New Paper On Exceptional European Heat – Another Example of Cherrypicking

There is a new paper that has just appeared that discusses the recent warm period in Europe in 2006 and 2007. It provides an excellent summary of an extreme weather event (and thanks to Juerg Luterbacher for sending to me!)

However, part of this paper is yet another example of following the IPCC policy, discussed yesterday, of ignoring inconvenient other peer reviewed research.

The paper is

Luterbacher, J., M. A. Liniger, A. Menzel, N. Estrella, P. M. Della-Marta, C. Pfister, T. Rutishauser, and E. Xoplaki (2007), Exceptional European warmth of autumn 2006 and winter 2007: Historical context, the underlying dynamics, and its phenological impacts, Geophys. Res. Lett., 34, L12704, doi:10.1029/2007GL029951. .

The abstract reads,

“Updated European averaged autumn and winter surface air temperature (SAT) timeseries indicate that the autumn 2006 and winter 2007 were extremely likely (>95%) the warmest for more than 500 years. In both seasons, the European SAT anomaly is widespread with anomalies up to three standard deviations from normal. The anomalous warmth is associated with strong anticyclonic conditions and warm air advection from south west. Phenological impacts related to this warmth included some plant species having a partial second flowering or extended flowering till the beginning of winter. Species that typically flower in early spring were found to have a distinct earlier flowering after winter 2007.”

An excerpt from the conclusions reads,

“As SAT [ seasonal surface air temperature] anomalies are expected to increase up to 5 (3) SD from 1961–1990 in autumn (winter) at the end of the 21st century [Scherrer et al., 2007], the AU06 and WI07 warmth discussed in this study may be seen as typical representation of upcoming climate change at continental scale.”

This paper, however, fails to recognize that regional predictive skill has not been shown on any multidecadal (or even yearly time scale) (e.g. see), nor whether in a global context, the warm period is unusual; see

Chase, T.N., K. Wolter, R.A. Pielke Sr., and Ichtiaque Rasool, 2006: Was the 2003 European summer heat wave unusual in a global context? Geophys. Res. Lett., 33, L23709, doi:10.1029/2006GL027470,

where we concluded

“We place the European summer heat wave of 2003 in the context of other extreme summer tropospheric temperature events from 22 N to 80 N since 1979, as well as globally using annual averages. The analysis is performed in terms of standard deviations (SD) exceeded and correlations between regional extremes and temperatures at larger spatial scales. As has been pointed out previously the heat wave was statistically unusual and was a deep tropospheric phenomenon. In this analysis we also find the following. (1) Extreme warm anomalies equally, or more, unusual than the 2003 heat wave occur regularly. (2) Extreme cold anomalies also occur regularly and occasionally exceed the magnitude of the 2003 warm anomaly in terms of the value of SD. (3) There is a correlation between global and hemispheric average temperature and the presence of warm or cold regional anomalies of the same sign (i.e., warmer than average years have more regional heat waves and colder than average years have more cold waves). (4) Natural variability in the form of El Nino and volcanic eruptions appear to be of much greater importance in causing extreme regional temperature anomalies than a simple upward trend in time. Extreme temperature anomalies in the wake of the1997–98 El Nino were larger than the anomalies seen in summer 2003 both in area affected and SD extremes exceeded. (5) Regression analyses do not provide strong support for the idea that regional heat waves are increasing with time.”

The Luterbacher et al paper also ignored the paper,

Fischer E. M., S. I. Seneviratne, D. Lüthi, C. Schär (2007), Contribution of land-atmosphere coupling to recent European summer heat waves, Geophys. Res. Lett., 34, L06707, doi:10.1029/2006GL029068. [see also].

That the Luterbacher et al paper chose to ignore these peer reviewed studies is another clear example of ignoring published work that raises questions about their conclusions. These papers should have been discussed even if the authors have reasons to refute them. They should have placed this recent very warm period in Europe in a global context if they are going to assert that this is the type of weather that should become routine in the coming decades.

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Filed under Climate Change Metrics, Climate Science Reporting

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