IPCC report reveals children expected to experience up to four times more extreme climate events

Temperatures in Australia have increased by 1.4 degrees over the last 110 years and it is more likely than not global temperatures will reach 1.5 degrees of warming in the near term, the Synthesis Report found.

Scientists from 47 countries agreed it was unequivocal human influence had warmed the atmosphere, ocean and land and every additional degree of warming was having cascading consequences, with developing nations bearing the brunt of extreme weather events while contributing the least greenhouse-gas emissions.

The report found while choices now will determine the extent to which today's children will live in a hotter world, the current trajectory is for a high-emissions future by 2100.

Under a high-emissions scenario, a child born in 2020 would live in a world that is about 3.5 to 4 degrees hotter than today by the time they are 80-years-old.

Mark Howden, a Vice Chair of the IPCC Working Group, said the current trajectory showed significant risk of increased heat waves, droughts, floods and cyclones.

In terms of the world children were inheriting, Professor Howden said the data showed potential for irreversible changes in terms of sea-level rise, species extinction and significant challenges in terms of future air quality.

"As the impacts mount, our capacity to deal with those impacts actually reduces," he said.

The latest IPCC report was adopted by all 195 member states following government negotiations ahead of the conclusion of the 58th Session of the IPCC in Switzerland on Monday.

The Synthesis Report integrates the main findings of the Sixth Assessment Report, which uses thousands of scientific papers to provide governments with information to develop climate policies.

Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have already occurred as a result of global-surface temperatures rising, the IPCC found.

Global-surface temperatures reached 1.1 degrees above 1850-1900 levels in 2011-2020 and it is now considered more likely than not to reach 1.5 degrees even under a very-low greenhouse-gas emission scenario.

Professor Howden said in almost all emission scenarios global warming reaches 1.5 degrees in the first half of the 2030s.

"The choices we take now will have consequences in coming decades and potentially for thousands of years," he said.

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To limit warming to 1.5 degrees, emissions would need to have declined by about 60-65 per cent on 2019 levels by 2035, and continue being cut over the following years.

Hard-to-abate residual emissions, including those from agriculture, aviation, shipping, and industrial processes would need to be counterbalanced by carbon dioxide removal methods.

With further warming, every region is projected to experience concurrent and multiple changes in climatic impact drivers more frequently.

Compound heatwaves and droughts are projected to increase, including concurrent events across multiple locations.

Due to relative sea level rise, current 1-in-100-year extreme sea level events are projected to occur at least annually in more than half of all tide-gauge locations by 2100.

Other projected regional changes include the intensification of tropical cyclones and increases in aridity and fire weather.

The IPCC report found limiting warming to 1.5 degrees and 2 degrees would involve rapid, deep and in most cases immediate greenhouse-gas emission reductions.

While some future changes were found to be unavoidable or irreversible, they could be limited by sustained and effective reduction of global greenhouse gas emissions if action was taken now.

Some sea-level rise is unavoidable for centuries due to deep ocean warming and ice sheet melt, and sea levels will remain elevated for thousands of years, according to the report.

However, immediate and sustained greenhouse-gas emission reduction would limit further sea-level rise acceleration.

The report found there was a gap between current levels of adaptation and levels needed to respond to impacts and reduce climate risks.

Professor Howden said it was becoming increasingly clear adaptation responses were fragmented, incremental, sector-specific and unequally distributed across regions.

He said, while the adaptation gap was widening, one of the messages of this report was there is hope.

"We are in a position where we can actually remove at least some of the sting of climate change," he said.

Vulnerable communities who have historically contributed the least to current climate change are disproportionately affected by its impacts, including rising sea levels, droughts and floods.

Approximately 3.3 to 3.6 billion people live in contexts that are highly vulnerable to climate change.

The report found investment in avoiding damages now would reduce adaptation costs in the future, despite requiring up-front investment.

Professor Frank Jotzo, a lead author of the IPCC's Assessment Report, said while emissions were still rising, the pace had slowed.

He said 18 countries can be identified as having reduced emissions substantially and consistently reducing emissions over time.

"If policy effort was consistently applied, right across the world, every sector, every country, then we'd see a halving of global emissions," he said.

Professor Jotzo said the difference between what is currently being deployed in terms of investment in clean energy technology and related systems and what needs to be deployed is about three to six times.

"So we need to scale up that kind of investment by three to six times the world over and that gap is especially large in developing countries," he said.

Professor Jotzo said developing nations were demanding financial assistance from rich countries to make those investments, which was not forthcoming to the level required.

"This is among the most contentious aspects affecting any international interactions on climate change and certainly also was once again in this approval session," he said.

"Who should pay for strong climate action in the interplay between rich and poor countries?"