By BJ Bjornson
David Roberts has a couple of posts up at Grist regarding the quite ugly situation facing us in regards to climate change. Starting with the second, Roberts notes some rather ugly points that doesn�t give one much in the way of optimism for humanity�s future.
We pretend that 2 degrees C is our threshold. Yet the climate scenarios and plans presented to policymakers do not actually reflect that threshold. As Anderson and Bows say, "most policy advice is to accept a high probability of extremely dangerous climate change rather than propose radical and immediate emission reductions."
Note, also, that most popular climate scenarios include an implausibly early peak in global emissions -- 2010 in many cases, 2015-16 in the case of the Stern Report, the ADAM project, and the U.K.'s Committee on Climate Change.
Why do climate analysts do this? Why do they present plans that contain wildly optimistic assumptions about the peak in global emissions and yet a high probability of overshooting the 2 degrees C target?
The answer is fairly simple, and it has to do with the answer to question (4), regarding what level of emissions reductions is reasonable to expect. According to the Stern Review and others, emissions reductions of 3 to 4 percent a year are the maximum compatible with continued economic growth. And so that's the level they use in their scenarios. Yet reductions at that pace offer very little practical hope of hitting 2 degrees C.
In other words, climate analysts construct their scenarios not to avoid dangerous climate change but to avoid threatening economic growth.
That would make sense if being richer would help us prosper in a 4 degrees C [7.2 degrees F] world. But ... no such luck.
That�s where we start looking back at the initial post, which notes that the long-stated target of 2 degrees C no longer looks like it will actually avoid the �acceptable� level of dangerous changes. Instead, the damage once expected at 2 C is now expected at much lower temperatures, which means that even the stated target is going to be bad.
He then gets into talking about what it will take to actually hit that target, and that doesn�t look too good either:
Anderson is adamant that the familiar targets almost all politicians and many scientists use in public -- e.g., "80 percent reduction in the rate of emissions by 2050" -- are deeply misleading. As far as the climate is concerned, the rate of emissions in 2050 relative to the rate of emissions today is meaningless. CO2 stays in the atmosphere for over a century; the atmosphere doesn't care what year it arrives. (Though targets in the distant future are comforting to politicians, for obvious reasons.)
The only thing that matters in limiting temperature rise is cumulative emissions, the total amount we dump into the atmosphere this century. When the total concentration of GHGs in the atmosphere rises, temperature rises. That is the correlation that matters.
. . .
Right now, global emissions are rising, faster and faster. Between 2000 and 2007, they rose at around 3.5 percent a year; by 2009 it was up to 5.6 percent. In 2010, we hit 5.9 percent growth, a record. We aren't just going in the wrong direction -- we're accelerating in the wrong direction.
. . .
The growth of emissions is making the task ahead more and more difficult. The longer we wait to start shrinking emissions, the faster we'll have to shrink them to stay under budget. Here's a visualization of what that means -- some sample reduction curves with varying peak years (the four different lines are based on the four main IPCC scenarios):
As you can see, if we delay the global emissions peak until 2025, we pretty much have to drop off a cliff afterwards to avoid 2 degrees C. Short of a meteor strike that shuts down industrial civilization, that's unlikely.
How about 2020? Of the available scenarios for peaking in 2020, says Anderson, 13 of 18 show hitting 2 degrees C to be technically impossible. (D'oh!) The others involve on the order of 10 percent reductions a year after 2020, leading to total decarbonization by 2035-45.
After that, things start getting scary:
It might seem that, given the extraordinary difficulty of hitting 2 degrees C, we ought to lower our sights a bit and accept that we're going to hit 4 degrees C. It won't be ideal, but hitting anything lower than that is just too difficult and expensive.
It's seductive logic. After all, to hit 4 degrees C we would "only" have to peak global emissions in 2020 and decline thereafter at the relatively leisurely rate (ha ha) of around 3.5 percent per year.
Sadly, even that cold comfort is not available to us. The thing is, if 2 degrees C is extremely dangerous, 4 degrees C is absolutely catastrophic. In fact, according to the latest science, says Anderson, "a 4 degrees C future is incompatible with an organized global community, is likely to be beyond 'adaptation', is devastating to the majority of ecosystems, and has a high probability of not being stable."
He goes on to explain that the reason for the potential instability is that the positive feedback loops such as melting Arctic permafrost releasing methane to cause greater heating and more melting start becoming self-reinforcing and negate whatever humanity does to try and stop its own emissions; the �tipping points� we always hear about. We might hit them before a 4 degree C change, but will almost certainly hit them with it.
At that level, there's good reason to believe that some positive feedbacks will become self-reinforcing. In other words, 4 degrees C would very likely be a way station on the road to much higher temperatures.
Moving back to the second post, the conclusion of the paper Roberts is using as a basis for these is pretty plain,
This is the stark conclusion drawn by Anderson and Bows: "The logic of such studies suggests (extremely) dangerous climate change can only be avoided if economic growth is exchanged, at least temporarily, for a period of planned austerity within Annex 1 nations and a rapid transition away from fossil-fuelled development within non-Annex 1 nations."
All of which points to, �not gonna happen�, at least within the current political climate. It basically boils down to one of those wishes that we hit peak oil fast enough to for the austerity and transition away from fossil fuels to become forced rather than planned, because if we have to hope for a planned austerity that does anything outside of rescue the gambling banksters corrupt politicos like what�s happening in Europe and the U.S. these days, it will never happen.