The world stands on the brink of failure when it comes to holding global warming to moderate levels, and nations will need to take “unprecedented” actions to cut their carbon emissions over the next decade, according to a landmark report by the top scientific body studying climate change.
With global emissions showing few signs of slowing and the United States — the world’s second-largest emitter of carbon dioxide — rolling back a suite of Obama-era climate measures, the prospects for meeting the most ambitious goals of the 2015 Paris agreement look increasingly slim. To avoid racing past warming of 1.5 degrees Celsius (2.7 degrees Fahrenheit) over preindustrial levels would require a “rapid and far-reaching” transformation of human civilization at a magnitude that has never happened before, the group found.
“There is no documented historic precedent” for the sweeping change to energy, transportation and other systems required to reach 1.5 degrees Celsius, the U.N. Intergovernmental Panel on Climate Change (IPCC) wrote in a report requested as part of the 2015 Paris climate agreement.
At the same time, however, the report is being received with hope in some quarters because it affirms that 1.5 degrees Celsius is still possible — if emissions stopped today, for instance, the planet would not reach that temperature. It is also likely to galvanize even stronger climate action by focusing on 1.5 degrees Celsius, rather than 2 degrees, as a target that the world cannot afford to miss.
“Frankly, we’ve delivered a message to the governments,” said Jim Skea, a co-chair of the IPCC panel and professor at Imperial College London, at a press event following the document’s release. “It’s now their responsibility … to decide whether they can act on it.” He added, “What we’ve done is said what the world needs to do.”
The transformation described in the document is breathtaking, and the speed of change required raises inevitable questions about its feasibility.
Most strikingly, the document says the world’s annual carbon dioxide emissions, which amount to more than 40 billion tons per year, would have to be on an extremely steep downward path by 2030 to either hold the world entirely below 1.5 degrees Celsius, or allow only a brief “overshoot” in temperatures. As of 2018, emissions appeared to be still rising, not yet showing the clear peak that would need to occur before any decline.
Overall reductions in emissions in the next decade would probably need to be more than 1 billion tons per year, larger than the current emissions of all but a few of the very largest emitting countries. By 2050, the report calls for a total or near-total phaseout of the burning of coal.
“It’s like a deafening, piercing smoke alarm going off in the kitchen. We have to put out the fire,” said Erik Solheim, executive director of the U.N. Environment Program. He added that the need to either stop emissions entirely by 2050 or find some way to remove as much carbon dioxide from the air as humans put there “means net zero must be the new global mantra.”
The radical transformation also would mean that, in a world projected to have more than 2 billion additional people by 2050, large swaths of land currently used to produce food would instead have to be converted to growing trees that store carbon and crops designated for energy use. The latter would be used as part of a currently nonexistent program to get power from trees or plants and then bury the resulting carbon dioxide emissions in the ground, leading to a net subtraction of the gas from the air — bioenergy with carbon capture and storage, or BECCS.
“Such large transitions pose profound challenges for sustainable management of the various demands on land for human settlements, food, livestock feed, fibre, bioenergy, carbon storage, biodiversity and other ecosystem services,” the report states.
The document in question was produced relatively rapidly for the cautious and deliberative IPCC, representing the work of nearly 100 scientists. It went through an elaborate peer-review process involving tens of thousands of comments. The final 34-page “summary for policymakers” was agreed to in a marathon session by scientists and government officials in Incheon, South Korea, over the past week.
…An early draft had cited a “very high risk” of warming exceeding 1.5 degrees Celsius; that language is now gone, even if the basic message is still easily inferred.
…Underscoring the difficulty of interpreting what’s possible, the IPCC gave two separate numbers in the report for Earth’s remaining “carbon budget,” or how much carbon dioxide humans can emit and still have a reasonable chance of remaining below 1.5 degrees Celsius. The upshot is that humans are allowed either 10 or 14 years of current emissions, and no more, for a two-thirds or better chance of avoiding 1.5 degrees Celsius.
The already limited budget would shrink further if other greenhouse gases, such as methane, aren’t controlled or if and when Arctic permafrost becomes a major source of new emissions.
But either way — in a move that may be contested — researchers have somewhat increased the carbon budget in comparison with where the IPCC set it in 2013, giving another reason for hope.
The new approach buys some time and “resets the clock for 1.5 degrees Celsius to ‘five minutes to midnight,’ ” said Oliver Geden, head of the research division of the German Institute for International and Security Affairs.
“1.5 degrees is the new 2 degrees,” said Jennifer Morgan, executive director of Greenpeace International, who was in Incheon for the finalization of the report.
Specifically, the document finds that instabilities in Antarctica and Greenland, which could usher in sea-level rise measured in feet rather than inches, “could be triggered around 1.5°C to 2°C of global warming.” Moreover, the total loss of tropical coral reefs is at stake because 70 to 90 percent are expected to vanish at 1.5 degrees Celsius, the report finds. At 2 degrees, that number grows to more than 99 percent.
The report found that holding warming to 1.5 degrees Celsius could save an Alaska-size area of the Arctic from permafrost thaw, muting a feedback loop that could lead to still more global emissions. The occurrence of entirely ice-free summers in the Arctic Ocean goes from one per century to one per decade between 1.5 and 2 degrees, it found — one of many ways in which the mere half a degree has large real-world consequences.
Risks of extreme heat and weather events just rise and rise as temperatures do, meaning these would be worse worldwide the more it warms.
To avoid that, in barely more than 10 years, the world’s percentage of electricity from renewables such as solar and wind power would have to jump from the current 24 percent to something more like 50 or 60 percent. Coal and gas plants that remain in operation would need to be equipped with technologies, collectively called carbon capture and storage (CCS), that prevent them from emitting carbon dioxide into the air and instead funnel it to be buried underground. By 2050, most coal plants would shut down.
Cars and other forms of transportation, meanwhile, would need to be shifting strongly toward being electrified, powered by these same renewable energy sources. At present, transportation is far behind the power sector in the shift to low-carbon fuel sources. Right now, according to the International Energy Agency, only 4 percent of road transportation is powered by renewable fuels, and the agency has projected only a 1 percent increase by 2022.
The report’s statements on the need to jettison coal were challenged by the World Coal Association.
“While we are still reviewing the draft, the World Coal Association believes that any credible pathway to meeting the 1.5 degree scenario must focus on emissions rather than fuel,” the group’s interim chief executive, Katie Warrick, said in a statement.