Aquatic Synergasms
06/04/08 16:31
A few years ago, the term “synergistic” was all the rage for National Science Foundation grant proposals and probably elsewhere in scientific funding venues. The term still seems to rage across the Intergovernmental Panel on Climate Change (IPCC; the U.N. body that focuses on “global warming” ). Synergistic basically means that the interaction between two of more forces is different than simply adding the forces together. In the western portions of North America, for instance, annual precipitation is becoming more variable (particularly with more droughts and higher rates of evaporation, resulting in drier and more frequently dry periods). Although fire is a natural part of the landscape in the region, the interaction of more fire and a drier climate is likely to transform the region as fires become more frequent and more intense. That’s a synergistic interaction.
I was writing a lot of grant proposals a few years ago and began spouting grantspeak early and often – it’s an unpleasant and mostly ugly mode of bureaucratic English. But it can be fun to ridicule. When I got carried away with the experience of synergies, I called them “synergasms.” Since then, I’ve preferred to point out tgat the experience of climate change synergasms is pretty widespread already.
For instance, in China the Three Gorges Dam (TGD) is a massive structure about 2/5ths of the way upstream from the mouth of Yangtze river. It’s currently the largest dam in the world. It represents both the hope of more than 4,000 years of Chinese struggle against flooding and climate variability and a massive environmental, social, economic, and cultural disaster. We’re stuck with TGD and its consequences for a long time.
Although TGD has many purposes, one of the most important is to reduce the impact of flooding. The Yangtze levels out below the dam, with only a gradual slope from there to the mouth of the river some 2,000 km to the east. And this area – the middle and lower Yangtze – is where the river has wandered over its long history. Large lakes and wetlands merge with the estuary and great marshes. Historically, these lakes along the shores were big enough for major naval battles to be fought, such as during the terrible Taiping rebellion of the mid-19th century.
These lakes and wetlands receive a great deal of their water from the river itself during its normal annual flooding. Thus, when the river gets high enough, some of the Yangtze’s water flows into these other water bodies – they are not the “standing” water bodies most of us think of. The river’s water also brings nutrients (and pollution), as well as sediment. The contents of these lakes are flushed by the river. Likewise, the fall of the river can drain these lakes and wetlands. Given that these systems are often intensively used by cities and pork farms (for sewage treatment) and by fish farmers, they need to be flushed. Regularly. The river’s annual flooding also serves as a signal for many kinds of wildlife to shift from one kind of habitat to another, such as moving from the main channel to the lakes for spawning. This cycle setss the natural flow regime for the river and the hydroperiod for its dependent lakes.
TGD has altered this ancient relationship by reducing the height of the normal flood. In effect, the lakes aren’t filled as much as normally, and they begin losing the little water they have pretty quickly. Given that the region is seeing more climate variability (more frequent droughts and floods), the interaction between TGD and climate change on the river can potentially be terrible during a drought. Last year – 2007 – looks to be the test case for this synergy. A talk with a research team focused on conservation of the Yangtze finless porpoise suggested that December and January saw the untimely separation of one major porpoise breeding lake, one of the last (and best) regions of habitat for the species. Early estimates suggested that the surface area of the lake was less than 5% of its historical norm for this time of year, potentially trapping several hundred porpoise into a tiny and probably pollution-rich and food-poor area. No word yet on how this experience of synergasm is going.
Nonetheless, synergasms will be the norm for freshwater. Most bodies of freshwater are used, managed, and influenced by people, often quite intensively. “Wilderness” is a spectacularly rare state for a freshwater system to be in during the 21rst century. And climate change in many cases is going to lead to more very difficult kinds of competition between humans and our needs and wild species and ecosystems and their needs. Expert more of the same. And hope for the porpoises.
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