Countries around the world cannot “pat ourselves on the back just yet” in the bid to tackle climate change, the Prime Minister has said.

In a video released to mark 100 days until the Cop26 climate talks in Glasgow, Boris Johnson praised the commitments made by world leaders so far, but said more needs to be done to “make a difference now to protect the planet for generations to come”.

But it came as activists urged the Government to “throw the kitchen sink at it” and said they want “deeds not words” from ministers.

Cop26 is being seen as the most important intervention since the Paris Agreement – the world’s first comprehensive treaty on tackling climate change – was secured at talks in France in 2015.

The UN summit in November is being described by the talks’ president, Alok Sharma, as the “last best chance” to keep alive a 1.5C warming limit – which requires the world to slash carbon by 45% by 2030 on the road to reaching zero emissions overall, or net-zero, by mid-century.

It also needs to deliver on a long-promised 100 billion US dollars (£73 billion) a year to help developing countries deal with climate change, ensure a green recovery from the pandemic, and address issues around delivering the Paris Agreement.

Mr Johnson said on Friday: “Around the world, in every continent, rich and poor nations alike have been putting forward ambitious emissions targets. It’s a great start, but let’s not pat ourselves on the back just yet. That is our planet, and our people need more.”

Promoting the UK’s achievements, he said the country is the first to pass net-zero legislation and is the “Saudi Arabia of wind” in terms of offshore wind capacity.

“We’re halfway to net-zero, we have carbon emissions lower than at any point since the 19th century, we’re ending support for fossil fuels overseas, and doubling our international climate finance,” he said.

“As host of Cop26 we want to see similar ambitions around the world.”

However Melanie Harwood, co-creator of climate education not-for-profit eduCCate Global, said the summit will be “nothing more than a talking shop”.

Speaking to the PA news agency at a demonstration outside Parliament, she said: “They’ll have this great meeting for two weeks and they’ll pat each other on the back. It’s not enough. They’ve let us down.”

Giles Goddard, 59, a vicar at St John’s Church in Waterloo, who works with Faith For The Climate, said: “We’ve only got 100 days until Cop and if Cop doesn’t really make a difference who knows what the future will hold, so we need governments around the world to step up.”

In recent days, developing countries have called on leading economies to increase efforts to cut emissions, deliver on climate finance – with a commitment to direct 50% to help them adapt to climate change – and to address the loss and damage being experienced by vulnerable nations.

And US special envoy for climate John Kerry has said that, by Cop26, major economies need to bring forward ambitious action and plans to deliver it.

Domestically, the UK Government is being warned that it needs to maximise its diplomatic efforts as hosts, led by the Prime Minister, to ensure the summit is a success.