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Are you ready for a four degree world?

In mid-July, as Prime Minister Gillard began to stump the countryside selling her carbon package, a conference at the University of Melbourne considered the prospect of climate policy failure. Climate…

Bush fires are just the start of the problems we’ll see in a world four degrees warmer. Sean Marshall/flickr

In mid-July, as Prime Minister Gillard began to stump the countryside selling her carbon package, a conference at the University of Melbourne considered the prospect of climate policy failure.

Climate scientists agree that the existing gap between climate science and climate policy is profound. If the international community – including Australia – merely meets its current emissions targets, we will see average global warming of around 4°C by the end of this century, and perhaps 6 to 8°C in centuries thereafter.

For three days, scientists, bureaucrats and members of the public examined the impacts of a four degree world on Australia’s environment, society and economy. It is the world of dramatic consequences that the carbon tax debate has so far neglected.

The transformations, both gradual and extreme, would be profound. Modelling by CSIRO indicates that, by 2100, average temperatures could increase by about 3°C to 5°C in coastal areas and 4°C to 6°C in inland areas.

There would be likely decreases in annual rainfall in southern Australia of up to about 50% but uncertain rainfall changes in other regions. Snow cover would fall to zero in most alpine regions.

Even small changes in mean global temperature will lead to dramatic changes in extreme weather events. But, as CSIRO scientist Kevin Hennessy suggests, “a warming of 4°C is likely to lead to increases in extremely high temperatures, extreme daily rainfall, extreme fire weather, large hail on the east coast, [increased] tropical cyclone intensity and extreme sea level events [storm surges]”.

As the Bureau of Meteorology’s Dr Karl Braganza explains, over time, in a changing climate system, what seem like record heat waves or rainfall events now will in the future seem normal, even mild.

What would this mean for Australia’s native plants and animals? Levels of endemicity are particularly high among Australia’s mammals, flowering plants, fish, reptiles, frogs and birds; this means many of them are only found here. Many of these endemic species have extremely narrow climatic and geographic ranges, predisposing them to risk from rapid environmental changes in the future.

Professor Lesley Hughes of Macquarie University reports that even relatively modest future warming of around 1°C will also have negative impacts on some ecosystems.

All these predictions are likely to be greatly exacerbated at 4°C warming and beyond, with climate change becoming an increasingly strong driver of local, and eventually global extinctions.

The impacts on marine life would be equally profound. At 4°C, the world’s oceans will be, according to Professor Ove Hoegh Guldberg, warmer, more acidic and less oxygenated – a state that has no analogue in the past 20-40 million years.

Sea level rise of up to about 1.1 metres by 2100 would likely increase to more than 7 metres over subsequent centuries. We would lose major ecosystems such as coral reefs and kelp forests, and see the disruption of present day fisheries and aquaculture by ocean warming and acidification.

These impacts have severe domestic economic consequences. For instance, the multi-billion dollar tourism and fisheries industries based around the iconic Great Barrier Reef would collapse. Similarly, Australian farming – which has learned to cope with extreme weather and a wide range of climatic regions – would be substantially transformed.

CSIRO’s Dr Mark Howden argues that projected weather changes across the major agricultural production zones would lead to a decline in production of core agricultural commodities. The area viable for growing crops will also change significantly.

Australia’s food surpluses will likely shrink and potentially become negative in some years and in some scenarios: certain Australian farm exports will be severely affected, as will domestic food security.

It is hard to know if we can adapt to these changes. As Professors Will Steffen and Dave Griggs emphasize, changes compound each other and are global, not just continental.

At 4°C, there is a significantly higher probability of tipping elements in the Earth system being activated, with reverberations around the world, including Australia. Examples include significant and rapid losses of ice from the Greenland and/or West Antarctic ice sheets and the conversion of the Amazon rainforest to savanna or grassland.

The reduction in the resilience of natural and managed ecosystems will affect the resilience of socio-economic systems in Australia and around the world. It will increase their vulnerability to other global non-climatic stressors and shocks, such as emerging pandemics, trade disruptions or financial market shocks. The state’s capacity to fund adaptation, mitigation and emergency measures – to rebuild cities and replace infrastructure – will be placed under increasing pressure.

ANU’s Professor Tony McMichael suggests that, as a result, living conditions for human populations, in Australia and elsewhere, would be surprisingly different from today. The environmental (and social) foundations of wellbeing, health and survival would have been progressively damaged.

Previous rapid temperature fluctuations of 3-5°C, historically, have caused great hardship, suffering, death and social-political disruption around the world.

Australia’s population health will face much more than frequent heat waves and weather disasters. There will be food shortages, malnutrition, increases in many infectious diseases (including epidemic outbreaks), widespread depression, anxiety and rural misery, and tensions and conflicts over resource shortages, population displacement and refugee flows.

It is also hard to assess the implications for regional security, but drought and food shortages would cause displacement of up to 250 million people across West Asia, South Asia, South-East Asia and Indonesia by the end of this century.

Sea-level rise and storm water intrusion would cause further massive dislocation of coastal communities, the abandonment of coastal cities, and severe economic disruption in China, Bangladesh and Indonesia. The abandonment of uninhabitable low-lying islands in the Pacific would create displace whole national populations.

At one point during his keynote speech, Professor Hans Joachim Schellnhuber, Director of the Potsdam Institute for Climate Impact Research and former climate adviser to the German Chancellor and the EU, asks rhetorically: “What is the difference between two degrees (of temperature increase) and four degrees?”

“The difference,” he said, “is human civilisation”.

The explicit message of this conference, then, is that we need to cut greenhouse emissions urgently. As the Climate Commission has said, this is the Critical Decade for action.

In 2007 the IPCC indicated developed countries should reduce their collective emissions by between 25-40% below 1990 levels by 2020, to help stay below 2°C warming. That was before recent emissions data showed that we are tracking at above the IPCC’s most pessimistic projections, suggesting that cuts at the top end of this range are now required.

Australia is the world’s 10th biggest aggregate emitter. We have the world’s highest per capita emissions. We are one of the world’s most affluent countries. Yet Australia’s short term target of -5% below 2000 levels by 2020 is among the weakest of all industrialised and major industrialising nations. If adopted by all industrialised countries, our target would see global average temperatures rise by more than 4°C by 2100.

Our effort is neither fair nor equal when measured against that of other comparably wealthy industrialised countries like the United Kingdom (which has cut emissions by 23% and aiming to halve them below 1990 levels by 2025) or even the efforts of China and Brazil.

In this larger context, the modest and politically astute start to decarbonising our economy is a critical first step. But if it fails to gather pace quickly, the heavy price of a soft start – as the ‘Four Degrees’ conference outlined - will be paid for by our children and by future generations.

Conference presentations are available at: www.fourdegrees2011.com.au

Join the conversation

33 Comments sorted by

  1. Peter Miller

    Digital Artist/Sound Designer/Composer at Scribbletronics

    Yup. We keep sayin' it, they keep sticking their fingers in their ears and humming.

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  2. Marc Hendrickx

    Geologist

    Another groupthink humfest!

    On a related topic will The Con be covering the work of Macquarie Uni's Murry Selby?
    His recent speech to the Sydney Institute titled: “Global Emission of Carbon Dioxide: The Contribution from Natural Sources” seems to imply something's amuck with the IPCC's attribution of CO2 sources.

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    1. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Marc Hendrickx

      Hi Marc, Carbon cycle is my thing, so sure I can look at it. Can you send me the text (or better still link for text). Of course, those of us who actually work on this stuff don't get our information from the IPCC reports -- it's a bit out of date by the time it appears, and citing the IPCC means that those who did the original work wouldn't get credit.

      If you or Selby think that the IPCC reports misrepresent the papers that they cite, then you need to be more specific. If you think that the papers cited by the IPCC are wrong thing you need to say which papers (and then the normal thing would be to submit a comment to the journal concerned).

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    2. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Ian Enting

      As a follow up, there was a talk at Sydney Institute, titled
      "Atmospheric Science, Climate Change and Carbon – Some Facts"
      on August 2nd, by Murry Salby (not Selby).
      The link from Murry Salby on the http://www.thesydneyinstitute.com.au/functions/weekly-seminars/past-seminars/ page gives a "page not found" message

      The publication list for Prof Murry Salby at Macquarie U doesn't seem to list any publications to do with carbon emissions.

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    3. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Ian Enting

      The podcast has the title that Marc gave - it's just the events list that gives it differently. It doesn't show the slides (Tim Lambert at Deltoid has requested them). Still, I think Tim is on the right track - this is the McLean error recycled for carbon.

      A couple of odd things about the talk: who is "we" that he keeps mentioning?
      It was supposedly presented at an international conference: which? Some blog comment suggests IUGG, but only Salby et al talk seems to be on ozone hole rebound -- intriguingly…

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    4. Marc Hendrickx

      Geologist

      In reply to Ian Enting

      If you want more information Ian, I suggest you get in touch with Murry directly. According to the Sydney Institute talk there is a paper. apparently accepted coming out in the next 6 weeks. Perhaps staff at The Con could look into this?

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    5. Marc Hendrickx

      Geologist

      In reply to Mike Hansen

      Debunked by a blog! Hardly the way peer reviewed science operates.

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    6. Marc Hendrickx

      Geologist

      In reply to Ian Enting

      Ian, I'd be interested in your take on it. Perhaps you can pitch a story to The Con.

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    7. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Marc Hendrickx

      By the time I got to it this afternoon, what commonly happens on Judith Curry's site was in full swing -- the whole thing had degenerated into a slanging match. I think that is where I saw the statement that Salby had presented his talk at IUGG.

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    8. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Marc Hendrickx

      I gave a talk in Edinburg in 2007: http://www.ms.unimelb.edu.au/~enting/dtalk/fblt1.pdf
      which included stuff on this.
      Slide 6 shows the feedback loop between carbon and climate. What I think Salby meant when he talked about the "sensitivity" was the strength of the left side: how much CO2 per kelvin warming. This depends on the time-scale. Slides 14 and 15 show how a Laplace transform analysis can describe this.
      I suggest that the ice core data show that on the timescale of a century or so, the…

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    9. Mike Hansen

      Mr.

      In reply to Marc Hendrickx

      More importantly Marc, the Skeptical Science article was June 2010 so over 12 months before Salby's talk. LOL

      If your reading comprehension had not failed you you would have seen that the SKS article was in response to a similar idea raised on Watt's blog. Relevant to the discussion I would have thought.

      Why did you raise Salby's talk as it is not yet a "peer reviewed article" then?

      Happy to point to Curry's blog but not SkS.

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    10. Marc Hendrickx

      Geologist

      In reply to Mike Hansen

      I pointed to Curry's blog as it seems for some strange reason you forgot to mention it.
      I mentioned the article as an item relevant to the on going discussion that editors of The Con may have missed. Note that I did not endorse the article.
      Interesting that you have made your mind up on it before it's even released. Do you live in a permanent state of confirmation bias?

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    11. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Mike Hansen

      The idea of ocean warming causing large shifts in CO2 was analysed in the peer-reviewed literature decades ago. The conclusion was that the 100ppm increase from 180ppm to 280ppm was too large to be SOLELY caused by the glacial-interglacial temperature change influencing CO2 solubility -- so the much smaller 20th century warming would definitely be too small.
      However, if Salby is relying on carbon-13, then he is probably invoking land-processes as the mechanism and the ocean stuff is irrelevant. All…

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    12. Eclipse Now

      Manager of Graphic Design firm

      In reply to Ian Enting

      Hi Ian,
      great to read your informed posts. Do you have a podcast on climate matters that you would recommend for people like myself with a humanities background? I'm thinking of something that debunks the Denialist myths that are always circulating, and Australian in focus. (I wonder if someone could team up with John Scott of SkepticalScience.com?)

      Secondly; if global warming feedback loops start to cascade out of control surely we'll resort to "emergency use only" measures like the Sulphur Gun?
      http://eclipsenow.wordpress.com/sulphur-gun/

      Is anyone aware of experts in solar insolation & crop performance? How much would the sulphur have to reduce incoming solar energy to offset 2 degrees, and how would this reduced sunlight impact on agriculture yields and other climate systems, like the Indian Monsoon?

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    13. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Eclipse Now

      Just a quick follow-up on one point (hope to respond to others later)
      from your site:
      "In my lifetime there have been a number of volcanic eruptions that spewed out far more sulphur than we are talking about and slowed global warming — yet neither of these side effects were noticed. "

      the volcanoes caused an observable decrease in temperatures - slowing global warming - for a few years. there is a series of nice papers by David Thompson and collaborators. If you do a careful job on analysing the relation to SOI (unlike McLean, Carter, de Freitas) and one other large scale circulation pattern, you can see the volcanic influence decline over the 4 or 5 years after the eruption

      CO2 growth rate dropped after Pinatubo, plausibly less decay/respiration at lower temperatures was a bigger effect than any decrease in biotic productivity,

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    14. Eclipse Now

      Manager of Graphic Design firm

      In reply to Mike Hansen

      Don't we *know* that it is our Co2 causing the problem because we can measure the proportion of some atomic particle differentiation between fossil Co2 and natural Co2? C12 or C14 or something? (I can't remember).

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    15. Eclipse Now

      Manager of Graphic Design firm

      In reply to Ian Enting

      Thanks Ian.
      So — just to clarify — the volcanic sulphur achieved what the pro-sulphur-gun guys said it achieved, a lowering in temperatures without negative side-effects like reduced agricultural output? Awesome.

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    16. Eclipse Now

      Manager of Graphic Design firm

      In reply to Ian Enting

      Ian, I just found this by your man! Argh! Now I'm wondering if I'm recommending something that could muck up the Ozone layer?

      From

      http://tinyurl.com/3zpydg9

      The study also finds that when aerosols get into the
      stratosphere, very rapid reactions that destroy ozone (especially
      in high latitudes) take place on the surfaces of aerosol particles.
      When ozone gets depleted, less UV radiation is absorbed in the
      stratosphere. This cools the polar stratosphere, and increases
      the stratospheric equator-to-pole temperature difference,
      creating a positive phase of the Arctic Oscillation. Ozone data
      were obtained from NASA’s Total Ozone Mapping Spectrometer
      (TOMS) satellite and ozonesonde observations.

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    17. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Marc Hendrickx

      I have put some discussion on my website at
      http://www.ms.unimelb.edu.au/~enting/echo.pdf

      It covers some of what I have said here and at Deltoid. So far it is mainly looking at Roy Spencer's analysis. Jo Nova seems to be saying that Salby is similar. Thus to the extent that it is a criticism of Salby, it is a criticism of Jo Nova's version of Salby, not necessarily Salby's version of Salby. My understanding from Salby's podcast is that he has looked at more spatial detail than Spencer.

      My aim is to add to it, e.g. add some plots of the data, answer some of Eclipse's questions, and maybe even get around to giant planets.

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    18. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Eclipse Now

      We "know" that humans have been burning fossil fuel recently (oxygen decrease measured) and pre-1950 (declining radiocarbon levels in tree rings etc (after 1950, nuclear testing put i lots of radiocarbon into atmosphere)).

      beyond this, things are less direct, and attribution depends on what combinations of
      change do or do not occur.

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    19. Ian Enting

      Honorary Senior Associate, Faculty of Science at University of Melbourne

      In reply to Eclipse Now

      Most atmospheric scientists would regard sulphur gun type ideas as very much a last resort because of such (poorly undertaood0 side effects.

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  3. Stephen Prowse

    Research Advisor at Wound CRC

    Group think indeed, but we do need to be much much more focused on learning to live in a warmer world.

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  4. Bob Bingham

    Mr.

    It's encouraging to hear scientists being forthright about the outcome of climate change. They have to speak out and put the dreadful outcome that we are facing squarely before the politicians and the public as it is only with strong support of the majority of people that the politicians will do something. Right wing politicians like Tony Abbot and the American Republicans take too much notice of the carbon energy companies to do anything useful unless there is massive public pressure and they will lose their electorate.

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  5. Kevin Cox
    Kevin Cox is a Friend of The Conversation.

    logged in via LinkedIn

    Why will the temperature increase stop at 8 degrees? Is this the temperature at which radiation out will match radiation in, given current life forms on the planet?

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    1. Eclipse Now

      Manager of Graphic Design firm

      In reply to Kevin Cox

      Great question Kevin. And what is 8 degrees based on? The IPCC seems to indicate ever-increasing fossil fuel consumption up till 2100. But geologists are breaking away from largely economical assumptions at the USGS about how much oil, gas, and coal there is to burn in the first place. There is a new peer review organisation breaking away from the increasingly fantastic assumptions of the USGS based at Uppsala University, Sweden.
      These guys say we are at peak oil now, and will see peak gas and coal…

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  6. Danderson

    logged in via Twitter

    From fourdegrees2011.com.au

    "The international community has agreed to limit global warming to 2 degrees Celsius above pre-industrial levels."

    Amazing isn't it. A climate which has always changed previously is now going to be regulated by the international community.

    Well personally I wouldn't mind 3-4 degree on top of the current average, so if you don't mind just let it ride a bit further fellas.

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    1. Eclipse Now

      Manager of Graphic Design firm

      In reply to Danderson

      That's a rather trite post there Danderson. Yes the climate has changed due in the past due to natural forcings. Pretending — as you seem to — that this has somehow escaped the attention of climate science does not reflect on them, but you. I think if you had a *clue* about the anticipated effects of 3-4 degrees you *would* mind, very much so.

      I just checked, and "it's changed before" is the number 1 Denialist myth.

      As they say:

      "Natural climate change in the past proves that climate is sensitive…

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    2. Peter Miller

      Digital Artist/Sound Designer/Composer at Scribbletronics

      In reply to Eclipse Now

      Also, many people (like Danderson) seem to think of the temperature increase as a nice balmy overall warming, without understanding that it's more likely to be a clumpy assault of extreme temps and possibly colder than average swings. He might feel different if his home gets hit by a +8 degree heatwave. A global increase in temperature doesn't imply local increases, necessarily.

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  7. Mark Carter

    logged in via Facebook

    Considering almost trivial factors like a rise in oil price or an increase in ethanol production trigger food price spikes and widespread hunger, expect a 4 degree temp rise world-wide to bring food production to its knees, and us with it.

    The modern world is almost totally dependent on a handful of crops which have very narrow environmental requirements. The writing is on the wall folks...

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  8. Iced Volvo

    Phsycian

    "...Climate scientists agree that the existing gap between climate science and climate policy is profound...."

    What is even more profound is the gap between the predictions of the climate models (on which the 4 degree is based) and actual reality!!!

    As seems to be the norm (especially for The Con and the ABC) Christoff follows the trend of non scientists talking about science!

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