2015 United Nations Climate Change Conference
Based on Wikipedia: 2015 United Nations Climate Change Conference
Two weeks after terrorists attacked Paris, killing 130 people, thirty thousand police officers fanned out across France. Checkpoints multiplied. Martial law gripped the nation. And into this tense, wounded city came the largest diplomatic gathering in history: representatives from 196 countries, converging to decide whether humanity would take meaningful action against climate change—or continue sleepwalking toward catastrophe.
The 2015 United Nations Climate Change Conference, known as COP21, ran from November 30 to December 12 at Le Bourget, a former airport north of Paris. The stakes were enormous. For over two decades, international climate negotiations had produced more frustration than progress. The Kyoto Protocol of 1997 had been a noble attempt, but its binding emissions targets applied only to wealthy nations, and the United States never ratified it. The Copenhagen summit in 2009 collapsed in acrimony and finger-pointing.
Paris would be different. It had to be.
The Problem in Numbers
Understanding what happened in Paris requires understanding the science that brought everyone there. Since the Industrial Revolution, humans have been burning fossil fuels—coal, oil, and natural gas—at an accelerating pace. This releases carbon dioxide and other greenhouse gases into the atmosphere, where they trap heat that would otherwise escape into space. The result is global warming.
How much warming is too much? Scientists had coalesced around a threshold: two degrees Celsius above pre-industrial temperatures. Beyond that point, the risks multiply dangerously. Sea levels rise enough to swamp coastal cities. Heat waves become deadly. Droughts intensify. Coral reefs die. Weather patterns grow chaotic and extreme.
But here's the troubling math: if countries continued on their existing trajectory, the planet was heading for four to five degrees of warming by 2100. That's not just uncomfortable. That's civilization-threatening.
Before Paris, 146 countries had submitted their intended climate pledges, known as Intended Nationally Determined Contributions, or INDCs. These were essentially promises about how much each nation would cut its emissions. When analysts added them all up, the result was sobering. Even if every country kept its promise perfectly, the world would still warm by about 2.7 degrees Celsius. Better than four degrees, certainly. But still overshooting the danger zone.
Why France Made Sense
The choice of host country wasn't arbitrary. France offered something unusual: proof that a wealthy nation could provide a high standard of living while generating almost no carbon from electricity.
As of 2012, over ninety percent of French electricity came from zero-carbon sources. Most of that was nuclear power, supplemented by hydroelectric dams and wind turbines. For delegates arriving from countries still dependent on coal, France demonstrated that decarbonization wasn't some utopian fantasy. It was achievable.
This matters because electricity generation is one of the largest sources of greenhouse gas emissions globally. Many countries, particularly developing ones, argued that cutting emissions meant sacrificing economic growth. France showed that wasn't necessarily true.
The Diplomatic Breakthrough
The key to understanding Paris lies in Washington and Beijing.
The United States and China are, by a wide margin, the world's two largest emitters of greenhouse gases. For years, each had used the other as an excuse for inaction. American politicians argued that any climate deal would be futile unless China participated. Chinese officials countered that wealthy nations had caused the problem and should fix it first.
This deadlock broke on November 12, 2014—more than a year before the Paris conference. President Barack Obama and Chinese President Xi Jinping stood together and announced a joint commitment to limit greenhouse gas emissions. The two nations that had been the biggest obstacles suddenly became the biggest advocates.
Obama later reflected on this shift: "We've led by example... we've driven our economic output to all-time highs while driving our carbon pollution down to its lowest level in nearly two decades. And then, with our historic joint announcement with China last year, we showed it was possible to bridge the old divide between developed and developing nations that had stymied global progress for so long. That was the foundation for success in Paris."
Think tanks had long understood this dynamic. As analysts at the World Pensions Council observed, as long as Washington and Beijing didn't put their political capital behind ambitious targets, the efforts of other governments remained little more than pious wishes. The Obama-Xi agreement changed the calculation for everyone.
The Pope Weighs In
Six months before the Paris conference, Pope Francis published an encyclical letter titled Laudato Si', which translates from Italian as "Praise Be to You." Encyclicals are among the most authoritative documents a pope can issue, and this one had a clear purpose: to influence the climate negotiations.
The pope called for nothing less than a transformation of human behavior. "Humanity is called to recognize the need for changes of lifestyle, production and consumption," he wrote, "in order to combat this warming or at least the human causes which produce or aggravate it."
For the world's 1.3 billion Catholics, this wasn't abstract policy analysis. It was moral instruction from the highest authority in their faith. The encyclical framed climate change not as a political issue but as an ethical imperative—a matter of justice toward the poor, who suffer most from environmental degradation, and toward future generations, who will inherit whatever mess we leave behind.
Twelve Days in December
The negotiations themselves were grueling. Diplomats worked through the night, argued over semicolons, and struggled to bridge seemingly irreconcilable positions.
One of the most contentious debates concerned the temperature target itself. The scientific consensus pointed to two degrees Celsius as the danger threshold. But for some countries, even that was too high.
Small island nations—places like the Maldives, Tuvalu, and the Marshall Islands—faced an existential threat. Even two degrees of warming would melt enough polar ice to submerge their territories. For them, the debate wasn't about economics or politics. It was about survival. They pushed hard for a more ambitious target: 1.5 degrees Celsius.
The Philippines joined this coalition, along with the Seychelles and other vulnerable nations. Their argument was simple: why should they accept a climate deal that guarantees their destruction?
The Paris Agreement
On December 12, 2015, French Foreign Minister Laurent Fabius brought down his gavel. The Paris Agreement was adopted by consensus.
The twelve-page document committed the world's nations to hold global warming "well below 2 degrees Celsius" above pre-industrial levels, while also pledging to "pursue efforts to" limit the increase to 1.5 degrees. That second phrase was a victory for the island nations, even if it fell short of a binding commitment.
The agreement called for net-zero greenhouse gas emissions during the second half of the twenty-first century. In other words, by sometime between 2050 and 2100, humanity should be absorbing as much carbon as it emits. Achieving the 1.5 degree target would require hitting that balance much sooner—sometime between 2030 and 2050, according to many scientists.
Perhaps most importantly, the agreement established a mechanism for ratcheting up ambition over time. Every five years, beginning in 2023, countries would conduct a "global stocktake"—an assessment of collective progress—and submit updated, more ambitious emission targets. The idea was to create a cycle of continuous improvement, even if the initial pledges fell short.
Fabius called it "ambitious and balanced" and an "historic turning point."
The Critics Had a Point
Not everyone celebrated. The Paris Agreement had a fundamental weakness: it lacked teeth.
Under the Kyoto Protocol, countries had faced binding emissions targets. Miss your target, and there were consequences. Paris worked differently. Each country would set its own target—called a Nationally Determined Contribution, or NDC—but the amount was entirely voluntary. There was no mechanism to force a country to set a specific target by a specific date, and no enforcement measures if targets were missed.
What would happen to countries that failed to deliver? According to János Pásztor, the United Nations assistant secretary-general on climate change, there would be a "name and encourage" system. Critics might call it "name and shame," but that's all the pressure the agreement could muster.
Some analysts were blunt about this limitation. The agreement, they observed, was "predicated upon an assumption—that member states of the United Nations, including high polluters such as China, the United States, India, Canada, Russia, Indonesia, and Australia, which generate more than half the world's greenhouse gas emissions, will somehow drive down their carbon pollution voluntarily and assiduously without any binding enforcement mechanism."
No carbon tax. No penalties. No factory-level monitoring. Just promises.
The Investment Angle
If governments couldn't force compliance, perhaps markets could.
Jeffrey Sachs, director of the Earth Institute at Columbia University, spoke at a pension fund conference held on the sidelines of COP21. His argument was straightforward: institutional investors—the pension funds and endowments that manage trillions of dollars—would eventually flee from carbon-heavy companies, regardless of what governments did.
"Every energy company in a pension fund's portfolio needs to be scrutinized from purely a financial view about its future," Sachs said. "Why is this a company we would want to hold over a five- to twenty-year period? If we continue to hold major energy companies that don't have an answer to a basic financial test, we are just gambling. We have to take a fiduciary responsibility—these are not good bets."
This wasn't environmentalism dressed up as finance. It was basic risk management. If regulators eventually crack down on carbon emissions, companies whose business models depend on burning fossil fuels will become stranded assets—worth far less than their current stock prices suggest.
What Happened Next
The agreement required ratification to take effect. Specifically, at least 55 countries representing at least 55 percent of global emissions had to formally adopt it through their domestic legal processes.
On Earth Day 2016—April 22—174 countries signed the agreement at a ceremony in New York. It was the largest single-day signing of any international agreement in history.
The 55-55 threshold was crossed on November 4, 2016, barely a year after the Paris conference ended. The agreement entered into force.
Then came complications. In June 2017, President Donald Trump announced that the United States would withdraw from the Paris Agreement, calling it unfair to American workers and businesses. The withdrawal couldn't take effect immediately due to the agreement's rules, and when Joe Biden took office in January 2021, he rejoined on his first day as president.
The Stocktake
The Paris Agreement's built-in review mechanism kicked in on schedule. In late 2023, at COP28 in Dubai, the first global stocktake was completed—an assessment of how the world was doing relative to its goals.
The verdict was sobering but unsurprising. Current efforts were insufficient to limit warming to 1.5 degrees Celsius. The gap between ambition and action remained wide. The stocktake emphasized the need for more climate finance and accelerated action across all sectors.
This was the Paris Agreement working as designed, even if the news it delivered was unwelcome. The point of the stocktake was never to declare victory. It was to measure the distance remaining and push countries to close the gap.
The Voices Left Out
The official negotiations in Paris involved national governments, but a parallel ecosystem of advocacy flourished outside the conference halls.
Indigenous peoples from every continent demanded recognition. The Wabanaki Confederacy, a union of First Nations peoples in what is now northeastern North America, sent representatives to highlight their opposition to hydraulic fracturing and proposed pipelines. As activist Winona LaDuke observed, "Canada is home to seventy-five percent of the world's mining corporations, and they have tended to have relative impunity in the Canadian courts."
Cities organized as well. The mayors of Paris and Rome had convened their counterparts from across the European Union earlier that year, arguing that urban areas—which produce the majority of global emissions—should be at the center of climate action. Local governments often move faster than national ones, and they wanted that recognized.
Labor unions pushed their own agenda. Sharan Burrow, general secretary of the International Trade Union Confederation, called for "zero carbon, zero poverty." She had a memorable way of expressing the stakes: "There are no jobs on a dead planet."
A Foundation, Not a Solution
Was Paris a success? The honest answer is: it depends on what happens next.
Al Gore, the former vice president who had spent decades advocating for climate action, offered a measured assessment. "No agreement is perfect, and this one must be strengthened over time," he said, "but groups across every sector of society will now begin to reduce dangerous carbon pollution through the framework of this agreement."
That word—framework—captures what Paris actually achieved. It didn't solve climate change. It created the scaffolding for solving it: a universal structure that every nation signed onto, with built-in mechanisms for increasing ambition over time.
The emissions targets announced in Paris weren't enough. Everyone knew that going in. The hope was that the ratchet mechanism—the five-year stocktakes, the peer pressure, the growing evidence of climate damage—would push countries toward bolder action.
Whether that hope proves justified remains an open question. The planet continues to warm. Extreme weather events grow more frequent and severe. The window for limiting warming to 1.5 degrees is rapidly closing.
But Paris established something that had eluded climate negotiators for decades: a global consensus that the problem is real, that action is necessary, and that every country has a role to play. That foundation, however imperfect, is what the world now builds upon.