There’s still time to act but no time to delay: UN climate report lead author

The next two decades are particularly critical. It will require sustained and concerted global efforts targeting rapid reductions in CO2, methane and other greenhouse gases to limit warming to 1.5°C.

It’s not too late to cap global warming to 1.5oC under the Paris agreement adopted by 191 nations, but we must step up action swiftly, says Monash University’s Associate Professor Shayne McGregor - a chapter three lead author of the latest UN Intergovernmental Panel on Climate Change (IPCC) Report, released today.

Even with the welcome acknowledgement of international governments on the role of humans in climate change, symbolised by the ratification of the Paris agreement in 2016, Associate Professor McGregor says there is still a long way to go to adequately address the changing climate.

The report warns that without sustained, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5°C or even 2°C will be beyond reach.

However, strong and sustained reductions in emissions of carbon dioxide (CO2) and other greenhouse gases over the next 20-30 years could limit climate change and see global temperatures stabilise, according to the report.

Associate Professor McGregor, from the School of Earth, Atmosphere and Environment, says our biggest fear should be of inaction when it comes to decreasing greenhouse gas emissions.

“Every small increase in warming leads to greater impacts. We are already seeing the consequence of human impacts on the climate with near global increases in heat and rainfall extremes, which have had severe impacts in many parts of the world, including Australia,” Associate Professor McGregor says.

“The next two decades are particularly critical. It will require sustained and concerted global efforts targeting rapid reductions in CO2, methane and other greenhouse gases to limit warming to 1.5°C in line with the Paris agreement.”

The report is the first instalment of the IPCC’s Sixth Assessment Report (AR6), due to be completed in 2022.

Climate science has progressed significantly since the last report in 2013. The global climate changes outlined by the first IPCC Climate Assessment Report in 1990, and echoed in subsequent reports, have been observed, and remain true for the future.

Associate Professor McGregor’s work on Chapter three assessed the impact of humans on past climate changes.

He says the report confirms that human influence has unequivocally warmed the climate system since pre-industrial times.

“Human activities have led to current atmospheric greenhouse gas concentrations that are unprecedented in the past 800,000 years,” Associate Professor McGregor says.

He says human influence has also been directly linked to temperature and rainfall extremes, the global retreat of glaciers since the 1990s, decreases in arctic sea ice between 1979 and 2019, a warming global ocean, and global sea level rise, which is changing three times as fast now as it was before 1971.

“In Australia for example, land areas warmed by around 1.4°C between ~1910 and 2020, largely due to human influence, while heat extremes increased and cold extremes decreased. These heat and cold extreme changes are projected to increase in the future and their magnitude is almost directly related to the level of warming reached,” Associate Professor McGregor says.

“It’s time to play the long-game like it’s our last game. Every bit of warming we mitigate with greenhouse gas reductions will reduce the risk of dangerous, irreversible, climate changes occurring.”

The landmark report incorporates a greater scientific understanding of climate change, while the new generation of climate models and new climate scenarios detail the possible future climate changes expected with various levels of emissions reductions in the future, providing policy makers a clearer understanding of the impacts of any actions taken.

For the first time, it also provides a more detailed regional assessment of climate change, to inform risk assessment, adaptation, and decision-making.  There’s also a new framework that helps translate physical changes in the climate – heat, cold, rain, drought, snow, wind, coastal flooding – into what they mean for society and ecosystems.

Climate change initiatives at Monash University

Monash is working at the frontiers of global climate and sustainability research through specialised and innovative institutes and research centres, along with every faculty of the University. With a focus on putting research into practice, Monash is helping to redefine how we live and thrive in a changing climate.

Associate Professor Shayne McGregor is based in the Monash School of Earth, Atmosphere and Environment (EAE), which includes one of the finest groups of weather and climate scientists in Australia, investigating everything from fundamental processes controlling rainfall and Antarctic ice sheet melting, to climate change predictions using computer models.

Reducing uncertainties in future climate projections requires cutting-edge science. The EAE is contributing to this through specialised projects and research institutes including the ARC Centre of Excellence in Climate Extremes (CLEX), the ARC Special Research Initiative in Excellence in Antarctic Science, which includes a global collaboration directed by Professor Steven Chown to Secure Antarctica’s Environmental Future (SAEF).

Monash IPCC authors

Monash authors invited to represent Australia's contribution to current and previous IPCC reports include Shayne McGregor AR6 WG1, Nigel Tapper AR6 WG2, Andrew Mackintosh - Special Report on the Oceans and Cryosphere in a Changing Climate, Julie Arblaster - AR5 WG1, Christian Jakob - AR5 WG1, Scott Power AR5 WG1, and Neville Nicholls - Special Report on Managing the risks of extreme events and disasters to advance climate change adaptation.

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