In November 2009, in the run up to the Copenhagen conference I published a post Climate crunch and Copenhagen: the fierce urgency of now. For my first climate change post in 2011 I’ve reposted most of that post, with slight variations, and leaving out the direct commentary on Copenhagen.
My intention is to remind people that action on climate change is urgent, and that there is a severe penalty in leaving action to a later date.
Substantively the post outlines the carbon budget approach to climate stabilisation which gives prime place to carbon equity. If Australia wants to show leadership in climate change internationally we should seek zero net emissions by 2030. We would still blow our equitable carbon budget which requires zero emissions by 2019, but with that kind of leadership we should get away with it. Also we should use our land and our forests to create carbon sinks in order to then go negative in net emissions.
The reprised post is below the fold.
Back in 2003 James Hansen was saying that we had about 10 years to get ourselves organised to tackle global warming and climate change. You ignore him at your peril.
For three days in May 2009 some of the best minds on the planet attended a curious meeting at Cambridge University, the St James’s Palace Nobel Laureate Symposium, to contribute their ideas and authority to some of the world’s most pressing challenges, in this case the climate crisis and its implications.
The choice of topic is not surprising. This was the second such meeting. The first was two years earlier at the Potsdam Institute for Climate Impact Research in Germany. So the list of participants included one Hans Joachim Schellnhuber, Director of said Potsdam Institute, Malte Meinshausen from the same place, Rachendra Pachauri, the IPCC head honcho, Lords Giddens and Stern, and a fella called Steven Chu, Secretary of Energy for the USA.
The message from our intellectual elders is captured in the phrase:
The fierce urgency of now…
As it happens the folk at Potsdam have been putting a bit of flesh on that message.
One of the more interesting scenarios for stabilisation I’ve seen recently came from Bill Hare of Potsdam in Chapter 2 of the Worldwatch Institute State of the World 2009 report:
This he reckons is the “emissions pathway required to limit warming to below 2 degrees Celsius with higher confidence”. Start early, go hard and reach zero emissions by 2050, then go negative. The trajectory is designed for a safe landing. After flirting with 2C the temperature is meant to come back to 1C above pre-industrial in the latter part of this century.
The same sort of thinking was contained in the Climate crunch issue on Nature where Malte Meinshausen did much of the heavy lifting. The basic concept here was that there is a limited remaining budget of carbon that we can put into the atmosphere before we hit 2C. The cumulative quantity of emissions is what’s important. Since industrialisation we’ve already used up half our allowable budget. We can do the same again and that’s it.
It is commonly thought that if we start later we have to cut harder, but that’s OK provided we reach the same end point by 2050. What Meinshausen et al are saying is that if we start later we have to hit that end point sooner than 2050. It’s the area under the line on the graph that’s important, stupid!
Hare was looking at a safe climate scenario. Meinshausen based his calculations on the riskier kind of scenario being adopted politically around the world of a 50% reduction from 1990 levels by 2050 and zero by about 2080:
This scenario has a 75% chance of not breaching the 2°C limit. The graph comes from an article by Stefan Rahmstorf, where he puts the situation in, well, very plain German. (For plain English, see RealClimate.) The budget for 2000-2050 is 1000gt of CO2 (or around 1500gt CO2e). But oops! we’ve blown a third of it already in the years 2000-2008! So our options are spelt out in Meinshausen’s second graph:
If we leave peaking global emissions from 2010 until 2015, the penalty is that the annual reduction rate goes up from 2% to 3.6%. I was actually shocked by the difference every five years makes. Remember the words of our elders!
50% reduction by 2050 depends on peaking in 2010. If you leave it until 2015 it has to be 90% by 2050 for the same climate outcome. Leave peaking to 2020 and we need zero by 2045.
The task becomes virtually impossible if you leave world-wide peaking later than 2020.
Now the Germans have taken the remaining emissions budget and looked at the implications for individual countries (now behind the paywall) if the budget is allocated equitably, based on population. Then they’ve specified how many years it would take major emitters to blow their budget at current emissions rates. Here are some of the results:
A few things stand out. Firstly, the US is in a hopeless situation. If, say, they bought credits from India and other developing countries there would be a massive transfer of wealth.
Secondly, no-one should be buying credits from China, which might come as a surprise to them. China will use up its budget by 2033 at current emissions rates.
Third, the future of the planet does depend critically on what the US and China do.
Australia presumably is worse placed than the US.
What the world has been doing lately is illustrated in Will Steffen’s recent report which contained this graph:
The Raupach et al 2007 paper which contained the original graph indicated that 70% of the increase in emissions was coming from developing and transitional economies. There is obviously an urgent need to equip these countries with renewable energy technology. We, the world, cannot afford for them to pollute their way to prosperity.
I think the Germans’ approach is rational and gives a new gloss to the phrase “common but differentiated responsibility”. Paying for the external cost of our lifestyles and exercising responsibility towards both the planet and posterity. We know that that the world does not operate according to reason but what the Germans have done provides a useful perspective with which to judge the outcomes of Copenhagen and subsequent meetings. So far they all FAIL.
I’ll finish with some comments from me, totally unqualified lay person.
First, two degrees isn’t safe. This from the RealClimate link:
We feel compelled to note that even a “moderate” warming of 2°C stands a strong chance of provoking drought and storm responses that could challenge civilized society, leading potentially to the conflict and suffering that go with failed states and mass migrations. Global warming of 2°C would leave the Earth warmer than it has been in millions of years, a disruption of climate conditions that have been stable for longer than the history of human agriculture. Given the drought that already afflicts Australia, the crumbling of the sea ice in the Arctic, and the increasing storm damage after only 0.8°C of warming so far, calling 2°C a danger limit seems to us pretty cavalier.
Second, I would understand that the Meinshausen scenarios are worked out with models that don’t include the longer term feedbacks James Hansen talks about. Even reaching Bill Hare’s 1C safe target would leave ice melting more than it is at present.
Third, as we saw in looking at Susan Solomon’s work, if we hit zero emissions tomorrow the climate would take a long time to recover. Delays measured in decades have consequences measured in centuries.
Fourth, no-one really knows when we might hit one of those dreaded tipping points that could by themselves ramp up the temperature a couple of degrees, or perhaps freeze Europe over.
That and more is why I’d prefer to take Bill Hare’s stabilisation path and shorten it to reach zero by 2030. But I guess it will take the world at least 10 years to wake up. By then it will be desperately close to game over as far as our emissions budget is concerned.
I think at least some of the European policy makers know. It’s the Americans, the Chinese and the rest of us that need to wake up.
The Holocene has been good for us as a species, but right now I fear we are heading somewhere else – somewhere called Perdition.
Update: I’ve added below an image from Hans Joachim (John) Schellnhuber, who is head of the Potsdam Institute and the boss of Rahmstorf and Meinshausen mentioned in the post.
Germany is a fairly typical advanced economy with per capita emissions similar to Great Britain and France. High polluting countries like the US and Australia, if they are not to bludge on the efforts of others, should hit zero before 2020. If we don’t do that we should be prepared to pay others not to pollute in order to make up the difference.
Remember that all this is based on a 75% chance (scarily inadequate) of staying within the ‘guard rail’ of 2C. People like Schellnhuber, Rahmstorf and Meinshausen know that 2C is too high for a safe climate. They invented the concept in the mid-1990s and it took over a decade to be accepted by policy makers. Meanwhile the science had moved on.
All this is profoundly depressing, but needs to be faced. Now.