Tropic of Chaos_ Climate Change and the New Geography of Violence - Christian Parenti [27]
Feedback Loops and Tipping Points
I was in Kenya in 2008, and when the Short Rains of that year finally arrived, they hit with tremendous force: flash floods left 300,000 people in need of relief aid. Landslides and floods displaced hundreds. Flooded pit latrines fouled many shallow wells, and typhoid was soon killing people. That year packed a one-two punch: drought chased down with violent flooding. By January 2009, 10 million people needed food aid to fend off starvation.6 According to the Kenya Meteorological Department, “aboveaverage temperatures in the Indian Ocean” had caused the heavy rains.7
Were the Kenyan calamities of that year definitively linked to climate change? No. The climate system is too complicated to blame any one weather event on anthropogenic climate change. But the trend lines all head in the same direction: as atmospheric carbon dioxide (CO2) rises, average temperatures increase and weather patterns become less stable.
Many civilizations have lived in the shadow of their own end-time narratives, and it is tempting to describe climate change as just such a vision, only played out in a secularized aesthetic. But climate change is real, and our understanding of how it is happening is based on very serious and reliable science. And the unraveling of the current climate system seems to be happening faster than scientists had predicted.
It is worth reviewing the facts once more. Researchers from a variety of disciplines—meteorologists, oceanographers, paleontologists, biologists, and so forth—are together arriving at fairly firm conclusions about how our climate works, what its history has been, and where it is probably headed due to our massive emissions of greenhouse gases. They note that Earth’s climate is warming, and this will have consequences soon—for most of us, within our lifetimes.
The outline of the scientific consensus runs as follows: For the last 650,000 years atmospheric levels of CO2—the primary heat-trapping gas in Earth’s environment—have hovered between 180 and 300 parts per million (ppm). At no point in the preindustrial era did CO2 concentrations go above 300 ppm. By 1959 they had reached 316 ppm and are now at 390 ppm. At current rates, CO2 levels will double by mid-century.
Climate scientists believe that any increase in average global temperatures beyond 2°C (35.6°F) above preindustrial levels will lead to dangerous climate change, causing large-scale desertification, crop failure, inundation of coastal cities, widespread extinctions, proliferating disease, and possible social collapse. They fear that beyond the 2°C threshold, climate change could become self-reinforcing due to positive-feedback loops.
Scientists now understand that ecosystems, and Earth’s climate as a whole, do not always operate according to a smooth linear logic. Instead, natural systems are prone to rapid and sudden shifts. The population of a species can decline slowly or collapse rapidly, almost at once. Witness the near total disappearance of bat colonies in the northeastern United States due to the white nose fungus or the sudden decline of honeybee populations in recent years. Both problems can hopefully be reversed, but they illustrate how quickly natural systems can break down.
Throughout the climate system there exist dangerous positive-feedback loops and tipping points. A positive-feedback loop is a dynamic in which effects compound, accelerate, or amplify the original cause. Tipping points in the climate system reflect the fact that causes can build up while effects lag. Then, when the effects kick in, they do so all at once, causing the relatively sudden shift from one climate regime to another.