Climate crunch time arrives

Three emission reduction trajectories

The Climate Commission has just released its first report (download from here) entitled The Critical Decade: Climate science, risks and responses. The report is clear, simple and succinct with excellent illustrations.

If you want to cut to the chase, the message is encapsulated in the highlighted graph. If we, the world, start to reduce emissions now (impossible) by 3.7% a year, we can get away with an eventual reduction of about 85% by 2050. If we start reducing emissions in 2020 we’ll need to reduce by 9% each year (impossible). If we start in 2015 we can get away with reductions of 5.3% per year (barely possible). But we will have to reach zero net emissions by 2040 and then go negative. Is that possible? Barely, if at all, I suspect.

If the graph looks familiar, it is in fact an adaptation and updating of Figure 3 in the post Climate crunch: the fierce urgency of now from 4 January, 2011. That was adapted from an earlier post of November 2009, so LPers have been forewarned.

But look! The reductions required with a 2020 start were 6% each year back then. Now it’s 9%. I assume this reflects the latest science.

The key messages are as follows:

    1. There is no doubt that the climate is changing. The evidence is overwhelming and clear.

    2. We are already seeing the social, economic and environmental impacts of a changing climate.

    3. Human activities – the burning of fossil fuels and deforestation – are triggering the changes we are witnessing in the global climate.

    4. This is the critical decade. Decisions we make from now to 2020 will determine the severity of climate change our children and grandchildren experience.

“This decade is critical. Unless effective action is taken, the global climate may be so irreversibly altered we will struggle to maintain our present way of life.” “Without strong and rapid action there is a significant risk that climate change will undermine our society’s prosperity, health, stability and way of life.

The longer we leave it the more difficult and costly it becomes.

The report has three chapters, reflecting the subtitle:

  • Developments in the science of climate change
  • Risks associated with climate change
  • Implications of the science for emissions reductions

I won’t give a summary of these, rather I’ll just highlight some bits on the way through.

The science

The report tells us that:

we know beyond reasonable doubt that the world is warming and that human emissions of greenhouse gases are the primary cause.

It is unapologetic about the IPCC report:

The IPCC AR4 has been intensively and exhaustively scrutinised, including formal reviews such as that by the InterAcademy Council (2010), and only two peripheral errors, both of them in the WG 2 report on impacts and adaptation, have yet been found (in a publication containing approximately 2.5 million words!). No errors have been found in any of the main conclusions, nor have any errors been found in the 996-page WG 1 report, which describes our understanding of how and why the climate system is changing. The IPCC AR4 WG 1 report provides the scientific input to the development of climate policy.(Emphasis added)


There is a short note telling us that we have 1,700 billion tonnes of carbon in the form of methane locked up in permafrost, twice as much as is present in the atmosphere now. One study tells us that about 100 billion tonnes are vulnerable to thawing this century.

It could be worse and going above the so-called 2C guardrail raises the chance that it will be. The stuff is leaking now. The problem as I see it is that it will continue to leak until we get the temperature down from where it is now, something that will take centuries. Since we have to go net negative in emissions before mid-century we are going to have to offset this leaking methane by taking carbon out of the air and sequestering it in some way.

Sea level rise

This is one area where there is still considerable uncertainty, mainly we because we don’t fully understand how decaying ice sheets behave. The report settles on a conservative range of 50cm to a metre by 2100, but we could reach 50cm by 2050. Taking the lower limit, one of the diabolical results is that the risk of extreme events such as flooding from storm surges, for example, increases disproportionately with sea level rise. Hence a 1 in 100 years event can amplify 1000 times to become a 10 times per annum event. This map shows the implications of a 50cm rise for Australia:

Figure 1(17): Multiplying factor for the increase in the frequency of occurrence of high sea-level events caused by a sea-level rise of 0.5 metres.

I’ve numbered the images I’ve selected sequentially and given the report’s numbers in brackets.

Ocean acidity

The ocean is already more acid that it has been for 25 million years, as shown in this graph:

Figure 2(18a): Ocean acidity over 25 million years and out to 2100

This is important in terms of the evolutionary adaptability of species. In geological time there have been times where ocean acidity has been greater. But changes have also been associated with major extinction events. Current changes are just too fast. This image shows what we can expect in the Great Barrier Reef:

Figure 3(20b): Anticipated impacts on the Great Barrier Reef

Remember that reefs and shell formation in other species are already being affected. The 2C ‘guardrail’ does not represent safety in terms of ocean acidity.

Changes in our weather

The story here is complex in terms of a climate change imprint and there is plenty of uncertainty about what will unfold. There are some fairly clear general observations, including the fact that the eastern half of the continent has become drier since about 1970 and the western half wetter, with the exception of the SW corner. Here is a record of the inflow to Perth dams:

Figure 4(22a): Inlow into Perth dams

What chance of returning to the pre-1975 pattern?

Extreme events

There is a very good little section explaining the state of play. This conceptual graph explains beautifully what is likely to happen with temperature rise:

Figure 5(25): Relationship between means and extremes with temperature rise

It’s the shaded area under the graph that counts.

The ’emissions budget’ approach

I was delighted to note that the report strongly embraced the ‘climate budget’ approach, which was the basis of my earlier climate crunch post. In fact the report uses the first three graphs I used there. Not so delighted about what it means.

It’s based on the notion that if we want ta 67% chance of staying within the 2C temperature increase guardrail then we must emit no more than 1 trillion tonnes of CO2 equivalent during the first part of this century. Three problems here. First, I don’t like the odds. Given the gravity of what might happen if we go over 2C I’d prefer 99.99% frankly.

Second, I don’t like the 2C guardrail. Ocean acidity is a problem below that level, so is sea level rise, the change of weather patterns and the implications for species extinctions. Moreover, tipping points like the frying of the Amazon and methane release have a fair chance of becoming problematic this side of 2C.

Third, we used up 30% of our budget in the period 2000 to 2008 inclusive.

Furthermore, I’m not convinced that the climate sensitivity assumptions behind the graph fully take account of longer term feedbacks.

Still 2C is a vast improvement on ‘business as usual’ or some half-arsed token effort, as this graph shows:

Figure 6(36): Temperature scenarios for BAU and 2C

Sceptics/denialist/contrarions all, please take a good look at where the red splash gets us by 2100. That’s what the best science available is telling us. Once you get to 4-5C you have an ice-free world, and 70 metres of sea level rise eventually. You have a high risk of major releases from all sorts of carbon sinks which would take the temperature even higher. Should it stop at 4-5C you have a a very different planet and the likelihood that civilisation as we know it would not survive. Implied are billions of deaths and a collapse of the human population.

At 5-6C you are looking at habitability only in residual parts of the planet.

Climate crunch is here

To finish, I repeat the initial image in a larger version and what I said earlier:

Figure 7(37): Three emission trajectories based on the budget approach and giving a 67% probability of meeting the 2 °C guardrail.

If we, the world, start to reduce emissions now (impossible) by 3.7% a year, we can get away with an eventual reduction of about 85% by 2050. If we start reducing emissions in 2020 we’ll need to reduce by 9% each year (impossible). If we start in 2015 we can get away with reductions of 5.3% per year (barely possible). But we will have to reach zero net emissions by 2040 and then go negative. Is that possible? Barely, if at all, I suspect.

It’s going to be a near-run thing. Rudd had it right when he said that climate change was the greatest moral challenge of out times. The challenge for Gillard is to seriously take up the challenge. The challenge for Abbott is to avoid being a bit of historical detritus. Best he just get out of the way and be taken out with the tide.

Elsewhere: Climate Progress has a post.

I haven’t attempted to round up local reaction other than a brief comment here.

61 thoughts on “Climate crunch time arrives”

  1. Cheers, Merc.

    Paul, if there is a big negative it is the wretched ‘two-page to the view’ format. Whoever was responsible for that deserves a rocket.

  2. But how does the government get this message out? I despair sometimes when I read the mainstream press and it’s still full of articles questioning the basics.

    Labor, the Greens and the independents have to work together to reach a carbon price that will actually be effective. The optimist in me says that can happen and that by the time the 2013 election comes around the electorate will have accepted it and realise that it’s not the end of their lives and their jobs. But, there’s so many stumbling blocks to that occurring. So many hoops to be jumped through. And so many elements in Labor who don’t want an effective price as they think it will effect their fiefdoms.

    Meanwhile the rest of the world pushes on. Oh well, I guess we can bludge off them.

  3. When real life comes to imitate a Kevin Costner movie we know something is seriously wrong.

    I wish I was joking…

  4. Like I’ve said in the past Brian, I think the implications of this are clear: we need to act as fast as possible, and whatever we do in terms of emissions reduction it most likely won’t be enough.

    We’re going to be left with geoengineering in one form or another; if we’re lucky and smart it’ll just be sucking CO2 out of the atmosphere rather than anything more drastic.

  5. Brian @3:

    Paul, if there is a big negative it is the wretched ‘two-page to the view’ format. Whoever was responsible for that deserves a rocket.

    Absolutely agree.

  6. The first and last graph is lovely – but assumes an effective global agreement.

    It won’t happen.

    China and India, let alone the rest of the developing world, will not tolerate having to accept the lower levels of economic development that that graph implies.

    It doesn’t matter how much you spin the science – the economics and politics are what matter.

  7. “China and India, let alone the rest of the developing world, will not tolerate having to accept the lower levels of economic development that that graph implies.”

    Why include India Occam? it has very low % of global emissions (5%), and its absolutely miniscule per capita.

    Come out and speak the truth: US and China are the two monster emitters. Or do you prefer not to blame whitey?

  8. Occam’s Blunt Razor, you don’t seem to have grokked the message that the economics aren’t going to stay favourable if we do nothing.

    Fine @ 4, I’m worried that if Labor loses power in 2013 there will be a serious attempt on the part of the goons on the other side to unpick what has been done on climate change and the NBN in particular. By 2016 it would be no longer a possibility.

  9. We’re going to be left with geoengineering in one form or another; if we’re lucky and smart it’ll just be sucking CO2 out of the atmosphere rather than anything more drastic.

    Robert M @ 6, I agree, and therein lies some scope for optimism.

    Occam, further on the developing countries, they need massive assistance with renewable energy technologies so that they can skip the carbon-intensive phase of development. We owe it to them.

  10. One thing the Greens should fight pretty hard on is limiting the amount of ministerial discretion on the big-picture parts of the ETS/carbon price.

    If Labor loses in 2013 and the Greens retain the Senate balance of power, we want a situation where the Greens and Labor can simply block amendments to the ETS and it continues to do its job.

  11. I would like to see Nick Minchin, Martin Ferguson and friends chained to posts at (current) high tide, so they can enjoy the fruits of their endeavours.
    I wonder if we could build a sea-wall out of deniers?

  12. Razor, you’re now using Joyce’s line. “Oh, we can’t do anything effective. Let’s do nothing at all”. As I said above, that’s called bludging. We’re helping to cause the problem, so we have a responsibilty to help solve it. I would have thought that was such a no-brainer.

    The official LNP line also ignores the changes which countries are making to policy. It’s a neat, but totally untrue, line to whinge that we’ll be the only country doing something. Just shows how Phoney Tony’s lies are biting.

  13. One of the advantages of an ETS over a “carbon tax”* Brian is that a whole swag of businesses will have an interest in protecting the value of the permits they have acquired. The LNP would have to trample the holy of holies — property rights — to subvert them. They might perhaps acquire them “on just terms” but this would be extremely costly and embarrassing, and thus improbable.

    That said, it would probably still be quite tricky to unwind a “carbon tax”, since it will have been factored into investment decisions, and the prices of all sorts of goods. The ALP declared at some point that it would rollback the GST but it proved beyond them. Running up to an election promising either to roll it back or change its purview would be seen as extremely destabilising and any fallout would redound on them. They’d probably have to foreswear doing anything in practice to avoid this wedge, which again, would be embarrassing for them.

    * used without endorsement to mean “fixed carbon emissions permit charge”

  14. The climate reports in the seventies had us heading into another ice age. How can that be? How could the accepted science be so wrong then?

  15. Hi Brian, nice summary thanks.

    I just wanted to note that the extreme events section is likely to be a bit simplistic (at least that’s the science coming out now) – the peak in your distribution of events should drop and become broader as you increase the likelihood of major weather events, so the reduction in probability of extremely low events in the left tail of your distribution might not drop by as much as your diagram indicates (we talked about this on a previous thread tho, so won’t rehash it here).

  16. @9 – I wasn’t ignoring the US – just didn’t include it, but you are right. The prospect of them doing much at all is very slim.

    Per capita means bugger all – just a method of guilting whitey. Total emmissions is what matter.

    India is important because with over a billion in population that is starting to develop into an energy hungry economically growing country looking for cheap energy they are going to want to burn lots of coal until their cows come home.

    @11 – Brian – we don’t owe developing countries anything.

    @12 – if the Greens wanted to block ETS changes then i’d be going to a DD election post haste. See how the Greens Senators like the thought of that.

    @14 – if you make a realistic assessment of what the science is telling us about the current state and expected future of climate change, the neglible impact of the current futile efforts to cut emmissions, the near 100% certainty that there will be no environmentally, economically or politically effective international agreement means that it is not a “bludging” position – it is a realistic assessment of the fact that any action is almost certainly a complete waste of time and money.

  17. @Tiny Dancer #18,

    The climate reports in the seventies had us heading into another ice age. How can that be? How could the accepted science be so wrong then?

    Let me guess – you haven’t researched the history of this claim for yourself, you’re just regurgitating it from somewhere else.

    Don’t confuse a great big media beat-up of a maverick hypothesis with what was broadly “accepted science” amongst the academicians. The media did a great big beat-up of “cold fusion” too, and that was never broadly accepted either, and with good reason in the end.

  18. Here we go again….arguing with morons and fatalists.
    What a complete and utter waste of time.

  19. TT and adrian, I waved Tiny Dancer’s comment @ 18 through because it illustrates how impervious some people can be to 30 plus years of science.

  20. You never know when a lurker might learn something, adrian.

    Anyway, for anybody who doesn’t know the original 70s sources containing very measured statements in a couple of peer-reviewed articles talking about long term trends and cycles over thousands of years, which were stripped of that millennial context and transformed into extravagant claims of predictable, imminent-any-time-now ice ages by irresponsible journalists, RealClimate has a great article on The Global Cooling Myth.

  21. @Brian, since you couldn’t use it as a good example of a substantive contribution, I guess it just had to be used as a dreadful lesson in the perils of parroting.

  22. OBR I guess I’m equally fatalistic about the chances of concerted action on carbon as well which in turn defaults to a couple of vague possibilities, one is the techno fix, some form of geo-engineering which works and the other is watching a slow speed train wreck unfold.

    The possibility of geo-engineering working first time and without unintended consequences is pretty small but you can bet your arse it will be tried once the impact of climate change really starts to affect wealth creation. Which leads to the next and most likely scenario in which the wealthy elites desert the sinking ship of civilisation and hightale it to some protected/fortified parts of the world and leave the rest of us to swim.

    After all what’s the point in being super rich if you can’t survive catastrophic global warming?

  23. Incidentally, am I the only person who sees the caption inside figure 5 as “less cold leather”? Doesn’t sound like a bad thing to me…

  24. sg @ 27, well spotted!

    tt @ 25, understood. That’s a great link to a RealClimate classic.

  25. Did you do that, Brian, or was it in the original report? If so, someone at the climate commission is surely looking at a greatly increased chance of some cold leather…

  26. Here we go again….arguing with morons and fatalists.
    What a complete and utter waste of time.

    Yes, a deliberate waste of time. These contrarians are carrying out the programmes given to them by their oily reptilian overlords. The urgency of mitigation is apparent, yet they are doing all in their power to slow us down. Something needs to be done about them. Maybe banishment would be going too far, but surely the mods can do something about them, such as disemvoweling. I would like to see a discussion of this.

    Actually, banishment might not be going too far. After all, Bolt has a reputation of censoring pro-AGW and progressive views. If Bolt can censor on ideological grounds, why can’t we?

  27. And no accident I’m sure that in question time all week not one mention of this truly troubling report but rather a fatuous line about who knew what and when, repeated over and over again about the WA govt. upping royalties.

    Best to avoid the reality of a serious threat to this nation and concentrate on the populist stance .


  28. This morning I needed an x-ray and because I like to do the age cryptic and it’s ordered, I grabbed the Hun.
    Considering that this rag is the preferred daily in Vic. I really have to express great doubt as to the intelligence of said majority.
    Oh! and unless what remains of the opposition to a Murdocracy led by the followers of this rag pull together it’s goodnight Dick.

  29. Thanks again for this, and all your work here Brian. I find it as helpful as I do depressing – tremendously. My first child will be arriving in October, and I fear for the world I am leaving her, and especially her children.

  30. Brian @ 3, the Acrobat menu is your friend. Try View -> Page Display. (I agree the thing shouldn’t have been given the two page view, though. It gives everyone the shits, unless they have a 24″ wide-screen monitor.)

  31. Thanks for the thanks, folks.

    DI(nr) no joy for me. Nothing on the menu. I right clicked, selected ‘Page display preferences’ then ‘single page’ rather than ‘two up’, click on OK and nothing happens.

  32. Climate Spectator has an article which sources the carbon budget approach via Paul Gilding to the Potsdam Institute, which is where I got the concept that I used in earlier posts in Nov 2009 and Jan 2011.

    The linked article stresses also that the report warns about the biological sequestration of carbon which is central to the Coalition’s approach. Good and well, it says as long as it doesn’t delay the adoption of low-carbon technologies:

    The report says “biosequestration schemes can remove carbon quickly from the atmosphere and also offer a number of important co-benefits, but the challenge is to ensure that linking bio-sequestration to the fossil fuel emissions sectors does not lead to any delays in the investment or deployment of low- or no-carbon technologies in those sectors.”

    It says sequestered carbon is vulnerable to human land use and management, which can change the amount of carbon stored in the long term. The only way to permanently “offset” fossil fuel combustion is if the sequestered carbon is subsequently removed from the land ecosystem and stored in an inert state or in a stable geological formation, thus locked away from the active atmosphere-land-ocean cycle.

  33. #37 Brian,

    James Hansen said recently that he estimates that the upper limit to bio-sequestration with a maximum worldwide effort is the removal about 50 ppm CO2 from the atmosphere. As you say, it is not a substitute for emissions reductions.

    He also said that he thinks that climate models are overestimating the amount of heat going into the deep oceans. The implications for planetary energy budget are that the cooling effect of aerosols may be being underestimated. These have a very short residence time in the atmosphere and will be reduced as Asian nations clean up air pollution with likelihood of acceleration warming.

  34. Thanks for the link, quokka. I tried “The Climate Show” some time ago and found it so boring I didn’t go back, but I’ll check it out tonight.

  35. I’ve never understood the right-wing mind. Bang on about personal responsibility, but try to avoid it at all costs.

  36. ‘Per capita means bugger all – just a method of guilting whitey. Total emissions is what matter.’

    Incorrect: total emissions plus historical emissions are what matter, since CO2 and other greenhouse gases stay in the atmosphere for decades.

    Once you understand this, its simply churlish – and empirically wrong- to deny the extra responsibility of developed nations for warming

    Which is not to say developing nations mustn’t act – but Brian is right and pragmatic to note that helping them jump the CO2 intensive phase of development must be part of this. They have a solid argument that the problem was caused largely by developed countries – therein lies our added responsibility. To suggest otherwise is to simply, as I say, to suggest dodging responsibility for past actions from which we still benefit. Per capita CO2 emissions are simply a measure of that.

    Its an easy argument to sell to people from developed countries that its only about current emissions, today – but it lacks integrity, and more importantly, it lacks a scientific basis: the emissions in the atmosphere are not just today’s.

    Incidentally, The Greens would love a DD election – they’ll get twice as many seats. This is why one will never be called by a major party.

  37. Pope’s cartoon in the Canberra Times today is very good, noting the task ahead, and where we are, politically, about now.
    (Sorry – its not on-line so can’t link.)

  38. You are perhaps being rather harsh on Tiny Dancer. The question deserves a fair answer because in July 1971 the late and enormously respected Stephen Schneider made news headlines when he warned of the possibility of an approaching Ice Age.

    The story is told by Fred Pearce in a New Scientist article in December 2006, “The ice age that never was”. Over the three decades to 1970, global climate was dropping and this dip can be seen in in current temperature history charts.

    Pearce writes:

    ‘Schneider tried to calculate the likely cooling effect of anthropogenic air pollution and compared it with the possible warming effect of carbon dioxide emissions, which it was now clear were accumulating in the atmosphere.

    ‘In Schneider’s early calculations, published in Science in 1971, the cooling effect was dominant. He said aerosols might have doubled since 1900 and could double again in the coming 50 years. Even allowing for warming from CO2, this could still mean a 3.5 °C drop in global temperatures, which “if sustained over a period of several years… is believed to be sufficient to trigger an ice age”.

    At the same time, research into the history and timing of past ice ages made it clear that there had been many more than the four originally guessed at, their appearance driven by regular planetary wobbles. Worse, it was now clear that ice ages were the norm rather than the exception. According to Kulka, the most recent interval between ice ages appeared to have lasted only 5000 years. Our present interglacial had already lasted 10,000 years. An ice age was long overdue.’

    Schneider subsequently realised that he had overestimated the cooling effect from aerosols, and underestimated the warming effect of CO2. He concluded that the latter was around three times the figure that he had previously used, and published a retraction of his earlier paper in 1974.

    So that’s what happened to the predicted ice age – although “predicted” is too strong a term: it was only raised as a possibility. There was a 20-year period of genuine climate cooling, a young scientist (Schneider was 26 when his first paper appeared) made some mistakes and people who find it convenient to do so recast the events as “science predicted an ice age, which didn’t happen, so why should we believe science now when it predicts climate warming?”

    The 1971 paper is available at

  39. The propositon that the developed world has caused all the warming is offset by the proposition that the developing world wants to develop on the back of all the hard yards put in by the developed world and risk taken on in creating the political, technological and economic conditions for advancement of mans condition.

  40. To add to my last – as the majority here no doubt support organised labour’s opposition to free loaders when it comes to industrial relations, I have no doubt you would have a similar bias to opposing free loaders in other areas of economic development.

  41. MikeM, Tiny Dancer’s mistake might be excusable if it weren’t for the fact that anyone with the critical faculties and reading ability of a sea-urchin would already be aware that the global cooling thing had been thoroughly debunked.

    So no, no-one’s been particularly harsh.

  42. Razor at 44 – if you factor in the exploitation of developing world resources to achieve that state, and the destruction or disruption of existing technologies in colonized countries. You do know about that, don’t you?

  43. Not to mention the strangely inequitable distribution of those industrial developments during the colonial era.

  44. The aerosols that were responsible for the slight cooling from the 1940s to the 1970s were the sulphur-based aerosols, particularly sulphur dioxide, which were emitted by burning coal for electricity. In the 1970s it was realized that these aerosols were causing acid rain, and they were banned. As a result, their cooling effect on the atmosphere was removed, allowing the warming effect of CO2 to go unchecked. This is why global warming began to appear in the 1970s.

    From time to time some scientist suggests that we reintroduce sulphur-based aerosols to counter global warming, but the suggestion is invariably knocked back because the negative effects of acid rain far outweigh the negative effects of global warming.

  45. We try to emit less sulphur dioxide, that’s true. But it’s hardly “banned”, I think.

  46. @49/50 – yes, you are right – should have jsut left them all alone to their own devices. None of the bad, but none of the good either.

  47. With the side effect of not having people running around claiming that they only got there because we invaded them and helped them.

    A net good, I’d say.

  48. @silkworm

    From time to time some scientist suggests that we reintroduce sulphur-based aerosols to counter global warming, but the suggestion is invariably knocked back because the negative effects of acid rain far outweigh the negative effects of global warming.

    Not the only reason to be very wary of “active” geo engineering. Climate models are not good enough to give precise predictions of exactly what the effects may be especially at regional level. Even worse, you can’t just do a bit to see how it goes – the consequences would simply unmeasurable and lost in the climate noise. And once you start you probably can’t stop for a very long time. The immediate, rapid rise in temperature could well be disastrous.

    Not to mention the very thorny political problem of who takes the decision.

  49. For those interested there is more detailed information on the decline of ocean basicity and its impacts on marine organisms here
    This information is more scientific than the “anticipated impacts” photo included above.

  50. See also at Skeptical Science:

    Endorsed by seventy academies of science from around the world, a June 2009 statement from the InterAcademy Panel on International Issues (IAP) stated the following.

    “The current rate of change is much more rapid than during any event over the last 65 million years. These changes in ocean chemistry are irreversible for many thousands of years, and the biological consequences could last much longer.”

    The IAP also stated that, if atmospheric CO2 were to reach 550 parts per million (ppm) along its current rapid ascent from its pre-industrial level of 280 ppm, coral reefs around the globe could be dissolving.

  51. From the Oz. Professor Steffen said:

    “If we don’t have an effective global agreement and temperatures keep rising well beyond the 2C target . . . then it will be extremely difficult (for the reef) to adapt to these conditions.”

    Professor Hoegh-Guldberg, who heads Queensland University’s Global Change Institute said:

    “We need to act very decisively on emissions or we are not going to have anything called the Great Barrier Reef; we might have something called the great weedy reef.”

  52. quokka @ 38, the other main point from the Hansen interview was that the ocean was less than 1C warmer during the Eemian yet the sea level was 6m higher.

    Hansen is saying that the 2C guardrail is too high. Dangerous climate change starts before that.

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