Background
The authors state that modeling studies in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) suggest that future heat waves over Europe will be more severe, longer lasting and more frequent than those of the recent past, due largely to an intensification of quasi-stationary anticyclone anomalies accompanying future warming, citing in support of this statement the publications of Meehl and Tebaldi (2004) and Della-Marta et al. (2007).

What was done
Jeong et al., as they describe it, "investigate the impact of vegetation-climate feedback on the changes in temperature and the frequency and duration of heat waves in Europe under the condition of doubled atmospheric CO2 concentration in a series of global climate model experiments," where land surface processes are calculated by the Community Land Model (version 3) described by Oleson et al. (2004), which includes a modified version of the Lund-Potsdam-Jena scheme for computing vegetation establishment and phenology for specified climate variables.

What was learned
The six scientists say their calculations indicate that "the projected warming of 4°C over most of Europe with static vegetation has been reduced by 1°C as the dynamic vegetation feedback effects are included," adding that "examination of the simulated surface energy fluxes suggests that additional greening in the presence of vegetation feedback effects enhances evapotranspiration and precipitation, thereby limiting the warming, particularly in the daily maximum temperature." In addition, they state that "the greening also tends to reduce the frequency and duration of heat waves."

What it means
Although Jeong et al.'s findings by no means constitute the final word on the subject of the ultimate climatic consequences of a doubling of the air's CO2 content, they indicate just how easily the incorporation of a new suite of knowledge, in even the best climate models of the day, can dramatically alter what the IPCC and other climate-alarmist organizations and individuals purport to be reality. The world of nature is so extremely complex that it is the height of arrogance -- or depth of ignorance -- to believe that the world's climate modelers are anywhere near being able to mathematically represent all that needs to be mathematically represented in a model of sufficient complexity to faithfully reproduce what actually happens in the real world of nature, and over the many orders of magnitude that they are reluctant to acknowledge are absolutely essential to obtain the answers we all seek, which are, of course, the correct answers, which are obviously still a long ways off.

References
Della-Marta, P.M., Luterbacher, J., von Weissenfluh, H., Xoplaki, E., Brunet, M. and Wanner, H. 2007. Summer heat waves over western Europe 1880-2003, their relationship to large-scale forcings and predictability. Climate Dynamics 29: 251-275.

Meehl, G.A. and Tebaldi, C. 2004. More intense, more frequent, and longer lasting heat waves in the 21st century. Science 305: 994-997.

Oleson, K.W. et al. 2004. Technical Description of the Community Land Model (CLM). Technical Note NCAR/TN-461+STR, 174p.