There will be more than 125 world leaders at the summit on Tuesday, the largest number of heads of government to ever attend a climate summit.
It's been convened by UN Secretary General Ban Ki-Moon as way to generate momentum for next year's climate conference in Paris. The hope is that Tuesday's summit will see leaders outline their plan of action for next year that could result in a new climate deal.
"That meeting will play a critical role in the Paris agreement," said Tim Gray, executive director of the group Environmental Defence.
There's been a lot of global foot-dragging over crafting a new climate agreement in the last few years, but environmental groups say next week could change that.
100,000 expected at march
A key reason for their optimism is the response to the People's Climate March in New York on Sunday leading up to the summit.
Organizers expect up to 100,000 people to march through the streets to press for action on climate change.
Over 1,000 organizations have signed up and thousands of Canadians are also expected to take part. There also 70 events planned in communities across Canada.
The sheer size of the New York event is unprecedented according to environmental activist Tzeporah Berman.
"We've seen a dramatic rise of extreme weather," said Berman in an interview with CBC News.
"So now people are starting to see and feel the impacts of climate change and that's why you see so many buses of Hurricane Katrina survivors coming to this march and, in fact, impacted communities and indigenous communities are leading this march."
And it's not just environmental activists. The UN Secretary General, U.S. senators and Canadian politicians including Green Party Leader Elizabeth May and Ontario's Minister of the Environment and Climate Change, Glen Murray, are also planning to be there.
Murray will march "to emphasize the importance of co-operation and collaboration with our partners if we are to overcome the challenge before us," said a statement from his office.
Canada's controversial climate legacy
But the momentum will need to continue as political leaders get down to business on Tuesday.
U.S. President Obama will address the summit during the day-long event. Prime Minister Stephen Harper will be in New York but is not going to the climate summit; Environment Minister Leona Aglukkaq will represent Canada.
"Through the course of the meetings Minister Aglukkaq will highlight the domestic and international actions that Canada is taking to address climate change," said a statement from Aglukkaq's office.
"The government is doing this through a sector-by-sector regulatory approach to reduce Canada's greenhouse gas emissions, record investments in green energy and taking a leadership role in international climate efforts."
But critics predict that Canada will be in for some serious criticism over the continued lack of national regulations to control greenhouse gas emissions from the country's largest source of carbon pollution — the energy industry.
"Despite repeated promises since 2008, Canada has given the oil industry a free pass," said Tim Gray in a briefing with reporters. "There is not a single federal law or regulation addressing carbon pollution from the tar sands or any other oil and gas facility in the country."
Obama looks to craft global deal
In contrast, the U.S. has introduced proposed measures to curb its largest source of carbon pollution — coal-fired power plants.
Obama sees action on climate as his legacy and the summit this week could outline his approach to crafting a new global deal, according to Jake Schmidt, international climate policy director at the Natural Resources Defense Council in Washington.
"He will be speaking to the world to say 'Yes I'm serious about dealing with this challenge and here are the set of measures I'm doing to deliver upon our commitments,'" said Schmidt.
But the bottom line is the summit will be a partial success if leaders can simply avoid the sniping and finger-pointing that has marred previous climate gatherings.
Tzeporah Berman predicts a shift in attitude towards climate change and its effects may play a role this time.
"It's not just scientists and environmental groups calling for these changes now," said Berman. "It's all of these conservative bodies. It's banks, it's world governments, it's the International Energy Agency."