While government policies, investments and regulations will propel emissions cuts, the IPCC made clear that individuals can also make a big difference. Reuters
That daunting task is still -- and only just -- possible, but current policies are leading the planet towards catastrophic temperature rises, the UN's Intergovernmental Panel on Climate Change (IPCC) made clear.
The world's nations, they said, are taking our future right to the wire.
The 2,800-page report -- by far the most comprehensive assessment of how to halt global heating ever produced, documents to "a litany of broken climate promises", said UN chief Antonio Guterres in a blistering judgment of governments and industry.
"Some government and business leaders are saying one thing -- but doing another. Simply put, they are lying. And the results will be catastrophic," Guterres said in a video message released at the same time as the UN report.
In recent months, the IPCC has published the first two instalments in a trilogy of mammoth scientific assessments covering how greenhouse gas emissions are heating the planet and what that means for life on Earth.
This third report outlines what we can do about it.
"We are at a crossroads," said IPCC chief Hoesung Lee. "The decisions we make now can secure a liveable future. We have the tools and know-how required to limit warming."
There are solutions, the report says, but they touch on virtually all aspects of modern life and require significant investment and need "immediate action".
The very first item on the global to-do list is to stop greenhouse gas emissions from rising any further.
That must be done before 2025 to have a hope of keeping within even the less ambitious warming targets of the Paris deal of two degrees Celsius above preindustrial levels.
Scenarios of catastrophic 2.5C of warming also have emissions peaking within three years.
Beyond that, the report said carbon emissions need to drop 43 percent by 2030 and 84 percent by mid-century to meet the more ambitious Paris goal of 1.5C.
"It's now or never if we want to limit global warming to 1.5C," said Jim Skea, a professor at Imperial College London and co-chair of the working group behind the report.
"Without immediate and deep emissions reductions across all sectors, it will be impossible."
And cutting emissions is no longer enough, the IPCC said. Technologies to suck CO2 out of the atmosphere -- not yet operating to scale -- will need to be ramped up enormously.
The 1.5C target is presently "beyond reach", even with the most updated global climate pledges, the IPCC said.
To get there the world must radically reduce the fossil fuels behind the lion's share of emissions.
Nations should stop burning coal completely and slash oil and gas use by 60 and 70 percent respectively to keep within the Paris goals, the IPCC said.
It warned that the current fossil fuel infrastructure if used to the end of its expected lifetime without capturing carbon emissions, would make it impossible to limit global warming to 1.5 degrees Celsius above preindustrial levels, the IPCC said.
While government policies, investments, and regulations will propel emissions cuts, the IPCC made clear that individuals can also make a big difference.
Cutting back on long-haul flights, switching to plant-based diets, climate-proofing buildings and other ways of cutting the consumption that drives energy demand could reduce greenhouse gas emissions by 40 to 70 percent by 2050.
"Rapid and deep changes in demand make it easier for every sector to reduce greenhouse gas emissions," including construction, food consumption, and transport, the report said.
With war in Ukraine spurring urgent efforts to transition away from Russian oil and gas in the West, observers said the report should sharpen nations' focus on climate commitments.