I. The Mediterranean: end of a temperate climate

«Ever more glow furnace days on the Mediterranean

Rome 43°C, Athens 45°C – so could soon summer everyday life look like in the Mediterranean regions: according to a new study, a climatic projection, the number of lethal hot days will strongly increase there – if the greenhouse gas output should rise further. A new study by several scientists confirms the fear that it might shortly become unpleasant in southern Europe: towards end of this century, extreme heat days could occur two to five times as frequently per season as on average in the past decades, the researchers write in the US specialized magazine "Geophysical Research Letters":

"Heat stress intensification in the Mediterranean climate change hotspot (Abstract)

(Noah S. Diffenbaugh, Jeremy S. Pal, Filippo Giorgi, and Xuejie Gao
West Lafayette, Indiana, USA and Trieste, Italy)

We find that elevated greenhouse gas concentrations dramatically increase heat stress risk in the Mediterranean region, with the occurrence of hot extremes increasing by 200 to 500% throughout the region.
This heat stress intensification is due to preferential warming of the hot tail of the daily temperature distribution, with 95.th percentile maximum and minimum temperature magnitude increasing more than 75.th percentile magnitude.
This preferential warming of the hot tail is dictated in large part by a surface moisture feedback, with areas of greatest warm-season drying showing the greatest increases in hot temperature extremes.
Fine-scale topographic and humidity effects help to further dictate the spatial variability of the heat stress response, with increases in dangerous Heat Index (cf. graphic) magnified in coastal areas.
Further, emissions deceleration substantially mitigates heat stress intensification throughout the Mediterranean region, implying that emissions reductions could reduce the risk of increased heat stress in the coming decades."
(Published June 15.th 2007)

"Rare events like the heat wave in 2003 will become the standard", says Noah Diffenbaugh, earth and atmosphere researcher at the Purdue University in West Lafayette (Indiana) and main author of the study. "The extreme events of the future will be without example in their consequences." What today are the hottest summer days, by the end of the 21.st century will become the coolest ones, according to simulations.

Summer days with "dangerous heat stress"

For their view into the future the researchers used the supercomputer of the national Chinese climatic centre in Beijing and fed it with two different, internationally common global scenarios: a pessimistic and a rather optimistic. In one case the output of carbon dioxide and other greenhouse gases rises exponentially, their content in the atmosphere doubles compared to today (A2 scenario); in the other one the world-wide emissions increase less strongly due to larger efforts of climatic protection, but even so by approximately 50% (B2 scenario).

These data were put into a regional climatic computer model. In the end it supplied a picture of the temperature extremes that can be expected on the Mediterranean up to the year 2099, and with a rather high spatial resolution of 20 × 20 km. Finally, Diffenbaugh and his colleagues determined the number of summer days with "dangerous heat stress" for groups of risk like older people and infants, derived from formulas used by weather forecast services. On the Mediterranean those are generally days with temperatures beyond 40.5ºC.

The results should bring sweat pearls to some people's foreheads already: The daily maximum temperature on the hottest days rises accordingly for instance in Paris from 27º to 35ºC, if greenhouse gas emissions will follow the A2 path without brakes. Also summer nights on the Seine would then be by the end of the century around full 4ºC warmer than today. In Rome and Tel Aviv heat periods could become the standard, when the thermometer would show only just 43ºC and more during the day. In Athens it might be even 45ºC and in Algiers 46ºC – with nocturnal maximum values of 28ºC and 29ºC. In the more optimistic B2 scenario temperatures would lie around 1.2ºC to 2ºC lower.»




… What are we all still waiting for?
For us to open our outside doors and dive into a sand dune?
For us to drink water from the Atlantic?
For us to die instantly from a heat stroke?
Tell me all about political summits and more… I just love being fooled!

RIC - Translation and editing