World leaders are gathering in Paris for the start of a UN climate change summit aimed at securing a long-term global deal on limiting greenhouse gas emissions.
The 2015 Paris Climate Change Conference, also known as COP21, will take place from Monday under tight security in the wake of the recent terror attacks in the French capital.
French authorities have clamped down on public demonstrations in the wake of the attacks, banning environmental campaigners' plans for a march in Paris to highlight the climate change issue.
However demonstrators have covered the city's Place de la Republiquewith shoes to reflect the steps that marchers have been prevented from taking.
Demonstrations have also been taking place across the world, including in London, where celebrities such as Dame Vivienne Westwood and Charlotte Church joined other campaigners on the streets.
What is COP21?
COP stands for Conference of Parties, an annual meeting of nations that make up the UN Framework on Climate Change - 195 nations in total.
This is the 21st meeting. The first was held in Berlin in 1995.
What is the aim of the conference?
The aim will be to find a way to reduce the global emissions of greenhouse gases - such as carbon dioxide and methane - over the coming decades to avoid the world’s average temperature increasing by no more than 2C by the end of this century.
Go above that rise in temperature, say scientists, and we tip over into “dangerous climate change” where there will be drastic increases in floods, storms, heatwaves and other catastrophic and irreversible environmental changes around the world.
These will disproportionately affect the poorest parts of the world, those least able to adapt.
At the moment, if the world does nothing, it is on course for a 5C temperature rise by 2100.
This might not seem like much, but bear in mind that the average difference between now and the Earth’s previous Ice Age was around 5C.
Small average temperature rises have enormous consequences.
Who is attending the conference?
French President Francois Hollande will welcome world leaders including David Cameron, US President Barack Obama, Chinese President Xi Jinping, German Chancellor Angela Merkel and Indian Prime Minister Narenda Modi.
The Prince of Wales has also accepted an invitation from President Hollande to deliver a keynote speech on the opening day of the summit.