Sunday, August 31, 2008

The blogosphere and the first day of class

Everything I'm doing on my first day of my intro class was inspired by the blogosphere.

There was a great post by Andy Revkin of the NY Times a few weeks ago, talking about disaster memory in elephants and humans. In a drought, old elephant matriarchs lead their groups to far-away water holes that don't dry up. Revkin makes the connection to human memories of disaster: are memories of what to do in a tsunami, or a drought, or a hurricane remembered? He comments that:

As I’ve said here before, it now seems in some ways that scientists are like society’s elders, with awareness of past disasters absorbed from years of studying mega-droughts recorded in tree rings, or coastal destruction etched in layers of sediment, or great earthquakes recorded in displaced stream beds.
He says "scientists." I say "geoscientists," because every one of these examples is the sort of thing that we study. And in a world in which geology is often left behind by adults, limited to memorizing rock types in grade school, those of us who teach general education science courses may have the last chance to give people access to the wealth of knowledge that geoscientists have accumulated.

So that will be the theme of my course introduction: how humans deal with a planet that, though perfect for life, can also be deadly.

I'm going to show these images:

Hurricane Gustav late on Sunday, from NOAA. New Orleans has been evacuated. Buses carried away those who didn't have cars of their own. The Superdome and the Convention Center are thankfully empty. Even if the city floods again (which I hope it will not), hopefully New Orleans has averted a repeat of the horrifying tragedy of all those people, trapped in their homes with water up to their roofs, or stuck in the Superdome with no way to leave the city. Three years is manageable on a human time scale. The wounds have not yet healed. People remember.

But what about disasters that happen less frequently?

The town of Chaiten, Chile, buried in mud by volcanic mudflows after the eruption of Chaiten volcano. Thanks to The Volcanism Blog for this picture.

Chaiten volcano was a caldera, a great circular hole left by an ancient eruption. It had been 9000 years since it erupted last, but in May, when it came to life, the warning signs were clear. The town of Chaiten was evacuated. And 4000 people are still alive who might not otherwise have been. Perhaps Chaiten was close enough to the volcano that the people would have left. But other towns (such as Armero, Columbia in 1985) have been destroyed by similar processes. When disasters happen 9000 years apart, it is unlikely that human memory (even if cultural traditions have been passed on) will be sufficient to tell people what to do. But geologists can be like elephants. We can remember.

And sometimes memory of the past isn't a sufficient guide for the future.

Extent of Arctic sea ice on August 30, from the National Snow and Ice Data Center.

Sometimes physical models provide guides when there is no obvious analogy in the past. The Arctic sea ice is melting. What does that mean, other than drowning polar bears, opportunities for new oil drilling, and arguments over who owns the floor of the Arctic Ocean? I don't have clear answers, but understanding the basics of climate science and oceanography can help make sense of what scenarios are more likely than others.

And then we come home to Durango.

I'm going to make them sketch and think about this picture while I find out who's in the class, and where they're from. I probably won't ask what kinds of stories their families tell, though I'm curious whether the Navajo students, in particular, understand some of their stories as warnings. (I have to show them how to use course management software and stuff as well. And remind them to buy the book.)

I stole the idea from Andy Revkin, and the examples from a recent post by Callan Bentley and older posts by The Volcanism Blog. Thanks, everyone, for good ideas. :)

Wednesday, August 27, 2008

Gustav and uncertainty

I'm watching the forecasts for Tropical Storm Gustav with dread.

Image: five-day track forecast for Gustav, from NOAA.

Three years ago this week, I began my first Earth Systems Science lecture with an image of a swirling cloud looming over the Gulf of Mexico. On the second day of class, I was asking students if they knew anyone from New Orleans, and whether they were all right. It was horrifying, particularly because I had used the geology of New Orleans as an example in classes for years, ever since I read The Control of Nature.

But even though Gustav appears to be headed on the absolute worst course for the city of jazz, levees, and elevations below sea level, Forecaster Franklin of the National Hurricane Center added this reminder to the end of Wednesday's 11 pm discussion:


Error. In other words: there are reasonable odds that we'll be wrong, and the storm will hit Houston or the Florida Panhandle.

I'm not a statistician. In fact, I've never taken a statistics class. (I'm embarrassed enough to have bought an undergrad statistics textbook, but not shamed enough to have buckled down and worked through it.) But I am a scientist and a teacher, and that means that I need to somehow get students thinking about uncertainty.

I'm not a weather modeler, so I think about uncertainties more in the context of measurements than of predictions. I learned about the concepts of accuracy and precision in chemistry classes, and about error estimates in intro physics. My geology classes never took on the topic directly. But it should be possible to think about the ideas in geology, as well. How good is that bearing you measured on your compass? When should I count your answer as "wrong" - when it's half a degree from mine? One degree? Five degrees? Even if you weren't balancing on a cliff with shaking hands, would our measurements always be identical? When I talk about uncertainty in class, it's usually in that context.

Uncertainty in weather models is something I know less about. I know, from reading the discussion of the hurricane forecasters, that they look at the predictions of a number of different models (which presumably use different ways to weigh the effects of wind shear and warm Gulf water and other weather systems). I don't know where the 300 mile uncertainty comes from. (Is it the same kind of sense based on experience as I have about the correctness of my compass measurements? Or is there a more formal statistical way to derive the model's uncertainty?)

I hope that Gustav does not become a teachable moment. May the predictions be wrong, and may the storm weaken. And may everyone be prepared, in the event that it is correct.

Tuesday, August 26, 2008

What kind of compass do you prefer?

I see that eight nine people have already voted in the poll I put up yesterday, even though I haven't found time to blog about it until tonight.

I'm putting together my classes for this semester. (I don't start until Sept. 1, so I've got a few more days.) One of the classes I'm teaching is our sophomore-level field methods course. The title might be misleading - the course is an introduction to geologic mapping, and leaves out many other things that geoscientists do in the field. (In fact, my intro class will be doing some of them in their stream lab.) On the other hand, geology isn't just a set of technical skills that one is trained to do - a geologist should be able to imagine what's hidden underground*, as well, and the skills in this class are designed as one step towards developing the ability to think spatially.

Geologic maps show what rocks are found near (or at) the surface, but they also provide the information needed to make a good guess at what might be hidden underground. That information comes from the orientations of layers of rock, and of fractures and cleavages and faults. And to find that information, we still use big, clunky, old-school geologic compasses. (GPS is great for figuring out where you are, and we use those, too. But the compass is still a basic piece of equipment.)

When I was young (*shakes cane*), I learned to measure bearings by measuring angles from north or south:

If that arrow in the middle of the circle was... oh, let's say it's the direction a current used to flow. I would have measured the direction of the arrow as being 45 degrees east of south (or in my field notes, S 45 E).

But that's not the only way to measure angles. A circle can be divided into 360 degrees, and compasses can measure bearings around a circle, starting with north and then spinning through east (at 90 degrees), south (at 180 degrees), and west (at 270 degrees), and finally getting back to north, if they didn't get dizzy and fall down in the meantime. Those kinds of bearings are known as azimuths. They're easier to deal with mathematically, because they're one number, always measured in the same direction. They confused me when I first dealt with them, because I'm lousy at memorizing numbers. (I hate combination locks.) I've gotten used to them, though, because I've worked with people who prefer them.

I always used to think that quadrant measurements were more intuitive. I think about directions as "southwest", not as "a bearing between 180 and 270 degrees." And I carry a protractor that measures angles between 0 and 180 degrees easily, but which requires me to subtract larger numbers in my head. (And I make mistakes when I do arithmetic in my head.) I prefer to make my maps in the field - they are tools for helping me think about what's going on, and if I wait until evening (or later) to compile them, I might have to hike miles and miles back to the same spot to collect more data. And that means that my favorite compass is one that gives me numbers less than 180 degrees.

I've seen more and more students who are at least as comfortable with azimuth measurements as with quadrants, though. And at least three of my colleagues prefer them. (And I've got a sinking feeling that I'm just hideously old-fashioned for carrying a quadrant compass.)

I'm not going to trade in my compass. It was expensive, and it still works, and I'm capable of converting the different measurements. (I can almost do it in my head. If I practice enough. Grading 20 labs every week gives me lots of practice.) And I always make students convert their measurements back and forth. (I still need to do the math in my own head, though, to check them.) But I'm curious what the current trends really are. Does anyone prefer quadrant compasses, or are people switching entirely to azimuth? Are the azimuth people primarily geophysicists? (Paleomag is easier in azimuth, I believe.) Are azimuth bearings easier to handle in GIS?

And if I carry a quadrant compass, should I carry a sliderule, too?

*Yes, I realize that may be a structural geologist's bias, but you know... in grad school, I could have been a geochronologist or a metamorphic petrologist. I've become a structural geologist by necessity, because my departments needed someone to teach spatial thinking more than they needed someone to unravel the exhumation histories of metamorphic rocks.

Wednesday, August 20, 2008

Geologists who don't deny human-caused climate change: my experience

I’m still thinking about perceptions of how geologists think about climate change. But this time I’m not going to try to explain it. This time I’m going to tell a story.

Before I get started, let me get one thing straight. I’m not going to go through the arguments for anthropogenic global warming, because 1) I’m not a climate scientist, and 2) other people have done it. I’m going to talk about how I came to be convinced. Hold on, because it’s far more convoluted than simply reading a paper and realizing that the conclusions were sound. In fact, I’m going to go way back.

I had been fascinated by glaciers since childhood - I grew up in Maine, and my favorite place, Mount Katahdin, was eroded into cirques and arretes that made it a far more spectacular mountain than one might expect from its elevation (5267 feet). Plus my yard was full of random rocks – so random that I was skeptical about stratigraphy when I first heard of it – and from an early age, I learned to blame the glaciers for making the lawn somewhat dangerous to mow.

My childhood was in the 70’s. I don’t know if I saw that infamous Newsweek cover about global cooling – I was eight years old at the time – but I remember a rather vivid nightmare about running away from an advancing glacier. (Just in case a climate denialist wanders in here and is impressed by my youthful prescience, I was also worried that the Loch Ness Monster’s cousin lived in the shallow, algae-slimed lake in town. I mean, I was eight. I wasn’t reading the scientific literature at the time or anything.)

And then, in the mid 80’s, I went to college in Minnesota. So when I first heard scientific discussions of climate change, it was in the context of understanding the ice ages of the past million years. We talked about glacial landforms in my geomorphology class, but we didn't talk much about what drives climate change. When we did, it was mostly a bit of arm-waving about Milankovitch cycles and about not really knowing what caused climate to change.

I first heard of the greenhouse effect in a student presentation in my Advanced Environmental Geology class in 1988. I don’t remember most of the presentations, but that one struck me as something weird, almost out of the realm of science fiction, but also worth paying attention to.

I started grad school at Stanford in 1989. At the time, Stanford was strong in the solid earth sciences, but had little expertise in surface processes, oceanography, or climate. (There were a couple of hydrogeologists, a micropaleontologist, and an organic geochemist on the faculty, and one grad student was working on marine records of El Nino events. And that was pretty much it.) But the new Dean proposed a program in Earth Systems Science, and there was a seminar series to start it off. I don’t remember most of what was discussed in the talks, but I think that that’s where I began to get the sense that global warming was something that I might have to worry about in my lifetime.

A few years later, after I had started my first job, I heard a convincing talk by Stephen Schneider, as part of a big symposium at a small liberal arts college. I heard Schneider speak again in 1998, I think, while I was on sabbatical (back at Stanford for a few months). And in the meantime, I read science fiction, especially the Mars books by Kim Stanley Robinson*. (If you haven’t read them, one of the plot points involves collapse of an ice sheet in Antarctica, and political chaos that results from rising sea levels in an overpopulated world.) I also spent the mid-to-late 90’s in a small department with a physical oceanographer and a marine geologist whose research included studies of Arctic Ocean currents and young ocean sediments off the Antarctic Peninsula. They were the only people I knew working on climate-related work, and the possibility of anthropogenic climate change was something that they discussed as an underlying principle, not as a fringe idea.

So throughout the 90’s, I viewed global warming as a problem for the distant future, supported by science, but something that might affect my kids. Maybe. When the Kyoto negotiations happened in the late 90’s, I had spent ten years hearing the same big picture from scientists: more carbon dioxide increases temperature; we are increasing carbon dioxide in the atmosphere; we’re going to cause climate to change.

In the early 2000’s, I was shocked to see the future already beginning to arrive, not science fiction any more, but real events. The Larson B ice shelf collapse in 2002 was especially disturbing. There were some other studies that came out at the same time that I can’t remember, but for a while, it seemed as though every week brought a new press release about yet another indication that climate change was already happening. AGU’s statement on climate change came out around the same time, I think. And I was teaching Earth Systems Science myself, so I felt obligated to try to understand climate, even if I had not been formally trained in it. And the papers that I’ve seen since 2002 haven’t shown any sign that the scientific understanding is changing. The science seems to have matured, to arguments over details of why glaciers behave in certain ways, and how various regions respond, and how sensitive is climate to carbon dioxide. But the basic concerns that drive the research don’t seem to have changed since I first heard about the greenhouse effect in the 80’s.

And in the meantime, the Northwest Passage opened.

I don’t study climate myself. I’ve specialized in rocks from the middle of the crust: old, hot, and deep. As far as research goes, I have nothing to add to the discussion. But geology is a related field, and in undergrad institutions, geology departments are the places where climate science is taught, if it is taught at all. And that means that, when climate scientists visit and speak, I pay more attention than I might to a talk by a geneticist or a string theorist.

Until there were signs that we might do something about carbon dioxide, I didn’t hear about people who were skeptical about anthropogenic climate change. And when I encountered them, I had already been convinced by fifteen years of talks by people who were trying to explain their research. I haven’t heard anything from the skeptics that makes me distrust Schneider or my oceanographer colleagues.

And I don’t have nightmares about glacial advance any more. (Now the Loch Ness Monster, on the other hand...)

*I know that being influenced by fiction isn't a good scientific argument. But that doesn't mean that fiction makes no impression on people.

Tuesday, August 19, 2008

Geologists and denial of human-caused climate change

There's an interesting post at Real Climate about a session on climate change at the International Geological Congress. Apparently, the session included quite a few speakers who are skeptical about human-caused climate change, which led Rasmus Benestad (the Real Climate contributer who wrote the article) to ask:

What is going on? Is there a higher proportion of geologists that have a completely different view on climate change, or was this a biased representation of the community?

To be honest, I don't know. I do know geologists who are skeptical about human-caused climate change. Most of them are retired petroleum geologists. (That may be due to sampling bias, however; Durango is one of those places where geologists go to retire, and the Four Corners Geological Society is affiliated with AAPG, so I drink with retired petroleum geologists about once a month.) But last fall, I also saw a talk by a petroleum geologist who tried to explain why he was convinced that humans are affecting climate, and saw a number of industry geologists thinking about what he said.

Here's an edited version of what I said in a comment on Real Climate. I'm curious what other people think. Why are many geologists resistant to the idea of human-caused climate change?

I’m a solid-earth geologist (structural geology, metamorphic petrology), and I agree with Steve Milesworthy. [Milesworthy observed that the arguments of skeptical geologists tend to be, essentially: 1) there have been natural warm spells in the past, so the current climate change is also natural; 2) life has survived climate change in the past; and 3) climate science is just modeling and can't be trusted.] But I think there's more too it than that.

The fundamental assumption of geology is uniformitarianism: the present is the key to the past. We’ve recently been trying to convince the world that we’re relevant to humans because the past can also say something about the future: earthquake hazards, volcanic hazards, flood hazards - geology can give a longer-term perspective than history, and tell us that, for instance, a 5000-year-old volcano is potentially dangerous.

Geologists can get misled by uniformitarianism, though. The past helps us understand the future, but only if the same physical and chemical processes are operating. It’s hard for geologists to accept that humans are more than temporary, surface-scratching creatures - that we can affect the underlying physical and chemical processes that drive the geology that we study. And it’s hard to trust ideas that come out of physical and chemical models when they aren’t confirmed by something that we see in rocks. (Geologists will often dredge up the example of Lord Kelvin’s attempt to determine the age of the Earth from heat flow calculations - Kelvin was very wrong, because his model was incomplete, not because models are inherently useless.) And geologists have known for a long time that climate changes, so if it was natural in the past, there’s no reason to blame humans…

…except that there are good reasons to blame humans, and climate scientists have built a convincing case based on many different lines of evidence. (Geologists should respect that; it’s essentially the same way that solid earth geoscientists build big ideas.) You can’t test whether humans cause climate change by looking at a time when humans weren’t around… it’s like proving that magma doesn’t cause metamorphism by looking at metamorphic rocks that were heated by other processes. Geologists should get that, because we think that way, too.

And most geologists who have been in grad school since the late 80’s do accept and respect climate research. If we’re in the same departments, or have climate researchers coming to department seminars, then we hear and understand the arguments. But people who work in government agencies that separate geology from climate, or who work in oil & gas or mining, or who work in academic departments that are strictly solid earth - well, those people aren’t directly exposed to the current thinking of climate researchers. And they are perfectly capable of thinking about climate like geologists did in the 70’s. (Milankovitch, Milankovitch, Milankovitch.)

So geologists should accept climate change, but there are lots reasons why some don’t. The reasons are bad, but they exist.

Wednesday, August 13, 2008

Yes, Virginia, there is life after tenure denial

Over at ScienceBlogs, DrugMonkey has a post about a former ScienceBlogger who left academia when it was clear that he wouldn't receive tenure. The blogger has moved to a non-academic job, and both misses and doesn't miss academia.

But that's not what I want to respond to. One of the commenters asked about other possible outcomes beyond leaving academia or being hired with tenure someplace else:

Can someone start over at the Assistant Professor level somewhere else?

Yes, it is possible. I did it.

When I was coming up for tenure, I figured that the world just ends if you're denied tenure. When it happened to me, I thought about switching to a more lucrative version of geology, or maybe getting pregnant and becoming a stay-at-home mom. But I also read job ads and saw three jobs that fit my interests (teaching-oriented institutions, looking for my specialty, in places where I wouldn't mind living). I applied for them and headed to the west coast for a week for a family vacation and exploration of other career ideas.

When I got back, two of the three places wanted to interview me. I flew out to Durango, interviewed, and was offered the job. I cancelled the other interview (because, really, what place can compete with Durango?) and, six months later, started a new job as an assistant professor. Again.

Why would anyone in her right mind start over as an assistant professor? Ummmm... well, there were a lot of reasons.

1) I loved teaching. The worst thing about leaving my first job was leaving my students. (I mean, they were writing letters to the school paper and crying in class and crying in my office... and those were the male students.) And I had a chance to do it again, in a school that had values similar to mine.

2) During the interview, the provost looked at my C.V. and said he couldn't believe that I hadn't gotten tenure. So I knew that I was capable of meeting the expectations here. To be pre-tenure without the fear deep in my gut... you know, working hard isn't bad. It's being afraid, worried that I would never be good enough... that's what was bad in the first job.

3) I got a job here. I still have people come up to me at conferences and tell me that they want my job. (I smile nicely and say: "NO.")

4) Did I mention that there are hot springs in this town? I had always wanted to live someplace with hot springs.

So... here I am. And I'm not the only person who has come out of tenure denial and walked into another academic job. (I can think of at least five other women geoscientists, some from research universities, some from liberal arts colleges... but all who were denied tenure and went on to have great careers at another institution.) It is definitely possible.

In my case, I was able to get interviews because 1) a lot of people thought that my first institution had made a major mistake, and 2) I applied to schools that valued my skills (and which were public, rather than private, so they didn't see hiring a reject as a mark against their reputations). And I made use of my outraged colleagues. I had something like nine people write recommendation letters for me. (My colleagues from the old institution, members of my dissertation committee, research collaborators, and... ummm... former undergraduate students. I don't generally think it's appropriate to ask students to write letters for me, but they were already in grad school and beyond my ability to help or hurt their careers.) If you've been denied tenure, it helps to have potential employers read glowing letters that talk about how stupid the administration of your previous institution was to let you go.

And I got the job offer because I was comfortable lecturing, and I was enthusiastic about the place. (And because they needed to hire a woman, but half the interviewees were women, so it wasn't as if I was the last female geologist in the universe and they were stuck with me.)

And now I'm tenured.

And did I mention that I live in Durango?

Sunday, August 10, 2008

Sprawl and the solar energy space problem

I've been fascinated by solar energy since the late 70's, but I recognize that there are practical problems associated with using it to replace fossil fuels right now. Efficiency of photovoltaics, cost, storage... ok, yeah. But there's one problem that has had me scratching my head since I moved to the Southwest: finding a place to put the panels.

The arguments seem to assume that the energy must be produced on land that's currently open space, disrupting the ecosystems more than a coal mine. But I look around me and see the ecosystems disrupted anyway... by shopping malls and big box stores and parking lots. And I've wondered: why couldn't all those rooftops be used to generate electricity?

Well, it turns out that they can be.

According to the New York Times, stores as diverse as Wal-Mart and Whole Foods are installing solar panels on their roofs. The efforts are concentrated in places with major tax incentives (which include New Jersey and Connecticut, which don't strike me as the best places for solar power) - the panels are still too expensive to compete with coal and natural gas. But if the costs change... Arizona and New Mexico, I'm looking at you.

And if that works, you know, they could cover those acres of parking lots with roofs, if they want more space.

Saturday, August 9, 2008

Question from a reader: Americans abroad?

I have another question from a reader, from the comments on another post:

Along the lines of you have any for a recent graduate looking for graduate schools and only finding schools in countries other than the U.S? I am interested in structural geology and tectonics and have a particular interest in the effect of past glaciers on pre-existing faults; more specifically how isostatic adjustment affects rates of faulting. I have found several researchers in Canada and was wondering if you knew anything in particular about Canadian graduate schools and/or funding?

One of my senior thesis students this year is going to grad school in Canada next year, for similar reasons: the best program for her interests was in Canada. I don't know the specifics of her funding, although I know she does have support lined up.

The nature of graduate programs varies between countries, but I've gotten the impression that the Canadian system is similar to universities in the US.

If you've got very specific research interests and have questions about any grad school (in the US or outside the US), I would suggest contacting the person with whom you want to work, and asking him or her*. They might not know (especially details about foreign student visas), but they might be able to direct you to someone who can answer the question. You also might find information on the university's web site. (For instance, I found this information by googling "university british columbia foreign student.)

*It's worth considering Female Science Professor's comments about e-mails from prospective grad students. If you've thought about your research interests, talk about them.

Any comments from readers? Advantages/disadvantages to doing a PhD in another country?

Thursday, August 7, 2008

Some of these rocks are not like the others...

I've been out scouting field trip sites for my intro class, and I want to test some observations. Non-geologists, I need your help! I've got four pictures here. The last two are of the same rock - the second is just a close-up picture taken a few inches from the first.

I'm curious what you see when you look at these pictures (aside from my office keys, which were the handiest thing available to use for scale). How are the rocks similar? How are they different? Any speculation on why they're different?

Rock #1:

Rock #2:

Rock #3:

Rock #3 up close:

(I'm asking because I'm thinking about how to get my students to look at the rocks like geologists do. My eyes have been trained to see certain differences, but I've found that my students don't see them. Maybe if I know what other people see, I'll be able to ask better questions in my lab.)

(Oh, and Mom: no, I didn't leave the keys on the outcrop. They are... ummm... oh, yeah, they're here on my desk.)

PS: I'm more interested in what you see than what you would call each rock. (The students won't have learned the terminology yet. I'm curious what they might see before they get caught up in memorizing new words.)

Saturday, August 2, 2008

Question from a reader: preparing for jobs in hydrology

I've got a question from a reader, and I'm probably not the best person to answer it. She's a sophomore geology/environmental science major, and she's looking for advice about how to prepare for a career in hydrology/environmental geology.

What will exist in three years? Where are we going? How do I ensure I will be marketable as a woman in the geology field? What things should I be involved in now that will help me then?

I don't have a crystal ball (and my Gore Mountain garnet, although big enough, is blurry and hopelessly stuck in the Precambrian). And worse, I've never worked outside academia. I get some ideas about what it takes to get a job by talking to recent alums, and to people who might hire my students, and to people on the internet, and by reading the American Geological Institute's workforce data snapshots. But that's not the same as having been there myself.

So, with those caveats, let me gaze into the Magic Garnet Crystal and see what it says.

What will exist in three years?

I get the sense that hydrology jobs have remained fairly steady, compared to petroleum and* mining (which have boomed). Hydrology seems to be driven by government regulation - local, state, and federal agencies hire hydrologists for monitoring or research or to collect data that will make it possible to tell what's changed, and private environmental companies exist to help other companies comply with regulations. So I think the future of hydrology depends on who wins the next election (at all levels of government). But hydrology doesn't seem to boom or bust the way the resource industries do.

Also, hydrology/environmental geology has hired geologists in the last twenty years. Petroleum and mining companies are currently trying to hire young geologists to replace the ones who are about to retire. My generation (who got work as hydrologists) isn't retiring yet, so hydro probably won't experience the same squeeze.

So my guess is that there will be jobs, but it will take some work and searching to find them. (I don't have a good idea of exactly what those jobs are likely to involve. Anyone reading want to answer?)

What things should I be involved in now that will help me then?

Employers often contact people that they know (college professors, students who have worked for them in the past) when they've got a job opening. My department gets a lot of e-mails asking whether we've got any good students who could work during a summer, or who are ready to take a full-time job. We've started forwarding the messages to all of our students, but if a professor can think of someone immediately, that person has an advantage in applying for the job. So you want your professors to know what you're interested in, and to think of you when those questions come up. (That's potentially a women-in-science problem, if the professor remembers the male students first.) Doing a good undergraduate research project on something related to hydrology might help you stand out.

Internships can be good opportunities to explore career options. Working for a government agency (like the USGS) during college can make it easier to move into a permanent position after graduation. And internships in the private sector can help you build a resume and might lead to a full-time job, as well. (Finding interships can be difficult. Talk to your professors, and check out your college's career center. They might have good leads.)

Networking in general helps, too. The Association for Women Geoscientists can be a good group for networking - the chapters have activities in various parts of the country, and the newsletter discusses career issues a lot. (Also, environmental geologists seem to be very well-represented in AWG.) There are mentoring sessions for students at regional and national Geological Society of America meetings. Some regions of the country have regional hydrology societies, which could also be good resources.

It may also be good to prepare to become a certified professional geologist. You can also become a student member of AIPG (the American Institute of Professional Geologists). (And even if you don't, there is career information on the student section of their website.)

How do I ensure I will be marketable as a women in the geology field?

You know, I don't think women have a lot of individual control over the sexism we experience. So... be good at what you do, be assertive, network, write and revise your resume, etc., etc., etc. It's not very different from advice I give to male students. But beyond that, if you don't succeed right away, if you get asked annoying questions about your personal life, if you get harassed... don't blame yourself. And keep trying. The biggest piece of advice I could give to a woman in science is: cultivate resilience in yourself.

The second biggest piece of advice would be to find friends (or family, or a partner) who will support you in what you want to do.

That's the advice of the Magic Garnet Crystal. It's full of inclusions, though, so it's not the most trustworthy oracle around. Hopefully some other readers will comment.

* See the comment by BrianR below. Brian works in the petroleum industry, and has seen hiring slow down this year.