'Modern warming trend can't be found' in new climate study

Opinion There's interesting news on the climate beat this week, especially given the background of the just-released IPCC AR5 report - which blames humanity for warming the planet. A new, comprehensive study examining temperatures in the Eastern Mediterranean region over the last 900 years indicates that global warming and associated climate changes actually haven't happened there at all.

"At several places in the Mediterranean the winter and spring temperatures indicate long-term trends which are decreasing or at least not increasing,” says Dr Ingo Heinrich from the Potsdam Helmholtz-Zentrum of the Deutsches GeoForschungsZentrum (German Geosciences Research Centre).

According to a Helmholtz Centre announcement highlighting Dr Heinrich's latest research:

For the first time a long temperature reconstruction on the basis of stable carbon isotopes in tree rings has been achieved for the eastern Mediterranean. An exactly dated time series of almost 900 year length was established, exhibiting the medieval warm period, the little ice age between the 16th and 19th century as well as the transition into the modern warm phase ... [however] the modern warming trend cannot be found in the new chronology.

Heinrich and his colleagues write:

The twentieth century warming trend found elsewhere could not be identified in our proxy record, nor was it found in the corresponding meteorological data used for our study.

So, ordinary meteorological data for the region backs up the trees' assertion that, in effect, there hasn't been any global warming at all in the Eastern Mediterranean: nor, perhaps, in other lowland regions of Europe.

But how can this be reconciled with the major global temperature databases? These agree that there has been no modern warming since late in the 1990s, but they show that there was significant warming in the decades before then - and most climate scientists think that warming was caused at least in part by human carbon emissions, which have continued and indeed increased seriously since then. Thus the IPCC predicts that warming will surely start up again at some point.

On the difference from the worldwide picture, the Helmholtz Centre statement has this to say:

It seems that especially temperature reconstructions derived from extreme sites such as high mountain zones and high latitudes do not always correctly reflect the climate of the different geographical regions. The past temperature variations in the lowlands of central Europe and in the Mediterranean are not well understood yet.

"Our results stress the need for further research of the regional climate variations," comments Dr Heinrich. He and his colleagues set out their work in this article published by the journal Climate Dynamics. ®