Since 2016, Harrison and his colleagues have been investigating whether it is possible to reduce coral bleaching in the Great Barrier Reef by altering the weather above it. As the planet heats up, unusually high ocean temperatures are stressing corals around the world, forcing them to eject their symbiotic partners: the photosynthetic single-celled algae that live in their tissues and provide them with much of their sustenance. Theoretically, machine-generated fog and artificially brightened clouds can shade and cool the water in which corals live, sparing them much of that stress.
…
Harrison’s project is essentially a highly localized version of geoengineering: the deliberate modification of the planet to counteract climate change. When Harrison began his undergraduate studies in the late 1990s, geoengineering was still largely taboo in the scientific community. In a paper that considered the history of such research, the climate scientist Stephen Schneider recalled that even the idea of including a single chapter on geoengineering in a 1992 National Research Council report resulted in “serious internal and external debates.” The physicist David Keith, now a prominent figure in the field, remembers colleagues in the ’90s telling him that pursuing geoengineering might tarnish his reputation and derail his career. Not much changed in the subsequent two decades, though there were some high-profile geoengineering blunders.
…
Since then, and especially in the past five years, the situation has evolved considerably. The failure to prevent the planet’s average temperature from reaching 1.5 degrees Celsius above the preindustrial base line, and the progressively obvious and lethal consequences of climate change, are rapidly shifting attitudes toward geoengineering. Interventions once deemed too risky to study are now viewed as potentially necessary. Geoengineering still faces substantial opposition: More than 550 scholars have signed a petition calling for an international non-use agreement that would severely restrict development and deployment of solar geoengineering, for example, a category that includes cloud brightening and other sunlight-reflecting techniques. Yet that appeal is countered by numerous endorsements for rigorous research on solar geoengineering and other climate interventions from prominent scientific organizations, including the United Nations Environment Program; the Royal Society, in Britain; the U.S. National Academies of Science, Engineering and Medicine; the American Geophysical Union; and the editorial board of the journal Nature. Just last year, the British government committed $75 million to such research, including outdoor experiments.
“Things have changed very quickly even in the last six months,” says Keith, who headed solar-geoengineering research at Harvard before moving to the University of Chicago in 2023 to establish a new climate-engineering initiative. “There’s a much higher level of interest. More senior political and environmental figures are willing to engage in a serious way. More people in the scientific core are talking about it. There’s new money. It feels different.”
Support for local and regional applications of geoengineering is growing in particular. Scientists who study Antarctica, for instance, are increasingly calling for physical interventions to stabilize the glaciers that are most likely to collapse. In addition to its limited scale, perhaps the compelling point in favor of Harrison’s project is its explicit goal to help save one of the world’s most celebrated ecosystems. If current trends continue, the compounding effects of global warming, ocean acidification and severe storms will devastate most of the planet’s tropical reefs by mid-to-late century, ultimately reducing them to fragmented havens tucked among swaths of slime-coated rubble. If we do not develop the means to protect them now, there won’t be much of anything left to protect.
…
Proponents of Harrison’s work counter that the limited scale and duration of localized geoengineering significantly reduce the inherent risks. The ship-based technology they are developing could be applied to just a few of the more culturally and ecologically important reefs among the nearly 3,000 that make up the Great Barrier Reef system. Even if cloud brightening were eventually deployed to protect the reef system as a whole — approximately the size of Italy — experts regard such an intervention less as a form of planetary engineering than a kind of regional weather modification, akin to cloud-seeding, which is already practiced in Australia, China, the United States and elsewhere to stimulate rain and reduce hail, primarily for the benefit of agriculture.
…
The idea of artificially brightening marine clouds began with puzzling satellite images of wispy white lines lacing the ocean. In 1966, the meteorologist John H. Conover proposed that such “anomalous cloud lines” were a product of oceangoing vessels. Subsequent research proved him right. A cloud typically forms when water vapor in the air condenses onto tiny airborne particles, which can be dust, salt, soot, pollen grains or microbes. As the particles accumulate water, they form increasingly large droplets, which collide and combine, eventually becoming a visible white cloud. Ship tracks, as they are now known, form around the copious airborne particles generated by ship exhaust.
…
Following a period of lab-based technological refinement, the next logical step is a substantially larger outdoor experiment. With three big ships working in tandem, Harrison thinks they could modify cloud cover across roughly 460 square miles of the Great Barrier Reef. He estimates that modifying weather over the entire reef system would likely require up to 800 cloud-brightening stations, which could be a mix of dedicated vessels, volunteer ships and anchored barges. Deployment at that scale is where some of the major obstacles to this endeavor come into focus. First, where is all that infrastructure going to come from? The single research vessel the scientists currently rely on is expensive and in demand among researchers. Acquiring an entire fleet of cloud-seeding ships, supplementing them with anchored stations and operating all that equipment continuously through the worst summer heat waves is a vastly more ambitious and costly proposition. Australia has committed an average of $200 million each year from 2014 to 2030 to fund all its reef restoration, adaptation and management efforts combined. This one intervention would probably exceed that entire budget. Even so, that’s a fraction of the roughly $4 billion that the reef contributes annually to the Australian economy, mostly through tourism.
https://archive.is/nHdFn
…
…
…
…
…