Climate experts warn that short-term snapshots of temperature data can be misleading: Focus instead on the bigger picture

Some wisdom from Insciences.org: In the hotly debated arena of global climate change, using short-term trends that show little temperature change or even slight cooling to refute global warming is misleading, write two climate experts in a paper recently published by the American Geophysical Union — especially as the long-term pattern clearly shows human activities are causing the earth’s climate to heat up.

In their paper “Is the climate warming or cooling?” David R. Easterling of the National Oceanographic and Atmospheric Administration’s National Climatic Data Center and Michael Wehner of the Computational Research Division at the Department of Energy’s (DOE) Lawrence Berkeley National Laboratory note that a number of publications, websites and blogs often cite decade-long climate trends, such as that from 1998-2008, in which the earth’s average temperature actually dropped slightly, as evidence that the global climate is actually cooling.

However, Easterling and Wehner write, the reality of the climate system is that, due to natural climate variability, it is entirely possible, even likely, to have a period as long as a decade or two of “cooling” superimposed on the longer-term warming trend. The problem with citing such short-term cooling trends is that it can mislead decision-makers into thinking that climate change does not warrant immediate action. The article was published April 25 in Geophysical Research Letters.

“We wrote this paper, which was carefully reviewed by other researchers and is scientifically defensible, to clearly show that even though our climate is getting warmer, we can’t expect it to do so in a monotonic way – or that each year will be warmer than the preceding year,” said Wehner. “Even with the climate changes caused by human activity, we will continue to see natural variability including periods of cooler temperatures despite the fact that globally averaged temperatures show long-term global warming.”

…“Climate scientists pay little attention to these short-term fluctuations as the short term ‘cooling trends’…are statistically insignificant and fitting trends to such short periods is not very meaningful in the context of long-term climate change,” the authors write. “On the other hand, segments of the general public do pay attention to these fluctuations and some critics cite the most recent period as evidence against anthropogenic-forced (human-induced) climate change.”…

William Blake's 1795 watercolor of Hecate