Climate science report paints dire picture, with consequences and opportunities for chemistry

On Aug. 9, the Intergovernmental Panel on Climate Change (IPCC) released its sixth assessment report on climate science. The message from the United Nations body is dire: thanks to the world’s industrial history of spewing carbon dioxide and other greenhouse gases into the atmosphere, some catastrophic effects, such as sea level rise, are now unavoidable.

However, the world does have the opportunity to head off more extreme average temperature increases and the associated consequences. Dramatic emissions cuts and adoption of technologies like carbon capture could reduce CO₂ emissions to net zero by 2050. That would ensure global average temperatures slightly exceed, then come back to around 1.5 °C above preindustrial levels, by the end of the century.

The IPCC report also focused on potent “short-lived climate forcers” like methane and black carbon, which warm the planet but don’t persist as long as CO₂. Changing atmospheric levels of these short-lived gases and particles could address global warming faster. “The report emphasizes short-term pollutants like methane because of their potential to shave peak temperatures,” says Rob Jackson, an earth system scientist at Stanford University who was not on the IPCC panel.

Some of the dire effects of climate change are inevitable. “Regardless of how quickly we get our emissions down, we’re likely looking at about 15–30 cm—or 6–12 inches—of global average sea level rise through the middle of the century,” said Bob Kopp, director of the Rutgers Institute of Earth, Ocean, and Atmospheric Sciences, speaking at an Aug. 8 press conference. “If we limit warming to well below 2 °C, it should take many centuries for sea level rise to exceed 2 m or 7 feet, which would be a far more manageable situation.”

Also inevitable are more extreme weather events, such as heat waves, heavy rainfall, and droughts, said Ko Barrett, senior adviser for climate at the National Oceanic and Atmospheric Administration’s research division and IPCC vice chair, at the press conference. The US Chemical Safety and Hazard Investigation Board flagged planning for such events as a critical need for the chemical industry when it investigated flooding and a fire at an Arkema plant in Texas due to Tropical Storm Harvey in 2017.

When it comes to mitigating climate change, “chemistry can make a huge impact,” says Amanda Morris, an inorganic chemist at Virginia Tech who is developing metal-organic frameworks (MOFs) to capture CO₂ for conversion into useful chemicals. “Getting us to those scenarios where we don’t have 3 or 4 °C of warming will require lots of technological advancement, and chemists from lots of different backgrounds can play a role.” The world needs better batteries, efficient ways to capture and store or convert CO₂, and more efficient solar cells, and “that’s all chemistry,” she says.

Chemists’ catalytic expertise may also help with removing atmospheric methane. Jackson touts a somewhat counter-intuitive strategy that involves oxidizing atmospheric CH₄ to convert it into CO₂. There is far less CH₄ in the atmosphere than CO₂, but CH₄ is 80 times as potent as CO₂ over a 20-year time frame, so this conversion would provide a net benefit, he says—even though CO₂ is longer lived.

But that won’t avoid the need to cut methane emissions, Jackson emphasizes. People emit more than half of all the CH₄ that goes into the atmosphere, with agriculture and fossil fuels playing an equal role.

A study published earlier this year suggests that detecting and addressing leaking natural gas wells, natural gas pipes, and other fossil fuel sources is the cheapest way to address methane emissions (Environ. Res. Lett. 2021, DOI: 10.1088/1748-9326/abf9c8). Figuring out where major leaks are has been a challenge—but that’s about to change, Jackson says. Publicly available data from methane-monitoring satellites scheduled to launch over the next couple of years, MethaneSAT and Carbon Mapper, mean “there won’t be anywhere to hide,” Jackson says.

Meanwhile, cutting emissions of greenhouse gases such as methane comes with an immediate side benefit in the form of better air quality. Methane, for example, catalyzes the formation of ground-level ozone, a respiratory irritant. And cutting methane emissions would also reduce other health-harming air pollutants that tend to be released at the same time, such as cancer-causing benzene, says Jackson.

“Some things are win-win,” says Joost de Gouw, an aerosol scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. “The climate benefits take a long time to manifest,” he says. “But it’s also good to make sure people understand there are other benefits to doing this, and they have a more immediate effect” such as better quality of life and lower health-care costs.