A number of people are concerned about geo-engineering and contrails. Their concerns are misplaced.
Cloud seeding, for purposes of rainmaking, has been going on for generations, especially when there are droughts. There has been no noticeable effect, either bad or good. If the contrails are for cloud seeding, nobody should worry because, regardless of what metals or other chemicals are used, the amounts are trillions of times less than what volcanoes produce.
Geo-engineering is an entirely different thing and serves two purposes.
The first is to increase the reflectivity of the earth so that less solar energy will fall on its surface, counteracting the carbon dioxide that causes the atmosphere to retain heat that would otherwise be re-radiated into space.
The second is to increase the fixation of carbon dioxide into the oceanic and terrestrial biospheres. Carbon dioxide, when not fixed, acidifies the oceans and interferes with shell formation. This damages the oceanic phytoplankton food chain.
Climate scientists are very concerned that international politics will prevent an effective and enforceable climate agreement. Absent such an agreement, the earth’s average temperature has about a 10 percent chance of increasing 9 degrees centigrade, which would make large land areas uninhabitable. Should we be on such a path, we will have no choice but to employ geo-engineering.
The reflectivity part of geo-engineering involves about one thousand 747 flights per year, injecting loads of sulfur dioxide into the stratosphere, creating lots of reflective clouds. These clouds will also promote rain. The cost of doing this is in the low billions of dollars, and is financially and technically feasible for a number of nations. Saudi Arabia, Iran, India, the United States, South Africa, Brazil, Japan, China, Russia, Australia and the European Union all come to mind. Any of these nations might have the motivation, resulting from catastrophic overheating or drought, to start on such a program without an international agreement.
The problem is that we really don’t have a good enough atmospheric model to be able to plan the flight paths of these planes to produce the desired result. Brazil might try to save itself with the effect that no rain falls in Africa. China might try to save itself with the effect that no rain falls in North America. This is a formula for war.
Several of us may remember television weather shows earlier this year, when extreme rainstorms affected the east and southeast while drought plagued the west. The effect was due to an unpredicted movement of the jet stream from west to east. Similar, but much more extreme effects, can occur due to misplaced tinkering with global cloud cover. Absent an excellent atmospheric climate model, any large-scale tinkering is bound to be misplaced. Furthermore, technology for ameliorating ocean acidification is far less understood than that for the atmosphere.
The best answer is an effective international agreement that rapidly reduces the amount of carbon dioxide introduced into the atmosphere; however, there must be a Plan B, a geo-engineering plan.
Enough of the parameters required for a useful atmosphere model are not well known. Nearly every week, in Science or Nature magazines, I see new parameters discovered or quantified. The latest one has to do with the distribution of iron from oceanic geothermal vents. Iron encourages the growth of phytoplankton. There are plenty more such things that need to be well understood before we can have a good model.
My message is this: people should encourage spending all the money necessary for model development because Plan B may prove inescapable. They should stop worrying about contrails, which are incredibly trivial compared to volcanoes.
Chet Seligman is a retired computational biologist who has lived in West Marin since 1971.