A deal for the world to transition away from fossil fuels was hailed as a historic achievement on Wednesday at the U.N. climate summit in Dubai, but there's a good chance it won't achieve its ultimate goal - holding global warming to 1.5 degrees Celsius.
For months, COP28 President Sultan al-Jaber had described that 1.5C limit - first stated in the 2015 Paris Agreement - as his "North Star" or guiding principle for the summit.
Scientists say that a global temperature rise beyond 1.5C above the preindustrial average will trigger catastrophic and irreversible impacts, from melting ice sheets to the collapse of ocean currents.
But year after year, that target slips further away - with the world's planet-warming emissions still rising, and temperatures hitting new heights.
This year will be the hottest ever on record, with the global average for 2023 a sweltering 1.46C above preindustrial levels.
In terms of global warming, which is measured in terms of decades, the world has experienced nearly 1.2C (2.2F) of warming.
The deal made in Dubai, called the UAE Consensus, would see the world commit to transitioning away from "fossil fuels in energy systems, in a just, orderly and equitable manner ... so as to achieve net zero by 2050 in keeping with the science."
But scientists said that, while the pact was unprecedented, it still wasn't enough for that outcome to be realized.
"It's a landmark result because it's the first time we've said we're going to reduce fossil fuel use," said James Dyke, an earth systems scientist at the University of Exeter in Britain.
"But you can forget about 1.5C."
TOO LITTLE, TOO LATE
The U.N. Intergovernmental Panel on Climate Change (IPCC), the main scientific body which informs the U.N. Framework Convention on Climate Change, has said that limiting warming to 1.5C with no or limited overshoot would require rapidly cutting greenhouse gas emissions.
Specifically, the world needs to cut its emissions from 2019 levels by as much as 43% in the next six years, 60% by 2035 and reach net zero by 2050 in order to prevent compounding impacts, such as thawing permafrost which releases long-trapped greenhouse gases, triggering even more warming.
The IPCC declined to comment on the outcome of COP28.
The world posted record high greenhouse gas emissions in 2022, rising 1.2% above 2021, according to the 2023 U.N. Emissions Gap Report.
The UAE Consensus does not commit the world to phasing out oil and gas, nor to near-term timelines for transitioning away from fossil fuels.
"It's like promising your doctor that you will 'transition away from donuts' after being diagnosed with diabetes," said climate scientist Michael Mann of the University of Pennsylvania.
If countries are to have even a 50-50 chance of limiting warming to 1.5C, they can emit only another 250 billion metric tons or so of carbon dioxide. At current emissions levels, that will be met in just six years, according to an October 2023 study in the journal Nature Climate Change.
"This mandate is still not even close to what's needed to accomplish the goals we agreed on in Paris in 2015," said climate scientist Katharine Hayhoe of Texas Tech University.
This is true for high-emitting developed countries who also haven't committed to greater support for developing countries in the energy transition, she said.
The UAE Consensus also calls on countries to accelerate new technologies, which could include "abatement and removal technologies such as carbon capture and utilization and storage" (CCUS).
This means the world could continue using coal, oil and gas, provided they can capture those emissions. Critics say the technology remains expensive and unproven at scale, and worry that it will now be used to justify continued drilling.
"Sultan Al-Jaber and everybody else ... they are committing to an overshoot scenario," Dyke said. "The plan is we're going to exceed 1.5C quite significantly, and then it's going to be the deployment of CCUS over the rest of the century to drag temperatures back down."
That's not necessarily the fault of COP28 alone, scientists said. The 1.5C goal was dead on arrival already in Paris in 2015, without the summit producing a clear plan back then to rapidly rein in fossil fuel use right away, they said.
WHERE'S THE BEEF?
Despite the COP28 Presidency's efforts to highlight food security as a pressing threat, the UAE Consensus does not attempt to tackle the sizeable emissions that come from agriculture and waste.
Farmlands, livestock and landfills account for one-third of the world's planet-warming emissions.
But they're also harder to bring down, with limited solutions on offer.
"Even if fossil fuels were phased out, if you don't tackle food systems, it's impossible to reach 1.5C," said agricultural scientist Emile Frison of the International Panel of Experts on Sustainable Food Systems.
The COP28 talks also saw a raft of new voluntary commitments, ranging from tripling renewables to reining in methane emissions from oil and gas operations.
An assessment by the International Energy Agency found that, even if those results were fully delivered, it would only close about one-third of the emissions gap to limit warming to 1.5C.