Scientists speak to us about the warming pause, while activists deny their work.

Larry Kummer, Editor

11 years ago

Summary: I feel sad watching the Left liquidate its credibility by denying climate scientists’ work on the pause in warming of the atmosphere since roughly 2000. Although their voices dominate the news media, we must not rely on activists to tell us about the world. We can see the cutting edge of science for ourselves. Seeing the world clearly is a requirement for our success in the 21st century.

“What we’ve got here is failure to communicate.”

— From “Cool Hand Luke” (1967), said first by a prison warden and later by the prisoner Luke (Paul Newman).

Activists have published scores of articles denying the existence of the “pause” (or “hiatus”). That’s politically convenient — the pause contradicts their narrative of imminent catastrophic warming and arouses doubt about the computer models that create the forecasts. But it displays an astonishing disregard for the work of climate scientists, and science — just like those on the Right they mock.

Here we again we see the similar behavior of Americans on both ends of the political spectrum, obvious to all who look — except the participants themselves. It’s one of the things that gives our politics that Oz-like air of absurdity.

While activists earnestly deny the pause, scores of peer-reviewed papers discuss the pause, analyze its causes and forecast its duration. We see the cutting edge of this work at the 2015 annual meeting of the American Meteorological Society, in their two sessions about the “Global Warming Hiatus”: Part I and Part II.

Global average temperature has increased by 0.80°C over the 20th century but this warming trend has slowed or even stalled for the past 15 years. This warming hiatus has caused much confusion and debate but at the same time offers a scientific opportunity to study climate change dynamics in action. Mechanisms proposed include a slowdown in net radiative forcing, and interference by natural variability.

This session showcases rapidly advancing research on the physical mechanisms and various impacts of this hiatus event. Topics of particular interest include interdecadal variability and the interaction with forced climate change, radiative forcing and related processes, and ocean heat storage as pertinent to the hiatus.

Especially note this one, an A-team climate scientist revising the consensus: Projections of a rebound in warming out of the current hiatus, Matthew H. England, University of New South Wales, Sydney, NSW, Australia. Abstract, red emphasis added:

Despite ongoing increases in atmospheric greenhouse gases, the Earth’s global average surface air temperature has remained more or less steady since 2001. Mechanisms proposed to account for this slowdown in surface warming include increased ocean heat uptake, the prolonged solar minimum and changes in atmospheric water vapour and aerosols.

While cool sea surface temperature in the east Pacific has been identified as a key component of the global hiatus, it is unclear how the ocean has remained relatively cool there in spite of ongoing increases in radiative forcing. Here we show that a pronounced strengthening in Pacific trade winds over the past two decades – unprecedented in observations/reanalysis data and not captured by climate models – is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface warming via increased subsurface ocean heat uptake.

The extra uptake has come about via increased subduction in the Pacific shallow overturning cells, enhancing heat convergence in the equatorial thermocline. At the same time, the accelerated trade winds have increased equatorial upwelling in the central and eastern Pacific, lowering SST there, which drives further cooling in other regions. The net effect of these anomalous winds is a cooling in the 2012 global average surface air temperature of 0.1 – 0.2°C, which can account for much of the hiatus in surface warming observed since 2001.

Simulations using coupled climate models suggest the hiatus could persist for much of the present decade if the trade wind trends continue, however a rebound of rapid warming is expected to resume once the anomalous wind trends abate.

England shows this graph of global surface temperatures compared to model projections. Note that the 5-year mean has fallen below the range of the projections in the two most recent IPCC reports. After his adjustments, it’s in the lower end of the range.
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