Three salient global mitigation pathways, assessed in light of the IPCC carbon budgets

In the course of preparing the new Greenhouse Development Rights web applications, we had to come up with a set of reference mitigation pathways which represented the choices before humanity, albeit in a simplified and schematic fashion.  In this paper — for this post is actually a paper — we present these three pathways —  a Strong 2ºC pathway, a Weak 2°C pathway, and a G8 pathway — and their levels of risk, in a fairly precise and technical manner.

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This paper examines the levels of risk associated with three widely discussed global mitigation pathways: a Strong 2ºC pathway, a Weak 2°C pathway, and a G8 pathway. A very large number of analyses and debates refer to these or quite similar pathways. This paper assesses the three pathways in the light of Working Group I’s recently released contribution to the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC 2013), which provided three specific global carbon dioxide (CO2) budgets, and associated them with specific risks of a global surface temperature increase of more than 2°C by the end of this century, relative to the 1850–1900 average.

Figure 1 presents the three pathways.

Figure 1. Three politically salient mitigation pathways: G8 (red), Weak 2°C (blue), and Strong 2°C (green). Also shown (dotted lines) are three pathways consistent with the carbon budgets given by the IPCC, consistent with limiting warming to 2°C with 66%, 50%, and 33% probability, given non-CO2 emissions as per RCP2.6.[1]

The key features of these pathways and the findings of our analysis can be summarized as follows:

The Strong 2°C pathway is defined to be an extremely ambitious mitigation pathway that can still be defended as being techno-economically achievable (Höhne et. al. 2013). Emissions peak in 2014 and reach an annual peak reduction rate of about 6.1% per year (6.0% for fossil CO2 only). Cumulative carbon dioxide emissions after 2012 are 780 gigatonnes CO2 (Gt CO2), which is well within the IPCC’s budget of 1,010 GtCO2 for maintaining a 66% likelihood of keeping warming below 2°C.

The Weak 2°C pathway is fashioned after well-known and often-cited emissions pathways that are typically presented as having a “likely” (greater than 66%, in the IPCC’s terminology) chance of keeping warming below 2°C.[2] Emissions peak in 2014 and reach a maximum annual reduction rate of 3.3% per year (4.4% for fossil CO2 only). Cumulative carbon dioxide emissions from 2012 onward are 1,270 Gt CO2. This exceeds the IPCC’s budget of 1,120 GtCO2 for maintaining a 50% chance of keeping warming below 2°C, suggesting that this pathway carries substantially higher risks than previously believed.

The G8 pathway, a marker of the high-level political consensus in developed countries, is based on emissions targets given in an official declaration of the Group of Eight industrialized countries at its 2009 Summit in L’Aquila, Italy (G8 2009). This pathway is not precisely specified in this declaration, but is sufficiently well-defined that we can compare it with the IPCC budgets. Emissions peak in 2020, decline by a maximum of 4.9% per year (6.0% for fossil CO2 only). Its cumulative carbon dioxide budget of 1,610Gt CO2 considerably exceeds the IPCC’s budget of 1,410 GtCO2 for maintaining a 33% chance of keeping warming below 2°C[3]. We thus find that its chance of keeping warming below 2°C is far less than 33%.

Table 1. Key data for the three pathways, and the IPCC carbon dioxide budgets against which to compare them.

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"Dangerous Climate Change" is already here, and the scientists know it.

The IPCC’s new assessment report hasn’t even been released, but the denialist fog machine is already running hard.  If you’re tired of it — and, frankly, if you’re tired of the smoothly-leveled understatement that we usually get from the IPCC — take a look at Is Climate Change Already Dangerous?, a new report by David Spratt of Australia’s Climate Code Red.

I’ll not summarize this report; there’s no point because it’s already a summary, one which sticks extremely close to the original scientific literature.  But I will say that its focus is the Arctic, which as you may have noticed is getting a lot of nervous attention these days.  And this for the very good reason that it’s melting before our eyes!  Spratt’s paper is excellent on this subject – it lays out the basics of the situation and gives you the citations you need to drill deeper.  Assuming you’re up to it.  The message, after all, is that we’ve already crossed the thin red line into the days of “dangerous climate change.”

What’s happening here?  Here’s a nice overview from Professor Peter Wadhams, of Cambridge University and the Catlin Arctic Survey.  The author of a recent paper called Arctic ice cover, ice thickness and tipping points and a leading authority on the polar regions, Wadhams says:

“I have been predicting [the collapse of sea ice in summer months] for many years. The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer… in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months. This collapse, I predicted would occur in 2015–16 at which time the summer Arctic (August to September) would become ice-free. The final collapse towards that state is now happening and will probably be completed by those dates. As the sea ice retreats in summer the ocean warms up (to +7ºC in 2011) and this warms the seabed too. The continental shelves of the Arctic are composed of offshore permafrost, frozen sediment left over from the last ice age. As the water warms, the permafrost melts and releases huge quantities of trapped methane, a very powerful greenhouse gas so this will give a big boost to global warming.” (Vidal, 2012)

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"Global Warming's Terrifying New Math" — Bill McKibben's call for a carbon divestment movement

— Tom Athanasiou, July 21, 2012

The new issue of Rolling Stone has a major essay by Bill McKibben, called Global Warming’s Terrifying New Math. It’s a must read, for a number of reasons. The big one is that McKibben’s call for a “carbon disinvestment” movement – aimed at breaking the hammerlock that the fossil cartel has on our civilization – is a big step forward. It’s not the only step we need to take (more on this below) but it would make a huge difference.

First up, Terrifying New Math is a fine science-for-civilians essay on the recent “extreme weather,” which has been monumental. In fact, the summer of 2012 may well turn out to be a decisive turning point in the climate war. Not to put too fine a point on this, but the deniers have obviously peaked, at least in the US, at least for now. Not that they’ve given up – or run out of funding – but at least they’re now in the rear view. I for one doubt that they’ll be taking control of the debate again.

Anyway, there’s a lot of extreme-weather color in this essay. Who knew that this spring, when it rained in Mecca at a temperature of 109 degrees, it was the hottest recorded downpour on the books? And McKibben does a great job of quickly moving on to key numbers, and then drawing some substantive conclusions.

The numbers are key to the story. McKibben chose three:

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Global Climate Justice gets its 15 Minutes: The UN workshop on “Equitable Access to Sustainable Development”

A few weeks back, deep in a diplomatic warren in Bonn, Germany, the UN climate negotiations convened their first major session since December’s “breakthrough” in Durban, South Africa.  It would be a bit of an understatement to say that Bonn didn’t go well.  See this rollup or, if you’re braced for the details, see the Climate Action Network’s coverage and commentary, and the Third World Network’s coverage and commentary, and the IISD’s summary.  The UNFCCC Secretariat will also be doing a report; no doubt it will be soon.

The “Youngos” in action

Despite the dead air of the Maritim conference hotel, Bonn was notable, for two reasons.  It was another halting step in our gradual collective awakening into the maddening grind of post-Copenhagen reality.  And – the topic here – it was the occasion for a formal, day-long, plenary workshop on the topic of “Equitable Access to Sustainable Development” (hereafter “EASD”).  The equity workshop (the video stream, in two parts, is here and here; the TWN’s summary is here) was agreed to and scheduled at Durban, and – if we’re clever and very lucky – it may someday be remembered as a step in the great post-Copenhagen reboot.

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Linked Fates — "Occupy" and the climate negotiations

Anyone who claims that the fate of the climate talks is bound to the fate of the Occupy movement better expect a bit of skepticism in return. Now, if it were Occupy and the Climate Justice movement, that would be a different story! Both are complex social movements, and both are driving hard for economic justice. Their overlap is inevitable. But the negotiations themselves? What have they to do with economic justice? What have they to do with the great divide between “the 1%” and “the 99%”?

It’s an easy question to ask. Too easy, actually.  It’s a question that raises others…

Beyond vague talk about “the most vulnerable countries and people,” few of us are really prepared to approach the climate crisis as a justice problem. So it should be said that it didn’t have to be this way. If justice had long been a major part of environmental politics, we’d be in better shape today. But it hasn’t been, not until recently, and the truth is that Big Green still isn’t really on board with justice environmentalism. In fact, it’s fair to say that today’s progressive enviros are the inheritors of a long tradition, and that it’s not a uniformly admirable one. The climate politics mainline, in particular, has long focused, almost exclusively, on the technical side of the transition problem. Not that there’s any hope without a technology revolution, but must it come packaged with a refusal to understand, let alone confront, the economic divide that’s at the core of the global climate-policy deadlock?

Things are changing now, or at least they could. But the past matters.

Remember Copenhagen? Remember the vitriol of the blame game that followed Copenhagen? Do try, because soon we’re going to see what, if anything, we’ve learned in the two years since that great debacle. As I write this, Durban, South Africa (the next Conference of Parties to the Climate Convention) is coming right up, and it will almost certainly join Copenhagen on the long list of grim, poorly-reported failures to make the international breakthrough that we so badly need. As Durban approaches, and then passes, we’re all going to have to decide what the hell we think is actually going on.

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You want Loopholes with that?

The bad news is that the climate/energy push just crashed and burned in the Senate.  The good news is that, in the wake of that crash,  the US climate community is having a robust Big Think.  The last time we had such an exchange was back after what, for lack of a better term, I will call the Great Copenhagen Disappointment.  Which raises an interesting question – do we only debate, openly and seriously, after we lose?

If so, and judging by the situation in Bonn, where an inconclusive post-Copenhagen “intersessional” just shambled a bit closer to December’s rematch in Cancun, we’re up for another round of disputation soon.  Not, of course, that disappointment in Cancun is certain.  It’s still possible that the wealthy countries are going to actually come up with the “fast start finance” that they promised back in Copenhagen.  Maybe they’ll even go beyond fast-start finance, and actually start acting like they want to make a meaningful international deal.  Because, frankly, it’s their move.

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The National Academies study, from a global point of view

A few days ago, I got mail from a colleague at Climate Action Network International, a communications guy, asking for a comment on the US National Academy of Sciences recent climate reports, or rather on the US emissions budget that is recommended / affirmed in these reports. It turned out to be quite an interesting request.

First up, though, these reports only strengthen the scientific case. For example, the IPCCs 2007 Forth Assessment Report says that sea levels could rise by between 0.6 and 1.9 feet by 2100, but recent studies have suggested that this is far too optimistic. The NAS reports incorporate this newer research and concludes that sea levels could rise by as much as 6.5 feet in during this century.

Second, I was a bit surprised by the way the NAS approached the problem of calculating the US emissions budget. The standard methodology in the climate world is to estimate a remaining global budget (which is hard) and then to work out the share of this budget that properly belongs to each country (which is harder). And you have to admit this approach makes sense; after all, when the US or any country takes a budget, less is left for everyone else; which is why climate, fundamentally, is a sharing problem. Anyway, I expected to find some version of this approach in the NAS reports. How else could they calculate a recommended US budget?

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After Copenhagen: On being sadder but wiser, China, and justice as the way forward

(Revised, Feb 19, 2010)

(For a snappier version of this analysis — without the charts! — see the Earth Island Journal)

First up, this is not another enumeration of confident judgments. I do not presume that Copenhagen was an unmitigated failure, or that this failure was Obama’s fault, or, as is the fashion, that China was the ugliest of them all. Nor do I suggest that the South’s negotiators made impossible demands. Or argue, with disingenuous resignation, that the UN process is obsolete. Or believe that, finally, only a US breakthrough really matters.

To be sure, Copenhagen was absolutely a failure, in the precise sense that it failed to catapult us into the fair and ambitious global mobilization that’s needed to prevent climate catastrophe. But this was never going to happen. What did happen, as the veteran Bangladeshi policy activist Saleem Huq put it, was a shaking of the traditional pieces of the global geo-political puzzle and their landing in a new and unfamiliar configuration. In this sense, the question of success and failure is moot. The real question is whether this new configuration offers us new ways forward, and if any of them lead beyond the “North / South impasse (a misleading formulation that implies an equal division of blame) to enable a meaningful global mobilization.

This question cannot be answered by the hard, uncompromising pragmatics of campaign logic. This is a time for reflection, not for pushing forward, one more meeting, one more demo, one more demand at a time. This time we need strategy as well as tactics, and we need it fast. 2010, which will culminate with another showdown in December in Mexico, is going to be another big year. As, for that matter, will 2011, and 2012, and all the other years in the brief period just ahead, the post-Copenhagen period in which we must, finally, begin to move.

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Getting China Wrong

It’s been a long time since Copenhagen.

A few weeks after it ended, chatting to a friend about some stupid comments I’d overhead during that long last night, he said that “everyone gets a pass for anything they said during the first week.” The first week after Copenhagen is what he meant — a time of exhaustion and near despair in international climate circles.

I bring this up because some of the stupid things that were said during that first week are still with us. There were plenty of them, of course, but this post doesn’t pretend to be comprehensive. It’s just about China.

Copenhagen, of course, was not a success. But it did change the game, in particular by establishing a framework in which both northern and southern countries can step forward to “pledge” to mitigation actions of various kinds. As they do, scientists and institutes around the world are tabulating the pledges, normalizing them, calculating their implied aggregate impact on global temperature, and — inevitably — drawing conclusions about which countries are doing their “fair share” and which are free riding on the efforts of others. Continue reading “Getting China Wrong”