Solar geoengineering

The historic Paris climate agreement started a mantra from developing countries: “1.5 to stay alive.” It refers to the international aim to keep global warming under 1.5 degrees Celsius (2.8 Fahrenheit) compared with preindustrial times. But the world will likely pass that threshold within a decade, and global warming is showing little sign of slowing. The world is already facing natural disasters of epic proportions as temperatures rise. Heat records are routinely broken. Wildfire seasons are more extreme. Hurricane strength is increasing. Sea level rise is slowly submerging small island nations and coastal areas. The only known method able to quickly arrest this temperature rise is climate engineering. (It’s sometimes called geoengineering, sunlight reduction methods or solar climate intervention.) This is a set of proposed actions to deliberately alter the climate. These actions include mimicking the cooling effects of large volcanic eruptions by putting la...

Imagine a future where, despite efforts to reduce greenhouse gas emissions quickly, parts of the world have become unbearably hot. Some governments might decide to “geoengineer” the planet by spraying substances into the upper atmosphere to form fine reflective aerosols – a process known as stratospheric aerosol injection. Theoretically, those tiny particles would reflect a little more sunlight back to space, dampening the effects of global warming. Some people envision it having the effect of a volcanic eruption, like Mount Pinatubo in 1991, which cooled the planet by about half a degree Celsius on average for many months. However, like that eruption, the effects could vary widely across the surface of the globe. How quickly might you expect to notice your local temperatures falling? One year? Five years? Ten years? What if your local temperatures seem to be going up? As it turns out, that is exactly what could happen. While modeling studies show that strato...