SINGAPORE - The United Nations on Monday released a “survival guide for humanity” after nearly 200 nations agreed on the wording of a major report that represents the most complete picture of climate change science in nearly a decade.

The Synthesis Report by the UN’s Intergovernmental Panel on Climate Change (IPCC) brings together the findings of its six major reports since 2018, and sets out the immense challenges humanity faces from the accelerating impacts of climate change, including more record-breaking weather disasters and quickening sea level rise.

But, crucially, the report also shows that there are many feasible and effective options to reduce greenhouse gas emissions and adapt to climate change, and that these options are available now and many are affordable.

“Today’s IPCC report is a how-to guide to defuse the climate time-bomb. It is a survival guide for humanity,” UN Secretary-General Antonio Guterres said on Monday at the release of the report in Switzerland.

Globally, nations are grappling with worsening impacts, such as floods, storms and droughts that are affecting millions of people, disrupting food, water and power supplies and causing spiralling health and insurance costs.

The report, approved during a week-long session in Interlaken, brings into “sharp focus” the losses and damages humanity is already experiencing and will continue into the future, hitting the most vulnerable people and ecosystems especially hard.

“Climate justice is crucial because those who have contributed least to climate change are being disproportionately affected,” said Dr Aditi Mukherji, who was one of the 93 authors of the Synthesis Report.

“Almost half of the world’s population live in regions that are highly vulnerable to climate change. In the last decade, deaths from floods, droughts and storms were 15 times higher in highly vulnerable regions,“ she added.

The IPCC says deep emissions cuts are needed this decade to have any chance of limiting global average warming to 1.5 deg C above pre-industrial levels – a level beyond which risks far greater climate-linked impacts.

Speaking at the press conference of the report’s launch, IPCC’s chair, Dr Hoesung Lee, said that three to six times the current amount of financing will be needed to put the world on a pathway to a safer, more equitable and sustainable future for all.

“It’s not just about the quantity of money. It’s also about how and where it is allocated. Vulnerable areas just don’t have enough money to fund the urgent need to adapt to climate change.”

United Nations Environment Programme’s executive director Inger Andersen stressed that climate change is throwing its “hardest punches” at the most vulnerable communities who bear the least responsibility for climate change, with Cyclone Freddy devastating communities in Malawi, Mozambique and Madagascar.

“So we must turn down the heat. We must help vulnerable communities to adapt to those impacts of climate change that are already here.”

While funding to invest in green energy is increasing, it is not enough and the world is struggling to cut greenhouse gas emissions, mainly from burning fossil fuels and deforestation. Adding to the pressure, investment in oil and gas is set to rise as producing nations try to cash in on global energy growth in defiance of UN calls to focus on green energy growth instead.

The report is also crucial in guiding discussions at the UN’s COP28 climate talks in Dubai at the end of 2023, where nations will be under pressure to significantly strengthen their pledges to cut emissions and hasten the phasing out of fossil fuels.

“The report is important as it is the last comprehensive science assessment of climate change by the IPCC for the next five to six years. By then, we’d know if the key 2030 goal of halving global greenhouse gas emissions on the path to net-zero emissions around 2050 can be attained,” said associate professor of science, technology and society Winston Chow at Singapore Management University.

“The distillation of our best understanding of climate science, impacts and mitigation in the Synthesis Report should inform governments everywhere – including in South-East Asia – on developing important multilateral policies to reduce worsening climate risks while reaching this much-needed net-zero goal,” said Prof Chow, a lead author of one of the IPCC’s recent reports.

The world has already warmed 1.1 deg C above pre-industrial levels and could reach 1.5 deg C in a decade based on present emissions levels.

“Climate change is a threat to human well-being and planetary health. There is a rapidly closing window of opportunity to secure a liveable and sustainable future for all,” the IPCC said in its 36-page summary for policymakers.

The IPCC said the choices and actions implemented in this decade will have an impact now and for thousands of years. Ambitious steps to cut emissions could lead to 1.4 deg C of warming towards the end of this century. Intermediate efforts could lead to 2.7 deg C of warming or continued high emissions could result in catastrophic average temperature rise of 4.4 deg C.

But while the prognosis is bad, the cure is already known and within humanity’s grasp, said the IPCC.

Rapidly scaling up green energy investments and spending on adapting to climate impacts, especially in the poorest and most vulnerable nations, will have long-lasting benefits that will reduce future losses for people and ecosystems.

The solution, said the IPCC, lies in climate-resilient development – which involves integrating measures to adapt to climate change with actions to reduce or avoid greenhouse gas emissions in ways that provide wider benefits.

For instance, many steps to cut emissions would have significant health benefits by lowering air pollution, promoting active mobility such as walking and cycling, and shifts to healthier diets.

The report details a range of emissions-cutting steps costing US$100 (S$135) – or less – per tonne of greenhouse gases to cut global emissions by half by 2030 on 2019 emissions levels. Wind and solar are by far the cheapest and achieve the largest cuts. But other steps include reducing methane emissions from the fossil fuel industry, halting the loss of natural ecosystems for development, more energy-efficient buildings, fuel-efficient vehicles and cutting food waste.

US$100 per tonne is about the level of carbon prices in the European Union’s mandatory emissions trading scheme, which covers around 40 per cent of the EU’s greenhouse gas emissions.

“So it’s not a prohibitively high price. And if the policy effort was consistently applied... in every sector, every country, then we’d see a halving of global emissions,” said Professor Frank Jotzo, head of energy, at the Institute for Climate, Energy and Disaster Solutions at The Australian National University in Canberra and member of the Synthesis Report core writing team.

“The report provides an unequivocal statement that the economic benefits of limiting temperature rise to below 2 degrees outweigh the economic costs of doing so,” he added.

“Let’s hope we make the right choices,” Dr Lee said. “Because the ones we make now, and in the next few years, will reverberate around the world, for hundreds, possibly thousands of years.”