5 ms·

Every time I read about prediction of where climate change is going, I can't help but feel that people are just hopelessly naive about our ability to predict.

Every time I read about prediction of where climate change is going, I can't help but feel that people are just hopelessly naive about our ability to predict. The greatest problem with current models is that they have simply no idea how the biosphere is going to react, and the biosphere has the capacity to undo every perturbation introduced by humans without raising a sweat. Don't get me wrong, I'm not saying that there is no global warming, or that humans aren't responsible - they are, the evidence for that seems pretty clear these days. But what we don't know is how that is going to change our world. Recent studies in evolution, are starting to indicate that species can (and do) evolve very rapidly in response to changes in climate. We are used to thinking of evolution as being something that happens over tens to hundreds of thousands of years, but we have now documented so many evolutionary changes that happened rapidly, from the iconic peppered moths to Galapagos finches, that current thinking is more that rapid evolution in response to a changed environment is the norm, not the exception. We predict, for example, that a whole swath of calcium-based lifeforms are going to go instinct if the Earth's oceans continue to rise in acidity. I would think that it is much more likely that some (if not most) are very rapidly going to develop mutations that allow them to fix calcium even in an acidic environment. If we start having more bush fires, then forests are going to rapidly evolve to rebound quickly from such disasters, or to reduce the likelihood of a bush fire getting out of control. Or what about on a more global scale. Who would like to bet that there won't be an algae that evolves that efficiently sucks out the heightened amount of carbon in the atmosphere introduced by humans, making the whole climate change debate null and void. Until we can't start modelling these times of changes in the biosphere, predictions based on models are pretty much useless, certainly once we get out beyond about 10-20 years. None of which is to say that we shouldn't be fighting against climate change - we should, if nothing else than because, for the reasons listed above, we can't predict the ways that climate change is going to impact us. Unpredictability is generally bad for economic development, which is pretty much the equivalent of saying that it is bad for human sustainability. But I really am sick of reading predictions for our global future that just can not be based on anything like a realistic understanding of how the biosphere is going to react to our continued forcing of the climate...

lobster_johnson 16y ago
> ... very rapidly going to develop mutations that allow them to fix calcium even in an acidic environment You don't seem to understand the nature of mutations. Mutations aren't "developed", they occur randomly and spontaneously as a consequence of errors in DNA replication. It happens all the time, to be sure, but it's not like entire populations are convulsing in a bombardment of mutations that produce lots of weird new features. Also, each mutation is random, and whether the mutated gene has a positive effect or indeed passed on to offspring is also completely random. In short, mutations aren't some kind of magic that happens at opportune times. So let's consider the corals. Perhaps a single coral will be hit by a mutation at some point that lets it survive in higher acid levels. Perhaps a few more. So the coral is able to survive and reproduce, and its offspring will also survive. Meanwhile, the surrounding coral reef is dying quickly. How will those monster corals survive? It will have to reproduce very quickly and expand in size dramatically in order to compensate for the diminishing reef, otherwise it will go down with the ship, so to speak; coral reefs are ecosystems where corals live in symbiosis with the organisms around them, and one part of the symbiosis dying would impact everyone else. Unfortunately, the amount that most corals grow in a year is measured in millimeters. The idea that a single coral would save an entire reef from dying is probably optimistic. And meanwhile, every coral in the world without this mutation would eventually die. Corals reproduce locally and don't move around much. For your idea to work, the mutation would have to hit a lot of coral reefs during the same time frame, and it would have to hit a lot of corals at the same time.
- demallien 16y ago
  You don't seem to understand the nature of mutations. It's not really a question of understanding mutations, that's just where the research seems to be leading us. Phenomena such as the rapid changes in fossil morphology puzzled biologists for much of the second half of the 20th century, but the latest research is suggesting that this is indeed a real effect, and not due to the spotty nature of the fossil record. In the lab, in simulations, and in the real world, we see populations change rapidly in the face of a rapidly changing environment. Don't believe me? Think how quickly the common cold has to mutate to remain viable when faced with the highly adaptive human immune system. Or how about how quickly MRSA has developed. Or how quickly we can change the appearance of a dog breed with selective breeding. Going back to the reefs, if you have a population with millions of individual organisms of each species spread over a large area, it is not unreasonable, due to genetic drift, to expect some of those organisms to already have a few tricks up their sleeve to handle increased acidity. Some will have trick 1, some will have trick 2 etc etc. As the acidity starts to rise, these organisms will have the better success at passing the genes onto their offspring. Those offspring have a good chance of inheriting different tricks from their other parent, making them even better at surviving in the acidified environment. So it goes, the greatest show on earth. The tl;dr version is that the mutations don't have to all hit at once - there will be many mutations already latent in the population due to genetic drift that will help make adapting much faster and easier. Still want to tell me that I don't understand the nature of mutations?

lobster_johnson 16y ago

> ... very rapidly going to develop mutations that allow them to fix calcium even in an acidic environment You don't seem to understand the nature of mutations. Mutations aren't "developed", they occur randomly and spontaneously as a consequence of errors in DNA replication. It happens all the time, to be sure, but it's not like entire populations are convulsing in a bombardment of mutations that produce lots of weird new features. Also, each mutation is random, and whether the mutated gene has a positive effect or indeed passed on to offspring is also completely random. In short, mutations aren't some kind of magic that happens at opportune times. So let's consider the corals. Perhaps a single coral will be hit by a mutation at some point that lets it survive in higher acid levels. Perhaps a few more. So the coral is able to survive and reproduce, and its offspring will also survive. Meanwhile, the surrounding coral reef is dying quickly. How will those monster corals survive? It will have to reproduce very quickly and expand in size dramatically in order to compensate for the diminishing reef, otherwise it will go down with the ship, so to speak; coral reefs are ecosystems where corals live in symbiosis with the organisms around them, and one part of the symbiosis dying would impact everyone else. Unfortunately, the amount that most corals grow in a year is measured in millimeters. The idea that a single coral would save an entire reef from dying is probably optimistic. And meanwhile, every coral in the world without this mutation would eventually die. Corals reproduce locally and don't move around much. For your idea to work, the mutation would have to hit a lot of coral reefs during the same time frame, and it would have to hit a lot of corals at the same time.

demallien 16y ago
You don't seem to understand the nature of mutations. It's not really a question of understanding mutations, that's just where the research seems to be leading us. Phenomena such as the rapid changes in fossil morphology puzzled biologists for much of the second half of the 20th century, but the latest research is suggesting that this is indeed a real effect, and not due to the spotty nature of the fossil record. In the lab, in simulations, and in the real world, we see populations change rapidly in the face of a rapidly changing environment. Don't believe me? Think how quickly the common cold has to mutate to remain viable when faced with the highly adaptive human immune system. Or how about how quickly MRSA has developed. Or how quickly we can change the appearance of a dog breed with selective breeding. Going back to the reefs, if you have a population with millions of individual organisms of each species spread over a large area, it is not unreasonable, due to genetic drift, to expect some of those organisms to already have a few tricks up their sleeve to handle increased acidity. Some will have trick 1, some will have trick 2 etc etc. As the acidity starts to rise, these organisms will have the better success at passing the genes onto their offspring. Those offspring have a good chance of inheriting different tricks from their other parent, making them even better at surviving in the acidified environment. So it goes, the greatest show on earth. The tl;dr version is that the mutations don't have to all hit at once - there will be many mutations already latent in the population due to genetic drift that will help make adapting much faster and easier. Still want to tell me that I don't understand the nature of mutations?