the urban carbon cycle

This article from Landscape and Urban Planning looks at carbon emissions and carbon sequestration in Beijing:

During the study period, carbon sequestration only offset 2.4% of carbon emission, indicating a serious imbalance of the city’s carbon metabolism. The city’s core built-up area expanded along eight axes, and its form fluctuated between simpler and more complex. From a small-scale perspective, the spatial pattern mainly showed expansion and aggregation of patches with high carbon emission and shrinkage and fragmentation of patches with high carbon sequestration.

I think this sort of study is useful as we think about what it would mean for cities to be truly sustainable either within their own boundaries or in the context of the larger landscape. 2.4% doesn’t sound like much, but if that is the answer with no system-level planning or management, could it be boosted to 5% or 10% with a more systematic approach to green infrastructure? The rest of the landscape (farms, protected forests, grasslands, and wetlands, and bodies of water) would do its share. Finally, technology would have to make up the remaining gap, if we really want to one day get to carbon neutral or even begin to role back the damage we have done to the atmosphere and oceans.

 

fish passage on the Mekong

According to NPR, Laos is building several dams on the Mekong and there’s an argument about whether the fish passage systems that have been designed will be effective:

“I’m confident that the mitigation measures we can employ here will allow fish to pass the barrier we’re going to create. From studies we’ve done, the impacts people are saying the project will cause, change in flow, quality, sediment distribution, fish food, none of those things are going to arise from this project.”

The risks the dolphins downstream face are real, Hawkins says, but he says that’s because of bad fishing practices, tourism and poor management. As for migratory fish that use the Hou Salong channel, Hawkins says, the fish passageways his company, Megafirst, are building around the site should take care of the problem…

“The effectiveness of such fish passage mechansims is quite OK, let’s say, quite well proven for European or North American rivers, where we have small number of species that are well known,” Meng says. “But in the Mekong, we don’t have five fish species which we have to take care of, we have 70, maybe even more, and we have no clue about them. So building something for them to migrate up and down with, that’s just guessing at the moment.”

Trandem of International River says fisheries experts estimate that at least 43 species of fish are likely to go extinct because of the impact of the dam, including the Mekong giant catfish, the world’s largest. Sedimentation — the silt the river carries downstream to Cambodia and Vietnam — is another problem. The Xayaburi will have major food security implications as well, Trandem says.

“By blocking sediment, we know that where there’s a lot of agricultural productivity and rice growing, these areas are going to suffer a lot because they’re no longer getting the same nutrients,” she says. “And so this will have a significant impact, especially in the Cambodian flood plains but also in Vietnam’s ‘rice bowl,’ which is really the center of rice production for region.”

This is all interesting to me because of the question of whether technology like fish ladders can mitigate our environmental impacts. Even if it can, I don’t doubt for a second that there is a lot of bad development going on that will impact the ecosystem regardless of what is done with fish passage.

 

the trophic theory of money

This is Brian Czech on the “trophic theory of money”:

Due to the fundamental structure of the economy, the size of the economy – as measured by GDP – is a perfectly valid indicator of environmental impact. Agricultural and extractive sectors form the base, which must expand to support the growth of manufacturing and service sectors – yes even the “information economy.” This structure, which is the closest thing in economics to an inescapable law of physics, gives us the “trophic theory of money,” which says that the level of expenditure (GDP, in other words) is proportionate to environmental impact including such tangibles as biodiversity loss, climate change, and pollution in the aggregate.

It makes perfect sense that the overall scale of human activity is proportional to environmental impact, at least for a given level of technological knowledge, which doesn’t change very fast. Where I think he is wrong is the idea that money is a good measure of that impact. If you drew a pyramid showing the environmental impact of various sectors of the economy, starting with the lowest “trophic levels” like agriculture, forestry, and mining, and continuing up to the service and information sectors, it would indeed be a pyramid – agriculture, forestry, and mining would have the biggest ecological footprints, then the footprint of various sectors would decrease as you worked your way up the scale.

However, if you drew the same pyramid based on the contribution of each sector to GDP, it would be inverted, with agriculture, forestry, and mining representing much smaller numbers of dollars changing hands, and higher-tech sectors much more. The reason, I think, is that agriculture and mining have been around forever, and have become very efficient from an economic perspective (although we certainly don’t count their true costs in an environmental sense). The rate of technological change is low in those sectors, and we have turned them over to a small number of firms that know how to operate very efficiently and drive costs down, making small profit margins on a large scale. Relative to historical levels, prices are low enough in these sectors that we can largely take these goods and services for granted, and the majority of us have some money left over to spend on more frivolous goods like electronics.

The high-tech industries are rapidly evolving and have many players competing against each other to come up with novel things that we have just figured out we are willing and able to pay for. The profit margins in these sectors, and the total number of dollars changing hands, are much larger. This allows a larger number of players to compete at smaller scales.

A fun place to look at these statistics yourself is the U.S. Bureau of Economic Analysis’s interactive tables.