The opening ceremony of the world leaders' summit at the 26th United Nations Climate Change Conference of the Parties (COP26) started on Monday, with over 120 world leaders gathered in Glasgow, Scotland. 

COP26 was delayed by a year due to the COVID-19 pandemic and is the first conference after the five-year review cycle under the Paris Agreement inked in 2015.

"We postponed COP26 by a year. But during that year, climate change did not take time off. And we know that the window to keep 1.5 degrees within reach is closing," said COP26 President Alok Sharma in his speech at the opening ceremony.

British Prime Minister Boris Johnson, in his opening address, warned world leaders that they faced a damning verdict from future generations unless they act decisively. 

"The anger and the impatience of the world will be uncontainable, unless we make this COP26 in Glasgow the moment when we get real about climate change, and we can get real on coal, cars, cash and trees," Johnson said.

Johnson on Monday announced an initiative to boost green infrastructure and technology investments in emerging markets, including a doubling of UK aid to more than 3 billion pounds ($4 billion) over five 
years. 

UN chief Antonio Guterres, following Johnson, also sent out a stern warning, saying that currently "we are digging our own graves" and the summit must act to "save humanity" and protect the planet.

"If commitments fall short at the end of this COP, countries must revisit their national climate plans and policies – not every five years (but) every year and every moment," Guterres said.

The United Nations was setting up an expert group to measure and analyse net-zero commitments of non-state actors, he added.

Issues high on the agenda of COP26 include completing the rules for the Paris Agreement's market mechanism and wealthy countries' unmet finance pledge to the developing countries to help them tackle climate-related challenges.