This story includes details on the pace of climate change that may be difficult for some readers. If you are feeling overwhelmed by this crisis situation here is a list of resources on how to cope with fears and feelings about the scope and pace of the climate crisis.
The world’s available carbon budget is running out faster than scientists expected, meaning that average global warming could routinely exceed 1.5°C by 2029 rather than the mid-2030s, warns a new study published yesterday in the journal Nature Climate Change.
“The window to avoid 1.5°C of warming is shrinking, because we continue to emit and because of our improved understanding of atmospheric physics,” lead author Dr. Robin Lamboll of Imperial College London told the BBC. “We now estimate that we can only afford to release about six years’ worth of current emissions before we are likely to exceed this key Paris agreement reference point.”
Holding average global warming to no more than 1.5°C was the signature goal in the 2015 Paris deal. In its latest assessment report earlier this year, the Intergovernmental Panel on Climate Change (IPCC) said countries would have to cut their emissions 43% from 2019 levels by 2030, 60% by 2035, 69% by 2040, and 84% by 2050 for even a 50-50 chance of hitting that target.
But the IPCC’s assessment was limited to scientific papers published through 2020. This week’s study adjusted the carbon budget estimate to include record carbon dioxide emissions over the last three years, along with the impact of other pollutants in the atmosphere.
“One of the most critical are sooty particles called aerosols, which mainly arise from the burning of fossil fuels,” the BBC explains. “They contribute heavily to air pollution but have an unexpected benefit for the climate because they help cool the atmosphere by reflecting sunlight back into space.”
It turns out that cooling impact has been far greater than scientists previously believed, the new paper concludes.
The difference is enough to remove 100 billion tonnes of carbon from a global budget that the IPCC estimated at 500 billion tonnes, the news story states. Add that to the last three years of emissions, and the remaining budget adds up to just 250 billion tonnes—at a moment when human activity is still generating about 40 billion tonnes of CO2 or equivalent per year. To avoid overshooting the 1.5°C target, the paper says, humanity would have to bring emissions to net-zero by 2034—16 years ahead of the 2050 deadline that has been at the core climate policy and action for years.
“There are no socio-technical scenarios globally available in the scientific literature that would support that that is actually possible, or even describe how that would be possible,” study co-author Joeri Rogelj of Imperial College London told the BBC. “So that really shows that having a 50% or higher likelihood that we limit warming to 1.5°C, irrespective of how much political action and policy action there is, is currently out of the window.”
Rogelj added: “That doesn’t mean that we’re spinning out of control to three or four degrees. But it does mean the best estimates suggest that we will be above 1.5°C of global warming.”