Archive for the 'Basic Concepts' category

How thoroughly have we examined the fossil record?

Jan 11 2010 Published by under Basic Concepts, Geology, Science

The big paleontological news of last week was the announcement that fossil footprints have been discovered that predate - by about 20 million years - the previous contender for the earliest fossil evidence of tetrapods. Naturally, this announcement led almost immediately to a new round of "learning anything new about evolution means that Darwinism is totally wrong" claims from the Creationists.

Their complaints don't impress me much. There's very little difference between the Discovery Institute's "if there were tetrapod footprints 20 million years before Tiktaalik, how can something Tiktaalik-like have been an ancestor to tetrapods" line and the far older "if we descended from apes, why are their still apes" canard. If you're interested in another explanation of why you shouldn't be bothered by having ancestors and descendants alive at the same time, PZ's written a good one. I'm going to look at a different question.

It seems like someone finds some new fossil form somewhere every couple of years that changes our understanding of the evolution of some major group of plants or animals. Paleontology has been a serious scientific pursuit for the better part of the last two centuries. How is it that we continue to make so many spectacular new discoveries? Shouldn't we be at the point where we're just filling in the little gaps in the fossil record?

How thoroughly have we actually examined the fossil record? How much rock have we actually looked through in our quest to understand the evolution of the major branches of life?

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Sooner or Later, We're Gonna Have a Really, Really, Really Bad Day

"Children are our hope for the future."

THERE IS NO HOPE FOR THE FUTURE, said Death.

"What does it contain, then?"

ME.

"Besides you, I mean!"

Death gave him a puzzled look. I'M SORRY?

Terry Pratchett

"Sourcery"

Bad Astronomy Blogger Phil Plait has written one of the most fantastically, outrageously, manically, humorously depressing books I've ever read, and I'm almost certain I mean that as a compliment. Death From The Skies provides a veritable smorgasbord of potentially deadly astronomical delights, each more exotic than the last. It's like having every Discovery Channel "The Sky Is Falling" special you can think of all packed into a single, 326-page volume. But there's a twist.

It's not sensationalistic.

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Global Warming, The Carbon Cycle, and Fish Poop.

ResearchBlogging.org

When we talk about the role of fossil fuels in climate chance, what we're really talking about is the carbon cycle. That's the term that scientists use to describe the different forms that carbon is stored in on the earth, and the different ways that it can move from form to form. Understanding the carbon cycle is one of the keys to understanding both the effect of burning carbon-based fuels and the issues involved in trying to take carbon dioxide out of the atmosphere. According to a paper in the latest edition of Science, there may still be some pretty significant gaps in our knowledge of the carbon cycle. In particular, it looks like our understanding of the way carbon moves through the oceans may have been suffering because we didn't know poop about fish poop.

Before we get down to the gritty details and talk about what poop has to do with anything, it might be good to start with a quick review of the carbon cycle. Actually, it might be even better to start with a quick review of one of those concepts that we all learn in third-grade physics, but don't think about much in our day to day world: the law of conservation of mass/matter.

Matter is not created or destroyed. Therefore the amount of mass in a closed system will remain constant no matter what happens.

Like most things in science, that might be a bit of a simplification, but when we're looking at something the size of the Earth, it's good enough. Relativity, quantum mechanics, and space dust might all complicate things a bit, but not enough to matter. For our purposes, we can reasonably assume that all the carbon that we're putting into the atmosphere in the form of carbon dioxide has been here since the earth was formed, and that if we want to take the carbon dioxide back out of the atmosphere, we're going to have to find somewhere on this planet to store the carbon.

With that in mind, let's look at the some of the more important ways that carbon can move through the crust, oceans, and biosphere, and atmosphere.

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