2010 et la crise climatique

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2010 et la crise climatique

Jay Gulledge, un des directeurs des études sur la question du changement climatique au PEW Center on Global Climate Change, estime que l’année 2010 marque peut-être une évolution importante sinon décisive de l’appréciation politique générale sur la question de la crise climatique. (Voir le 17 août 2010, sur PRW Climate.org.) Les événements climatiques ont déjà été extrêmes durant ces huit derniers mois (il en rappelle un certain nombre) et ils se concentrent aujourd’hui sur les deux catastrophes qu’on pourrait juger comme géographiquement contigües et climatologiquement liées : les incendies en Russie et les inondations au Pakistan.

«One might think that too much rain in Pakistan would have nothing to do with too little rain in Russia, but two expert analyses by CNN meteorologist Brandon Miller and Weather Underground meteorologist Dr. Jeff Masters find that the two are connected. The Russian heat wave is associated with an intense dome of high atmospheric pressure that has settled in over Eastern Europe. This dome is so immovable that it is blocking the flow of the jet stream, which typically determines where mid-latitude storms drop their rains. A similar “blocking high” was in place over Western Europe during the extremely deadly 2003 European heat wave. The block over Russia forced the jet stream to dive far southward, carrying with it a great deal of moisture that normally would have watered Russia’s substantial wheat crop. Instead, that rain fell in northern Pakistan, combining with the already abundant rainfall normally associated with the Asian Monsoon this time of year. The combination of the two was just too much, so while Russia’s crops withered and burned, Pakistan’s crops drowned.

»Returning to the question everyone wants answered: What can we say about the connection between these events and climate change? As usual, there is no definitive answer about these specific events, but direct observations show that extreme weather events have become more frequent in the past half-century, and in the extreme cases that have been studied, the mechanisms are those that one would expect from global warming. At the most basic level, more droughts and heat waves are expected because of hotter, longer-lasting high pressure systems that dry out the land, as witnessed in Russia. On the other hand, more floods are expected because hotter air evaporates more water from the surface and holds more moisture. When the conditions are right, that moisture is released, creating a deluge, as witnessed in Pakistan. The same basic phenomenon was behind the unusually heavy snowstorms that hit the U.S. East Coast this winter… […]

»So it is reasonable to conclude that, in aggregate, the documented increase in extreme events is partially a climate response to global warming, and that global warming has increased the risk of extreme events like those in Russia and Pakistan. On the other hand, there is no scientific basis for arguing that these events have nothing to do with global warming.»

Jay Gulledge aborde alors la question de savoir si l’on peut encore soutenir la position intermédiaire, ou opportuniste, dans le débat sur la crise climatique, qui est l’affirmation qu’il y a des “gagnants” et des “perdants” dans la crise climatique. Cette idée a été surtout développée pour la Russie qui, à côté d’un réel scepticisme pour la crise climatique, a développé l’idée qu’elle pourrait être “gagnante” si cette crise climatique se développe effectivement. Jay Gulledge revient sur une déclaration de Medvedev du 30 juillet 2010, qui a déjà été commentée de diverses sources (voir le Center of National Amercan Security, le 5 août 2010), et qui semblerait marquer un changement important de l'appréciation russe de la crise climatique, vers l'appréciation d'une crise réelle et fondamentale.

«Economists and security analysts frequently argue that Russia is likely to be a climate change “winner,” since warmer temperatures could reduce heating fuel consumption, lengthen the agricultural growing season, and open up transportation routes and access to mineral and energy deposits in the Arctic. But these types of analyses inevitably focus on a few simplistic variables, while neglecting a plethora of more complex and likely negative impacts. It seems clear that Russia will not benefit from warm weather this year, and if this type of event were to become common in future decades, it is hard to see Russia being a climate-change winner, even if it is rich on oil and gas money. Moreover, Russia is fighting an ongoing extremist insurgency at home that has ties with both Al Qaeda and the Taliban in Afghanistan and Pakistan. Does Russia “win” if the Taliban and other hard-line extremists step in to fill the void left by an ineffectual government and international aid response to the floods in Pakistan?

»It’s time to put to rest the overly simplistic notion that there will be clear winners and losers in a warmer world. I had the privilege of working with top-flight national security experts on a report published by the Center for a New American Security and the Center for Strategic and International Studies in 2007, called The Age of Consequences: The Foreign Policy and National Security Implications of Climate Change. In the executive summary, we wrote:

»“A few countries may benefit from climate change in the short term, but there will be no ‘winners.’ Any location on Earth is potentially vulnerable to the cascading and reinforcing negative effects of global climate change. While growing seasons might lengthen in some areas, or frozen seaways might open to new maritime traffic in others, the negative offsetting consequences—such as a collapse of ocean systems and their fisheries—could easily negate any perceived local or national advantages. Unchecked global climate change will disrupt a dynamic ecological equilibrium in ways that are difficult to predict. The new ecosystem is likely to be unstable and in continual flux for decades or longer. Today’s ‘winner’ could be tomorrow’s big-time loser.”

»Remarkably, Russian President Medvedev seems to get the point. Speaking to an international gathering, in front of TV cameras, the president was forthright: “Practically everything is burning. The weather is anomalously hot. What's happening with the planet's climate right now needs to be a wake-up call to all of us, meaning all heads of state, all heads of social organizations, in order to take a more energetic approach to countering the global changes to the climate.”»

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