segunda-feira, 12 de dezembro de 2011

A brutal lógica das alterações climáticas

 Um estudo científico de  Kevin Anderson e Alice Bows deixam-nos com zero margens de negociações
Let's walk through Anderson's logic. 
1. How much can global average temperature rise before we risk "dangerous" changes in climate? The current consensus answer is: 2 ºC [3.6 ºF] above pre-industrial levels.The 2 ºC number has been around for over a decade and was reaffirmed by the Copenhagen Accord just last year. Deciding on an "acceptable" level of temperature is a political and somewhat arbitrary judgment, of course, since it lets one number stand in for a wide range of heterogeneous considerations. But it's an important marker. And when it was first developed, it was based on the science of the day.

Here's a chart attempting to show, in simplified form, what amount of temperature rise will produce dangerous effects (the red zones) and what the 2 ºC level means:

Seems sensible enough. But there's a hitch: Climate science has not stood still for the last decade. According to the latest research, the level of damages once expected at 2 ºC is now expected at considerably lower temperatures. Here's a graph that shows science's evolving understanding:

As you can see, the 2 ºC "guardrail" that separated acceptable from dangerous in 2001 is, in 2009, squarely inside several red zones. Today, the exact same social and political considerations that settled on 2 ºC as the threshold of safety by all rights ought to settle on 1 ºC [1.8 ºF]. After all, we now know 2 ºC is extremely dangerous.

At this point, however, stopping at 1 ºC is physically impossible (we can thank our past inaction for that). Indeed, as we'll see, stopping at 2 ºC is getting close to impossible as well. There is no longer any reasonable chance of avoiding "dangerous" climate change, so 1 ºC vs. 2 ºC is a somewhat academic debate. At this point we're just shooting to avoid super-duper-dangerous. Regardless, the numbers that follow are based on 2 ºC.
Digo e repito sempre: estamos numa encruzilhada em que privado/público deixará de fazer sentido quando cair todo o carbono e pesticidas reflectidos em nossas vidas. SE NADA houver um empoderamento colectivo em refrear a banca, descredibilizar as empresas de rating e colocarmos os autores e "empresas" de paraísos fiscais em Tribunais Internacionais, o quanto antes...não auguro nada de bom. 

Para saber mais

  1. Kevin Anderson Beyond 'dangerous' climate change artigo (paper)
  2. The brutal logic of climate change, por David Rogers (faz uma análise do artigo científico)

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