The oft-cited 2030 deadline to reduce global greenhouse gas emissions by 45% is actually a stepping stone to the even more significant goal of total decarbonization by mid-century, InsideClimate News reports, in a review of the science behind a target date that has been cited frequently in the race for the U.S. Democratic Party’s 2020 presidential nomination.
The 12-year (now 11-year) deadline has received extensive attention in the year since the Intergovernmental Panel on Climate Change (IPCC) released its landmark report on pathways to keep average global warming to 1.5°C. “Mid-century is actually the more significant target date in the report, but acting now is crucial to being able to meet that goal,” InsideClimate writes, citing Duke University climate mitigation specialist and IPCC lead author Drew Shindell.
“We need to get the world on a path to net zero CO2 emissions by mid-century,” Shindell said. “That’s a huge transformation, so that if we don’t make a good start on it during the 2020s, we won’t be able to get there at a reasonable cost.”
InsideClimate traces the process by which scientists calculated the carbon budget and decarbonization deadlines in the report, working backwards from a knowledge of how greenhouse gases warm the Earth’s atmosphere. “They figured out how much extra heat we can stand,” explained Colorado State University climate researcher Scott Denning. “They calculated how much CO2 would produce that much heat, then how much total fuel would produce that much CO2. Then they considered ‘glide paths’ for getting emissions to zero before we burn too much carbon to avoid catastrophe.”
Which is how the 12-year deadline became such a ubiquitous tagline—even though that’s not what the IPCC intended.
“All this work gets summarized as ‘in order to avoid really bad outcomes, we have to be on a realistic glide path toward a carbon-free global economy by 2030.’ And that gets translated to something like ’emissions have to fall by half in a decade,’ and that gets oversimplified to ’12 years left’,” Denning said. “There’s certainly a grain of truth in the phrase, but it’s so oversimplified that it leads to comically bad misconceptions about how to get there, conjuring up ridiculous cartoon imagery suggesting we just go on with life normally for the next 11 years and then the world ends.”
Quite the contrary, InsideClimate says, noting that “the world will still exist” if humanity overshoots the 1.5°C and 2.0°C thresholds. “The climate impacts and risks will be higher and the temperature will be higher,” said Glen Peters, research director at the CICERO climate research centre in Oslo. “But in terms of deadlines, we have already missed the deadline. We should have started mitigating decades ago, then we would have the problem solved.”
Penn State University researcher and veteran climate hawk Michael Mann said the science behind the 2030 target is sound. “The controversy stems from people mischaracterizing the carbon reduction timeline as a threshold for climate disaster,” InsideClimate writes. “He noted that people promoting climate science denial and delay have also latched on to the phrase ‘to intentionally try to caricature the concern about climate change’.”
InsideClimate summarizes the impacts that would come along with a slower decarbonization pathway. They include longer, hotter heat waves, more frequent, crop-killing droughts, intensified flooding, faster glacier loss and sea level rise, and the various tipping points—some of which we may have already passed—where rapid change in different Earth systems drives faster warming. But some scientists say the arbitrary, 12-year deadline misses the complexity in those overlapping realities.
“In the physical climate system, there are no scientists claiming that there is a magical threshold that we breach or don’t breach that determines whether we have a habitable climate system,” said UCLA climate scientist Daniel Swain. So while the “next decade is incredibly consequential for what we do,” the “emphasis that’s being placed on this specific 12-year window as a differentiator between existential crisis or not is problematic.”
Reducing a longer conversation to the one headline “negates some of the risks that already exist and that will continue to build no matter what,” he explained. “And it also potentially suggests that anything short of complete victory in the next 12 years is pointless, which is exactly the opposite of the truth. At any point along the spectrum, more progress is always going to be better than less progress, less warming is always going to be better than more warming.”
Denning suggested looking at the 2030 deadline through a different lens and talking about what success will look like, rather than failure.
“Solving the problem by 2030, 2040, or 2050 requires a new global energy infrastructure, which is arguably easier and less expensive than past infrastructure shifts like indoor plumbing, rural electrification, the automobile and paved roads, telecommunications, computers, mobile phones, or the Internet,” he said. “All of these past changes cost tens of trillions of dollars, adjusted for inflation. All of them were hugely disruptive. All of them took a decade or more, completely changed the industrial and economic and social landscape, and created bursts of growth and productivity and jobs. And arguably, all of them made life better for huge numbers of people.”