For years, climate scientists have been saying that time is increasingly of the essence if the world is to stave off the worst effects of the climate crisis. But they have repeated it once again in the third and final installment of the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which was released on Monday. The technology to do so is on hand, they emphasized, if governments can commit to the needed changes in policy.
The new installment—compiled by 278 scientists synthesizing more than 18,000 studies—highlighted some bright spots since the last assessment report was published in 2014, notably the plummeting costs of renewable energy. But it also underscored that the world has a quickly closing window to meet the goals of the 2015 Paris climate agreement to keep warming below two degrees Celsius by the end of the century—and ideally to limit it below 1.5 degrees C. This will likely be the final IPCC report on mitigating climate change before we are effectively locked into an emissions trajectory that would surpass that threshold.
As it is, current pledges and policies put in place by governments around the world are not even close to fulfilling that goal: without much more ambitious action, temperatures will rise by about three degrees C by 2100, the report says. At its release on Monday, United Nations Secretary General António Guterres called the document “a file of shame, cataloguing the empty pledges that put us firmly on track toward an unlivable world.”
To learn more about the key insights of the report, Scientific American spoke with one of its lead authors, Sarah Burch, a climate policy researcher at the University of Waterloo in Ontario.
[An edited transcript of the interview follows.]
How has our scientific understanding changed and the key messages shifted, compared with the previous IPCC report in 2014?
I think that the most important messages out of this current assessment cycle are: For the first time, we have evidence of real, sustained greenhouse gas reductions from some countries over a period of 10 years or more. Those are greenhouse gas reductions that can’t be tagged only to an economic disruption like the 2008–2009 crisis or COVID. So it’s not a blip. It’s sustained reduction, which is heartening. And we also have solutions in every sector [such as transportation and power generation]—which is very exciting—many of which are scaling up rapidly and closer to working at scale. So that’s good news as well. And those solutions that we have could be responsible for up to a 50 percent reduction in emissions by 2030, so there’s so much promise there. But of course, the very important flip side—and really the strongest message that we have out of this assessment cycle—is that over the past 10 years, we’ve also seen the largest increase in average global greenhouse gas emissions in human history. So emissions globally are not going down; they’re going up. And that means that unless we have immediate—not five years or 10 years from now—but immediate and deep greenhouse gas reductions, that 1.5-degree-C target is out of reach. So that’s not great news.
Something that this report discusses that was not anticipated in the 2014 report is the significant decrease in the costs of renewable energy. What possibilities does that open up?
The cost of solar [energy] per unit has gone down 85 percent and wind by 55 percent, lithium-ion batteries by 85 percent. And those were not completely unexpected but much, much more significant drops in cost than were anticipated in the last assessment cycle. So that’s a really important, I think, factor in looking forward to see whether or not we can produce enough low-carbon renewable energy to meet our needs. And we do have to keep in mind that, as we’re, as some people say, electrifying everything—as we’re electrifying transport, both individual electric vehicles, as well as public transport, electrifying industrial processes and electrifying buildings—that means we need to not just swap out solar and wind for fossil fuels. We need to rapidly scale up the quantity of energy we’re producing from solar and wind. That’s a real challenge. But I think the reductions in costs are another one of those reasons for hope.
What are some of the barriers to achieving the deep, rapid emissions reductions we need?
There’s a really interesting part of the report that talks about the potential of individual choice and individual action to reduce greenhouse gas emissions. And that untapped potential, the report says, is between 40 and 70 percent of our emissions reductions [by 2050]. However—and it’s a big however—individuals are locked into high-carbon pathways in many circumstances. So when our cities are built around internal combustion engines, when our buildings are built to low-efficiency standards or to rely on fossil fuels, when you have to live very, very far from where you work or play in order to be able to afford a home or because of the way cities are zoned—that ties your hands. And you just can’t make choices that are lower-carbon. So individual actions are important, but changes to infrastructure, to the way cities are designed to fuel-efficiency standards, to the way vehicles are built and distributed, all that kind of unshackles us and allows us to make those low-carbon decisions.
The report also … says that we need a 300 to 600 percent increase in finance to really accelerate this [clean energy] transition. So we’re not even in the same universe, currently, that we need to be. But there you can also view [these barriers] as enablers. Another way to view this is that finance is an enormous enabler. We could move faster if we had more finance. We could move much faster if we design our cities to be compact and complete. We can move much faster if we invest in R&D in some key areas. But I would stress that this report highlights that a lot of the technologies already exist. It’s deploying them and scaling them up—that’s the tricky bit.
Many have become increasingly vocal about the need for wealthier countries—which have contributed the most to greenhouse gas emissions—to provide developing nations and small island countries with funds to adapt to climate change and make the energy transition. It seems like this report helps make that case.
Related to that, I think, are some really important findings. The chapter that I’m a part of is the final chapter in the report, which is about the linkages between climate change and sustainable development and how we accelerate the transition there. I think it’s such an important message. We’ve collectively agreed to the sustainable development goals. There’s so much that we want in a sustainable future: We want clean water; we want zero poverty; we want healthy communities. And we just can’t get there without really ambitious climate change action today, in the very short term. The flip side of that, of course, is that making progress on climate change delivers a really rich array of co-benefits. So if we do this right, we can make communities more beautiful and more livable; we can enrich and conserve nature; we can improve air and water quality; we can address our goals for justice and equity. There are real synergies there between climate change and all of the other things that matter to us, our sustainable development priorities.
I think that the messages around justice are really, really important. A just transition will mean leaving nobody behind as we move toward low-carbon, resilient societies. That means reskilling and upskilling workers whose livelihoods are currently in the oil and gas sector so that they can move into these good, lasting jobs of the future in renewable-energy sectors. It means ensuring that our carbon pricing and other tools don’t unfairly impact those on lower income. The just transition is, in my view, a crucial element of an accelerated transition.