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The koala in the coalmine

If we need an indicator that climate change is upon us, we need look no further than Australia’s koala. The koala family (Phascolarctidae) has existed in Australia for tens of millions of years, yet in…

Wild koala in the Western Downs region of Qld exhibiting abnormal behaviour due to drought conditions. P. Murphy, December 2009

If we need an indicator that climate change is upon us, we need look no further than Australia’s koala.

The koala family (Phascolarctidae) has existed in Australia for tens of millions of years, yet in a mere evolutionary blink of 200 years, this unique Australian marsupial is declining significantly in many areas of its natural range.

Koalas are highly vulnerable to unprecedented heatwaves and just like humans, they suffer from heat stress and dehydration in extreme temperatures. Bushfires such as the Coonabarabran fires that burnt out 100,000 hectares can also decimate koala and other wildlife populations.

In the past decade, we have experienced the hottest temperatures on record followed by floods and cyclones. While many climate change cynics claim that this is just part of the natural climate variability (Dorothy McKellar’s Sunburnt Country hypothesis), the evidence suggests that recent extreme weather events are not typical.

Rather, they are becoming more common and going beyond the natural range of variability. For example, Roma in southern inland Queensland, experienced record flooding three years in a row and has now experienced record January temperatures. Across western Queensland and New South Wales, temperatures remained in the mid to high 40s for 10 days. These changes in climate are consistent with climate change predictions; a hotter climate with extreme wet periods such as that experienced in Queensland and northern New South Wales in late January.

Our research on the effects of climate change on the distribution of koalas and their eucalypt food resources used a “pessimistic” climate change scenario that represents a future of rapid economic growth, a global population that peaks in mid-century and a continuation of high energy demand being met by fossil fuel sources.

This was the correct choice. That scenario is no longer pessimism, but is tracking reality.

Our climate envelope modelling found that koalas occur at a maximum temperature of 37.7°C. However, the recent Australian heatwave and the weather conditions before the Black Saturday bushfires in 2009 - with temperatures exceeding 40°C for consecutive days - are two examples of the koala being pushed beyond its climatic threshold.

Koala population crashes have been documented after such drought and heatwave events, most recently an 80% decline in the Queensland Mulgalands following the 10-year drought.

In New South Wales, Queensland and the ACT, where koalas are now listed as vulnerable under Commonwealth law, our research has found that koalas and many of their critical food trees will contract and shift eastwards. Here, potential “climate change refugia” are rapidly diminishing due to urban development.

By 2050, the only climatically suitable areas for koalas and their habitat will occur in patchy regions closer to these coastal areas. In these areas, their numbers are often sharply declining due to other factors such as habitat loss, disease, cars collisions and dog attacks.

We should take heed from what is happening to the koala because it is likely that our agriculture and towns will be facing similar risks from climate extremes; well beyond our limits to adapt to.

How can people and the natural environment, upon which human wellbeing and in fact survival depends, co-exist? It is time for all our decision-makers to recognise the urgency of the problem, look to the future and proactively address the fundamental challenges of environmental sustainability and climate change mitigation. Our very future depends on it.

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24 Comments sorted by

  1. Frank Arthur

    logged in via Facebook

    People are part of the natural environment. It’s partly because many seem to think they are separate from it that we are facing such huge environmental problems.

  2. Chris Owens


    Meanwhile in a parallel universe, the deniers are about to take government and wind back the few feeble measures taken.

  3. Robert McDougall

    Small Business Owner

    and of course the return on our superannuation is soooooooooo much more important.

  4. Tim Scanlon


    Interesting. How big an impact is the climate in comparison to encroachment and habitat loss? Also, is the impacts on the koala and its food equal or is one more impacted than the other?

    1. Christine Adams-Hosking

      Research Officer, Global Change Institute at University of Queensland

      In reply to Tim Scanlon

      Dear Tim,

      The predicted and already observed impacts of warming on koalas is acting in synergy with the other impacts you mention such as habitat loss.
      As for your other quesiton of the impacts on koalas and their food trees, this varies spatially across the landscape. Ecology is very complex.

    2. Tim Scanlon


      In reply to Christine Adams-Hosking

      Thanks Christine. That confirmed my thinking, but I just wanted to check if there were any 'simple' results. I'd imagine the trees are suffering based upon recharge, and rainfall, which will vary with soil type and area, much as they are here in WA.

  5. Comment removed by moderator.

    1. In reply to Gerard Dean

      Comment removed by moderator.

  6. Gerard Dean

    Managing Director

    Can the authors be taken seriously when they write over the top statements such as, "We should take heed from what is happening to the koala because it is likely that our agriculture and towns will be facing similar risks from climate extremes; well beyond our limits to adapt to."

    Humans are a very adaptable and nasty animal. We can live in the extremes of the Saharan Africa to the bitterly cold arctic regions.

    Koalas are threatened because we are taking more and more of their land with our urban sprawl. Country towns are struggling not because of hot days, rather because of farm mechanisation and depopulation.

    This article is big on emotive climate change spin and small on the real reasons for the decline in koala numbers.

    Move on, nothing to see here.

    Gerard Dean

  7. John Nicol

    logged in via email

    One has to wonder what stimulates people to write an article such as this, claiming "scientific" understanding, when so much of what has been written is so easily met with counter arguments.

    The koala, lives in an extraordinarily diverse environment from the top of Cape York, to Melbourne, on the islands, in the inland regions, where they are subject to horrendously varied conditions. The suggestion that even 5 degree increase in temperature is going to cause them distress boarders on the…

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    1. Mike Swinbourne

      logged in via Facebook

      In reply to John Nicol


      I think the thing that stimulates people to write articles like this claiming a scientific understanding is.... a scientific understanding. And that begs the obvious question - what stimulates people like yourself to write long diatribes when you obviously completely lack any scientific understanding of the subject?

      Did you know that the koalas that live in Cape York are different to the koalas that live in Victoria?

      Did you know that the eucaplypts they feed on are different, and…

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  8. Eric Vanderduys

    Ecological Researcher

    I think this article is quite confused, and unfortunately adds little to climate change discussion, and the effects thereof. The opening paragraph "If we need an indicator that climate change is upon us, we need look no further than Australia’s koala" is a strong statement, yet the article provides no, or at best weak, evidence for it. I believe that Koalas are threatened by a large number of processes, listed in this article and others in The Conversation by Christine. I also believe in climate…

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    1. Nick McKenzie

      Account Manager

      In reply to Eric Vanderduys

      Is it possible that climate change and habitat loss, while relevant, are not the main concern for Koala's?
      I think a major point of fact overlooked in the article is the change in our countries bush fire regime... Since European settlement and the cessation of 'fire stick' farming etc etc, many now believe our fires, while not as often and not as many, are much larger, much hotter and threrefore much more destructive!
      Surely this would have some sort of effect on an animal that lives in flammable tree's..........

    2. Eric Vanderduys

      Ecological Researcher

      In reply to Nick McKenzie

      Hi Nick, It is possible (and I agree) that climate change may not be the main concern for Koalas. I think that habitat loss is a major concern for them. I think fires are very important - not necessarily always bad - but certainly important. Teasing out the effects of different types of fires (e.g. hot, late dry season vs cool, patchy early dry season), is a very challenging area of research but a fair bit of it is happening. I think we can be sure that "the answer" to the question "what's the best fire regime?" will very much depend on desired outcomes, species/ecological communities targeted.

    3. Dianna Arthur


      In reply to Nick McKenzie

      Loss of habitat is part of the problem we need to face.

      The changes we have wrought to ecosystems (such as deforestation) are a part of the damage we have caused along with flagrant use of fossil fuels, excess use of fertilisers, pesticides, development proceeding without or in disregard to environmental impact and the latest insult to the environment; hydraulic fracturing (fracking). All of which changes koalas' (and every other indigenous life-form & introduced species) habitats. Some plants…

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  9. Dianna Arthur


    Excellent article presenting the consequences of our actions on environment. If animals long adapted to Australia's often extreme climate are unable to cope with the increasing frequency of extreme weather events and we continue to ignore all that is happening here and around the world...

    How can we expect a Liberal party which has no climate policy (Direct Action being little more than empty words) to make long term progressive policies for the future? Interview with Tony Abbott on 774 this morning was a cringe inspiring 20 minutes - the only areas where Abbott did not stumble over his words was when he was on the 'safe' territory of fault finding in the Federal Government or claiming he could find the dollars that Labor apparently can't.

  10. Sally Boteler

    customer service officer at health & leisure

    Thanks for a great article.

  11. Philip Dowling

    IT teacher

    All animal populations vary over time. This is generally the result of a variety of factors. For a study to be scientific as opposed to descriptive, it would need firstly to identify each factor, and then to quantify the relative significance of that factor as a starting point. Feedback factors also need to be identified.
    Kangaroos for example control their fertility in times of drought.
    Implicit in many studies is the notion that populations should remain static based on some arbitrary point in time.
    Charles Darwin did not subscribe to this latter day view.
    Incidentally I found it puzzling that a particular population of koalas was ignored.

  12. Julie Squire


    Quick fact check: the Coonabarabran fires did not burn out 100,000ha - the largest, the Wambelong fire in the Warrumbungles, burned out 56,000 ha. There may be some conflation with previous fires in the region; in 2006 the "Pilliga 4" fire burned out 92,000ha of the Pilliga Forest (north of Coona); in 1997 a monster in the Pilliga Forest burned out 140,000ha. I happen to agree with the premise of the article - if the margins are changing it pays to watch marginal creatures. The koala is only one…

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  13. Caroline Copley


    I am trained in biology and have a different perspective, one that involves both speculation and reason. However I would like to say that although I personally think that Koalas may be a very climatically resilient animal, all species have limits of tolerance for temperature and other factors e.g. nutrients. It should be noted that carbon and nitrogen cycling are very closely linked in terms of the soil ( I have just learnt about this in my (upgrade) studies). Thus problems with climate do not…

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  14. Caroline Copley


    Afterthought to my post below.
    Recent research has found that placental mammals arose after the K-T boundary, and therefore were not tested by that event as were the marsupials, birds, snakes etc.
    Thus the marsupials have been through severe events and survived unscathed. Placental mammals, of which we are one, have been through the glacial-interglacials of the past few thousand years, as well as no doubt a few others prior to that.
    But do any of them compare to the K-T event, or to the current climate crisis, which is being severely exacerbated by habitat destruction?
    So do we really know what we are in for, and as the article implies, and will we get through?? I think that may even be a reasonable question rather than hysteria under the circumstances of the many resource issues (water, food, energy etc) we seem to have created, along with global soil decline and climate change.
    The koala knows.

  15. Erin Auguste

    logged in via Facebook

    I think Christine's article was grate , thanks for your information, I can see some people are getting mixed up with what she is trying to say ,yes there are many contributing factors to to Koalas decline , however yes I agree ,I believe the hotter climate is also affecting them , I live in Western Australia working with Koalas for over 15years in wildlife parks , captive koalas both Victorian and Queenslanders and each year I watch them suffer more and more in our summers ,drinking more water than usual and just not eating enough ,it gets worse each year ,koala means no drink its an aboriginal word for an animal that used to get its moisture from its food ,not any more koalas are drinking because there isn't enough moisture In there food ,love to hear more about this Christine