Australasian Science: Australia's authority on science since 1938

The Biodiversity Benefits of Limiting Warming to 1.5°C

By Australian Science Media Centre

Global temperatures are on track to rise by 3.2°C by 2100. A new study estimates that if this occurs, 26% of vertebrates, 49% of insects and 44% of plants would be unable to survive in about half of the areas they currently inhabit, compared with just 4% of vertebrates, 6% of insects and 8% of plants if warming is limited to 1.5°C.

A paper just published in Science by a UK and Australian collaboration … 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.

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% 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.

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?

Dr Paul Read is an ARC Research Fellow at the University of Melbourne.

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.

Professor Ary Hoffmann is from the Faculty of Biosciences at the University of Melbourne.

“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.

Dr Andrew King is Climate Extremes Research Fellow at the ARC Centre of Excellence for Climate System Science, University of Melbourne.

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... 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 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.

Professor Caroline Sullivan is Establishment Director for the National Centre for Flood Research, and from the -Marine Ecology Research Centre at Southern Cross University.