Here are a few selected facts from their readings, for your consideration:
- "Each day, planet Earth receives about 10^19 kcal of solar energy." The textbook compares this amount of energy to the energy of 100 million atomic bombs. For your reference, one kcal is equal to 4184 joules.
- "Most of this energy is absorbed, scattered, or reflected by the atmosphere or by Earth's surface."
- " . . . only 1% is converted to chemical energy by photosynthesis."
- " . . . on a global scale this is enough to produce about 170 billion tons of organic material per year"
- "When energy flows as organic matter . . . much of it is lost at each link in (the) food chain."
- "The efficiencies of energy transfer (from one level of the food chain to the next) usually range from 5 to 20%. In other words, 80 to 95% of the energy . . . never transfers from (one level) to the next."
- "An important implication of this stepwise decline of energy in a trophic tructure is that the amount of energy available to top-level consumers (carnivores) is small compared with that available to lower-level consumers (herbivores)."
- This explains why "food chains are limited to three to five levels; there is simply not enough energy . . . to support another (level in the food chain)."
For example:
1,000,000 kcal of sunlight > 10,000 kcal of plant vegetation > 1,000 kcal of primary consumers > 100 kcal of secondary consumers > 10 kcal of tertiary consumers
- "Eating meat of any kind is an expensive luxury, both economically and environmentally."
- "Based on the rough estimate that 10% of the energy available in a trophic level (level of the food chain) is available at the next higher level up ... the human population has about ten times more energy available to it when people eat corn than when they process the same amount of energy of corn through another tropic level and eat corn-fed beef."
- "It is likely that as the human population expands, meat consumption will become even more of a luxury than it is today."
- Demand for meat drives up the prices of grains, fruits and vegetables because "potential supply of plants for direct consumption as food for humans is diminished by the use of agricultural land to grow feed for cattle, chickens and other meat sources."
And the pièce de résistance: Boss Hog: America's top pork producer churns out a sea of waste that has destroyed rivers, killed millions of fish and generated one of the largest fines in EPA history.
What do you think of this post format? It makes it much easier for me to share interesting facts & ideas that I'm thinking about on a short time budget, but it's no good if you guys find it unpleasant to read. If it's a hit, then let me know if there are any topics in biology you'd like me to cover.
Textbook cited: Biology: Concepts & Connections. 5ed. Campbell, Reece, Taylor & Simon.
6 comments:
I still think that (while vegetarianism can support a much larger population), it's the "expanding human population" part that causes us problems.
Even if humans learn to photosynthesize energy, a population that expands exponentially will still outgrow it's available resources, no matter how vast they are. On the other hand, a stable sized population could subsist on just about any level of the food chain without sabotaging itself...
This is true.
Did you know that the human population is no longer growing exponentially? It is, however, still growing pretty fast.
You know that my take (and actually, the textbook's take as well) is that we're going to need to find ways to live together successfully until we're able to reach a sustainable situation.
I thought about it some more, and I guess what I don't like about your argument is that you seem to be saying, "Since eating more vegetarian food isn't the ultimate solution, it's not an option worth investing in."
But there is no panacea. Arriving at sustainable future is necessarily a multi-step multi-angled process.
Eating vegetarian alone is not enough, but it does provide practical benefits right now. One of them is the ability to feed a burgeoning population... for now.
Others include decreased carbon emissions, decreased poluting, decreased risk of breeding super pathogens, and decreased deforestation.
Not a bad haul for something that really takes very little effort on part of the eater. (That is, making more vegetarian choices isn't hard. Trying to become a vegetarian cold turkey probably is.) Plus your grocery bill will be cheaper. ;)
You're right of course. Just because we have bigger problems isn't really a reason to ignore smaller (more soluable) ones. I think my argument is put forth half because it's appropriate, and half out of omnivorous guilt.
But I don't think my argument is quite as simple as just rejecting half-solutions. Increasing the world's capacity to support humans (by decreasing our needs via diet or whatever) seems a little bit like loaning money to a gambling addict. You're pretty sure they'll just gamble that away too, in fact, giving them more money may encourage that. On the other hand, you don't want a loan shark to break their thumbs either... just like I wouldn't want the human race to have to deal with famine or energy crises. But will the temporary solution take us farther from facing up to the ultimate solution??
That said, there's no reason for educated westerners like us to not make vegetarian choices. I also don't want humanity to outgrow it's resources before we even have a chance to think bigger!
I do think your concern is a good one.
If we increase the human carrying capacity of the planet by eating fewer animals products, are we accomplishing more than delaying crisises?
The answer may be no, but right now I believe we have many reasons to hope for a positive outcome.
As we've seen, the human population is no longer growing exponentially. We also know that access to good health and education, and women's rights, tend to bring about negative population growth rates. This is great news!
We're also seeing positive trends in environment and sustainability awareness. These are household concepts in Western countries, and many other countries also. The Pentagon recently told Bush that the biggest threat to Americans is climate change, not terrorists. And Jack Layton (NDP) just released bill C-377, the Climate Change Accountability Act".
There's also the new, rapidly expanding field of green technology.
And that's where it gets more complicated than just choosing more vegetarian options. :) Ensuring that these positive trends continue towards a sustainable, human friendly future may take a lot of effort and some amount of luck.
I'm out of time. But I wanted to comment on some of the many, easy ways we can support positive trends. (UNICEF's schools come to mind, where are fabulous. So is the OLPC that Daniel posted on recently.)
Cheers,
Rachael
This just confirms my usual angry rant, that we would have done ourselves all a favor if we had realized this before climate change came into the picture.
If we had been outraged by the treatment of animals (habitat loss, oil spills, factory farms etc) 20 years ago, we would have saved ourselves as well if we found alternative fuel, demanded the billions spent on the war were spent on trains instead, and gone vegetarian.
Now that it's too late, and our arses are on the line, sure now we do something. Sheesh.
Great post.
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