Two grey wolves huddled closely together in a field

The Quadra Project: Structural Change

Systems are complicated. Indeed, we are just beginning to understand how complicated and unpredictable they are. And they include everything from biological ecologies to global weather.

Systems are integrated. Each part of a system is connected to all the other parts, so that any change in any part influences all the other parts. Usually, small changes are absorbed into the system with little apparent effect. But introduce enough changes, or alter key components, and something unpredictable happens. In Systems Theory, this is called “emergence”, and is marked by a sudden and unpredictable restructuring of the entire system.

Emergence, in biological systems, is called trophic cascades. A classic example is the series of events that occurred in Yellowstone National Park when wolves were removed. Without the wolves to raise the anxiety level of the elk, the ungulates peacefully browsed the seedlings, causing the forest to age into old trees with no replacement saplings, but also making the entire system vulnerable to forest fires. The elk then ate the underlying bushes, causing a collapse in insect, bird, beaver and fish populations. Without the stabilizing effect created by the wolves, the elk population exploded and the collapse accelerated. When wolves were introduced to Yellowstone, the entire system began to correct itself.

A similar event took place on the northwest coast of North America with the decimation of sea otters at the end of the 19th century. Without these mammals to eat the sea urchins, the populations of these echinoderms exploded. They ate the bull kelp beds that were the nurseries for many species of fish, so the decline in fish populations caused a cascading effect on sea birds, seals and whales. Even the salmon runs suffered, along with the populations of bear, insects and songbirds. Trees grew less vigorously because they were no longer being nourished by the carcasses of the dead salmon.

In the Serengeti of Africa, the trophic cascade phenomenon explained a curious mystery. Why, biologists wondered, could this heavily grazed grassland support such an immense population of animals? Agricultural efforts to raise such populations of cattle in comparable areas resulted in the decimation of the grasslands and an ecosystem collapse. The key turned out to be the apex predators. Lions, cheetahs and hyenas kept the wildebeests, zebras and gazelles on the move, preventing them from overgrazing and degrading any particular area. At the same time, animals on the move distributed urine and feces over wide areas, aiding plant growth while preventing localized contamination.

Climate, as a system, may be more complicated than its biological counterpart, and the experiment we are conducting by increasing the global temperature with greenhouse gases will likely yield surprising results given the unpredictability of emergence. We are changing the factors that have created regular weather, but we don’t know when the incremental changes might shift from gradual to something radically different. This may already be occurring, but we won’t know definitively until it happens.

One of the major effects of global warming is to decrease the temperature differential between the tropics and the poles—the poles are heating 3 to 4 times faster than the tropics. It is this temperature differential that fuels the jet streams, which keep weather patterns moving around the planet. As the polar-equatorial temperature differential decreases, the jet streams tend to move more slowly. As they wander, they lock weather patterns into place for longer periods, or draw particularly cold air southward from higher latitudes or warmer air northward from lower latitudes. We experience this as protracted weather extremes: sometimes colder than normal and sometimes hotter than normal, with the average always being slightly warmer in conformity with the 1.2°C temperature rise since pre-industrial times.

The weather changes are compounded by humidity changes. A 1.0°C temperature increase raises humidity levels by 7% and precipitation by 14%, resulting in heavier rainfalls or snowfalls when they do occur—perhaps for longer periods. So changed weather patterns will likely increase the frequency and intensity of floods and droughts.

Ocean currents are also powerful regulators of weather, and they are affected by the same dynamics that influence jet streams. Like the atmospheric winds that distribute weather around the planet, ocean currents move heat. Warmer, less dense tropical water rises and heavier, colder polar water sinks, creating circulation patterns that help to cool the tropics and to warm the mid-latitudes and poles. If, however, the poles are heating more rapidly than the tropics, then the convection currents lose the temperature differentials that energize them. The melting of polar glacial ice reduces the salinity and thus the density of the northern oceans, also impeding the convection effect. Should these ocean currents stop because of emergence, then global climate changes almost everywhere would be immediate and dramatic.

Systems, which regulate much of what happens on Earth, are precariously balanced. They usually tolerate a little change without much effect. But, introduce enough change, and at some unknown point, we get radically reorganized ecologies and weather systems that we had never anticipated. Then gradual suddenly stops being gradual.

Ray Grigg for Sierra Quadra

Top credit: Two Grey Wolves – Photo by Caninest via Flickr (Public Domain)