Mercredi 27 juin, la Commission européenne devrait demander une forte condamnation de la France en raison de la pollution par les nitrates en Bretagne

http://www.la-croix.com/article/index.jsp?docId=2307115&rubId=4076  

Published online: 4 May 2007; | doi:10.1038/news070430-11 / http://www.nature.com/news/2007/070430/full/070430-11.html

Tackling greenhouse gases looks to be affordable

International report sets out costs of bringing down global emissions.

Michael Hopkin

Bringing greenhouse gas emissions under control looks to be both achievable and affordable, on the basis of the most recent report of the Intergovernmental Panel on Climate Change (IPCC).

Today marks the end of an often fraught week of talks by the IPCC's Working Group III, which evaluates strategies to counter the rising levels of greenhouse emissions.

Their summary report, released in Bangkok, Thailand, says that stabilizing atmospheric greenhouse gases at a level likely to avoid the worst effects of global warming would cost no more than 3% of global economic productivity by 2030 - an average of 0.12% per year.

This is cheaper than many observers had expected it to be, and most see it as affordable; environmental groups represented on the panel, such as Greenpeace, have called it a small price to pay.

But US officials say that this would lead to a global recession, and argue that greenhouse levels should be stabilized at a higher level. "This report underscores the importance of a strong curve of emissions reductions," says James Connaughton, chair of the White House Council on Environmental Quality. "But no world leader will pursue a strategy that would lead to economic recession."

Published online: 18 April 2007; | doi:10.1038/news070416-8 / http://www.nature.com/news/2007/070416/full/070416-8.html

Changes to pesticide spraying could reduce GM harm

Leaving just 2% of transgenic crop rows unsprayed could boost diversity.

Michael Hopkin

Turn off a bit of the pesticide spray to be kinder on birds. Punchstock

British crop researchers are claiming that they have developed a method to stop transgenic crops from damaging the biodiversity of weeds and seeds. By leaving two rows in every 100 unsprayed with pesticides, enough diversity can be preserved to prevent knock-on effects on birds and other animals, they calculate.

The method could help farmers to reap the economic benefits of planting herbicide-resistant crops while avoiding the environmental damage of blanket pesticide spraying, say researchers led by John Pidgeon of Broom's Barn Research Station in Bury St Edmunds, UK.

Farmers typically spray pesticide on their crops using a multi-jet boom sprayer up to 24 metres wide. "All they would have to do is turn off the outside two nozzles," says Pidgeon.

This reduction would allow weeds to produce seeds in the unsprayed rows, preserving plant diversity and giving birds and insects a source of food, Pidgeon and his colleagues say in a paper published online by Proceedings of the Royal Society B.
Obvious idea

The researchers undertook their work after the UK government's Farm Scale Evaluations (FSE) reported in 2003 that herbicide-tolerant sugar beet and oilseed rape can damage biodiversity because of the vigorous pesticide regimes used to manage these crops.

Pidgeon is surprised that the idea of leaving some rows unsprayed has never been evaluated before. "It occurred to me about four seconds after the [FSE] results were published - it is desperately obvious," he says.

They haven't yet tested the idea of leaving small strips of cropland untouched by pesticide. Instead, they extrapolated from the FSE experimental results for sprayed and unsprayed fields to see how much needed to be left alone to encourage biodiversity. Leaving 2% of the crop untouched should allow weed seeds to grow; leaving 4% unsprayed allows weed plants to flourish, they predict.

Although genetically-modified herbicide-tolerant (GMHT) crops are grown throughout the United States, they will not be approved in Europe unless seed producers such as the US giant Monsanto can show that their strains will not harm the environment any more than conventional ones do. This makes it surprising that they have not yet tested the beneficial effects of leaving rows unsprayed, says Pidgeon's co-author Joe Perry.

Such a proof of principle could be carried out in just one growing season and could even be done with non-genetically-modified test strains, he adds.

Win-win?

Whether the practice can be enforced, however, remains unclear. "Will farmers do it, and how do you tell they have really done it?" asks Matthew Heard, an ecologist at the Centre for Ecology and Hydrology in Huntingdon, UK. "Farmers just want to maximize yields." Losing some of the unsprayed 2% to weeds might not seem to them like a good deal.

Pidgeon claims that his technique will allow farmers to boost their profits - GMHT sugar beet is thought to be worth an extra £150 ($299) per hectare than conventional varieties - and completely avoids the damage to weed and seed diversity. "If you leave 2% unsprayed, GMHT sugar beet is actually better for the environment [than normal sugar beet]," he says. "It's a win-win: economically and environmentally."

Nevertheless, "there are weeds and there are weeds", warns Les Firbank, a researcher at the Institute of Grassland and Environmental Research in Okehampton, UK. Some pests, such as black grass, are devastating to crop yields while not really providing much benefit to wildlife. Farmers would much prefer to find subtle ways to encourage broadleaved weeds.

Heard argues that restoring British biodiversity will take more than the "gimmicky" idea of leaving rows untreated with pesticide. Decades of intensive agriculture have already damaged wildlife; farmers should be trying to fix this previous damage by leaving wider margins around their fields, he says. "What we want to do is reverse these disastrous historical impacts," he says.

References

1. Pidgeon J. D., May M. J., Perry J. N. & Poppy G. M. Proc. R. Soc. B, doi:10.1098/rspb.2007.0401 (2007).

Des manifestations sont organisées jusqu'au 31 mars dans toute la France à l'occasion de la « semaine sans pesticides»

Le système agricole français est-il « verrouillé » ? Oui, ont répondu les scientifiques de l'expertise collective « Pesticides, agriculture et environnement » menée par l'Institut national de la recherche agronomique (Inra) et l'Institut de recherche pour l'ingénierie de l'agriculture et de l'environnement (Cemagref) (1).

Le modèle agricole français fait difficilement sa mue. Et les experts d'énumérer certains des blocages : la rationalité économique basée sur les rendements « induit le recours aux pesticides » ; « un secteur de conseil en protection des cultures dépendant de la vente des pesticides tend à favoriser l'emploi de pesticides » ; le fait que ce soit « les mêmes entreprises » qui assurent « la distribution des semences, des pesticides et des engrais, et la collecte des récoltes » renforce cette tendance, d'autant plus que ces mêmes entreprises rechignent à distribuer des variétés rustiques ou résistantes à certains bio-agresseurs, etc.

Les scientifiques ajoutent des arguments socioculturels : la « culture du champ propre », sans mauvaises herbes ni maladies, prégnante chez les agriculteurs, l'aversion à l'idéologie « écolo » considérée comme « illégitime dans l'univers socio-technique de l'agriculteur » ou l'« aversion au risque » qui pousse aux traitements systématiques, d'autant plus qu'une pratique économe en pesticides exige à l'inverse plus de connaissances et une présence accrue dans les champs.

La France, troisième consommateur mondial de pesticides

Ce constat très officiel explique que la France reste le troisième consommateur mondial de pesticides (78 000 tonnes en 2005) sans qu'aucune tendance nette à la baisse ne se dessine au-delà des variations annuelles : après les années record de consommation 1998-2001, avec un marché annuel de phytosanitaires autour de 2 milliards d'euros, celui-ci oscille depuis entre 1,6 milliard et 1,9 milliard d'euros (1,7 milliard pour 2006).

Or, ces consommations massives sont à l'origine d'une pollution chronique des eaux, jugée « préoccupante » par l'Institut français de l'environnement : 229 substances chimiques différentes ont été identifiées dans les eaux de surface, et 166 dans les nappes d'eau souterraines ; 49 % des points de mesure présentent une qualité moyenne ou mauvaise, selon l'institut.

Une deuxième expertise historique apporte un éclairage tout à fait inédit sur la genèse de cette situation. Pesticides, révélations sur un scandale français (2), l'ouvrage de François Veillerette, président du Mouvement pour les droits et le respect des générations futures (MDRGF) qui milite pour les alternatives aux pesticides et organise la « semaine sans pesticides », et de Fabrice Nicolino, journaliste, chroniqueur dans le cahier « Sciences & éthique » de La Croix, remonte aux sources du système agricole national.

Confusion et collusion des intérêts

Les deux auteurs ont mené une étude fine de ces hommes qui ont fait l'agriculture française après la guerre. Les objectifs éminemment louables de l'autosuffisance alimentaire inciteront à s'engouffrer sur la voie de l'agriculture intensive : tous travailleront main dans la main au service de la cause commune, les services du ministère de l'agriculture, notamment le service de la protection des végétaux et la commission d'étude de la toxicité, les scientifiques de l'Inra et les industriels dits « de la protection des plantes » qui développent les engrais et les produits chimiques.

Très vite cette complicité se transformera en confusion et collusion des intérêts, les mêmes hommes clés se chargeant de concevoir les substances chimiques à mettre sur le marché, de développer des variétés de plus en plus productives et en même temps d'homologuer et d'étudier la toxicité de ces substances.

Dans ce système, l'administration n'est plus à même de défendre l'intérêt collectif, de garantir la protection de la santé et des milieux, et les agriculteurs eux-mêmes sont loin de maîtriser les règles du jeu. ...

http://www.la-croix.com/article/index.jsp?docId=2298767&rubId=5547  

Astronomers hash out defense against asteroids

A billion dollars needed to spot potential killer impacts.

Jeff Kanipe

Crash landing: how do we stop this from happening? Don Davis/NASA

Astronomers trying to save the world from Earth-threatening asteroids have this week composed a white paper outlining the threat and what needs to be done about it.

Although it isn't their first white paper on the subject - that was released in 2004 - it is the first mandated by Congress. This, scientists hope, may mean that their conclusions will be taken more seriously by decision-makers in Washington.

In 2005, Congress passed a bill authorizing NASA to search for asteroids as small as 140 metres that could possibly strike the Earth. The bill, however, provided no money for the search. Scientists at the Planetary Defense Conference, held 5-8 March in Washington DC to compose the new white paper, were quick to point this out.

On Monday, Simon 'Pete' Worden, director of NASA's Ames Research Center, said that the cost of finding at least 90% of the 20,000 estimated potential Earth-killers by 2020 would cost about $1 billion. US government employees, including NASA scientists, don't usually make public requests for more cash, but Worden was clear: "We know what to do, we just don't have the money."