The Intergovernmental Panel on Climate Change (IPCC) has released the first part of its Sixth Assessment Report, Climate Change 2021: The Physical Science Basis (IPCC Report).
The IPCC prepares comprehensive ‘Assessment Reports’ about knowledge on climate change, its causes, potential impacts and response options. The Working Group I contribution to the Sixth Assessment Report is the scientific understanding of the climate system and climate change, with unreleased contributions from Working Group II focusing on impacts of climate change and vulnerability, and Working Group III concentrating on mitigation of climate change.
The most recent IPCC Report was finalised on 6 August 2021 and forms part of the most comprehensive study into climate change to date. Since the last IPCC report in 2014, the Fifth Assessment Report, there have been various scientific improvements to allow for an “improved understanding of human influence on a wider range of climate variables”. These improvements still equal the same underlying finding –
“It is unequivocal that human influence has warmed the atmosphere, ocean and land.”
The IPCC Report notes that in 2019 carbon dioxide concentrations were higher than at any time in the last two million years, and that there is a 66 to 100 per cent chance the atmosphere has warmed by 1.07°C from 1850–1900 temperatures. The last IPCC report in 2014 noted a smaller rate of increase in global temperatures from 1998 to 2012. However, this was a temporary event, with the past five years being the hottest five years in the instrumental record since 1850.
More relevantly for Australia, the findings are more extreme. Based on the scales of scientific confidence used by the IPCC, there is very high confidence or “at least a nine out of ten chance” that Australia has already warmed 1.4°C since 1910.
There is medium confidence that the last time Earth was this warm was at the Last Interglacial around 125,000 years ago, which was caused by orbital variations that take thousands of years to have an effect. There is also medium confidence that the last time global surface temperature was sustained at or above 2.5°C higher than 1850–1900 temperatures was more than three million years ago, before a land bridge connected North and South America.
The IPCC Report acknowledges that we have locked in temperature increases until at least the mid-century under all emissions scenarios, and provides a clear and authoritative understanding of how the Earth’s climate is changing. This presentation of climate science will be relevant when world leaders meet at the next climate summit in Glasgow in November this year, particularly, in discussions on strengthening Nationally Determined Contributions under the Paris Agreement and deepening emissions reductions.
Politically strategic climate change litigation has been an increasingly utilised tool for seeking systemic change and compensating losses caused by climate change. As of January 2020, the total number of climate change cases filed globally has reached approximately 1,444, up from 1,302 in 2019, according to the Climate Change Litigation Database.
As noted in the IPCC Report, advances in scientific understanding of climate change are influencing this expansion of climate litigation. Attributing extreme weather and impacts from warming to specific events and losses has overcome a significant hurdle that caused many early climate cases to stumble at the causation issue. The causation argument, drawing links between emissions and harm, manifested in different forms. For example, ‘Australia only emits 1.1% of global emissions’ or ‘emissions from one coal mine cannot be linked to loss in one indigenous community’.
The IPCC Report represents a clear scientific consensus that humans are responsible for climate change and provides an opportunity for climate litigation to better establish the relationship between emissions and harm, and to quantify the environmental impact of projects, policies and laws. We have already seen how authoritative climate science can impact judicial decisions overseas, such as in Urgenda Foundation v. State of the Netherlands, but also increasingly in Australia.
Earlier this year, the Federal Court of Australia in Sharma v Minister for the Environment  FCA 560 found that the Commonwealth Minister for the Environment has a duty to exercise discretion under the Environment Protection and Biodiversity Conservation Act 1999 (Cth) with reasonable care so as not to cause Australian children harm from the extraction of coal and subsequent emissions. Justice Bromberg was able to find a novel duty because the Minister would foresee that the approval of a coal mine extension would expose young people to a risk of personal injury. All of the unchallenged evidence of climate change remains available to the Minister and was to be regarded as being within her knowledge. Because the Court established that “a risk is real and foreseeable”, the Court was willing to accept that the emissions from the expansion of the coal mine, even if only “infinitesimal”, will contribute to warming and may surpass a tipping point. This judgment relied heavily on IPCC findings, referring to “IPCC” 31 times.
Another recent example of successful climate litigation in Australia is a New South Wales Land and Environment Court case, Gloucester Resources Limited v Minister for Planning  NSWLEC 7. In this judgment, Chief Justice Brian Preston refused development approval for a new open cut mine that would produce 21 million tonnes of coal. The refusal was based on various grounds, including the direct and indirect contribution of the mine to climate change. The Chief Justice referred to the IPCC as “the world’s most authoritative assessment body on the science of climate change”, using its findings to support the conclusion that “all of the direct and indirect emissions of the [coal mine] will impact on the environment” and that the causal link provides justification for refusal. It is highly likely that without IPCC research and findings, it would be harder for courts to conclude that new coal mines should be refused –
“In short, an open cut coal mine in this part of the Gloucester valley would be in the wrong place at the wrong time.”
Themes litigants struggled with around causation, calculating loss and politicisation are remedied by authoritative, non-partisan climate science such as the recent IPCC Report. While the latest IPCC Report findings are dire, they provide another important tool to support climate litigation in every jurisdiction, including in Australia.
Authors: Dr Joseph Monaghan & Christopher Watt
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