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.
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