Should we always think global?

Let’s face it: Global scale research seems sexy. Not only is it large in scale, making it seem more important and far reaching, but also may get more publication attention because of the broad focus. I do feel, however, that some topics do not require to be studied at the global scale to be important for understanding global issues.

Take for example a paper that we discussed last week, by Sieswerda et al. (2001). The authors tried to determine the relationship between ecosystem integrity and human health at the global scale. They performed regression analysis relating an index of ecosystem integrity to life expectancy for different countries. The two seemed to be related but when the authors controlled for GDP (a socio-economic component), the relationship between these two variables fell apart. This is not surprising. If two people (one rich, one poor) are placed in a degraded area, the richer person will be able to insulate her or himself from the potential impacts and therefore their health will be less affected than that of the poor person who must rely on their immediate surroundings. In this way it is no surprise that this relationship is not clear at the global level and that the question could have been better examined at a smaller scale.

When wanting to examine patterns at the global scale using large indexes and averages only mask trends at the smaller scale. I would like to suggest that global studies that compile and compare results from many smaller studies offer more useful information than scaling up. For example, the Millennium Ecosystem Assessment tried to assess the relationship between ecosystem services and human well-being at the local, regional, and global scale. They found that the link between ecosystem service provision and human well-being was evident at smaller scales (e.x. the fertility of the soil will impact the well-being of the farmers who rely on it for food provision and income), while the relationship was not clear when using global averages and indexes (most ecosystem services are degraded, while global human well being is increasing everywhere). This assessment is still useful however, because it examined the relationship between ecosystem services and well-being at many levels and found where the relationship held and where it did not, while if it had only looked at global averages this relationship would not be evident. Further, by focusing more locally you may be better able to address differences in climates, cultures, or policies.

I do not mean to minimize the importance of understanding global scale patterns, but I think that the scale of the relationship should drive the scale of the study. If we return to the study done by Sieswerda et al. (2001), it is intuitive to me that the integrity of a local ecosystem will impact one’s health more than that of an ecosystem on the other side of a country. In this way perhaps this relationship should be examined in a series of small studies all of which can be compared to form a global understanding, as opposed to using broad indexes.

Both global and local scale studies can be valid, however, I think that instead of being caught up in the move to think global, researchers need to be more critical about knowing at what scale the relationship they seek to understand acts. This will make the findings more relevant and useful for future study.

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