EXPERT REACTION: The biodiversity benefits of limiting warming to 1.5°C

I’m not sure that there are too many surprises here and these types of predictions have been made before.

The authors add invertebrate data which I agree is worthwhile but many invertebrates also have a substantial adaptive capacity and high inherent rates of increase which can reduce impacts and increase the ability to counter climate change through evolutionary changes and through plastic changes in phenotypes such as using diapause to avoid extreme events.

I don’t have access to the methods section but it looks like the authors have undertaken correlative climate modelling which does not really consider adaptive capacity and has been criticised in the past. There are also winners under climate change whose distributions will expand. And there are drivers other than climate change which will be important for invertebrates and other species. For instance the paper mentions a german study showing a decrease in insect biomass (not populations as mentioned in the study here) of 75%. But in that paper the authors indicate that this decrease in biomass is potentially associated with habitat destruction and chemical use, not just climate change.

So you can’t decide that one factor is a driver without considering all components. I don’t doubt that climate change will lead to negative effects on the distributions of many species but there are other factors that will act to reduce impacts and these are likely not captured by the approaches used here, and of course there will also be winners

Climate scientists are tired of understating the case and no amount of talking seems to be getting the message across that we need to change if we care about the entire planet's wildlife, including us. 

A paper just published in Science by a UK and Australian collaboration led by Dr Rachel Warren of the Tyndall Centre for Climate Change Research is a mighty effort as a piece of research, but it's also a mighty effort in trying to paint a silver lining on a thundercloud. Habitat loss of species is a good proxy for pressures towards extinction and this paper simultaneously tells us how many species we could 'save' by delivering on the Paris agreement. The problem is that the subtext outlines our actual effects on the demise of the world’s species and adds another 150,000 species or so on top of past and vast efforts to measure it. 

It's an appropriately sober, careful analysis, so what lies beneath its beautifully dry and scientific language? Let’s cut to the chase; first, it’s already happening worldwide, as the authors point out. Second, it’s conservative. It doesn’t even begin to look at ecological interactions, natural disasters, or tipping points.  So, be assured, whatever it implies is already something of a ‘best case’ scenario. 

The worst hit? Insects and plants. Including all the wonderful little beasties that pollinate 80 per cent of our foodstuffs before it’s packaged up in plastic and wacky advertising crap and sent around the world to satisfy urbane tastes for perfect specimens of ‘out of season’ produce. Go out in the garden and tell me the last time you even saw a bee? Then amphibians; children love frogs - I did. Then all the rest of the world’s creations beloved of most of us under the guidance of the great and sainted David Attenborough. Say goodbye to Paradise. Oh, and Australia. Australia is one of those countries that benefits the most if we actually got off our fat arses and did something about it all. But that’d be a bit inconvenient, wouldn’t it?

Heatwaves are already causing mass die-offs of coral reefs, possums, flying foxes and lizards. Mathematical models suggest such calamities could escalate rapidly as the thermometer rises, and that even small differences in future temperatures will be hugely important biologically.

It is quite obviously that near-term climate change will reshape the living world. Biological systems are finely posed, and the current changes in climate will result in both gradual and sudden collapses of biological systems.

Worse, there are amplifying effects of climate change like extreme weather events, fires and irruptions [sudden increases in populations] of pests and diseases. All these ecological changes are in train now, some are in plain sight.

The surprising thing is there is not more self-interested concern globally that natural and production landscapes and seascapes are on the brink of ecological collapse and that this will affect our health, food security and economies.

Australia has the worst recent extinction record of any country in the world. Zoos Victoria has committed that no Victorian terrestrial vertebrate species will go extinct on our watch – a commitment made more difficult by the many unknowns associated with a changing climate.

The research by Warren et al. suggests that Australia is one of the countries most likely to be affected by increased global temperatures. This is particularly concerning for animals restricted to Australia’s alpine region, like the critically endangered mountain pygmy possum, alpine she-oak skink and Guthega skink.

These species are highly adapted to colder environments and would be threatened by warmer temperatures, changes to food sources, encroachment from other species into their habitat and increased fire risk. The mountain pygmy possum, for example, requires a thick blanket of snow to safely hibernate and survive winter. They also rely on migratory Bogong moths as a key food source – the loss of invertebrates, as suggested by this new research, could be catastrophic.

While this is a global issue, as the world’s first carbon neutral zoos, we know there are small changes everyone can make to reduce their footprint and assist species conservation, like reducing your waste, reusing products and recycling.

This study adds to the growing body of evidence that finds large benefits in achieving the Paris global warming targets. It is remarkable that achieving the 1.5°C global warming target relative to the 2°C target has such a big effect on the numbers of species likely to experience large losses in their geographic range.

This and other studies are helping to quantify the benefits of limiting global warming to the 1.5°C target and they are stacking up. If we are to meet the Paris global warming targets and reap these benefits then stronger emissions reductions are necessary.

Once again, evidence is growing of the need to limit the rise in global temperatures, with this Science paper showing specifically how serious the impacts will be on global biodiversity. With a wide range of species and taxa being discussed, it is clear that restraining temperature rise to 1.5°C above pre-industrial levels will reduce the risk of biodiversity loss and extinction much more than even the achievement of the more generally accepted 2°C target of the current climate negotiations.

This is clearly a massive challenge, since we are already struggling to agree on how higher limits can be achieved. Mitigation measures to reach these goals put a massive challenge on land-use actions, with vast areas of land dedicated to carbon capture likely to exacerbate any impact of warming on habitats and species.

All of this indicates the need to recognise the urgency of the need for adaptation. We humans have to recognise that it is up to us to build the future we want. As the authors point out, biodiversity through insects, birds and microbes is what drives our food system, and if we don’t want to face global famine in the not too distant future, we must act now. This means we need to protect larger and more diverse areas of the planet and all its biomes [communities of plants and animals that have common characteristics for the environment] if we are to ensure that the ecosystem services, which underpin our life-support system, are going to continue to be available for future generations.

This is particularly relevant for the east coast of Australia, which already has the dubious title of world leader in land clearing (and thus habitat loss) amongst all of the developed nations.