•Protests - which are normally a vibrant feature of COP summits - are likely to be subdued.
•The past year has seen extreme weather regularly linked to climate change.
The UN's annual climate change summit opens on Sunday with hosts Egypt billing it as the world's "watershed moment" on climate action.
More than 120 world leaders are heading to the Red Sea resort of Sharm el-Sheikh.
About 30,000 people will attend the two-week summit, known as COP27, though some activists are staying away over concerns about Egypt's rights record.
The past year has seen extreme weather regularly linked to climate change.
The summit will open with welcome speeches from the UN's new climate change chief, Simon Stiell, and Egyptian Foreign Affairs Minister and COP27 President-Designate Sameh Shoukry.
Mr Stiell was previously a senior government official in Grenada, the low-lying Caribbean nation where climate change is an existential threat.
Mr Shoukry said last week that the conference would be "the world's watershed moment on climate action".
There will also be key addresses from diplomats and scientists including Hoesung Lee, chair of the IPCC, the United Nations body for assessing the science related to climate change.
COP27 will really begin in earnest on Monday with a World Leaders' Summit, when heads of state and government leaders deliver five-minute addresses outlining what they want from the meeting.
PM Rishi Sunak is expected to urge world leaders to move "further and faster" in transitioning to renewable energy.
He will also tell leaders not to "backslide" on commitments made at last year's COP26 summit in Glasgow.
At that meeting, there were powerful speeches from people like Barbadian PM Mia Mottley, who told an enrapt audience that temperature rises of "two degrees is a death sentence" for island nations.
World leaders will speak on Monday and Tuesday, and once they depart, conference delegates get down to the business of negotiation.
Mr Stiell has called for this summit to be focused on turning last year's pledges into action and "get moving on the massive transformation that must take place".
All of that will come down to money.
Developing nations - which are at the forefront of climate change - are demanding that previous commitments to finance are upheld.
But they also want there to be discussion on "loss and damage" finance - money to help them cope with the losses they are already facing from climate change rather than just to prepare for future impacts. This would be the first time the issue has been put on the formal agenda of a COP summit.
The urgency of the climate change issue has been evident during the past 12 months with devastating flooding in Pakistan as well as in places including Nigeria and extreme heat in India and Europe in the summer.
Ahead of the conference a series of major climate reports were released outlining progress on reducing greenhouse gas emissions.
The UNEP emissions gap report concluded that there was "no credible pathway" to keep the rise in global temperatures below the key threshold of 1.5 degrees above pre-industrial levels.
This 1.5 degree limit was agreed back in 2015 in the Paris Agreement at the 21st UN Climate Summit, COP21. All subsequent climate summits have focused on developing actions to achieve this goal.
As well as all the formal negotiations there will be hundreds of events over the two weeks with exhibitions, workshops and cultural performances from youth, business groups, indigenous societies, academia, artists and fashion communities from all over the world.
Protests - which are normally a vibrant feature of COP summits - are likely to be subdued.
Egypt's President Abdul Fattah al-Sisi, in power since 2014, has overseen a widespread crackdown on dissent. Rights groups estimate the country has had as many as 60,000 political prisoners, many detained without trial.
Mr Shoukry has said that space would be set aside in Sharm el-Sheikh for protests to take place. However, Egyptian activists have told the BBC that many local groups had been unable to register for the conference.