The campaigners are demanding that BP immediately ends all exploration for new oil and gas.
Environmental activists have blocked access to BP's headquarters ahead of its annual general meeting demanding it ends all exploration for new oil and gas.
Greenpeace volunteers arrived at the oil giant's offices in St James' Square, central London, at around 3am on Monday where they encased themselves in specially designed containers.
The containers, which weigh several tonnes each, are being used to blockade all the main entrances to prevent staff from entering.
Business as usual
The boxes feature photos from photographer Gideon Mendel's Drowning World project, which looks at the impact of the climate emergency on people across the globe.
The campaigners are demanding that BP immediately ends all exploration for new oil and gas and switches to investing only in renewable energy. If it does not, Greenpeace is calling for it to wind down its operations completely and go out of business.
The blockade comes ahead of BP's AGM with shareholders this week, and volunteers have set up a camp to attempt to keep the building closed for the next seven days.
A spokesman for Greenpeace said that by 8am police had attempted to clear the area of pedestrians but had not made any arrests.
Paul Morozzo, one of the volunteers in the containers, said: "We're shutting down BP's HQ because business as usual is just not an option.
"BP is fuelling a climate emergency that threatens millions of lives and the future of the living world. The science is clear - we must stop searching for new oil and gas if we want a liveable planet. BP must clean up or clear out."
Mr Morozzo added: "For too long, BP and the oil industry have paid lip service to climate action while lying and lobbying against it behind the scenes and spending billions scouring the world for more oil and gas.
"The reality is that BP's whole business plan is a heavy bet against our hopes to avoid a climate catastrophe and must change."
According to Greenpeace's research, BP is outspending other oil giants on lobbying campaigns against climate action and spent 16 billion US dollars (£12.6 billion) adding to its oil and gas reserves in 2018.
Greenpeace said only 500 million dollars (£392.8) was invested in alternatives to fossil fuels.
Tess de la Mare is a reporter for the Press Association.