Should We Still Heed the IPCC?

Imagine you're aboard a commercial jetliner on a really foggy approach to your destination.   The aircraft has a ground speed of 220 miles an hour.  You're ten miles from the runway.   The pilot's altimeter is out of whack, telling the pilot that you're a thousand feet higher than you really are.   How many minutes will it take before your plane touches down safely on the runway?

Yeah, okay, you're probably going to be a smoking hole in the ground long before your ever reach the runway.   This brings me to the Intergovernmental Panel on Climate Change, the IPCC.

The IPCC has become the climate change altimeter of choice for many governments.   The Panel's reports are what they use to gaze into the future and to shape their climate mitigation and adaptation policies.   Yet, time and again, we find the IPCC projections and timelines seriously understated.   And critics are saying the optimistic errors are leading us into dangerous territory.


As the latest round of United Nations climate talks in Doha wrap up this week, climate experts warn that the IPCC's failure to adequately project the threats that rising global carbon emissions represent has serious consequences: The IPCC’s overly conservative reading of the science, they say, means governments and the public could be blindsided by the rapid onset of the flooding, extreme storms, drought, and other impacts associated with catastrophic global warming.

"We're underestimating the fact that climate change is rearing its head," said Kevin Trenberth, head of the climate analysis section at the National Center for Atmospheric Research (NCAR) and a lead author of key sections of the 2001 and 2007 IPCC reports. "And we're underestimating the role of humans, and this means we're underestimating what it means for the future and what we should be planning for."

A comparison of past IPCC predictions against 22 years of weather data and the latest climate science find that the IPCC has consistently underplayed the intensity of global warming in each of its four major reports released since 1990.

The tendency to underplay climate impacts needs to be recognized, conclude the authors of a recent paper exploring this bias. Failure to do so, they wrote in their study published last month in the journal Global Environmental Change, "could prevent the full recognition, articulation and acknowledgement of dramatic natural phenomena that may in fact be occurring."

The conservative bias stems from several sources, scientists say. Part can be attributed to science's aversion to drama and dramatic conclusions: So-called outlier events — results at far ends of the spectrum — are often pruned. Such controversial findings require years of painstaking, independent verification.