Dame Emma Thompson has delivered a bizarre 'climate crisis' mock weather forecast at an Extinction Rebellion protest this evening.

The star, 60, spoke outside the BBC Broadcasting House in central London and warned Britons they face 'crop failures' and might have to eat their own pets to survive.

She stood in front of two maps, held up by activists in swimming cap and goggles, that showed areas at risk of flooding by 2030, and warned of catastrophe if temperatures continued to rise in the country.

Dame Thompson said: 'And now earth lovers, to the weather… For those of you expecting a habitable future, we have some pretty gloomy projections for you.

Emma Thompson gives the final weather forecast this evening alongside a climate change protester

Standing in front of a map of the UK claiming to show areas at risk of flooding by 2030, Dame Emma said: 'And now earth lovers, to the weather…

A climate change activist wearing a snorkel and goggles addressed the crowd next to Thompson

'Climate crisis trends show an increased chance of warmer, wetter winters and hotter, dryer summers, along with an increase of frequency and intensity of extremes.

'Better wrap up warm, stockpile food and remember there is a surprising amount of food in the average household pet.

'Looking ahead we are on course to sail past our 1.5 degree centigrade target putting us on track for long lasting and irreversible change.'

The 60-year-old is an avowed climate change activist and has joined the group on its protests earlier this year.

But the environmentalist came under fire earlier this year for flying from Los Angeles to join Extinction Rebellion demonstrators in the capital.

Extinction Rebellion protesters blocked roads outside a BBC building ahead of tonight's episode of Question Time

Dame Emma Thompson delivers a peculiar fake weather forecast outside Broadcasting House

Addressing the accusations of hypocrisy in an interview with ITV's Rageh Omaar, she said: 'The message from Extinction Rebellion wasn't that no one can fly, it was that for decades now we have been asking for clean energy and this has been ignored.

'I may well be hypocritical by flying but I'm conscious of flying so I fly much less, but sometimes I have to when I'm working.

'But I'll continue to find ways to get to places without flying.'

In the forecast this evening, she added: 'General consensus does suggest there is an imminent crisis forecast, but not for politicians who seem to think this moist and fertile rain is ideal for growing an economy.

'As we move across the country, with severe flood warnings showing almost everywhere, and a thick fog covering Westminster, it is an uneasy picture.

'Expect crop failures, water contamination, damaged houses and ruined lives, and we will see these persistent weather fronts continue to wreck havoc across the nation, albeit with one or two days of dry and settled weather.'

Extinction Rebellion protesters blocked roads outside a BBC building ahead of tonight's episode of Question Time and held a banner saying 'This is an emergency'

Thompson delivered the weather forecast in front of the map showing potential future flooding in the UK

Actress Dame Emma Thompson at a previous protest

An activist take s picture of a leaflet Emma Thompson is holding as she gave a mock weather forecast on Thursday evening

'Looking at the edges, we can see an estimated 3,000 kilometres of our coastline receding, although that is great news for the Tory heartlands, which will soon be expecting sea views encroaching across the hills,' Dame Emma said.

'All the signs are telling us to act now, but as our chief adviser King Canute once said, never let a rising tide get in the way of a good election.'

The stunt was organised as part of the climate change protest group's 'Election Rebellion' demonstrations across the UK.

Around 20 protesters gathered outside Broadcasting House in Portland Place, holding a banner that read Tell The Truth.

Some were dressed in diving equipment to illustrate their claims of a the threat of flooding in the UK in 2023.

Reading the forecast, Dame Emma said: 'Taking a closer look at London we see that 23 underground stations are at significant risk of flooding, with 57 at high risk.

'These climate trends could bring chaos to the inner city, but with underground drivers being retrained as gondoliers there are promising signs the economy will stay afloat.

'Thank you Boris.'