Steve Singleton on Jan. 20 wrote that (1) global temperature has “level(ed) off and cool(ed) ... the past 15-17 years, and (2) 17 years is the minimum length of time necessary to “separate human-caused warming from the ‘noise’ of purely natural climate fluctuations.’”
Mr. Singleton correctly alerts us to a leveling off of observed global warming but the hiatus was from 2008 to 2012, five years — not 17 years — and the usual length of a climate period average is 30 years.
Year 2013 did break the hiatus but there is little confidence about why the hiatus at all, except for “purely natural climate fluctuations.”
We do, however, have abundant evidence that the Earth is warming and has warmed for about a century.
We see the effects in shrinking ice packs and snow sheets, rising sea levels, and rising ocean temperatures, and probably in the frequency and magnitude of extreme weather events.
What has moved along with global warming is the concentration of carbon dioxide along with methane and nitrous oxide in the atmosphere to levels not experienced in memory.
We should put our energy into understanding how these greenhouse gases work with oceans, soils, clouds and tundra and deciding how we want to respond to the very real costs of the effects of warming.
I understand people may be skeptical of both the observation of warming and its linking to greenhouse gas emissions. I ask only that citizens figure out how these things may work and not reduce the argument to “for or against.”
Like it or not, normal science does work a bit like voting and the climate scientific community has voted overwhelmingly that global warming is a fact and it is related to human activity. This does not mean dissenters cannot be found.
So far, however, these dissenters have not been persuasive to their peers. Science prizes dissent but dissenters must do a superior job of explaining what we observe before we turn away from normal science.