A couple of interesting pieces relevant to ecosystem modeling and greenhouse gas accounting in this week’s issue of Science:
- It’s been hypothesized that the biogeochemistry of sodium (Na) may be important to consider when modeling the terrestrial carbon cycle (Ecosystems Say ‘Pass the Salt!’). While elements like N and P are well-recognized as a limiting factor for plant biomass accumulation in many systems, this new theory suggests that Na may be limiting for detritivores, thus slowing the rate of organic matter turnover and potentially increasing net carbon stores in such systems. If the effect turns out to be significant it’s potentially big news for ecosystem ecology models, which rarely consider elements beyond C, N, and P.
- After a poorly-understood lull in the early 2000’s, global concentrations of the potent greenhouse gas methane (CH4) are once again rising at pre-lull rates (Methane on the Rise—Again). This one is particularly interesting because during the lull there was a big divergence between what GHG accountants calculated we were emitting (‘bottom-up’ method) and what atmospheric scientists were measuring (‘top-down’ method). Also, concentration gradients and isotope analysis seem to suggest that much of the growth is attributable to biogenic sources in tropical latitudes, rather than from permafrost melting or fracking leaks. And the article comes with a great quote: “data without models are chaos, but models without data are fantasy.”
One other big news item: the US State Department environmental impact statement on the Keystone XL pipeline has been released. Lifecycle assessment played a prominent role in the study, and while it deserves a detailed critique in a future dedicated post, spoiler alert: their consequential LCA apparently found that the Canadian oil-sands are likely to be exploited with or without the new pipeline, so the huge CO2 potential of this new source was NOT attributed to the pipeline, against the wishes of many activists.