No Climate Change Effect On US Forest Growth
When the group first set their hiking boots in New Hampshire’s Hubbard Brook Experimental Forest (HBEF), they thought they would find a clear effect of climate change on the dramatic 90% nitrogen level drop in temperate forest watersheds over the last 46 years. As a powerful driver of ecological processes, warming was a prime suspect, particularly given the higher soil temperatures and longer growing seasons of recent years. Instead, they found that the fall in nitrogen levels stems from a cocktail of human influences, including heavy logging, air pollution, and agricultural fertilizer as well as climate change—and that these inputs are obscuring the true baselines against which we can meaningfully judge any “change.”
“We have to be very clear about what a baseline is, and we cannot just assume a simple effect due to climate change,” Hedin said. He stressed the importance of scientists providing the public with accurate representations of how social and ecological factors are tied together within an ecosystem. “The process of science is often divide and conquer, but when it comes to climate change it’s the interactions that really matter.” That’s a crucial message not just for scientists, but also for policymakers and the public: that a single focus on a single issue doesn’t really work in the real-life laboratory. The world outside the test tube is a complex one – largely because of our presence in it – and when we put together our natural experiments or concoct climate legislation it’s worth remembering the messy fingerprints we leave behind every day that are muddying every equation.
“Most startling is perhaps the lack of any evidence for direct effects of climate change on net vegetation growth and plant [nitrogen] demand,” the scientists wrote in their paper, published in a February issue of the Proceedings of the National Academy of Sciences.
So they wanted to find an effect, were honest enough to report they couldn't find one but witter on as though they did..
Comparisons among stations should be made with caution because data have not been corrected for possible instrument bias. -99.0 is the missing value when the weather station is not operating. Otherwise if a day is missed, the value for that day has been estimated from values at the other stations. Estimated values are not flagged. The Fahrenheit to Celcius conversion and rounding to whole degrees Centigrade leads to considerable underrepresentation of -5, 0, 5, 10, etc. values.