Today’s letter is devoted to a major scientific study, published one month ago in the journal Science, and to surrounding commentaries about the importance of the study. The study itself was authored by over 100 scientists, coming from universities and other institutions all over the globe, who worked on an experiment conducted at CERN’s facilities near Geneva. The project confirmed the existence of an atmospheric process that creates massive quantities of aerosols suited to serve as nuclei needed for cloud formation, especially meaningful in pristine areas such as the polar regions, where other types of nuclei are relatively uncommon. Here is a link to the abstract—https://science.sciencemag.org/content/371/6529/589, and to another which features a short video plus a scripted interview with a CERN scientist, Jasper Kirkby, who participated in the study: https://videos.cern.ch/record/2751181. According to Kirkby, “The implications for the future are notable. Global iodine emissions have increased three-fold over the last 70 years and may continue to increase in the future as sea ice becomes thinner. The resultant increase of iodic acid cloud condensation nuclei could increase longwave radiative forcing from clouds and provide a positive feedback mechanism that accelerates the loss of sea ice in the Arctic.”
Further commentary was published by QUANTAmagazine in an article entitled, “Cloud-Making Aerosol Could Devastate Polar Sea Ice,” found at this link: https://www.quantamagazine.org/cloud-making-aerosol-could-devastate-polar-sea-ice-20210223/. The author of the article presents a clear explanation of the study’s value with the help of three scientists, including Jasper Kirkby. One other, Andrew Gettelman, is a prominent figure in modern cloud research, an author of numerous other studies based on cloud models that tend to upwardly revise the regular IPCC projections of future climate change. What follows are a number of significant excerpts I picked out of the QUANTA article:
“They (researchers) further suggest that, as the Earth continues to warm from rising levels of greenhouse gases, this process could be a major new mechanism for accelerating the loss of sea ice at the poles — one that no global climate model currently incorporates.”……”Just as dew condenses onto blades of grass, water vapor in the atmosphere can condense around aerosols to create clouds”…..”Global iodine emissions have tripled over the past 70 years, and scientists predict that emissions will continue to accelerate as sea ice melts and surface ozone increases. Based on these results, an increase of molecular iodine could lead to more particles for water vapor to condense onto and spiral into a positive feedback loop.”…..”The results could also help scientists understand how much the planet will warm on average when carbon dioxide levels double compared with pre-industrial levels. For decades, estimates have put this number, called the equilibrium climate sensitivity, between 1.5 and 4.5 degrees Celsius (2.6 to 8.1 degrees Fahrenheit) of warming, a range of uncertainty that has remained stubbornly wide for decades. If Earth were no more complicated than a billiard ball flying through space, calculating this number would be easy: just under 1 degree C, Kirkby said. But that calculation doesn’t account for amplifying feedback loops from natural systems that introduce tremendous uncertainty into climate models”…..”Clouds generally cool the planet, as the white tops of the clouds reflect sunlight into space. But in polar regions, snowpack has a similar albedo, or reflectivity, as cloud tops, so an increase in clouds would reflect little additional sunlight. Instead, it would trap longwave radiation from the ground, creating a net warming effect.”
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I somehow get the feeling that the polar sea ice effect these scientists are looking for is already here, produced holistically by the total amount of precipitable water (PW) that is in place and being measured. If I’m right, the ice effect will increase whenever the total amount of overhead PW increases, regardless of how the mixture is divided between vapor and clouds.
Carl