Sunday, April 8, 2007

Earth's warming and evidence from Mars

I just read (via Peter Gordon []) that yesterday's LA Times reported global warming on Mars. As Peter writes this is uncomfortable evidence for those that deny that humans contribute but a fraction to changes in temperatures on earth.

Clue to Mars' warming is seen

The planet's darkening surface could account for its temperature rise, scientists report.

Global warming on Mars? It turns out you don't need belching smokestacks and city-choking traffic to heat up a planet. Changes in surface reflectivity may also do the trick, according to research published Thursday in the journal Nature.The research team, composed of scientists from NASA's Ames Research Center in Northern California and the U.S. Geological Survey, compared images of Mars taken by the Viking missions in the 1970s to pictures taken a quarter century later by Mars Global Surveyor.The surface was noticeably darker in the new pictures, said Lori Fenton, a planetary geologist at the Carl Sagan Center in Mountain View, Calif., who worked with Ames scientists on the project. Plugging in a climate model developed at Ames, the research team said the changes in surface reflectivity could account for a 1 degree Fahrenheit rise in the surface temperature of the planet. "That's a significant amount," said Rich Zurek, lead Mars scientist at the Jet Propulsion Laboratoryin La CaƱada Flintridge, who was not involved in the research. The scientists believe the changes in surface reflectivity —known as albedo — are caused by wind-driven dust storms that occasionally sweep the entire Martian surface. The storms fill the air and cover the surface with fine grains that are more reflective than the bedrock. Several big storms preceded the visit of Vikings 1 and 2 in 1975, Fenton said. Comparatively, there was less heavy wind and, consequently, more light-absorbing bedrock in the picture taken by Mars Global Surveyor in 2000. If Mars is getting hotter, that could explain one finding that has puzzled planetary scientists since it was discovered several years ago: the loss of carbon dioxide ice at Mars' south pole. The CO2 ice forms a cap on top of water ice that ranges from several feet to several hundred feet in thickness. Each of the last few years, scientists have seen holes develop in the CO2 layer late in the Martian summer. So does all this mean Mars is undergoing a new round of climate change like the one that dried up its ancient lakes and drove its waterunderground? Fenton is unsure. What's going on at the south pole "is an indication of at least regional temperature change," she said.

Tuesday, March 20, 2007

So what's between good science and the earth warming hypothesis?

Eclectecon just posted
[] the following:

Chris Essex, Ross McKitrick, and Bjarne Andresen recently published a paper [Jl. of Non-Equilibrium Thermodynamics, Vol 32, 1 - 27, 2007] in which they demonstrate that using different metrics leads to different conclusions about whether the earth is really warming. Here is the abstract:
Physical, mathematical, and observational grounds are employed to show that there is no physically meaningful global temperature for the Earth in the context of the issue of global warming. While it is always possible to construct statistics for any given set of local temperature data, an infinite range of such statistics is mathematically permissible if physical principles provide no explicit basis for choosing among them. Distinct and equally valid statistical rules can and do show opposite trends when applied to the results of computations from physical models and real data in the atmosphere. A given temperature field can be interpreted as both ‘‘warming’’ and ‘‘cooling’’ simultaneously, making the concept of warming in the context of the issue of global warming physically ill-posed.
Their conclusion is strong [emphasis added]:
There is no global temperature. The reasons lie in the properties of the equation of state governing local thermodynamic equilibrium, and the implications cannot be avoided by substituting statistics for physics.... Since temperature is an intensive variable, the total temperature is meaningless in terms of the system being measured, and hence any one simple average has no necessary meaning. Neither does temperature have a constant proportional relationship with energy or other extensive thermodynamic properties.Averages of the Earth’s temperature field are thus devoid of a physical context that would indicate how they are to be interpreted, or what meaning can be attached to changes in their levels, up or down. Statistics cannot stand in as a replacement for the missing physics because data alone are context-free.Assuming a context only leads to paradoxes such as simultaneous warmingand cooling in the same system based on arbitrary choice in some free parameter. Considering even a restrictive class of admissible coordinate transformations yields families of averaging rules that likewise generate opposite trends in the same data, and by implication indicating contradictory rankings of years in terms of warmth.The physics provides no guidance as to which interpretation of the data iswarranted. Since arbitrary indexes are being used to measure a physicallynon-existent quantity, it is not surprising that different formulae yield different results with no apparent way to select among them. The purpose of this paper was to explain the fundamental meaninglessness of so-called global temperature data. The problem can be (and has been) happily ignored in the name of the empirical study of climate. But nature is not obliged to respect our statistical conventions and conceptual shortcuts. Debates over the levels and trends in so-called global temperatures will continue interminably, as will disputes over the significance of these things for the human experience of climate, until some physical basis is established for the meaningful measurement of climate variables, if indeed that is even possible.It may happen that one particular average will one day prove to stand outwith some special physical significance. However, that is not so today. Theburden rests with those who calculate these statistics to prove their logic and value in terms of the governing dynamical equations, let alone the wider, less technical, contexts in which they are commonly encountered.

Friday, February 16, 2007

Cultural facilities tend to cluster (in Tel Aviv)

In New York City there is the theater district. In London there is the west end. In Tel Aviv the cultural facilities seem to be randomly distributed. But, are they?

Gilles Benguigui, Idan Porath and I spent some time examining the variety of such facilities in Tel Aviv. First we used the old nearest neighbor method to identify clustering.

The method calculates the ratio between the average short distance between every two points and the expected average short distance of completely spatially random distribution. The ratio of the two is an index for the spatial point distribution and for spatial order.

The method is subject to some well-known drawbacks. It indicates a random distribution of points in cases that there are some clusters with random distribution of points inside the clusters. Also, the results are sensitive to the choice of boundary of the area within which the points are distributed. When the boundary of a geographic entity is ill-defined defined, it is difficult to apply the method.

To deal with this problem we created the all distances analysis. It is free of these defects. The all distances analysis method takes into account the distances between every point to all other points in the examined area.

We concluded that despite first appearances the cultural facilities cluster. Furthermore, there are several distinct clusters, each possessing particular characteristics. These characteristics were confirmed by a detailed survey of users.

Sunday, February 11, 2007

Semester break at the Technion

It is the end of the Fall/Winter semester at the Technion. We start late (in October) and finish in February. The Spring semester will start in mid-March and end in the beginning of July.

The upshot is that I am off to a conference and visits to various campuses in the USA.

Tuesday, February 6, 2007

Jerusalem will be environmentally friendly, but ultra-orthodox

Jerusalem is a relatively poor city. It is the home of a large ultra-orthodox population that is characterized by men who study Torah and women that produce very many children and work to support their families. It is also the home of government employees. Although there is a high-tech industry in Jerusalem, many of its employees reside outside city limits.

For many years now, policy makers in Jerusalem have targeted ways to attract new, young and professional population to the city. One of the means that has been proposed is to create a new stock of housing for these families, away from the religious neighborhoods. It was hoped that by so doing the stigma of Jerusalem as a place dominated by "blue laws" will be replaced by an image of comfortable suburban living in the midst of nature in the Judean hills.

A land- use plan was commissioned from the Israeli/Canadian architect Moshe Safdie. The plan proposed 20,000 housing units west of the city around the main road connecting Jerusalem with the center of the country.

Today, the Israel National Planning Board rejected the plan after a prolonged debate to the sound of vocal protest from various groups wishing to preserve the green areas around the city. The mayor of Jerusalem has adopted the view that it is possible to create a sufficient stock of housing within the current city limits. Based on a new study he claims that it is possible to build 40,000 housing units within the city.

There is no doubt that dense urban fabric is to be preferred. It creates a smaller environmental footprint by encouraging the use of public transportation facilities and lowers CO2 emissions. However, there may be a significant cost associated with the new policy. It is my suspicion that Jerusalem will find it difficult to attract young, upwardly mobile families and that the outflow of young people to Tel Aviv will continue. It is likely that we will have a green , non-pluralistic and relatively poor capital city.

Sunday, February 4, 2007

High-rise residential buildings and Pigou

This Thursday I was an "expert witness" before the Israel National Planning Board concerning an objection launched by a local Planning Board to a 1,200 residential complex that includes a number of high-rise buildings. Among the arguments that were presented against the project was the high cost of maintaining high-rise buildings and the possibility that over time the project will turn into a slum. An additional argument of the officials of the local Board was that the quality of life of the residents in the complex will be adversely affected by the noise of the highway and train station next to the complex.

These arguments should be contrasted to the arguments of Ed Glaeser in a recent article in the New York Times
[URL:]. Ed Glaeser points out the contribution of Manhattan residents to environmental quality. They use less land per capita and their usage of private cars is much smaller than that of other cities. All this is due to the high density in Manhattan.

In this spirit I suggest that we encourage the construction of high-rise, dense residential complexes next to major transportation infrastructure and that we make them accessible to lower income residents by appropriate negative Pigou taxes, in relation to their contribution to the reduction of negative externalities. This is not to say that higher income residents should not benefit from such taxes.

It is common for economists to advocate taxes on negative externalities in the context of market activities. The so-called Pigovian taxes (after Arthur Pigou) should be levied on producers who pollute the environment to encourage them to reduce pollution, and to provide revenue which may be used to counteract the negative effects of the pollution. Greg Mankiw keeps track of economists who advocate Pigovian taxes. [See
Also, see the manifesto of the Pigou Club:].

Sunday, January 28, 2007

Andrew Gelman says that economists are fun

I could not help it and have to direct your attention to Andrew Gelman's blog Gelman wrote:

"Sarah Igo came yesterday in our seminar to tell us about her recent book, The Averaged American. It was a lot of fun, and she commented that when she speaks to historians, they just let her speak, but we're more fun because we interrupt her frequently. I assured her that if interruption=fun, then economists are the most fun of all..."

I have to add that Israeli economists are extra fun...

Clusters of high-rise building in Tel Aviv

Two colleagues (Lucien Benguigui, our PhD student Rafi Roth) and I just completed a major study concerned with the evolution of high-rise buildings in Tel Aviv. We conducted empirical analyses of the temporal and spatial evolution of the city in 3D and we built corresponding cellular automaton (CA) simulation models.

Until some 15 years ago economists were satisfied with observing cities through a prism of stylized facts and the Alonso type mono-centric urban model. The recognition of the existence of "edge cities" led to models with multiple centers. Both types of models suggest that high-rise buildings tend to cluster in space.

In our study clusters are defined as spatially continuous concentrations of buildings of pre-defined heights. We succeeded to generate 3D clusters by means of our cellular automaton model. The rules of behavior are relatively simple and have an economic intuition. More recently we attempted to identify empirically clusters of high-rise building in Tel Aviv over time with the help of GIS.

The results are interesting. The frequency distribution of building heights displays twin peaks. More, interesting, using a variety of measures we identified clusters already in the 1970s. However, over time the clusters tend to weaken.

These days we parade our results at various conferences.

Figure 1 Distribution of heights in Tel Aviv 2003

Figure 2 Distribution of heights of high buildings in Tel Aviv 2003 with exponential fit

Sunday, January 21, 2007

Is there technology based solution to global warming?

Last November I wrote about the important research of Nir Shaviv and his co-researchers at the Hebrew University in Jerusalem concerning global warming [see]. According to Shaviv's model, recently (partly) tested at CERN (see, the major source of influence on the earth's temperature is solar activity that causes ionization and cloud formation.

Added evidence was provided by the Danish National Space Center (DNSC) Sky experiment that was published in the Proceedings of the Royal Society. Shaviv reported as follows []:This is the Royal Society's press release on the publication of Svensmark et al.: “Using a box of air in a Copenhagen lab, physicists trace the growth of clusters of molecules of the kind that build cloud condensation nuclei. These are specks of sulphuric acid on which cloud droplets form. High-energy particles driven through the laboratory ceiling by exploded stars far away in the Galaxy - the cosmic rays - liberate electrons in the air, which help the molecular clusters to form much faster than atmospheric scientists have predicted. That may explain the link proposed by members of the Danish team, between cosmic rays, cloudiness and climate change.”

Now the Shaviv team proposes a theoretical model that provides an insight concerning a possible technology that can reduce global warming. If solar activity does not provide the means for cloud formation over the Pacific Ocean, a set of giant lasers firing horizontally high in space can create the required effect.

I am far from capable of judging these ideas. But in the absence of contrary evidence, it makes me skeptical about size of the anthropogenic influence on global warming and hopeful that technology will provide the answer. I would like to hear some cogent discussion of the Shaviv hypotheses.

Richard Musgrave and Jesse Burkhead

I read in Greg Mankiw's blog ( that Richard Musgrave passed away.

Musgrave was a hero at the Maxwell School when I was a student there some 30 years ago. He visited and gave guest lectures in a heavy accent. He was a short man and already then he had a huge mane of white hair.

Musgrave was a star at Maxwell not the least because the focus of research at Maxwell was set by my teacher, the late Jesse Burkhead. Jesse emphasized the expenditure side of the budget. All the PhD students worked on productivity measurement in the public sector. We all read repeatedly Musgrave's The Theory of Public Finance as well as the Burkead and Miner Public Expenditure.

It was very clear to all at Maxwell that Musgrave initiated a revolution in public finance by introducing analytics. Burkhead used Musgrave's framework to do empirical work.

Saturday, January 13, 2007

Lifeline electricity rates - 2007 version

In 1975 I was part of a study team charged with examining "lifeline rates" for electricity in the USA. At the time energy prices were extremely high and the world was in the midst of an energy crisis. Last week a member of the Israeli parliament proposed that people with low incomes will be provided with electricity free of charge.

It is not surprising that a politician should propose such a policy. It is somewhat surprising that Israel Electricity Corporation, still a vertically integrated government monopoly, is behind the policy. IEC is in a process of battling the intention of the government to restructure it and to introduce competition. The company is not well regarded in the public. The employees of IEC receive the highest salaries in Israel. IEC support of the policy may make it somewhat popular among the potential beneficiaries.

Just as 30 years ago, it is my opinion that this is an economically bad policy. As any first year student of economics knows distorting relative prices will cause an inefficient allocation of resources. Poverty should be addressed directly, by creating jobs. If such a policy is not enough a second best approach consists of transfer payments.

There is nothing good about lifeline rates.

We need more roads

Above is a photo of the main freeway entering Tel Aviv.

It is an accepted knowledge among urban economists that for much of the income scale, the income elasticity of car ownership is close to 1. In other words, in western countries a percentage increase in income is expected to generate a similar percentage increase in car ownership.

Israel is experiencing, and is expected to experience, a relative rapid growth in GDP per capita. There are think tank groups in Israel that predict and propose policies that will bring Israel to among the 10 highest income countries in the world within the next 20 years. I am not sure that this will happen. However, income is expected to grow and so will car ownership.

This expected growth raises an important policy issue. Already today, the density of cars on roads is creating massive traffic jams on inter-urban roads and especially during morning in-coming traffic hours and during afternoon exiting traffic hours. The cost in work time lost and in property and life losses due to traffic accidents is enormous. The number of car accident victims in Israel is greater than the losses due to wars.

There is no doubt that improvements in mass transit infrastructure will alleviate the situation, somewhat. And indeed, investment in inter-urban rail and suburban light rail systems is massive and is expected to grow. And so it should.

However, there is a need to invest in roads as well. It is unreasonable to think that people who do not reside within walking distance of fixed rail corridors will be consumers of these systems. As the cost, in terms of time, increases the demand for mass transit is expected to decrease. Therefore, unless we invest in roads the density of cars on roads will continue to grow and the associated cost with it.

Obviously, I am for the use of the price system to regulate the allocation of road space. As of now, the cost of owning and using a car in Israel is exorbitant. The tax on the purchase of a car is upwards of 100 per cent. The cost of gasoline is equally high in comparison to the USA. It is peculiar that Israelis are unwilling to part from their cars.

Sunday, January 7, 2007

Low housing prices and high price of land

In today's real estate section of Haaret'z newspaper, Arik Mirowski reports that in Haifa land price changes do not reflect changes in the value of apartments. Land prices are steady at US$ 150 thousands, while apartment prices, especially in the better neighborhoods have been sliding for several years now. Mirowski does not provide an explanation. He raises a question.

As a possible explanation Mirowski suggests that land prices have a quality of options. As such land prices are subject to greater volatility than apartment prices. In Haifa they indicate that finally the housing market is likely to take off. The situation of relatively high land prices in the better areas of the city and stagnant housing prices has been going on for the last three years.

Here is an alternative explanation. For the last 15 years every attempt to generate a land use change and to provide the market with a housing product that was in demand faced a massive opposition from various "green" groups. The local planning board lacked political leadership and almost no significant project was approved in Haifa. Land developers are rare animals in Haifa. The rate of housing starts has declined and most importantly, new housing products do no correspond to demand characteristics.

In other words, there is pent up demand and no supply. Land prices reflect the pent up demand and the location characteristics of the better areas in the city. The existing housing stock does not match the demand requirements. Existing demand migrates outside of Haifa. As a result housing prices are stagnant.

The housing market in Haifa is waiting for a political leader who will bring back the construction industry and allow them to build the type of housing that people want to buy.

Thursday, January 4, 2007

Topology of urban transportation networks

Dr. Efrat Blumenfeld-Lieberthal informed me of her recent research and agreed that I share it here. Efrat was my PhD student at the Technion. I am trying to persuade her to share my blogging chores on a regular basis. Here are Efrat's words...

There are two major contributions of the science of networks to transportation and urban systems. The first suggests that complex networks have the characteristics of small world networks, i.e. most nodes are neighbors of one another (have high clustering coefficient), but each node can be reached from all the other nodes by a small number of steps (short average path). The second contribution demonstrates that one of the best measures to characterize the nature of a network's morphology is the degree distribution of networks, which is the probability that each node has a specific number of links. It was found that in many types of complex systems the degree distribution obeys a power law. In other words, in complex systems there are few highly connected nodes and many nodes with low connectivity.

Cities are complex systems by their nature. Similarly to the organization of other complex systems (e.g. the WWW or the molecules in a cell) urban networks have no central force that affects their spatial structure. Thus, it is reasonable to assume that the spatial behavior of the components of urban systems would fit these characteristics of networks. In 2006 at the Centre for Advanced Spatial Analysis, at University College London I studied transportation networks of urban systems in different countries. I considered the cities as the nodes, while highways, railways, and air routes represented the links. I found that that these networks share some common characteristics. Apparently, the topology of the transportation networks revealed the type of economy to which they belonged (e.g. stages in the economic development of countries). The following figures present the number of links (degree) as a function of the clustering coefficient for different cities in different countries. This presentation indicates the connectivity levels of each city. It can be seen that all Western European countries present similar characteristics, while Poland and the USA behave differently.

Figure 1 – Germany

Figure 2 – Italy

Figure 3 – UK

Figure 4 – Poland

Figure 5 – USA

Tuesday, January 2, 2007

Royal odor externalities

Photo of the town Aqabah from the south-west.

The local newspapers in Israel reported recently in small print that King Abdullah II of Jordan launched a complaint with the Israeli government concerning unpleasant odors that reach his vacation home in Aqabah, across the border from Eilat, on the Red Sea. The source of the odor is cows that belong to Kibbutz Eilot several miles north of Eilat.

In his blog on January 1, 2007 Matt Kahn wrote (

Does the Coase Theorem Apply in the Middle East? Cross-Border Odor Disputes
It's a hard life being a king. All work and no play but at least he provides an interesting case study for environmental econ teachers. Perhaps the siting of this livestock facility is no accident? International borders are a convenient place to locate such noxious stuff.Jordan king complains of Israeli odors….

This is an old story that comes to life whenever the direction of the wind is from the north-west. Most days the situation is bearable for the King and unbearable for the Israeli and European tourists in Eilat's hotels (to the left in the photo).

It is high time to impose an odor tax and to remove the externality.