Some 150 world leaders including President Barack Obama joined U.N. Secretary-General Ban Ki-moon Monday in kicking off two weeks of high-stakes climate talks near Paris.
Environmental activists hope that the images from the United Nations conference will send a powerful message of unity on the issue of global warming.
The COP21 meeting comes at a somber time for France, which is reeling after extremists linked to ISIS killed 130 people around the capital. Immediate fears of repeat attacks have prompted extra-high security and a crackdown on environmental protests.
Each leader will give a speech about what their countries are doing to reduce emissions and slow climate change. After the leaders leave, negotiators have two more weeks to work on a deal before the talks are scheduled to wrap up Dec. 11.
"It is the future of humanity that is at stake at this conference," French President Francois Hollande told 20 Minutes newspaper. "History will severely judge the heads of government if, in December, they miss this opportunity."
In his address to the summit, Obama highlighted that glaciers were "melting at a pace unprecedented in modern times" and warned of "submerged countries and abandoned cities" unless action was taken.
He added: "One of the enemies we will be fighting at this conference is cynicism ... Let their be no doubt. The next generation is watching what we do."
When global leaders got together aiming to create a sweeping climate treaty in Copenhagen in 2009, they left with an acknowledgement that there was a global warming problem but no solid commitment to address that issue.
"It'd be hard to have more of a failure than Copenhagen was," Jamie Henn, communications and strategy director for 350.org, a climate activists group, told NBC News. "I think there's a recognition worldwide that we're running out of time to address climate change … our hope is Paris sends a clear signal that the world is moving away from fossil fuels."
All members of the G-20 have submitted their own plans for addressing global warming. The Obama administration laid additional groundwork last year by securing an agreement with China to cut carbon emissions drastically by 2030 and a deal with Brazil to increase renewable energy production.
Activists expect that the plan that emerges from the Paris summit will address a decrease in fossil fuel emissions and increase financing to help the developing world reduce its dependency on nonrenewable energy.
"This will be the first international legal agreement that has firm commitments from all the major bidders," Jake Schmidt, director of the international program at the Natural Resources Defense Council told NBC News. "The U.S. actually seeking action domestically and not just talking about it has a huge ripple effect."
America's target is based on the plan already announced in China last year to reduce emissions by 26 to 28 percent below 2005 levels by 2025.
"President Obama really came up with his targets based on what he thinks that he can do administratively using I'd say the easiest and most politically palpable tools to him," said Benjamin Schreiber, Friends Of the Earth's climate and energy program director.
Still, the warm glow over such steps can only last so long, environmental activists say.
Climate Action Tracker, which has analyzed all of the plans submitted, writes that "none of the G20 INDCs are in line with holding warming below 2 degrees Celsius, or 1.5 degrees Celsius," which is the global goal of the climate talks. That is also the point at which climate experts say "severe drought, rising seas and supercharged storms as well as food and water security become routine challenges."
"We're expecting that we'll have an agreement of some sort that will not get us anywhere near the two degrees of warming that is the stated objective of the negotiations. We don't have such high expectations for these negotiations that we think this is a once-in-a-lifetime moment," Schreiber said. "As a result, we're not going to end up on a pathway towards getting where we need to be."
While Paris definitely won't come close to fully addressing climate change, some think it's an important step forward, since the U.S. and China, the two largest polluters, will actually be participating and some countries have started to rely more on renewable energy.
"[The U.S. has] the largest responsibility to really help lead the world in solving this problem," 350.org's Henn said. "The pledges on the table are stronger than what we've offered in the past and perhaps go nearly as far as the administration can with the current Congress. We think this is one piece of a continuing and ongoing pathway to getting us where we need to be."
Climate change legislation has been a hotly-debated topic in Congress and the U.S. has been unable to promise that lawmakers will follow through with any resultant plan. Currently, the proposal is based on executive actions that President Obama has taken, not climate legislation that's been voted on.
"It's absurd that a handful of climate-deniers in the U.S. Congress can hold back the entire world from addressing a critical issue that's facing our climate … it's morally reprehensible," Henn said. "Congress has made it clear that they won't sign any politically binding treaty … it would be a parody if the stakes weren't so high. Instead, it's a growing tragedy."
Despite Congress, Obama has still been able to create a Clean Power Plan, which aims to decrease emissions, and veto the Keystone XL Pipeline.
"We were quite pleased with Obama's rejection of the Keystone XL pipeline, which to us was an indication that the administration thanks to pressure from millions of Americans has begun to really stand up to the fossil fuel industry," Henn said.
But Keystone XL is just one step in a long battle to reduce the U.S.'s reliance on fossil fuels.
"President Obama is not going to be doing enough, and so we're going to be calling (him) out. This is his last time to really build an international climate legacy, in eight years of his presidency he has squandered the opportunity to build a lasting international climate legacy," Schrieber said. "Climate change is not going to be solved by just one pipeline. Climate change is going to require a really massive concerted effort."