere, the oceans, and snow and ice the remarkably consistent signal of a warming trend across the region cannot and should not be ignored. We now have our canary in the coal mine."

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Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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