A sobering new piece in the journal Nature finds that October's dire UN science report about the ongoing and future effects of climate change may have actually underestimated the pace of global warming.
Why it matters: The new analysis, if borne out, widens what's already a huge gulf between the expected human and ecological toll from high levels and rapid rates of warming and the failure of governments worldwide to bring about the steep carbon emissions cuts that could prevent runaway temperature increases.
The big picture: The Nature piece sees a "good chance" that a temperature rise of 1.5 °C, or 2.7°F, above preindustrial levels could arrive by 2030 if emissions continue unchecked.
- That's a decade earlier than the UN science body envisioned in their report.
- "Policymakers have less time to respond than they thought," writes Texas A&M University atmospheric scientist Yangyang Xu. The other authors are University of California, San Diego climate scientist Veerabhadran Ramanathan, and UC-San Diego political scientist David Victor.
What they found: The authors see three big trends combining over the next 20 years that will make climate change "faster and more furious than anticipated."
- Carbon emissions: They're rising again after a plateau in 2014 to 2016.
- Air pollution: Ironically, governments' success in improving air quality is speeding up the temperature rise. That's because tiny particles known as aerosols in traditional pollutants help to reflect sunlight back into space. This blunts some of the warming due to greenhouse gas emissions.
- Natural climate cycles: The authors point to natural climate fluctuations that favor the increased release of heat from the oceans. One is a cycle of changes in the Pacific Ocean that may be heading back into a mid-latitude warming phase. The other is less mixing of surface and deep waters in the Atlantic, which keeps more heat at the surface.
What's next: The Nature piece says the accelerated warming calls for a suite of responses from scientists and policymakers that focus more heavily on the nearer-term.
- One of them are aggressive efforts to cut "super-pollutants" — methane, soot and hydrofluorocarbons — that are emitted in far lower amounts than CO2 but have an outsized and relatively near-term warming effect.
- And "various climate engineering options should be on the table as an emergency response," they write. They call for research, testing, and technical readiness to deploy the controversial idea of spreading aerosols into the stratosphere to reflect some solar energy away from the planet.
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