The most ambitious goal of the Paris Agreement – namely, not exceeding the 1.5 degrees Celsius threshold of increase in average global surface temperature over land and oceans compared to pre-industrial levels – is now, in effect, out of reach. This is confirmed by a new report from the United Nations Environment Programme (Unep), which warns that the limit will inevitably be breached within the coming years. Governments around the world, in fact, have failed to act sufficiently to mitigate climate change, despite repeated warnings from the scientific community.

The scientific community, for its part, had already sounded the alarm a year ago that it would no longer be possible to keep global warming within what had been identified as a kind of "safety threshold". Beyond which, the impacts in terms of extreme weather events will be immeasurably more severe than those we are experiencing today. Nevertheless, Unep itself explains that it remains possible to commit to a trajectory that would allow us to return below the threshold as quickly as possible.

Unep's climate proposal: "An overshoot, a peak and a decline"

The report identifies a pathway entailing "an overshoot, a peak and a decline", considered "the best option that remains to minimise the magnitude and duration of that overshoot and attempt to return below the 1.5-degree threshold as soon as possible".

The outlined trajectory focuses on mitigating climate change by curbing greenhouse gas emissions and achieving carbon neutrality – that is, net-zero emissions – as soon as possible, through every available means. At the same time, it proposes an adaptation plan "aimed at reducing the vulnerability of societies, communities and economies in the face of current, foreseeable and unforeseeable impacts".

The report nonetheless underlines and acknowledges that "there are limits to adaptation". It will be virtually impossible, for example, to make large cities liveable if summer temperatures climb to 50 degrees Celsius. Some impacts are indeed "irreversible", Unep reiterates, "particularly if the peak of global warming is not sufficiently limited".

The report acknowledges the limits of adaptation to climate change

"The heatwaves, catastrophic wildfires and deadly floods we are already witnessing are merely a warning of what lies ahead. We must make the overshoot of the 1.5-degree threshold as brief as possible. This requires that our level of ambition be surpassed as well," commented United Nations Secretary-General António Guterres.

"If we remain above the indicated limit, there is no favourable scenario," echoed Inger Andersen, Executive Director of Unep. "Everywhere in the world, extreme heatwaves already show that the consequences will materialise more rapidly, strike harder and last longer. The price to pay will be human lives lost, and profound upheaval."

Inger Andersen: "If we remain above 1.5 degrees, there is no favourable scenario"

For this reason, Andersen continued, "the time has come to step up our efforts. We can, and must, take the right path by reducing greenhouse gas emissions, strengthening resilience and adaptation, and ensuring that any overshoot of the 1.5-degree threshold is as limited and as short as possible." Otherwise, the risk is of crossing points of no return, such as the destabilisation of ice sheets or the collapse of the Amoc current that regulates the Planet's climate.

Concretely, the least severe scenario foresees reaching a peak of +1.8 degrees Celsius of global warming compared to before humanity began burning coal, oil and gas on a massive scale, in the mid-nineteenth century. All other possible scenarios are, however, far more pessimistic. And, Unep reiterates, "every additional tenth of a degree intensifies impacts, exacerbates extreme weather events, ecosystem degradation, the submersion of island nations and coastal areas, damage to human health, food security, water resources, nature, cities, infrastructure and economies".

The situation, in other words, is dire. It is essential to limit emissions as much as possible, act on production systems, and choose what is truly necessary to continue using and what is not, starting with the most energy-intensive activities.