It never rains but it pause

There has been a veritable deluge of new papers this month related to recent trends in surface temperature. There are analyses of the CMIP5 ensemble, new model runs, analyses of complementary observational data, attempts at reconciliation all the way to commentaries on how the topic has been covered in the media and on twitter. We will attempt to bring the highlights together here. As background, it is worth reading our previous discussions, along with pieces by Simon Donner and Tamino to help put in context what is being discussed here.

The papers and commentaries address multiple aspects of recent trends: the climate drivers over recent decades, the internal variability of the system, new analyses and model-observation comparisons – much as we suggested would be the case in any discussions of model-observations mismatches last year. We will take each in turn:

Climate drivers

Two papers (which I was an author on) are focussed mainly on examining the impact of updated forcings on the temperature: Santer et al (2014) ($) looks in detail at the impact of small volcanoes post-2000 on the vertical structure of temperature changes, while the commentary by Schmidt et al (2014) (OA, with registration) also updates the solar, aerosol and GHG forcing to estimate what the CMIP5 ensemble would have looked like if it had used this input data instead of the earlier estimates and initial forecasts (panel b in the figure).

Internal Variability

The contribution of internal variability to decadal trends is the focus of commentaries by Lisa Goddard (OA) and Martin Visbeck (OA). They focus on recent trends in ocean heat uptake, the Pacific Decadal Oscillation and the potential for initialised decadal predictions (such as Keenlyside et al) to capture these variations. These relate to both the earlier Kosaka and Xie and England et al papers, but are mostly reviews.

[Update: See also the Clement and DeNezio perspective in Science.]

New analyses

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  1. B.D. Santer, C. Bonfils, J.F. Painter, M.D. Zelinka, C. Mears, S. Solomon, G.A. Schmidt, J.C. Fyfe, J.N.S. Cole, L. Nazarenko, K.E. Taylor, and F.J. Wentz, "Volcanic contribution to decadal changes in tropospheric temperature", Nature Geoscience, vol. 7, pp. 185-189, 2014.
  2. G.A. Schmidt, D.T. Shindell, and K. Tsigaridis, "Reconciling warming trends", Nature Geoscience, vol. 7, pp. 158-160, 2014.
  3. L. Goddard, "Heat hide and seek", Nature Climate Change, vol. 4, pp. 158-161, 2014.
  4. M. Visbeck, "Bumpy path to a warmer world", Nature Geoscience, vol. 7, pp. 160-161, 2014.
  5. A. Clement, and P. DiNezio, "The Tropical Pacific Ocean--Back in the Driver's Seat?", Science, vol. 343, pp. 976-978, 2014.