For all the less-than-encouraging news about climate change—rapid sea-level rise, the land itself transforming, serious trouble brewing under Antarctic glaciers—we’ve been getting plenty of hope. The price of renewable energy is crashing, for example, and we’re moving toward a cleaner, electrified future faster than you may realize.
That shift is clear in a darn near uplifting paper that publishes today in the journal Nature: Modeling by an international team of scientists shows that if nations uphold their recent climate pledges, including those made at COP26, humanity may keep warming under 2 degrees Celsius above pre-industrial levels, the goal outlined in the Paris Agreement. It isn’t under the 1.5-degree threshold we’d really want (the agreement’s more optimistic goal), but it’s far from the extreme warming of 3, 4, or even 5 degrees, as some scenarios projected prior to the agreement. And it will only happen if nations carry out their promises to quickly decarbonize their economies—which isn’t guaranteed.
“Those very high emissions trajectories that people used to talk about don't look quite so likely today,” says Christophe McGlade, head of the energy supply unit at the International Energy Agency and a coauthor of the new paper. “It's a bit of good news because it shows that the world has made progress in terms of policy and technology over the past few years.”
To land on this rosier scenario of under 2 degrees of warming, McGlade and his colleagues scrutinized climate pledges that nearly 200 countries made between the Paris Agreement, which was signed in 2015, and the end of the COP26 conference last November. These are known as “net-zero” pledges. The US, for example, has committed to net zero by the year 2050, meaning that by then it will be putting as much carbon into the atmosphere as it’s removing. This is a rather sticky concept, in that a country can keep emitting greenhouse gasses as long as it’s also sequestering them with carbon removal technologies. These exist, but not at anywhere near the scale required to make a dent in atmospheric carbon concentrations. Countries could (and should) also bolster ecosystems that naturally sequester carbon in growing plants, thus offsetting emissions.
The researchers used all of those pledges to estimate global emissions in the future, then plugged that into a climate model, which calculated a temperature rise of under 2 degrees by the year 2100. (For reference, we’re already at about 1.2 degrees above pre-industrial levels.) “What this shows is that if governments achieve what they have said they want to achieve in terms of their net-zero pledges, this will be the first time that we would limit warming to below 2 degrees Celsius,” says McGlade. “There's never been enough policy commitments, or enough policy momentum, up to the COP26 conference that would have limited warming to below 2 degrees.”
In addition to that political movement, several trends have been converging to make this progress possible. For one thing, the costs of solar and wind power, as well as lithium-ion batteries to store electricity, cratered by up to 85 percent between 2010 and 2019, according to the most recent UN Intergovernmental Panel on Climate Change report. “It's really been very, very impressive and is one of the key reasons why we actually get this result in the paper,” says McGlade. “In many cases, it's cheaper to deploy a new wind farm or a new solar farm than to deploy a new coal-fired power plant. That's the case in many, many places around the world today.”
