| Are you just leaving the library now? |
| I saw you get there at 8 am! |
| Yeah, I've been there all day. |
| What for? |
| They hired a cute new librarian or something? |
| I wish. |
| No, it's the presentation that I will give in Environmental Science the day after tomorrow. |
| What's it about? |
| I heard you were really excited about the class. |
| And Dr Schnee also calls you for the "arcane" questions, as he calls them. |
| It's about environmental damage in the Yucatan. |
| Excuse me, what? |
| Or is that where? |
| Yucatan. |
| It's a state in Southeast Mexico. |
| So what's happening there? |
| Agriculture is having a really adverse impact on the environment. |
| There are too many farmers doing too much farming. |
| It's really destroying the forests and ruining the soil. |
| Deforestation is a major problem there now. |
| How did you learn about this? |
| I don't recall Dr Schnee saying anything about it in lecture. |
| Yes, but my brother went there last month, |
| you know, to look at the old cities like the Mayan Indians built. |
| That's what first got me interested. |
| Your brother Tom? |
| No, Dick, Harry's twin. |
| Anyway, he told me how few trees there were now and how much empty ground that grows almost nothing. |
| He said the place looked more like the desert than jungle in some parts. |
| It brought environmental damage. |
| So I started looking for materials in the library. |
| Here, look at this magazine. |
| What's in it? |
| It's an old issue of "National Geographic". |
| It includes interviews with tourists who've been there in the past few years. |
| It's pretty bad. See the photos? |
| I see the photos, but one or two photos don't prove anything. |
| Then read what the article says. Right there. |
| The first thing it points out is how soil samples show it's hard for anything to grow there. |
| It says how an area of 21,000 square kilometres has lost most of its forest in the past ten years. |
| See, there are graphs. |
| As the number of farmers increases, the acres of forest have decreased. |
| It's an inverse relation. |
| So how big is that state? |
| I'm sorry, but I've never really learned the metric system. |
| It's bigger than the state of Massachusetts! |
| That's shocking! |
| Anything else? |
| There's lots of else. |
| Scientists say there's a "growing area" of about 10.5 square kilometres where nothing can grow at all. |
| It's like the beginning of a desert. |
| Oh yes. |
| What Dr Schnee called "desertification". |
| But, why can't anything grow there? |
| I've never really studied soil chemistry. |
| I'm just starting to look into that subject, |
| but my sister Marie is a geologist |
| and she says the problem is that the soil has too much saline, |
| with no plants helping to adjust the chemistry. |
| Apparently, that's a common problem with soil types throughout the areas with rainforest. |
| Once you lose the plant cover, it's difficult to bring it back. |
| Reforestation is almost impossible, even if the land is not being used for other purposes. |
| Wait a minute. What is "saline"? |
| Saline is salt dissolved in water. |
| Scientists who've gone there have taken measurements. |
| They do this by gathering a sample of the soil and running a simple test that shows the ionisation of the solution. |
| The Geology Department in our own university has reviewed the soil at the site, too. |
| They're right. It looks pretty bad. |
| The level of salinity is going up. |
| But the plants that would solve that problem can't be planted in soil like that. |
| There is a narrow spectrum of salinity in which the plants will grow. |
| And once you pass the threshold, there is no way to put the problem right? |
| Exactly. It's possible that no one can do anything to stop the trend now. |
| All because of human greed! |
| Wait a second. |
| How do you know these "scientists" can be trusted? |
| What kind of reputation do they have? |
| Are they reliable? |
| Oh they're definitely reliable. |
| They include four members of the faculty from the Geology Department right here at MIT. |
| Here, study these photographs and check the damage yourself. |
| That's what Dr Horst who wrote the book here did. |
| He's newly appointed, but Dr Schnee says that he's brilliant. |
| So, where are you going now? |
| I'm headed over to the Geography Department to borrow a map for my presentation. |
| You know, this whole problem could have been avoided! |
| The farmers there in the Yucatan... |
| Uh, Pete?? |
| What? |
| Go take a break! Leave some studying for the rest of us. |