Monday, January 14, 2013

New paper finds European temperatures are not unusual or unprecedented

A new paper published in Climate of the Past reconstructs temperatures in Switzerland from 1444 to 2011 on the basis of grape harvest dates and finds temperatures were about the same as today at the beginning of the record around 1450 AD, and that temperatures of today have been matched or exceeded several times in the past. In addition, the paper finds European temperatures during the summer of 1540 were 4.7 °C to 6.8 °C higher than those of 2003, causing more extreme heat & drought than the "record breaking" heat & drought of 2003. 
Added red horizontal line shows reconstructed temperatures (11 yr moving average) were about the same as today at the beginning of the record ~ 1450 and that temperatures of today have been matched or exceeded several times in the past.
Clim. Past, 9, 41-56, 2013

An underestimated record breaking event – why summer 1540 was likely warmer than 2003

O. Wetter1,2 and C. Pfister1
1Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
2Institute of History, Section of Economic, Social and Environmental History (WSU), University of Bern, Bern, Switzerland

 Abstract. The heat of summer 2003 in Western and Central Europe was claimed to be unprecedented since the Middle Ages on the basis of grape harvest data (GHD) and late wood maximum density (MXD) data from trees in the Alps. This paper shows that the authors of these studies overlooked the fact that the heat and drought in Switzerland in 1540 likely exceeded the amplitude of the previous hottest summer of 2003, because the persistent temperature and precipitation anomaly in that year, described in an abundant and coherent body of documentary evidence, severely affected the reliability of GHD and tree-rings as proxy-indicators for temperature estimates. Spring–summer (AMJJ) temperature anomalies of 4.7 °C to 6.8 °C being significantly higher than in 2003 were assessed for 1540 from a new long Swiss GHD series (1444 to 2011). During the climax of the heat wave in early August the grapes desiccated on the vine, which caused many vine-growers to interrupt or postpone the harvest despite full grape maturity until after the next spell of rain. Likewise, the leaves of many trees withered and fell to the ground under extreme drought stress as would usually be expected in late autumn. It remains to be determined by further research whether and how far this result obtained from local analyses can be spatially extrapolated. Based on the temperature estimates for Switzerland it is assumed from a great number of coherent qualitative documentary evidence about the outstanding heat drought in 1540 that AMJJ temperatures were likely more extreme in neighbouring regions of Western and Central Europe than in 2003. Considering the significance of soil moisture deficits for record breaking heat waves, these results still need to be validated with estimated seasonal precipitation. It is concluded that biological proxy data may not properly reveal record breaking heat and drought events. Such assessments thus need to be complemented with the critical study of contemporary evidence from documentary sources which provide coherent and detailed data about weather extremes and related impacts on human, ecological and social systems.

 Final Revised Paper (PDF, 919 KB)   Supplement (139 KB)   Discussion Paper (CPD)   

1 comment:

  1. The New 21st Century Paradigm Shift in Climate Change Science

    Carbon dioxide is no blanket. The "blanket" is produced by non-radiative diffusion processes primarily involving nitrogen and oxygen at the surface-atmosphere boundary. If the only consideration were the effect of water vapour and carbon dioxide you'd be sleeping under a handkerchief.

    Discover "The 21st Century New Paradigm Shift in Climate Change Science" (on the Principia Scientific International website) and discover what real physics has now proved, completely negating any significant relevance of the old 20th Century radiative greenhouse concept.

    No back radiation caused the Earth's surface to be 288K (or the Venus surface to be over 730K) all on its own, somehow multiplying the Sun's energy. What did cause it was thetemperature distribution brought about by diffusion of kinetic energy in a gravitational field, and this process continues to maintain surface temperatures as atmospheres absorb direct incident Solar radiation, the only possible radiation that can keep them at the observed temperatures. For more detail read “Planetary Surface Temperatures. A Discussion of Alternative Mechanisms”published by PSI in November 2012, as well as this week's article mentioned above and linked below.

    Doug Cotton