G7 leaders face the foremost important decisions in human history as they seek to tackle global climate change , Sir David Attenborough has said.
The naturalist will address world leaders gathered in Cornwall on Sunday as they began plans to chop carbon emissions and restore biodiversity.
Ahead of the meeting, Sir David warned that humans might be "on the verge of destabilising the whole planet".
Climate change is one among the key themes at the three-day summit in Carbis Bay.
The group of seven - the united kingdom , US, Canada, Japan, France, Germany and Italy - are expected to pledge to almost halve their emissions by 2030, relative to 2010 levels.
The UK has already surpassed that commitment, previously promising to chop emissions by the equivalent of 58% on 2010 levels.
Prime Minister Boris Johnson will hold a news conference on Sunday afternoon, the ultimate day of a summit where he has clashed with EU leaders over the Brexit deal's requirements for checks on goods from Britain to Northern Ireland .
And after the summit, US President Joe Biden are going to be met by a Guard of Honour at Windsor Castle, where he will have tea with the Queen.
The G7 countries are thanks to set how they hope to satisfy the emissions target.
This is expected to be through phasing out petrol and diesel cars, stopping most direct government support for the fuel sector overseas, and ending all unabated coal use as soon as possible - meaning any remaining coal plants will got to have invested in technologies like carbon capture and storage.
In advance of the session, Sir David said: "The wildlife today is greatly diminished. that's undeniable.
"Our climate is warming fast. that's definitely . Our societies and nations are unequal which is unfortunately plain to ascertain .
"But the question science forces us to deal with specifically in 2021 is whether or not as a results of these intertwined facts we are on the verge of destabilising the whole planet.
"If that's so, then the choices we make this decade - especially the choices made by the foremost economically advanced nations - are the foremost important in human history."
China, which consistent with one report was liable for 27% of the world's greenhouse gases in 2019 - the foremost of any country - isn't a part of the G7.
The Earth's average temperature is about 15C (59F) but has been much higher and lower within the past.
There are natural fluctuations within the climate but scientists say temperatures are now rising faster than at many other times.
This is linked to the atmospheric phenomenon , which describes how the Earth's atmosphere traps a number of the Sun's energy.
Solar energy radiating back to space from the surface is absorbed by greenhouse gases and re-emitted altogether directions.
This heats both the lower atmosphere and therefore the surface of the earth . Without this effect, the world would be about 30C (86F) colder and hostile to life.
Scientists believe we are adding to the natural atmospheric phenomenon , with gases released from industry and agriculture trapping more energy and increasing the temperature.
This is referred to as global climate change or heating .
The G7 leaders will endorse an idea aimed toward reversing the loss of biodiversity - a measure of what percentage different species sleep in ecosystems - by the top of the last decade .
The plan will include supporting the worldwide target to conserve or protect a minimum of 30% of land and oceans by 2030.
Prime Minister Boris Johnson, who is hosting the summit, is additionally launching a £500m fund to guard the world's oceans and marine life.
The "blue planet fund" will help countries including Ghana, Indonesia and Pacific island states, tackle unsustainable fishing, protect and restore coastal ecosystems like mangroves and coral reefs, and reduce marine pollution.
Hundreds of protesters brought streets to a standstill in Cornwall on Saturday, with many campaigning for cleaner seas and action on global climate change .
A major UN report from 2019 said that global emissions of CO2 must peak by 2020 to stay the earth from warming quite 1.5C - the so-called safe limit.
Mr Johnson said protecting the earth was "the most vital thing we as leaders can do for our people".
"There may be a direct relationship between reducing emissions, restoring nature, creating jobs and ensuring long-term economic process ," he said on Saturday.
