HISTERIA Y activismo de invernadero: así es como Bjorn Lomborg califica lo ocurrido tras la publicación del reciente informe del Panel Internacional del Cambio Climático. No es el informe lo que critica, sino la torticera manipulación de sus conclusiones entre medios de comunicación y políticos. Cito algo extensivamente, pero es que vale la pena:

The IPCC has produced a good report - an attempt to summarise what the world's scientists know about global warming. Unlike the Bush administration, caught downplaying the science, the IPCC squarely tells us that mankind is largely responsible for the planet's recent warming. And, unlike Al Gore, who has travelled the world warning that our cities might soon be under the oceans, it refrains from scaremongering.



But lost among the hype is the unexciting fact that this report is actually no more dire than the IPCC's last report, issued in 2001. In two important ways, this year's effort was actually less dire.



The report reflected the fact that since 2001, scientists have become more certain that humans are responsible for a large part of global warming. Otherwise, though, this report had a definite sense of déjà vu . Estimates of temperature increases, heat waves, and cold waves are all nearly identical to those produced six years ago.



The report did, however, contain two surprising facts. Both went unmentioned in most reports. First, the world's scientists have re-jigged their estimates about how much sea levels will rise. In the 1980s, America's Environmental Protection Agency expected oceans to rise by several metres by 2100. By the 1990s, the IPCC was expecting a 67-centimetre rise. Six years ago, it anticipated ocean levels would be 48.5 centimeters higher than they are currently. In this year's report, the estimated rise is 38.5 centimeters on average.



This is especially interesting since it fundamentally rejects one of the most harrowing scenes from Al Gore's movie An Inconvenient Truth. In graphic detail, Mr Gore demonstrated how a 20-foot rise in the sea level would inundate much of Florida, Shanghai, and the Netherlands. The IPCC report makes it clear that exaggerations of this magnitude have no basis in science - though clearly they frightened people and perhaps will win Mr Gore an Oscar.



The report also revealed the improbability of another Gore scenario: that global warming could make the Gulf Stream shut down, turning Europe into a new Siberia. The IPCC simply and tersely tells us that this scenario - also vividly depicted in the Hollywood movie The Day After Tomorrow - is considered "very unlikely". Moreover, even if the Gulf Stream were to weaken over the century, this would be good, as there would be less net warming over land areas.



So why have we been left with a very different impression of the climate panel's report? The IPCC is by statute "politically neutral" - it is supposed to tell us just the facts and leave the rest to politicians and the people who elect them. This is why the report is a careful and sensible document.



But scientists and journalists - acting as intermediaries between the report and the public - have engaged in greenhouse activism. Elsewhere calling for immediate and substantial cuts in carbon emissions, the IPCC's director even declared that he hoped the IPCC report would "shock people, governments into taking more serious action".



It is inappropriate for somebody in such an important and apolitical role to engage in blatant activism. Imagine if the director of the CIA published a new assessment of Iran, saying: "I hope this report will shock people, governments into taking more serious action."



Climate change is a real and serious problem. But the problem with the recent media frenzy is that some seem to believe no new report or development is enough if it doesn't reveal more serious consequences and more terrifying calamities than humanity has ever considered before.



Indeed, this media frenzy has little or no scientific backing. One of England's foremost climatologists, Mike Hulme, director of the Tyndall Centre for Climate Change Research, points out that green militancy and megaphone journalism use "catastrophe and chaos as unguided weapons with which forlornly to threaten society into behavioural change". In his words, "we need to take a deep breath and pause."



A 38.5cm rise in the ocean's levels is a problem, but by no means will it bring down civilisation. Last century sea levels rose by half that amount without most of us even noticing.



The UN tells us that there is virtually nothing we can do that would affect climate change before 2030. So we have to ask the hard question of whether we could do better by focusing on other issues first - helping real people improve their lives and resilience so they can better deal with the world's challenges.

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