The 2015 Paris Agreement on climate change called for capping global warming at well below 2 degrees Celsius above the pre-industrial level, and ideally closer to 1.5C.

Now head of the European Climate Foundation, Tubiana remains a key player in crafting global climate policy and ensuring that the deal is implemented, including at the COP26 summit in Glasgow.

AFP interviewed Tubiana by telephone at the weekend on the sidelines of the UN talks. Her answers have been condensed and edited for clarity.

- You have said greenwashing is the new climate denial. What does that mean? -

I am of course happy about the many 2050 net-zero commitments, both from governments and the private sector. It was a target of the Paris Agreement, and it is great that this is now the benchmark.

But most of these commitments cannot be verified. There is no mechanism for ensuring delivery, no capacity or authority to check these claims.

Then there is the role of offsets. (Credits for planting trees or other carbon-reducing actions that can be bought to compensate for emitting C02 or other greenhouse gases).

Many companies -- especially oil and gas firms -- include a lot of offsets in their net-zero plans. But there is solid research showing offsets currently don't deliver any substantive emissions reduction. If that is true then this is a form of cheating. This is why I say greenwashing is the new climate denial.

It is dangerous because it undermines the companies and financial investors that are actually reducing their emissions.

In the end, greenwashing delays climate action because it tempts others to say: If this oil & gas is still producing massively in 2050 by using offsets, why should I do anything?"

- What do you think about the major announcements so far at COP26?-

These are voluntary commitments with no real legal framework, no peer-review pressure. So we don't know how they will be implemented.

That said, some are quite significant.

The declaration to end deforestation by 2030 is not as new as claimed, but is much better than the one in 2014.

I think the methane announcement -- more than 100 countries agreeing to collectively cut methane emissions 30 percent by 2030 -- is very promising, even if the biggest methane emitters have not signed up.

But we need a legal instrument -- a protocol -- for methane, like the one we have for HFCs (hydrofluorocarbons, a powerful manmade greenhouse gas).

A third significant announcement -- which came before COP26 -- was that of South Africa's 2030 and 2050 targets for reducing greenhouse gases.

And now, with the $8.5 billion in support from EU countries, plus the UK and potentially the US, there's a financial instrument to back them up.

An announcement on phasing out coal is a lot shakier, and not that clear. We have already seen Poland backtracking, and South Korea is finally not sure they are happy to have signed.

- How do these announcements relate to the UN climate negotiating process? -

Glasgow could become the city of two tales.

One is a tale of fantastic mobilisation and progress. The other one -- which we see with the protests in the street -- says that it's not really happening and companies are just cheating.

If we don't have something to bridge that difference, it will be very difficult to have an agreement.

Benchmarks and commitments that rely only on the goodwill of the actors -- that will not work.

For me credibility and accountability are the keys words for this week.