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What the IPCC Report Means for Australia

The latest IPCC Assessment Report on climate change was released last month, three months before the UN Climate Change Conference (COP26) in Glasgow. Ian Hore-Lacy and Chris Mulherin discuss what the report says, its implications for Australia—and suggest what they acknowledge is one “provocative” future possibility.

This article originally appeared in the September 2021 issue of The Melbourne Anglican.


How should we think about climate change? On the one hand, there are the more politically correct views that speak of a climate emergency. On the other hand are those who point out that the climate has always changed incrementally so they deny either that there is a problem or that human intervention can amount to much.

Then there are more nuanced positions, addressing diverse options for action against cost and practicality, while calling out unwarranted claims. Hope, they say, is both realistic and psychologically necessary. And for Christians, of whatever climate-change persuasions, hope in the God who is sovereign should be part of their perspective. Another essential contribution to a Christian (or any other) perspective—whatever “position” we take on the issues that face us—should be the very best science.

The science of climate change is monitored and reported on by the IPCC—the Intergovernmental Panel on Climate Change—which reports every few years on the scientific consensus. Each IPCC Assessment Report is made of parts produced by three Working Groups. And, if you were watching the climate news in August, you will have noticed that the Working Group I report on the physical sciences (AR6-WGI) is out now.

AR6-WG1 was released with a good deal of fanfare as the Glasgow climate change conference in November approaches. It is an impressive publication of more than 3700 pages, plus a 150-page Technical Summary and a shorter Summary for Policymakers urging action on emission reductions.

In great detail, the AR6 scientific report shows little that is new or changed from its predecessor AR5 eight years ago; nor is the content unexpected. It confirms the IPCC conclusion that most observed global warming is caused by human activities: that’s just over one degree of warming in a bit more than a century. And, for the first time, the IPCC report provided detailed regional assessments.

Although it doesn’t convey any impression of the science being settled, AR6-WGI does significantly firm up our understanding of the complex science involved in the world’s climate, so we have a better idea of what is happening. That’s a great starting point for Christian concern about being responsible stewards of God’s creation.

On the basis of more accurate science, the report’s scenarios to 2100 are clearer and cover a broader range of emissions futures than AR5; there is less uncertainty due to better understanding of climate drivers and feedbacks. The possible futures outlined include high CO2 emissions scenarios without climate change mitigation, as well as a low CO2 emissions scenario reaching net zero CO2 emissions around mid-century. Lower emissions lead to less warming and associated climatic and ocean effects. The report also tones down some earlier, more alarmist, possibilities regarding so-called tipping points and runaway climate change. It says, with a high degree of confidence, that “net zero” is our only long-term option:

The near-linear relationship between cumulative CO2 emissions and maximum global surface temperature increase caused by CO2 implies that stabilising human-induced global temperature increase at any level requires net anthropogenic CO2 emissions to become zero.

However, the science can only take us so far. It is up to governments to decide how to respond to the best information to hand: “So what?” is the pertinent question, as science hands over to politics and ethics. There is no obvious reason why the world cannot adapt to envisaged changes in climate, though that will clearly be easier in the reduced emissions scenarios.

The stark question that must be resolved is how to achieve those reduced emissions when the main emitting countries have no immediate intention of reducing, and in fact are clearly increasing their emissions strongly. Apart perhaps from the US with 15 per cent of world CO2 emissions (versus China, India and Russia with 40 per cent between them), there is nothing that any other country can do that will make any substantial difference to world climate. So, those Western governments with tiny shares in the climate-change pie must balance the value of setting an example against practical economic management. Like decisions in the current COVID crisis, there are many opinionated lay “experts” and vested interests, but the burden is on governments to weigh up ethical aspects and long-term implications of all courses of action.

What might that mean for Australia? One obvious policy proposal is to reduce from our more than 50 per cent reliance on coal for electricity generation. But replacing reliable, dispatchable generation with intermittent renewables such as wind and solar incurs rapidly increasing system costs as the proportion of renewables rises. No country such as ours (without the ability to import and export electricity) has yet achieved any major replacement of reliable sources with wind and solar.

To end on a provocative note, if Australia wants to head anywhere near “net zero” CO2 emissions, we will probably need to rely heavily on nuclear power—historically far safer than coal and part of God’s abundant provision for humanity. However, to put that option on the table requires a significant change in policy that is long overdue.


Ian Hore-Lacy is a fellow of ISCAST—Christians in Science and Technology, author of ‘Responsible Dominion: A Christian Approach to Sustainable Development’, and Senior Adviser for the World Nuclear Association.

Chris Mulherin is Executive Director of ISCAST and tutors in Introduction to Climate Change at the University of Melbourne.

The AR6-WGI report and shorter versions can be found on the IPCC site: www.IPCC.ch