A dizzying blitz of pledges to curb methane emissions, phase out coal-fired power, stop overseas fossil fuel financing, and halt deforestation would appear to have moved the dial towards the Paris Agreement's most ambitious goal of capping global warming at 1.5 degrees above pre-industrial levels.

With a rise of 1.1C to date, storms, heatwaves and floods have become more frequent, intense and deadly.

An International Energy Agency (IEA) tally of the commitments, along with one by India to boost renewables and reach net zero by 2070, found they would hold warming to 1.8C -- not good enough, but way better than the "catastrophic" 2.7C projected by the UN just last month.

US special envoy John Kerry, a 30-year veteran of climate geopolitics, said he "had never counted as many initiatives and as much money -- real money -- being put on the table."

But not everyone was equally impressed.

On the streets, climate activist Greta Thunberg, leading a global protest march on Saturday, branded COP26 a "failure" and an exercise in greenwashing.

Several of the marquee pledges last week, while still signifiant, were considerably less that meets the eye, analysts pointed out.

"We've run the numbers -- the IEA scenario still leaves an enormous emissions gap in 2030," researchers at Climate Analytics reported, highlighting the need to slash global emissions nearly in half within a decade to keep 1.5C within view.

- 'Two truths' -

Many frontline negotiators were not happy either.

"This first week is a disappointment," said Ahmadou Sebory Toure, chair of the G77-plus-China group, a negotiating bloc of more than 130 poor and developing countries, the largest in the UN climate forum.

"Most of our concerns are not truly or effectively being taken into account," the Guinean diplomat told AFP in an interview.

Toure lambasted the failure of rich nations to cough up $100 billion a year by 2020 -- a pledge first made in 2009, and now postponed to 2023 -- to help vulnerable nations decarbonise their economies and cope with climate impacts.

"After the sub-prime crisis in 2008, the US mobilised $8 trillion -- and that was just for one country," he said.

Many experts and negotiators commented on the stark contrast between the competing narratives, and wondered if they could be reconciled during the home stretch of the talks, which run through Friday.

"We have two different truths here," said Helen Mountford of the World Resources Institute.

"We've made much more progress in some ways that we could have ever imagined even in a couple of years ago, but at the same time we're nowhere near enough."

For Laurence Tubiana, head of the European Climate Foundation and, as France's top negotiator, a main architect of the 2015 Paris Agreement, "Glasgow could become the city of two tales".

"One is of fantastic mobilisation and progress," she told AFP.

"The other -- which we see with the protests in the street -- is that it's not really happening and companies are just cheating."

- 'Deficit of credibility' -

"There is no mechanism for ensuring delivery, no capacity to check these claims," she added, noting that the flurry of pledges last week were made outside the framework of the UN talks.

"That is why I say greenwashing is the new climate denial."

UN Secretary Antonio Guterres raised a similar concern in launching the 13-days talks.

"There is a deficit of credibility and a surplus of confusion over emissions reductions and net zero targets," he said, announcing the creation of an expert group to measure the claims of non-state actors, whether local governments or multinationals.

The "two COPs" may well collide during a formal "stocktake" on Monday of the first week, in which countries and negotiating blocs will air their views and grievances.

Some will call for an accelerated timetable for revising voluntary emissions reduction plans, currently submitted every five years.

Many will point to a lack of progress on issues that have stymied the talks for years: an architecture for international carbon markets, setting up a common timetable for national carbon cutting pledges, and a host of issues related to finance.

"It is too soon to know whether this is Glasgow half full or half empty," said Alden Meyer, a senior associate at climate policy think tank E3G.

"In the end, it has to be a balanced packaged. Nobody will come out with everything they want."