Halfway There

In high school I was introduced to the concept of “global warming”; the idea that the lifestyle I had been living was causing harmful, irreversible change to the environment shocked me and redirected my life immediately. Since then the term has lost some of its credibility and has subsequently been replaced by “global climate change” mostly, in my opinion, to remove ammunition from the sceptics proclaiming that a longer summer and less harsh winter might be quite enjoyable. In the last 8 years the term has adapted in my life and been subdivided into multiple categories which all come down to “anthropogenic effects”. With this term I encompass (to name a few) habitat fragmentation, loss of biodiversity and perhaps most importantly, urbanisation. All three of these concepts are dealt with in this month’s chosen article: “Global forecasts of urbanexpansion to 2030 and direct impacts on biodiversity and carbon pools” by Seto, Güneralp and Hutyra (2012). As an “environmentalist” (read: person aware of the severity of the situation facing humans today) my biggest problem is trying to get my peers to understand that nothing is localised, that everything has an impact and that our actions are affecting the world in a temporally specific manner. This article is the latest weapon in my arsenal.

A large part of being informed about the severity of the global situation is feeling an obligation to educate those who don’t, and within that to work towards mitigating the problems. I see this paper as vital movement towards quantifying the possible path our civilisation is on. The fact that most people see urbanisation as a localised issue is one that sits with me daily and is a major tenant of the article. The world is getting smaller and smaller every day and our ability to mark the planet is increasing exponentially. This article makes the point that in one generation we will possibly globally urbanise land the equivalent size of South Africa. That is, there is a probability greater than 75% that 1,2 million square kilometres of land will be expanded into. Although the authors do not go into great detail about the methods they used to calculate these probabilities, they do explain that a probabilistic model was created using global land cover from 2000, urban population projections and gross domestic profit, and that five sources were used to create the model. As someone who enjoys mathematics, statistics and models, I would have liked more information about the workings of the model but the paper speaks loud enough to drown out my worries about fairly calculated probabilities.

I understand that with an increasing population, urbanisation is, to some extent, inevitable; but is it too much to ask that that expansion be efficient? The authors point out that urban area is expanding on average twice as fast as urban populations are. The denialist retort in this case could be that if space is a limited resource, at some point we will reach a sort of “equilibrium”, and that reaching that “equilibrium” is inevitable so it doesn't matter if it happens now or 50 years from now. Although this might be true it is our job as “environmentalists” to point out that every expansion has a cost to biodiversity and ecosystem services. Ecosystem services include the systems that allow us to have clean water, food, a stable climate and crop pollination, and biodiversity plays a role in many of these systems. As human populations grow, demand on these systems increase and it is vital that they are conserved. For this reason the authors include a study of the overlap of areas with a high probability of expansion and global biodiversity hotspots. To localise the point, one of the mentioned biodiversity hotspots is the Cape Floristic region which has a 75% or greater chance of losing 1100 square kilometres to urbanisation by 2030. Overall urbanisation of biodiversity hotspots is expected to increase by 160% from 2000 to 2030 with some areas, such as The Eastern Afromontane, the Guinean Forests of West Africa, and the Western Ghats and Sri Lanka hotspots experiencing increases of urbanisation of between 900% and 1900%. Not only are these regions associated with biodiversity but they additionally act as large carbon stores and the authors dedicate a section of the paper to the impacts that expansion will have on carbon pools. So, not only will the inevitable expansion impact biodiversity, but it could act to increase levels of carbon in the atmosphere (a known driver of climate change). To bring the point home just a little more the authors include an analysis of the endangered and critically endangered animals which occur in the regions likely to be urban by 2030. It is important to note that the paper does not take into account the additional pressures and indirect impact that this expansion could have and as such can be considered a conservative assessment of the situation.

Reading this paper has opened my eyes to the importance of global scale realistic forecasts that explicitly deal with human driven changes. I believe the biggest problem with it could be that the information will reach so few non-environmentalists. Perhaps this blog can work to fix that. Whatever stance you choose to take on politics, religion, social organisation or climate change, the problem of anthropogenic effects on the environment is one that faces us all. The world is smaller than we think and our ability to affect its composition is growing every day. The authors suggest that we look to Aldo Leopold (A 19th century ecologist who developed a set of land ethics) and Sir Alex Gordon (a forward thinking British architect) for guidance in policy making and design, considering development that allows for future changes and moves to sustainable practices. I would include that space-use efficiency and optimisation are of the utmost importance in urban land-use, agriculture, and ecosystem service conservation. As the authors direct you to Leopold and Gordon I add a direction to the concept of biomimicry and the words of Janine Benyus “Anything that we design—a product, a process, or a policy--has to ultimately pass muster in the biological realm. It has to help us thrive, but it also has to keep the habitat intact for our successors. A robin building a nest and an architect building a building should have the same concern: “How will the chicks fare here?”

Reference
Seto K. C., Güneralp B., and Hutyra L. R. (2012) Global forecasts of urban expansion to 2030 and direct impacts on biodiversity and carbon pools. Proceedings of the National Academy of Sciences 109: 16083‐8.