LONDON: Nearly 150 global leaders are gathering in Paris amid tight security for a critical UN climate meeting. The conference, known as COP21, starts today (Monday) and will try to craft a long-term deal to limit carbon emissions. Observers say that the recent terror attacks on the French capital will increase the chances of a new agreement. Around 40,000 people are expected to participate in the event, which runs until December 11. The gathering of 147 heads of state and government is set to be far bigger than the 115 or so who came to Copenhagen in 2009, the last time the world came close to agreeing a long term deal on climate change. One important part of the conference started on Sunday evening. The Adhoc Durban Platform on enhanced action was brought forward to “offer an opportunity to make the best possible use of the very limited time available”, the UN said. While many leaders including Presidents Obama and Xi Jinping were always set to attend this conference, the recent violent attacks in Paris have encouraged others to come in an expression of solidarity with the French people. Unlike at Copenhagen, the French organisers are bringing the leaders in at the start of the conference rather than waiting for them to come in at the end, a tactic which failed spectacularly in the Danish capital. More than half a million people around the world took part in climate change marches over the weekend, a co-organiser said on Sunday, as protesters urged politicians to take action.From Sydney to Stockholm and Cairo to Cape Town, an estimated 570,000 took to the streets in 2,300 separate events across 175 countries, a new record for a set of global marches, co-organiser Avaaz said. “This is the problem of our generation and the next,” said Katia Herault, a climate protester in London who had only a Nemo costume protecting her from pouring rain and howling winds. The 37-year-old Frenchwoman was one of around 50,000 marchers at London’s Hyde Park on Sunday calling for action on the eve of the United Nations climate summit in Paris. Many were dressed in animal costumes — from bumblebees to cows, from polar bears to exotic fish — while others brandished placards reading: “There is no planet B”, “Our Children Need a Future” and “We Want 100 percent Clean Energy” in scenes replicated across the world. At the London event, Oscar-winners and multi-million selling musicians rubbed shoulders with protesters from the Pacific islands to Scandinavia. “This is very personal to me. This is to do with my land. This is to do with our people,” said 37-year-old Mikaele Maiava from the Tokelau Islands, a territory of New Zealand threatened by rising waters. Fashion designer Vivienne Westwood was also on the march from Hyde Park to the British parliament as leaders from 150 countries prepare to meet in Paris to hammer out a plan to cut emissions. Actress Emma Thompson, who has campaigned against oil drilling in the Arctic, said she had seen the effects of climate change during a visit there last year. “It helped me understand in a much more visceral, real way what was happening to the planet,” the actress told AFP. “So I’m here today to really get behind the climate summit in Paris which is actually a really historical event.Rocker Peter Gabriel, founder of the band Genesis, said climate change was “a serious threat” and said any pact negotiated in Paris should have a “real means of enforcing the talk, which I’m sure will be in abundance.” “Politicians want to get re-elected. If there’s enough of us, and this is happening all over the world, then they will respond,” he said.The people-powered protests kicked off with marches across Australia, with 45,000 gathering in Sydney. “There’s nothing more important that I can be doing at the moment than addressing climate change,” said Kate Charlesworth, a doctor and Sydney mother.In Copenhagen, some 5,000 people marched to parliament. Four of the protestors were dressed as polar bears to promote a sculpture they will bring to Paris during the climate summit, depicting a dead polar bear covered in oil. In Stockholm, around 4,000 people marched under grey skies, while in the Finnish capital Helsinki organisers reported a turnout of between 1,500 and 2,000 people.Further south in Spain, some 20,000 marched in the Spanish capital, the biggest climate march in Madrid’s history, Greenpeace said. Activists formed human chains in Paris and Brussels, the latter made up of around 4,000 people.“I hope that this chain shakes all the politicians in Europe and the rest of the world to forge a deep and sincere deal,” said protester Stephane Eelens. In Berlin, around 15,000 marched from the central train station to the Brandenburg Gate, where a stage had been set up decorated with a globe clouded in black smoke.Around 1,000 people joined a march in Athens from the Acropolis to the parliament, carrying banners reading “Solarise Greece” or “Go renewable”. A group of 20 children led 10,000 people in Madrid, many holding green balloons and green hearts with messages that read “The Earth is Your Home” and “Help Me Be Happy”.“We’ve got marches happening all around the world — from Ouagadougou to London here to Nepal,” said Sam Barratt, campaign director for Avaaz.