Thirty-three years ago, on a sweltering summer day in 1988, NASA scientist James Hansen stood up in front of Congress and testified about an existential threat to the planet: The climate was changing. Heat-trapping gases from fossil fuels were pushing up the global temperature and would lead to more extreme heat and drought in the future. It wasn’t the first warning about the problem, but it helped spur a response. Even George H.W. Bush, campaigning for president at the time, pledged to take on the “greenhouse effect.” The same year, the United Nations launched the Intergovernmental Panel on Climate Change, also known as the IPCC.
A year later, the fossil fuel industry launched an organization to help sow doubt about the problem, funding researchers who were willing to argue that climate science was uncertain, even as internal research at Shell and Exxon detailed the catastrophes that were likely to come from the use of their products. Governments moved slowly to respond, and emissions continued to grow.
We’re living with the consequences of delayed action now, as CO2 levels in the atmosphere have reached a record high. In the Pacific Northwest, hundreds of people and more than a billion marine animals died in the extreme heat wave in June; in an attempt to escape the heat, baby birds jumped out of their nests before they could fly. In Europe, unprecedented flooding killed more than 170 people and swept away houses. In China, record-breaking rain poured into a subway line and killed 14 people, leaving others trapped until they could be rescued. In Siberia, more than 200 wildfires have burned this summer, and obliterated forests have released records amounts of CO2. Brazil is facing a historic drought. In the Gulf of Mexico, overheated water supercharged Hurricane Ida, which left more than a million people in Louisiana without power and caused at least 52 deaths in the Northeastern U.S. After the latest bleak IPCC report explaining how much worse the situation could get, UN Secretary-General António Guterres said that the report was a “code red for humanity.”
Earlier this year, the Biden administration pledged that U.S. would hit net-zero emissions by 2050, and cut emissions 50% by the end of this decade to start reaching that goal. Other countries, and dozens of companies, have the same mid-century emissions goal. Hitting those targets will require massive changes. But they arguably don’t go far enough. The goals center around trying to limit global warming to an increase of 1.5 degrees Celsius—but we’re already seeing catastrophic impacts as the Earth’s temperature has risen only around 1 degree. Current rates of emissions are so high that it’s likely that we’ll blow pass the 1.5 degree threshold within a decade, far earlier than 2050, and then face the challenge of trying to bring the temperature back down to “only” a 1.5-degree rise later in the century. Even if the goal is a 1.5-degree limit, we’ll have to move faster to reach it. And with the future of civilization at stake, we should rethink whether the goal is ambitious enough.
The problem with 1.5 Celsius
Scientists started to understand how CO2 heats up the Earth as early as the mid-1800s. But it wasn’t until a century later, in the 1970s, that someone first proposed that society should aim for a specific limit on global warming—and it was an economist, not a climate scientist, who made the suggestion that the limit should be 2 degrees Celsius. It was essentially a back-of-the-envelope calculation, and based partly on what seemed to be technologically and politically possible, not what might be ideal for the planet. But the 2-degree goal began to get political support.
Decades later, at the Paris climate conference in 2015, global leaders finally negotiated a voluntary agreement to limit warming to “well below” 2 degrees by the end of the century by cutting emissions. But some small countries like the Maldives—an island nation that’s particularly vulnerable to sea level rise—pushed for an extra goal to try to aim for a 1.5 degree limit instead, recognizing that half a degree of warming would make impacts far worse, especially for certain areas of the world. The final Paris agreement includes both the 2-degree target and an agreement to “pursue efforts” to keep warming to 1.5 degrees.
“The target at 1.5 was quite a surprising turnaround that sort of emerged out of the shadows in the Paris conference in 2015, largely driven by some quite marginal voices who suddenly started talking about 1.5, whereas all the political consensus before that was around 2 degrees,” says Tim Jackson, a professor of sustainable development at the U.K.’s University of Surrey. After the conference, the IPCC studied the science, and put out a report in 2018 that concluded that 2 degrees of warming would, in fact, have significantly worse impacts than 1.5 degrees. At 2 degrees of warming, for example, tens of millions more people will be exposed to extreme heat, and 99% of coral reefs would likely disappear. The impacts get even worse if the global temperature increases above 2 degrees.
The goal to reach net-zero emissions by 2050 is derived from those findings. In order to have a reasonable chance of keeping the average global temperature from rising more than 1.5 degrees, the 2018 report said, the world needs to reach net zero by 2050, meaning that any remaining emissions would be balanced out by carbon removal from trees and technology for pulling CO2 from the air. By 2030, we’ll have to cut emissions by at least 45%.
But 1.5 was never a magic number, and a 1.5-degree rise isn’t “safe.” Right now, the average temperature on Earth is about 1.1 degrees hotter than it was in the late 1800s. And we’re already seeing repeated billion-dollar catastrophes. “If we’re looking at the sorts of scales of disruption that we’re looking at with 1 degree, it could be quite significantly worse at 1.5 degrees,” Jackson says. Coral reefs might not completely disappear at 1.5 degrees of warming, but 70% to 90% may still be wiped out. Storms and droughts and flooding will get worse than they are now. More than a billion people will be exposed to more frequent extreme heat. There’s no question that aiming for 1.5 degrees is better than aiming for 2 degrees. But should we be more ambitious, and plan for a future that reduces the global temperature even more?
“Is it reasonable to set our global targets at a level that will undoubtedly cause mass displacement, thanks to unlivable heat, rising seas, land degradation, etcetera?” asks Erica Dodds, the CEO of the Foundation for Climate Restoration, a nonprofit focused on removing excess carbon from the atmosphere. “Especially when those who have contributed the least to climate change, i.e., the global South, stand to suffer the most from its impacts? While meeting the 1.5-degree Celsius target will require unprecedented large-scale systemic change—largely from industrialized nations—many would argue that a more ambitious target is critical for the sake of equity and survival, especially for those most vulnerable to climate impacts.”
We’re already barreling toward 1.5 degrees
Even if the target is set to the lower 1.5 degrees, we’re on track to blow past it. The most recent IPCC report, released in August 2o21, calculates that we have a “carbon budget” left of around 400 billion tons—meaning that humans can only emit roughly that much CO2 and still have a reasonable chance of keeping the global temperature below 1.5 degrees. (The odds that this calculation is correct are 66%, so even that chance is not guaranteed.)
The world emits around 42 billion tons of CO2 a year. If emissions stay high, we might pass the 1.5-degree threshold within a decade. The IPCC report says that it’s likely to happen sometime before 2040. It’s possible that we’ll break through temporarily within the next few years if a specific month is especially hot. Depending on how quickly the world uses up the remaining carbon budget, we could permanently pass the threshold sooner rather than later. “I think at the global level, that budget is blown by around 2028,” Jackson says. “Of course, any carbon that you emit after that, it’s just making the problem worse, because you’re kind of in carbon overdraft if you’ve blown your budget.”
When the carbon budget is divvied up between countries, the biggest emitters have the least time left, meaning it’s necessary to aim for net zero far earlier than 2050 or make incredibly steep cuts in emissions now. Jackson recently studied the U.K., which also aims to reach net zero by 2050, and calculated that its share of the world’s remaining carbon budget would be around 2.9 billion tons, based on the population. But since the U.K. was historically responsible for more emissions that most countries—and developing countries still need to grow—he recalculated that it only had a “fair carbon budget” left of around 2.5 billion tons. The country emitted around 455 million tons of CO2 in 2019.
Depending on how steeply the country decides to cut emissions, it might have to reach net zero as early as 2025 or 2030. That’s obviously not going to happen. (In a similar calculation, the U.S. Climate Action Network argues that the U.S., the biggest polluter in history, needs to reduce emissions 195% by 2030, compared to 2005 levels, to contribute its fair share towards the Paris agreement. Its report suggests cutting domestic emissions 70%, and then helping developing countries reduce their own emissions to meet the rest of the goal.)
For a country like the U.K., “the only way to get to net-zero emissions in three years is to turn off the economy,” says Bob Kopp, director of the Institute of Earth, Ocean, and Atmospheric Sciences at Rutgers University and one of the authors of the recent IPCC report. “It’s just not a feasible thing.” But it is true, he says, that the biggest polluters will have to get to net zero faster than by the middle of the century in order for the whole world to hit the 2050 goal. Developing countries, which are growing faster, will need more time. The next report from IPCC, which will be released in February 2022, will look at what needs to happen in more detail. But “simple logic says that the world is not going to be at net zero in 2050 if developed countries are just getting to net zero in 2050,” Kopp says. The same thing is true for companies. Because some businesses will take longer to decarbonize, others will have to hit net zero far sooner than 2050.
Sweeping changes to all aspects of the economy must happen for the world to hit the net-zero goal by the middle of the century. A report from the International Energy Agency outlined 400 milestones, saying that we’ll have to install the equivalent of the world’s largest solar plant every day by 2030, stop selling new gas and diesel cars by 2035, and stop new investments in oil and gas projects now. The report said that there’s only a “narrow path” left to hit the goal. Given the scale of the challenge, it may seem impossible to do more. That doesn’t mean we shouldn’t try.
“Some already believe that the 1.5-degree goal is out of reach because the scale of mobilization that it will require is unprecedented,” says Dodds. “Others argue that setting an ambitious goal—even with the recognition that we may fail to meet it—will leave us in a better place than aiming for a barely survivable target. Given that climate change is a bigger threat than humanity has ever faced before, it doesn’t seem unreasonable to expect that the world will respond with more ambitious action than historical trends would suggest.”
It’s still possible to move farther and faster
Things can still speed up. “For as long as I have worked on this issue and tried to help solve this crisis, the goals at any given time have always represented a kind of compromise between what the science says and what people think is the maximum the political and economic systems can handle,” Al Gore told Fast Company in a recent interview. “But now, the science is much more precise, and the urgency attached to it is properly much greater than it was. It would be better for all of us if we could get to net zero tomorrow. As the world begins to move, and as this huge change picks up momentum, it may well be that the target will be moved to a shorter timeframe. I certainly hope so.”
From a technical perspective, the world can decarbonize faster than the 2050 schedule. “Reducing emissions has been the call to action for decades, and progress has been exceptionally slow,” Dodds says. We already have much of the key technology needed, such as cheap renewable electricity, and can deploy it faster. We can move to electric vehicles faster. Companies like Amazon, while arguably not moving as quickly as technologically possible, are already aiming to hit net zero by 2040, ahead of the Paris goal. Governments can move faster to install new infrastructure, from charging stations for electric cars to streets designed for walkable neighborhoods.
At the same time, we can move faster to scale up CO2 removal both through natural methods, like protecting and restoring forests, and through technology like direct air capture plants. “The amount of [carbon dioxide removal] that will be needed to reach net zero will depend on how much we’re able to cut our emissions: The more we emit, the more we’ll need to remove,” says Dodds. “In order to be safe, then, we should be targeting a goal like climate restoration, the safe and permanent removal of excess atmospheric CO2 to return us to preindustrial levels and ensure a habitable planet for future generations. Climate restoration is indisputably ambitious, but this bold goal can help build the investment and political momentum needed to dramatically scale up our global capacity for carbon dioxide removal.”
Already, calculations of what it would take to reach net zero by 2050 rely on large amounts of CO2 removal. Many scenarios also assume that the world will “overshoot” the 1.5-degree goal, and then have to use CO2 removal to later bring the temperature down. But the world could make the choice to move more quickly to decarbonize, and use even more CO2 removal to bring the global temperature down much farther.
The question is left for society: Are we willing to do more? “Almost anything is possible, given enough effort and enough energy and resources put into the challenge,” says Damon Matthews, professor and research chair in climate science and sustainability at Concordia University. “I think a year and a half ago, most people would have said it would not be possible for governments to force citizens to stay home for a year and not travel . . . or create a vaccine within a year of pandemic emergency. These things are—on the scale of what is possible—pretty low. And yet we achieved them. Yes, it’s possible, but we need to decide that it is possible and make it a priority.”