Substantial reductions in the use of fossil fuels are needed to tackle the climate crisis, a new UN report has warned.

Meeting goals agreed by countries to limit temperature rises to 1.5C or below 2C to avoid the worst impacts of climate change requires rapid, deep and immediate greenhouse gas emissions cuts in all areas, it says.

The UN’s Intergovernmental Panel on Climate Change (IPCC) science body has released the third part of its sixth assessment report, spelling out how to cut emissions by switching to increasingly cheap renewables and fuels such as hydrogen, as well as energy efficiency, capturing carbon and planting trees.

It highlights how consumers can be encouraged to make green choices in eating more plant-based diets, heating homes, taking up walking and cycling or driving electric cars, and how cities can be made greener, more walkable and healthier.

The report, which draws on 18,000 studies and sources, pitches scientific findings on climate change into an already heated debate over energy supplies and costs prompted by rising oil and gas prices amid Russia’s invasion of Ukraine.

A meeting to agree the 63-page summary of the report for policymakers, approved in a line-by-line process involving scientists and representatives of 195 countries, overran by more than two days as delegates wrangled over the text, which is now deemed to have been approved by governments.

Finding international agreement on climate change sparks fierce debate between countries that remain heavily reliant on fossil fuel use or revenues and those most vulnerable to rising temperatures beyond 1.5C, which they warn would be a death sentence for their nations.

And within the UK, the current energy crisis has provoked clashes over whether to speed up the shift away from oil and gas with clean heating, renewables and insulation or to boost domestic fossil fuel supplies from the North Sea or fracking.

The Government is due to set out its new energy strategy on Thursday with expectations of support for offshore wind and new nuclear reactors, but not cheap onshore wind.

The UN report finds there are still routes to curbing global warming to 1.5C, but without immediate action it will be impossible to achieve.

Report co-chair Jim Skea said: “It’s now or never, if we want to limit global warming to 1.5C. Without immediate and deep emissions reductions across all sectors, it will be impossible.”

The world is well off track to make the necessary emissions cuts, with pollution continuing to rise and pushing temperatures towards dangerous levels, and there is more private and public money flowing into fossil fuels than into climate action.

But the report says the costs of solar and batteries needed for electric vehicles have plunged by 85% in the last decade and their deployment has soared, while wind power has fallen by 55% in price.

Some countries have brought in effective laws and policies that have led to falls in emissions.

And it finds the economic benefits of cutting emissions exceed the cost of the action needed, while trillions of dollars of coal, oil and gas assets could become “stranded” as the world takes action to limit global warming.

UN secretary general Antonio Guterres said the report was a “litany of broken climate promises”, and called for an urgent shift of investment from fossil fuels towards renewables, protecting forests and cutting methane emissions.

The latest study follows two previous instalments of the overarching sixth assessment report, the first of its kind since 2014.

The first set out a “code red” warning on what humans are doing to the planet, and the second detailed impacts of climate change and our options for – and limits to – adapting to rising temperatures.

The latest report finds that based on policies implemented up to the end of 2020, the world faces temperature rises of 3.2C by 2100, and warming of 2.8C even if all the climate action pledges for the next decade are delivered on.

To give the world an even chance of limiting temperatures to 1.5C, immediate action is needed, with 43% cuts in greenhouse gases on 2019 levels by the end of this decade.

Emissions have to peak by between 2020 and before 2025 to limit warming to 1.5C or 2C, with rapid and deep reductions in the coming decades, including for methane which is produced through activities including farming and oil and gas production.

The report warns that measures to remove carbon dioxide from the atmosphere are “unavoidable” if the world is to reduce emissions to zero overall by the second half of the century to meet the temperature goals.

But these measures, which range from restoring forests to developing technology that directly captures carbon from the air, can have risks.

IPCC chairman Hoesung Lee said: “We are at a crossroads. The decisions we make now can secure a liveable future. We have the tools and know-how required to limit warming.”

Report author Michael Grubb, from University College London, said: “Annual emissions over the past decade were the highest in history, but there is increased evidence of climate action in some areas, remarkable progress in low carbon technologies, and at least 18 countries with sustained emission reductions.

“There is clear economic and technical potential to meet the kind of reductions that would be needed, but we are a long way from being on track in terms of what is actually going on.”

Jan Christoph Minx, from the University of Leeds, added: “We really need to change course, we need to end the age of fossil fuels and enter an age of climate policy. This has not happened yet.”