Monthly Archives: October 2006

Blogs in teaching

I have been thinking about the possible uses of blogs in the teaching of environmental economics.

Until now I have used a selection of good economics blogs to show students how the theory they learn in class can be used to analyze everyday policy questions, as done very well in the Environmental economics blog.

I was skeptical, however, towards including blogging as course assignment. This is usually done by asking students to create their own blog and to post comments on other blogs. I thought such an assignment could be seen as an infringement of students’ rights to privacy. After all, blogs are public (so I thought until yesterday) and it seemed inappropriate to force students to participate with their writing to such a open, public forum.

Yesterday, thank to colleague Jere Majava, I stumbled across the blog platform WordPress . WordPress offers the possibility to fine-tune the degree of privacy of one’s blog by choosing between public blog (the usual case) and a blog accessible only few chosen by the blog’s owner. A per-post password option is also offered for public blogs, making it possible to restrict access to some posts.
Such privacy options make it easier to introduce blogging as part of course assignments, as they leave to the students the choice over the degree of privacy they want to maintain on their writings.

It also makes blogs more flexible to be used as platforms for students’ portfolios. Students can set up their learning portfolios as a blog. They can start posting with fully private blogs, especially if their portfolio is meant to function only as a tool for self-reflection and documentation of study progress. Later, if they see it fit, they can decide to open their blog other students so as to take advantage of peer-assessment, or to teachers, making it easier for them to follow the student progress.

Blogs as platforms for student portfolios have the advantage compared to traditional word-processing programs of being accessible from any computer with a internet connection, of providing a the flexibility regarding the degree of privacy, and of being, at least up until now, available for free.

Check Blogsperiment
a project weblog about online learning in higher education, journalism and blogging“.

Climate change and the Gulf Stream

I have followed with some apprehension the often repeated claim in the media that the Gulf Stream is driven by the thermohaline circulation and that the addition of great masses of fresh water due to the melting of ice sheets may lead to its shutdown. I live in Finland and scenarios forecasting the average temperature in this country falling dramatically due to a shutdown of the Gulf Stream really worried me.

In a letter to the Economist, where that claim had once again appeared, Carl Wunsch, Cecil and Ida Green Professor of Physical Oceanography at
MIT, assuaged my apprehension.

He writes:
Your statement that “The Gulf Stream is driven both by the rotation of the Earth and by a deep-water current called the Thermohaline Circulation” is false. The Gulf Stream is a wind-driven phenomenon (as explained in a famous 1948 paper by Henry Stommel). It is part of a current system forced by the torque exerted on the ocean by the wind field. Heating and cooling affect its temperature and other properties, but not its basic existence or structure. As long as the sun heats the Earth and the Earth spins, so that we have winds, there will be a Gulf Stream (and a Kuroshio in the Pacific, an Agulhas in the Indian Ocean, etc)…The primary mechanism of heat transport in the ocean is the wind-forcing of currents that tend to push warm water toward the poles, cold water toward the equator. Widely disseminated and grossly oversimplified pictures showing the ocean as a “conveyor belt” have misled people into thinking ocean circulation is driven by a sinking motion at high latitudes…If the sinking were stopped by adding fresh water (a deus ex machina often invoked to change the climate), the Gulf Stream would hardly care except in so far as the wind system changed too. The amount of heat transported by the system would shift, but could not become zero…Many writers, including scientists, toss around the words “Thermohaline Circulation” as though they constituted an explanation. In the ocean, most of the movement of heat and salt, the real Thermohaline Circulation, is driven directly and indirectly by the wind field. Thus the Gulf Stream, and hence the wind, rather than being minor features of oceanic climate are best regarded as the primary elements. Many real climate change effects exist and require urgent attention; focusing on near-impossible Gulf Stream failure is an unproductive distraction.

See also the comment in Real Climate .