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Wednesday, September 14, 2005

Race and mortgages

Everybody knows that American blacks pay more for their groceries than American whites do. The same, it seems, is true of mortgages. (Update: I just, you know, actually read this first sentence. And no, it doesn't mean that American mortgages pay more for their groceries than American whites do. OK, you can continue reading now.)

Yesterday, the Federal Reserve released a major lending survey (PDF), looking, among other things, at the question of whether blacks pay more for their mortgages than whites do.

The answer, unambiguously, is yes. Subprime mortgages – housing loans which cost about 2 percentage points more than those for people with good credit – are a booming business at the moment: some $530 billion of such loans were written in 2004, up from $35 billion in 1994.

And it turns out that among low-income homebuyers, about 39.2 percent of blacks but only 12.9 percent of whites took out such loans.

Clearly, discrimination is going on, right? Not so fast. As the New York Times notes, "a large part of the contrast between mortgages to blacks and whites could be attributed to differences in lending institutions". Here's what the report says:

Most of the reduction in the difference in the incidence of higher-priced lending across groups comes from adding the control for lender to the control for borrower-related factors. For conventional first-lien home-purchase loans, the mean unadjusted incidence of higher-priced lending was 32.4 percent for blacks and 8.7 percent for non-Hispanic whites, a difference of 23.7 percentage points. Borrower-related factors account for about one-fourth of the difference. Adding to this adjustment the control for lender reduces the remaining gap markedly, to 7 percentage points.

In other words, we start off with an enormous gap, of 23.7 percentage points, which needs to be explained. About a quarter of that gap – 6 percentage points – can be accounted for factors relating to the borrowers themselves, such as their income, the type of property securing the loan, whether there's a co-applicant, even property location down to census tract.

A much large chunk of the gap, however – about 11 percentage points – is accounted for by differences in lenders. Blacks, it would seem, disproportionately get their mortgages from high-priced (subprime) lenders rather than from other sources – even after controlling for factors such as income and creditworthiness.

That brings the remaining gap down to 7 percentage points, and racism is by no means the most likely explanation for it. Crucial factors such as borrowers' credit scores and the amount they have available for down-payments are not included in the Fed's data, so they could account for that final bit of the difference.

Nevertheless, there's no doubt that blacks pay more for their mortgages than whites do, and that the single biggest reason for this is that they go to expensive mortgage shops. The mortgage shops don't discriminate between blacks and whites: a white person going to the same shop would get the same rate. But it seems that the shops selling mortgages mainly to blacks charge higher rates than the shops selling mortgages mainly to whites.

Concludes the Fed report:

Black and Hispanic borrowers taken together are much more likely than non-Hispanic white borrowers to obtain credit from institutions that report a higher incidence of higher-priced loans. On the one hand, this pattern may be benign and reflect a sorting of individuals into different market segments by their credit characteristics. On the other hand, it may be symptomatic of a more serious issue. Lenders that report a lower incidence of higher-priced products may be either less willing or less able to serve minority neighborhoods. More troubling, these patterns may stem, at least in part, from borrowers being steered to lenders or to loans that offer higher prices than the credit characteristics of these borrowers warrant.

So there are two things to worry about here. Firstly, why aren't the low-cost lenders lending to blacks as much as they lend to whites? Are the big national mortgage shops less willing to operate in low-income black neighborhoods than in low-income white neighborhoods? Secondly, are the shops which do operate in low-income black neighborhoods taking undue advantage of the fact that lower-cost shops aren't operating there? Are they selling their customers higher-priced products just because they can?

Loan sharks have known for centuries that the poor can be much more profitable than the rich when it comes to lending money. It would make sense for subprime lenders to set up shop in areas where major financial institutions with more competitive lending rates are few and far between. And those areas, it would seem, are predominantly black.

In other words, even if no one is behaving in an explicitly racist way, a result starkly diffentiated along racial lines can still emerge. How to address that problem is a major issue for the Fed, and this report should be welcomed as the first step in doing so.

Posted by Felix at 15:55 EST | Comments (7)

Monday, September 12, 2005

Hurricanes and global warming

According to Nick Kristof of the New York Times, MIT's Kerry Emanuel is a "hurricane guru". Conveniently, Mr Emanuel published a major hurricane study in Nature just before Katrina hit the US. What did that study say? According to Kristof,

There are indications that global warming will produce more Category 5 hurricanes... Nature magazine this summer reported a new study by Kerry Emanuel, a hurricane guru at M.I.T., indicating that by one measure hurricanes have almost doubled in intensity over the last 30 years.

That's what Elizabeth Kolbert, in the New Yorker, thinks Emaneul is saying, too:

In a paper published in Nature just a few weeks before Katrina struck, a researcher at the Massachusetts Institute of Technology reported that wind-speed measurements made by planes flying through tropical storms showed that the “potential destructiveness” of such storms had “increased markedly” since the nineteen-seventies, right in line with rising sea surface temperatures.

But wait! Here's Paul Recer, in Slate:

There is one hurricane scientist who believes he has found a possible link between global warming and storm intensity. But it's an entirely theoretical one. In the Aug. 4 edition of Nature, Kerry Emanuel of the Massachusetts Institute of Technology presented math models that he said "show a substantial increase in potential intensity with anthropogenic global warming, leading to the prediction that actual storm intensity should increase with time." Emanuel concedes, however, that the observed storm intensities do not match what the models predict and that his study can only "suggest" that global warming "may" lead to more intense storms. In the New York Times last week, he agreed with Gray and Klotzbach that the increase in hurricane activity the last two years "is mostly the natural swing."

What's this about the New York Times? It turns out that alongside Nick Kristof's opinion column, the NYT's news staff talked to Mr Emanuel as well. Here's what the article says:

In an article this month in the journal Nature, Kerry A. Emanuel, a hurricane expert at the Massachusetts Institute of Technology, wrote that global warming might have already had some effect.
The total power dissipated by tropical cyclones in the North Atlantic and North Pacific — including typhoons in the Pacific and Indian Oceans — increased 70 percent to 80 percent in the past 30 years, he wrote.
But even that seemingly large jump is not what has been pushing the hurricanes of the past two years, Emanuel said, adding, “What we see in the Atlantic is mostly the natural swing.”

It certainly seems as though Slate's Recer is being economical with the truth. Obviously it's silly to blame global warming for an individual catastrophe like Hurricane Katrina, or even for an uptick in hurricane intensity over a short period of time like two years. That's likely to be natural swing. But if you look at the past 30 years, then clear anthropogenic patterns can start to emerge.

But don't take my word for it: Kristof helpfully links to the actual paper (PDF). Emanuel seems clear, saying that that storm intensities are measurably greater now, and that global warming is at least in part responsible.

And once you read the paper, Recer seems even more disingenuous. While it's true that "the observed storm intensities do not match what the models predict," Recer fails to inform us that that's because the observed storm intensities are actually much greater than what the models predict. Far from the correlation with global warming being "entirely theoretical", the observed data more than backs the theory up.

Observed storm intensities in the north Atlantic and western north Pacific have more than doubled over the past 30 years. Meanwhile, a model based on sea surface temperature alone would predict that those intensities might increase by about 10%. There is another model, however, based on temperature in the troposphere more broadly, which shows storm intensities increasing by about 40%.

Emanuel's conclusion is that only part of the increase in storm intensity can be explained by the increase in sea surface temperature. Other factors, like sub-surface temperature (which has also been rising) are likely to be needed to explain the rest of the increase – as well as cyclical factors.

But is Emanuel just a lone crank? That's the impression that Recer gives:

After 24 years of relative quiet, more than 30 major hurricanes have churned in the Atlantic since 1995. Most researchers, however, think that increase has nothing to do with global warming. Those who study tropical cyclones say that Katrina was part of a natural cycle of angry storms that will batter North America for decades.

But note that Recer is fudging a little here: while the sharp increase over the past ten years might be cyclical, would "most researchers" say the same thing about the increase over the past 30 years? Here's the graph:

What Emanuel is talking about is the steady increase from the mid-1970s, not the shocking increase from the mid-1990s. Yes, hurricane intensity is obviously cyclical, to some extent. But that doesn't preclude a secular increase as well.

But this is where science journalism starts to break down. We can't all go back to primary sources and check for ourselves; and in any case, the vast majority of us are quite unqualified to read charts like the one above. Ultimately, we have to take it on trust that journalists are presenting research fairly. It could be true, pace Recer, that most scientists think that increased storm intensities have nothing to do with global warming. On the other hand, Kristof doesn't simply site "most researchers": he cites names and papers of many scientists saying quite the opposite.

What would be great would be if a qualified scientist could give us a layman's guide to exactly what the broad mass of scientists really believe about such things. I wonder if my sister might be intersted in providing such a thing.

Posted by Felix at 20:18 EST | Comments (7)

Monday, September 05, 2005

Opting In

Grey mizzle across the country, a hanging mist, traffic fluidly moving through the capital’s centre, commuters buying coffee, picking up the free paper, listening to their ipods. Schoolchildren on a train, the first day of term after the summer, a little apprehensive, a little excited, grey and red uniforms. I feel a great warmth for the working, participating, world this morning. Policemen in their fluorescent yellow jackets, taxi drivers waiting to take passengers to offices. People transforming from lovers to parents to passengers to workers. Cycle gear being replaced by suits. The world is moving, the day is starting and it’s not even 9am yet.

I’ve been thinking about this ‘growing up’ thing since Felix’s last post. I’ve been to a wedding and watched two friends do the thing they really want to do: get married, make a commitment to each other, live together... and by that I mean really live, lebensgefährter, travel through life together. Other friends have had kids lately, something that has made them so happy, has been absolutely rewarding. Something they really wanted to do. It’s quite something to feel capable, ready, grown-up enough, to not only want these things but to carry them out. To opt in.

I fear I may have been wrongly represented. Or rather, people may have assumed my stand-point by virtue of the last year in a strange place, ‘a wonderfully simple bubble’ as commented by Span. A number of people wondered if going to Antarctica was running away from something, escaping reality, and I used to vehemently defend it as an alternative way to ‘opt in’ to life rather than opt out. (Similarly, I think ‘gap-year’ is a terrible expression, suggesting an acceptable one year ‘out’ of the real world.)

What you may not know is that I have been thoroughly enjoying being a part of the working world since coming back. Making my contribution to the 9-5 world that I know so little about. I love flexi-time and take great satisfaction in swiping-in and out every day. I like my dull job. It's exciting in the bigger picture, perhaps, but the daily process of number-crunching is a far cry from laughing with the midday stars. I like coming home at a reasonable time and having an evening to take whatever class I fancy, cook dinner or meet folk in the pub. I love the house that I share with one friend. Today, I even like the rain. And sure, I can see that ten years of this might become monotonous and dull – but so could ten years on the ice.

I have never lived such a routined life as at Halley. So today, for the record, I’m all about opting-in. Choosing the life you want. Having babies, buying houses, going to work and contributing to the flow of whichever city you live in. In Cambridge, it’s biking along the river and shopping in the market. In London, it’s watching people on the tube and magicking myself from one side of town to the other on the buses using my swish new oyster card. In Edinburgh this weekend I enjoyed being a tourist, admiring the great old buildings and being swung around the dancefloor, clueless, at a ceilidh. Yes, cities have grown this way because enough people have actively chosen this life. And there’s nothing wrong with that at all.

Posted by Rhian at 10:45 EST | Comments (1)

Thursday, September 01, 2005

Beloved Hydroxyl

I dedicated my Ph.D. thesis ‘to the hydroxyl radical, omnipresent but ever elusive, you have a wicked sense of humour’.

In retrospect, this may seem a little theatrical. But at the time I truly felt that I had been chasing this mysterious species for four years, day and night, had sacrificed my life and happiness for it in fact, and to no joy. I thankfully had a thoughtful supervisor and after four years of drowning in a mud pool and banging my head on a brick wall he and my examining committee found it within themselves to take pity on me, and allow me to submit a negative thesis. Two hundred and forty-four pages on how not to measure hydroxyl radicals.

But I loved my project, I truly believed in it, I saw the potential it had to physically expand our knowledge base and thereby our understanding of atmospheric chemistry around the world. I did indeed dedicate my life at the time to this doomed technique, and proving it would never work was sodden with mixed emotions. I was glad that no-one would ever have to repeat all those terrible experiments pointlessly, but I was also gutted.

Hydroxyl radicals are great, so informative about the immediate air composition, and the method we were developing should have made them cheap and simple to measure everywhere in the world.

Our method involved bubbling air through soluble aspirin and then analysing the final solution. Hydroxyl radicals in the air react with aspirin to form a product (2,5-dihydroxy benzoic acid if you must know) that is extremely fluorescent. Separating reactants and products is relatively simple and the concentration of the final product should be able to tell you how much hydroxyl is in the air providing you know how long you bubbled for and what the flow rate was. It really was that simple.

The two-hundred odd pages I mentioned above were dedicated to all the other things that also react or interact with aspirin to produce the same result. Light, ozone, bacteria, you name it. Even when we had got rid of most of them, there was still an interference left and so, regrettably, we gave up. For what we wanted to do, the method was rubbish.

Unfortunately for me, the best methods to measure atmospheric hydroxyl radicals are still big and flash and expensive. They are actually wonderful instruments, fascinating and amazing, but their cost necessarily means that there aren’t many in the world.

Hydroxyl radicals, in contrast, are everywhere. Or a tleast they’re everywhere that there’s any chemistry kicking off. They are present in tiny concentrations: fractions of a part per trillion (that’s one hydroxyl in 10,000,000,000,000 anything elses) but they are crucial to keeping the chemistry happening. Where there is pollution, they break it down and in so doing are themselves destroyed and created. Where there is light, they are the mechanism that perpetuate photolytic chain reactions. They are sometimes known as the dustbin of the atmosphere but I prefer to think of them as little pac-men, munching their way through the ever changing game. In fact, these are the same things that we are told we have to control inside us by taking lots of antioxidants like tea, red wine and garlic. Oxidising the air: good in general. Oxidizing your stomach: not so good. They themselves aren’t good or bad, they’re molecules. They are however, extremely powerful and effective. And better yet, a great indicator of everything that’s going on around them.

Because of their low concentration and short lifetime (less than a second between being produced and reacting with something else), they respond incredibly quickly to changes in atmospheric composition. During the solar eclipse a few years ago, for instance, the Leeds FAGE machine got some stunning data showing an immediate drop-off of hydroxyl radicals when the sun disappeared and an immediate return to their prior concentrations when the light returned. So they’re good indicators of what’s going on in real time on a second-by-second basis. Which is why I was so keen to develop a method that was cheap and cheerful,- so we could get this data at every monitoring site from Halley to Weybourne.

Well, I may have not yet seen a global hydroxyl measurement network being implemented for the cost of some pain-killers but I have seen hydroxyl measurements in Antarctica. And that for me was pretty special. The ultimate combining of two dreams I guess. To be honest, it was special for everyone concerned, and not only for scientific reasons. First the ship didn’t get in so the project was postponed by a year, then the ship did get in, the lab got built but we didn’t think there would be enough energy for this beast to run in the second summer when it was due to arrive. Then the beast got in, the power supply was sufficient but the ice was weak and it looked like the beast may never get out… from beginning to end, getting FAGE to the Antarctic was an investment of nerves and faith as well as money.

There was an inherent risk even if the logistics would have run smoothly, too: weather. As I said before, hydroxyl radicals are around in small concentrations on the best of days. The best of days are sunny, clear, calm and long. On foggy, windy, stormy, or icy days it was unlikely there would be enough radicals around to measure them at all even if the machine stood up to the conditions. And we didn’t know what kind of conditions it would withstand. I had been told clearly at the start of last season that if we got two complete days of data, that would be fine. If we got a week, that would be great.

As it turned out, the FAGE boys collected the longest data set from the instrument ever, anywhere: 5 weeks of continuous measurements. And that in one of the most remote and technically challenging places in the world. Everyone related with the project should be rightfully proud.

Posted by Rhian at 14:18 EST | Comments (2)

Hot (a science blog)

It’s a hot, smoggy day in London and I’m sitting on an overcrowded train. It’s too hot for this many people to be in one space. In fact, it’s too hot for this many people to be in one place: London. The city feels unnecessarily full. And all these people so abstracted from what I would call the real world.

Our culture consumes us. All that energy that goes into simply existing,- what to wear (will I get sweat patches, would make-up run), how to get about, packed diaries of events planned weeks in advance still being juggled on the day, mobile phones ringing and bleeping, news to digest, scheduled exercise.. and that’s not to mention buying food, washing, sleeping, eating and having fun. The world I care so much about feels very far away despite being right under my feet.

It would be difficult to convince anyone right now to not travel in an air-conditioned car for 45 minutes instead of this 2 hour commute although it probably matters even more on a day like today. Really truly, will that one journey make any difference? Really truly, in the grand scheme of things? No. Will any of it make a difference? I don’t know. Is it too late? Maybe. These aren’t the answers you want to hear from a committed environmentalist and they aren’t the answers I want to give. In many ways, the whole field of climate research is incredibly dissatisfying: the more we convince ourselves that climate change is real, the more we are doomed. I do believe it, most definitely, and not only because I want to and that the science I have studied is convincing. The thing that has probably persuaded me most is meeting well respected, senior, eminent scientists who have been convinced by the data. Unlike me, these people didn’t enter the field as idealists and environmentalists hoping to find a solution to the world’s problems. These men (mainly) were pure scientists, kineticists, physicists, chemists, biologists and mathematicians whose expertise was called upon about 30 years ago to try and figure out if the climate was changing and, if so, how. They had no vested interest in the result: moral, political or economic.

The application of pure and applied sciences to climate research first grew within the individual disciplines. Then, more recently, a whole new interdisciplinary field grew, commonly known as Earth System Science. Applied science has always existed but the focus shifted from trying to understand the intricacies of a particular field, now, to trying to predict what may happen in the future.

I am an atmospheric chemist: we look at chemical processes happening in the air. Because it’s only possible to know so much, we generally represent the air as a box with arrows in and arrows out and the stuff we are really interested in happening in the middle. Often chemicals leave our theoretical box and are deposited to leaves (hand over to biologists), water (oceanographers), the ground (earth scientists) and the ice (glaciologists). To figure out how the chemicals are entering our box, we need to know about wind (meteorologists), radiation (physicists) and emissions from the cryosphere, biosphere and oceans.

Every other discipline does the same but only in the last few years have we reached the stage where we can stack these boxes, in all dimensions necessary to overlaps sides with everyone, and see what happens when you try and simulate the whole world. We have also only recently had the computer power required to run simulations of this world into the future and back to the past. Inevitably, the models often go wrong at the interfaces of the boxes since these areas have had less attention in the past: we know less about what happens here.

This is where interface studies come in, like the one that sent me to Halley. We were studying the interface between the snow and air (cryosphere and atmosphere). Understanding these processes should help the big picture in lots of ways, from interpretation of ice cores (a common record for past climates) to better guesses at processes occurring in high clouds that are made of ice particles. Similarly, there are people studying the interface between the air and oceans, forests, cities, deserts and rock. All of this information is incorporated into models that simulate the world, try to reproduce the past and present and predict the future. And the more data comes in from a wide range of areas, the more certain we become that our climate is rapidly changing and is doing so due to man-made influences. But sitting on this overcrowded train on the hottest day of the year, I don’t feel the relevance of any of this to me.. or of me on it. I don’t care. There are more important things to worry about, like what I’m going to have for dinner tonight or when I can see my friends.

Posted by Rhian at 14:09 EST | Comments (4)

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