The greatest show on earth

Climate change denialism seems to be in vogue at the moment so I wanted to write a bit about that.

What people often don’t understand with climate change is that it’s not just about sea levels rising gradually over the next 100 years. The more important point is that the environment is an incredibly complex system balanced in a sort of stable but highly precarious equilibrium upon which relatively minor changes can have unpredictable and large effects.

Example 1: Suppose you have an insect which feeds on trees over the summer then dies out in the cold of the winter. With climate change, the temperatures become a couple of degrees milder during the winter and some insects manage to survive the winters. After a few generations, by the miracle of natural selection, you have an insect population which can survive throughout the year. The insect has no effective predators, a comfortable climate and more food than it can dream of, so it reproduces at an exponential rate. The trees evolved to handle a stable population of the insect, and because they can’t adapt nearly as quickly, vast areas of trees become infected and will eventually die out. This is happening on a large scale to North America’s trees, including but not limited to the conifer forests in Yellowstone park.

Example 2: Then you have entirely counter-intuitive environmental damage due to human interaction: Suppose you have a plant which tends to be very small but needs a large amount of sunlight. It grows in areas also inhabited by larger and denser trees and shrubs, which obscure the sunlight, but that’s fine because natural fires sweep the area every few years, destroying taller plants and keeping the floor open to direct sunlight. But then humans come along and decide that fires are bad, so they extinguish the fires and prevent them from spreading. Now, the dense shrubs grow unabated, obscuring light from the smaller plants on the floor, which struggle and eventually die. This is what’s happening to the Venus Fly Trap, one of nature’s most unique plants.

What a human would perceive as a small change to environment can rapidly destabilise large ecosystems, which, like it or not, we exist within.

Climate change has occurred all throughout the earth’s history. However, it has occurred at a very slow pace, and this gives natural selection a chance to evolve plants and animals that can survive their changed environment. Climate change is now rapid enough that most living creatures simply have too long a reproduction cycle to stand a chance of adapting.

Check out this xkcd for a striking representation of just how fast things are changing. Scroll down and follow the dotted line.


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