“The actions to take the world economy to a sustainable, net-zero carbon dioxide pathway are well understood. Many are already being rolled out, are low-cost, and bring other benefits.”

This synthesis report, the closing chapter of the IPCC’s sixth cycle of assessment, is the most comprehensive analysis of climate change across the globe and the definitive stocktake of the committee’s work over the past seven years.

It finds human activities are definitively responsible for all global warming since 1850, reflecting more than a century of unsustainable and inequitable fossil fuel consumption and land use, and patterns of consumption and production.

The science is clear: the global surface temperature was 1.1 degrees higher in the decade between 2011 and 2020 than it was between 1850 and 1900, and greenhouse gas emissions have continued increasing.

In every region, people are dying from extreme heat. Climate-driven food and water insecurity is expected to worsen with increased warming, and when these risks combine with events such as pandemics or conflicts, they become even more difficult to manage, the report found.

Every future increment of global warming will intensify the many hazards, but deep, rapid, and sustained reductions in emissions could lead to a discernible slowdown in global warming within around two decades, the report says, and to discernible changes in atmospheric pollution within a few years.

All the modelled pathways that limit warming to 1.5 degrees, and those that limit warming to 2 degrees, involve rapid and significant – and, in most cases, immediate – emission reductions in all sectors this decade.

The report authors echo warnings from the International Energy Agency that new oil and gas field exploration must end, and new coal-fired power stations should not be built. The carbon emissions from existing and planned fossil fuel infrastructure already surpass the remaining carbon budget for 1.5 degrees.

The ANU’s Professor Mark Howden, another of the report’s authors, said the IPCC’s summary left no doubt climate change was a present danger to people and to natural systems.

“It triggers many alarm bells that we cannot afford to ignore,” Howden said.

“There’s also intergenerational equities which are highlighted: a child born now is likely, on average, to have experienced three to four times as many extreme climate events in their lifetime as their grandparents did.”

Vulnerable communities that have historically contributed the least to climate change are the worst affected, and in the past decade, deaths from floods, droughts and storms were 15 times higher in highly vulnerable regions, the report summary found.

“Climate justice is crucial because those who have contributed least to climate change are being disproportionately affected,” said Aditi Mukherji, an IPCC report author.

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Not only do clean energy and technologies reduce climate pollution, they are also good for global health, the report finds, as the benefits for people’s health from air quality improvements alone are roughly the same, or possibly even larger, than the costs of reducing or avoiding emissions.

Greenpeace Australia Pacific chief executive David Ritter described the IPCC findings as a “screaming siren” and a call to action to use solutions already at hand.

“We must cut emissions faster, and overcome the vested interests that corrupt our democracy and stand in the way of deploying vital solutions at vast speed and scale, to secure the survival of millions of people, whole ecosystems and innumerable species,” Ritter said.

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