Field of Science

Freeman Dyson on Climate Change

The New York Times has an article on eminent physicist Freeman Dyson's skepticism of climate change arguments. Several passages struck me in particular:
Dyson agrees with the prevailing view that there are rapidly rising carbon-dioxide levels in the atmosphere caused by human activity. To the planet, he suggests, the rising carbon may well be a MacGuffin, a striking yet ultimately benign occurrence in what Dyson says is still “a relatively cool period in the earth’s history.” The warming, he says, is not global but local, “making cold places warmer rather than making hot places hotter.” Far from expecting any drastic harmful consequences from these increased temperatures, he says the carbon may well be salubrious — a sign that “the climate is actually improving rather than getting worse,” because carbon acts as an ideal fertilizer promoting forest growth and crop yields. “Most of the evolution of life occurred on a planet substantially warmer than it is now,” he contends, “and substantially richer in carbon dioxide.” Dyson calls ocean acidification, which many scientists say is destroying the saltwater food chain, a genuine but probably exaggerated problem. Sea levels, he says, are rising steadily, but why this is and what dangers it might portend “cannot be predicted until we know much more about its causes.”
Beyond the specific points of factual dispute, Dyson has said that it all boils down to “a deeper disagreement about values” between those who think “nature knows best” and that “any gross human disruption of the natural environment is evil,” and “humanists,” like himself, who contend that protecting the existing biosphere is not as important as fighting more repugnant evils like war, poverty and unemployment.
His basic argument seems to be that, yes, human activity is causing global temperatures to rise, but this may not be a bad thing. Life, and humanity, will adjust to life in the new climate through adaptation and evolution, and may even emerge richer and stronger.

In a long-term sense, he is completely right. Life on earth has survived much greater shocks in the past and will likely continue to adapt and evolve as long as the sun is shining. We humans are a particularly adaptable bunch; we don't need to wait for genetic evolution to change our behaviors. We have devised ingenious solutions to our problems in the past, and we could probably think of something to carry us through whatever changes may come.

But the problem with this argument is the short-term. Humanity and life in general may be infinitely adaptable, but the fact is that, for the moment, we have adapted to life on the planet the way it is. We depend on certain plants and animals for food. These plants and animals in turn depend on other plants and animals, as well as certain chemicals and climate conditions. Every step in this chain is, for the moment, perfectly adapted to the climate of the present. Nature has even devised its own mechanisms to keep the current climate in place: for example, ocean bacteria help regulate the earth's temperature and atmosphere. We are, at present, in a state of equilibrium.

Massive increases in carbon dioxide, leading to rapid temerature growth, would push us out of equilibrium. Nature's homeostatic (equilibrium-maintaining) mechanisms would be insufficient to maintain our current climate, and large changes would occur. Food chains would have to be restructured as intermediate links go extinct. Some species would win and some would lose in the scramble to adjust to the new status quo.

Ecologists know that an ecosystem pushed out of equilibrium will eventually reach some new equilibrium state. But the details of this new state are impossible to predict ahead of time. Which species will dominate? What new food chains will form? This is the big question of climate change; no one can really say.

As far as we humans are concerned, the odds that this new state will be better for us are pretty low. Consider, for example, that the typical American diet is built from a relatively small variety of fruits, vegetables, grains, and animals. And the genetic variety within these crops is decreasing as breeds become standardized within the agriculture industry. It's unlikely that the specific plants and animals we depend on will be winners in the new equilibrium, since they, like us, are adapted to what we have now. We will have to scramble to change how we eat, as well as where we live, thanks to sea level changes. Millions of lives will be disrupted in this change. We have to ask ourselves, as a society, if we this disruption is an acceptable tradeoff to maintain our current energy habits a little longer.

As mathematician and ecologist Simon Levin said, “Nature is not fragile... what is fragile are the ecosystems services on which humans depend."

Reader Show-and-Tell

One of the joys of writing a blog like this is receiving comments from people I've never met in real life, but who have stumbled upon my blog from somewhere in webland, and found something on it worth responding to. It's really great to know my ideas are bubbling out and reaching people.

So this time I'd like to put aside my usual format and get to know some of my readers a little better. If you don't mind, I'd be very grateful if you can drop a comment answering these:

1. Who are you? (student, researcher, generally interested person, ...)

2. How did you find this blog?

3. What topics interest you most within those I've discussed?

4. What else interests you, either within or outside of the complex systems field?

Those who I do know in real life are also quite welcome to respond!

Two great links about the economy

1. Eduardo Porter has an excellent Op-Ed in the New York Times comparing the evolution of huge bonuses for bankers to the evolution of excess blubber on bull elephant seals--good for the individual seal (bank) but bad for the species (financial sector.) I couldn't agree more.

2. The collaboration between This American Life and NPR news that brought us the excellent show about the mortgage meltdown are back again with the clearest explanation I've heard to date on how our banking system is screwed.

On the Definition of Life

Last post we discussed a theory for the origin of life on earth, and we found that a proper definition of life is necessary to even begin addressing the question. This post, I'd like to dig deeper into the definition issue.

I strongly feel that life is a process, and should be defined in terms of what it does, not what it's made of. But adopting a process-based definition of life means we must consider whether our definition applies to entities that we think of as non-biological. For example (as my dad pointed out upon reading my previous post) crystals replicate their structure. Should they be considered alive? Computer viruses reproduce en masse; are they alive? Are "25 things about me" Facebook posts alive?

The example of crystals, more than anything else, convinces me that although reproduction is the central feature of life, it is not sufficient for defintional purposes. Crystals have not changed their nature since they first appeared on the earth. Their abitily to "adapt" is limited to conforming to the shape of their environment; they have produced no novelty in their billions-year history.

A glance at the wikipedia page on this subject gives us several other criteria we may wish to include, such as homeostasis (the ability to regulate one's internal evironment), and metabolism (the ability to convert raw materials to energy.) But these also seem peripheral to what I would consider the principal feature of life: its abilty to create new innovations in the world. These innovations are the product of evolution, so (as faithful reader samineru suggested), we should focus on entities that don't just reproduce, but evolve.

Evolution requires that:
  • Entities compete for the chance to reproduce, based on their characteristics.

  • Whenever an entity reproduces, its characteristics are passed on to its offspring, with slight variation.

These requirements rule out crystals: It would be hard to say that crystals are competing in any meaningful sense, and variations in the structure of a crystal are not (as far as I know) passed down onto other crystals seeded by it. "25 things about me" posts also don't compete, and small innovations in one post are not typically passed down into the other posts inspired by it. So neither crystals nor facebook memes are alive by this definition.

Computer viruses are more tricky. I don’t know of any viruses that mutate and pass mutations on when they spread. But one can imagine this happening in the near future: viruses producing their own innovations and finding ever more devious ways to infect other computers. If they did, would we call them alive? By this definition, we would.

Such questions are central to the field of artificial life. Artificial life (or “alife”) researchers write computer programs in which entities compete and evolve according to abstract sets of rules. There is debate in this community over whether they are actually creating life with these programs, or merely simulating it.

Many other intelligent people have written on the definition of life; I recommed these articles for further reading.