Has the Paris Agreement started to work? The numbers are in

3 hours ago 3

As global heat records keep tumbling, a new analysis shows the Paris climate treaty is having an impact, with warming on track to reach 2.6 degrees if nations meet their commitments, rather than 4 degrees as was predicted before the agreement was signed in 2016.

Western Australia’s Ningaloo Reef in August during a mass bleaching.

If warming continues on this track, Australia will still see a significant increase in days of extreme heat, but far fewer than was the case, according to a new analysis by the independent expert group World Weather Attribution and Climate Central.

Their report finds that an increase of 25 hot days per year is expected at 2.6 degrees of warming in Australia, which is expected to warm faster than the global average, in contrast to an increase of 59 days per year at 4 degrees of warming.

As a result, seven-day heat events in south-eastern Australia, similar to the weather that fuelled devastating bushfires in 2019, are now about 2.5 times more likely and 0.9 degrees hotter than they would have been without human influence. Over the past decade, the likelihood of such events has increased by 38 per cent.

Under current national emissions reduction plans under the Paris treaty that aim to limit warming to 2.6 degrees, future events of this rarity are expected to be about 1.5 degrees cooler than they would otherwise be, though still around 1.4 degrees hotter than if they occurred today.

Under the treaty, signatory nations are expected to continue to set new and more ambitious emission reduction targets to stabilise the climate temperature rise below 2 degrees and as close to 1.5 degrees as possible.

Despite the progress made under the Paris Agreement so far, carbon levels continue to increase in the atmosphere, and the global average temperature has already increased by around 1.4 degrees since the industrial era began, with the 10 years to 2024 being the hottest on record.

This week, 160 scientists issued a warning that the first so-called climate “tipping point” had been breached, with warming waters causing coral dieback around the world over the course of a marine heatwave that began in 2023.

“Observations confirmed that 2023-2025 experienced the fourth global coral bleaching event on record, and the second within the past decade,” wrote the authors of the Global Tipping Point report, led by scientists at the University of Exeter. “In this event, coral bleaching affected every ocean basin, with 83.7 per cent of corals experiencing bleaching-level heat stress by April 2025.”

The scientists wrote that the tipping point had been breached because at 1.5 degrees of warming, waters have already become too hot for warm-water corals to thrive. Other tipping points the world was approaching was the dieback of the Amazon rainforest and the collapse of climate-regulating ocean currents.

A second study published in the journal Nature on Thursday shows that Australia’s tropical rainforests are no longer sucking carbon from the atmosphere but are instead emitting carbon, the chief warming agent in the atmosphere, because more trees are dying due to extreme heat.

Between 1971 and 2000, these forests acted as a sink, absorbing an average of 0.62 tonnes of carbon per hectare per year, the study found. This has dramatically reversed, with the forests now releasing an estimated 0.93 tonnes of carbon per hectare per year between 2010 and 2019. This decline is occurring at a rate of 0.041 tonnes of carbon per hectare per year, a rate greater than observed in the Amazon and African tropics.

“The cause of this decline in carbon sink strength … is the escalation of carbon losses … associated with increasing tree mortality,” says the study. This increased mortality has not been offset by new growth, as biomass gains from stem growth have remained stable or even slightly decreased over time. While there has been an increase in recruitment of new trees, these gains are small compared to the losses from mature tree deaths.”

Signatories to the Paris Agreement will meet next month in Belem, Brazil, for negotiations that will cover how to accelerate the transition from fossil fuels to slow global warming.

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