Swedish activist Greta Thunberg yesterday accused wealthier nations of inventing ways to avoid slashing their greenhouse gas emissions, branding their climate action "misleading" at a summit in Madrid.

The UN climate forum tasked with saving the world from runaway global warming has become an "opportunity for countries to negociate loopholes and to avoid raising their ambition" to act on climate, the 16-year-old told delegates.

“Countries are finding clever ways around having to take real action."

Nations are gathered in Spain's capital to finalise the rulebook of the 2015 landmark Paris climate accord, which aims to limit global temperature rises to "well below" two degrees Celsius and to a safer cap of 1.5C if possible.

A number of sticking points remain even as the two-week marathon negotiations enter the final days. Nations are at odds over how the fight against climate change should be funded and how carbon trading schemes should be regulated.

In addition, there has been preciously little progress over the issue of "loss and damage" funding - how countries already dealing with the worst impacts of climate-related extreme weather and drought should be compensated.

Delegates and observers at the COP25negotiations in Madrid told AFP that Washington was pushing for a change in the rules of the UN climate convention that could let history's largest emitter largely off the hook when it comes to "loss and damage" funding for developing nations.

Thunberg, who started her one-girl climate strike in her native Sweden a year ago but has since been catapulted to international stardom, told negotiators that their promises were a world apart from what was needed.

“Recently a handful of rich countries pledged to reduce their emission of

greenhouse gases by so and so many percent by this or that date, or to become climate neutral or net zero in so and so many years," she Said.

"This may sound impressive at first glance, but even though the intentions may be good this is not leadership. This is not leading, this is misleading."

UN chief Antonio Guterres on Wednesday appealed to industry to "shift into a high gear" by greening their businesses and dragging carbon emissions down.

The call came as a report on Tuesday said the Arctic had experienced its second warmest year since 1900, raising fears over low summer sea ice and rising sea levels.

The average temperature in the 12 months to September was 1.9 degrees Celsius higher than the 1981-2010 average, according to the Arctic Report Card of the US National Oceanic and Atmospheric Agency (NOAA).

The UN says emissions must drop 7.6 percent globally every year to 2030 to stay on track for a 1.5C world.

At little over IC of warming since the industrial period started, Earth in 2019 was shook by a string of deadly wildfires, super storms and floods made more intense by the changing climate.

Despite dozens of meetings and thousands of specialists working to implement the Paris accord, global emissions have increased by four percent in the years since the deal was signed.