Forests make heatwaves ‘initially warmer’

During heatwaves forests reduce their evaporation, causing the atmosphere to warm up even more, say researchers.

During extremely long periods of heat, however, this reduction enables the forests to continue their evaporation for longer, so the net effect is ultimately one of cooling in relation to the surroundings, explained a team of scientists led by Ryan Teuling from Wageningen University in the Netherlands.

Writing in the journal Nature Geoscience, Dr Teuling worked on the investigation in collaboration with climate researchers from a number of European countries.

The study was prompted by recent heatwaves in Europe, which had raised interest in questions about the influence of land use on temperatures and climate.

Up to now, scientists had assumed that a lack of precipitation during heatwaves automatically led to a reduction in evaporation.

That reduction was thought to be less for forests, because trees, with their deeper root systems, have more water available to them. Examination of the precise role of land use, however, has been largely neglected up to now.

The study found large differences in evaporation strategies during heat waves. Grasslands evaporate more at higher temperatures and stop only when no more water is available.

Forests, in contrast, respond to higher temperatures by evaporating less, which leaves more water at their disposal.

During brief heatwaves, therefore, the greatest warming is found above forests, but during prolonged heat waves the increased evaporation of grasslands ends up causing a shortage of water.

This can lead to exceptionally high temperatures, such as those measured in France in the summer of 2003.

This mechanism might also offer an explanation for the unusually high temperatures near Moscow this summer, the researchers suggest.

In these types of extreme situations, forests in fact have a cooling effect on the climate.

The research was done on the basis of observations made above forests and grasslands in Europe by an extensive network of flux towers. For areas without towers, satellite data were used.

Source: Wageningen University press release

Date: 06/09/2010

Weller in the woods…

“Modfather” Paul Weller has announced a series of gigs in spectacular woodland locations across the UK this summer as part of Forestry Commission Live Music 2009.

The commission, in a press release, goes on to say:

Described as both the ‘modfather of rock’ and ‘Britpop’s elder statesman’, Paul is ultimately acknowledged by the media, fellow musicians and the public as one of the greatest singer-songwriters of British popular music.

Since his early days in The Jam, then Style Council and subsequently as a hugely successful solo artist, Paul continues to make pioneering music.

Last year saw the release of the critically acclaimed number one album ‘22 Dreams’, his ninth solo album in a career spanning over three decades.

He will be performing at the following venues:

Friday 5 June – Thetford Forest, Near Brandon, Suffolk
Friday 12 June – Delamere Forest, Delamere, Cheshire
Friday 19 June – Sherwood Pines Forest Park, Near Edwinstowe, Notts
Saturday 20 June – Westonbirt Arboretum, Near Tetbury, Glos
Friday 26 June – Cannock Chase Forest, Near Rugeley, Staffs
Saturday 27 June – Dalby Forest, Near Pickering, N Yorks

Tickets go on sale from Friday 16 January, costing £33.00 (subject to booking fee), from the Forestry Commission Box Office 01842 814612, online at or over the counter from the venues.

The commission was quick to add that the tour was self-sustaining, paying for itself. It added that the gigs were also generating “valuable revenue to plough back into the woodland in a variety of environmental and social projects”.

For more information, please visit:

Source: Forestry Commission UK press release

Date: 13/01/2009

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