Friday, October 15, 2010

Lost in the Clouds - Blog Action Day 2010 "Water"

Blog Action Day is an annual event on 15 Oct (since 2007) that brings together bloggers around the world to write on a certain topic of pressing importance. This year's theme is "Water", and it ties in well with something that I've been meaning to write about for some time.

A week ago, I was fortunate to hear Dan Janzen, the ecologist and conservationist known for his work in setting up the Guanacaste National Park in Costa Rica, speak in person. His talk was great - you could tell that he's a no-nonsense personality who speaks his mind and is frank about his opinions on conservation. One very small part of his talk was a series of three photographs that he showed, of one of the cloud-forest mountain peaks in that park. In the first picture, taken in the 1970s (if I remember right), it's shrouded in a permanent fog. The next picture, taken a few years later, shows much sparser wisps, and the most recent one is completely bone-dry. The sky is blue and totally clear. Rising temperatures have lowered humidity and lifted cloud cover above the level of the mountains. The cloud forest has lost its cloud.

When we think of water issues and the environment, we tend to think about pollution in rivers, about salinization of groundwater, or eutrophication in lakes. This is water that we can see flowing or pooled up, that people can drink from, swim in, and fight over. But that's just one part of the water cycle we all learn about as children, when we drew arrows in our textbooks going from the ocean to the fluffy white clouds and back down as rain to the green fields below. In cloud forests, declining humidity has a strong biotic impact. They have been implicated in population crashes of frogs and other animals. As the fog rolls across these peaks, though, they also drip into streams and rivulets that feed waterways down below: a direct impact of climate change on water availability for both nature and people.

It's not just something that only affects picturesque spots far away in the exotic tropics, either. A major part of the water supply to the state of California comes from the spring thaw of the snowpack on the mountains of the Sierra Nevada range, which form part of the mountainous backbone that runs up the Western half of North America. Winds blowing in humidity-laden air from the Pacific is forced up the slopes of the Sierra Nevada, where it condenses in the cold upper reaches of the mountains and falls as precipitation; in the wintertime this is in the form of snow that accumulates until the thaw. This is also why Nevada is such a dry place - it sits in the 'rain shadow' of the range. As temperatures rise, however, the quantity of condensation and precipitation will decline and likewise the water that can be supplied to the inhabitants of California, both human and non-human. This water stress will force choices to be made between serving people and preserving the environment, as described in my previous post.

In the grand scheme of things, though, the environment will bounce back in some form. The Sierra Nevada is a relatively young mountain range, formed by uplift less than 10 million years ago. As they rose up, they cut off the formerly extensive lakes inland in the Great Basin behind them from the rivers that had led from them to the coast. The lakes eventually dried up and disappeared, causing the extinction of their fauna, as did the freshwater fishes in the former rivers. As the mountains grew further, however, rivers once again flowed, fed by the precipitation intercepted by the range. The fishes that now populated them were instead secondary re-invasions of freshwater habitats by marine fishes. (Oversimplified version of a much more intricate and fascinating story.) Life went on even in the face of drastic change. What's different about this time, though, is the time scale. The environment is now changing in tens and hundreds of years instead of thousands and millions. It's a sobering thought to think that long after we humans disappear, some alien paleontologist looking through the fossil record of the former Earth would find our age to be one of the great Mass Extinctions in the history of life. We manage to slake our thirst, but at the same time have poisoned the well for everyone.

(Stay tuned for Blog Action Day updates at our partner blogs: Coastal Cleanup Singapore, Otterman Speaks, Wild Shores Singapore.)

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