On Tuesday-Wednesday 25-26 June, GCRI hosted an online lecture by Itsuki Handoh titled ‘Phosphorus and Chemical Pollution as Global Catastrophic Risks’. (See the pre-lecture announcement.) Handoh is an Associate Professor at the Research Institute for Humanity and Nature (RIHN), Kyoto.
A starting point for the talk is recent research on planetary boundaries, describing nine global-scale environmental thresholds that, if crossed, could have very harmful effects.[1] The planetary boundaries paradigm has grown influential, especially in international environmental governance. For example, it was featured prominently in the report An Action Agenda for Sustainable Development released earlier in June 2013 by the UN Sustainable Development Solutions Network.
Phosphorus and chemical pollution are two of the planetary boundaries identified. (Phosphorus is listed as part of a dual-boundary with nitrogen.) As Handoh explained, both phosphorus and chemical pollution are ultimately about chemical imbalance in the Earth system. The other planetary boundaries identified are climate change, biodiversity loss, stratospheric ozone depletion, ocean acidification, global fresh-water use, land use change, and atmospheric aerosol loading. A tenth boundary has also been suggested for primary productivity [2].
The phosphorus planetary boundary is about disruption to the global phosphorus biogeochemical cycle. The disruption is driven mainly by the use of phosphorus as an agricultural fertilizer [3]. Phosphorus is used as fertilizer because it is essential for living organisms. But excess fertilizer becomes ‘run-off’ from farms and accumulates in bodies of water. There, it disrupts marine ecosystems by feeding certain organisms such as algae and phytoplankton, a process called eutrophication. This is already a problem in many places.
A related problem, and possibly a much larger one, is the possibility of phosphorus run-off triggering an oceanic anoxic event (OAE). Handoh’s work shows that human use of phosphorus could trigger an OAE within several centuries or millennia [4]. An OAE could cause major changes to ocean ecosystems, possibly including widespread loss of fisheries or other harms to humanity. Indeed, past OAEs are associated with mass extinction events. But there is a lot of uncertainty surrounding OAEs. Indeed, some of the discussion in the lecture questioned whether an OAE would even be harmful to humans, given that it might only affect some parts of oceans, including only some oxygen minimum zones.
The chemical pollution boundary is about the buildup of chemicals that are toxic to humans and other living organisms. Major types of chemical pollution include persistent organic pollutants, heavy metals, nuclear waste, plastics, and endocrine disruptors. The health consequences include growth inhibition, compromised immune systems, impaired cognition, and cancer. Handoh emphasized that while the harms of chemical pollution are well known at local scales, there has been very little global-scale analysis.
Handoh proposes that marine animals at the top of the food chain could be good candidates to study. Chemical pollution gets more concentrated higher up the food chain, a process called bioaccumulation. Handoh is analyzing mass mortality events of 34 marine mammal species including seals, walruses, and whales. He’s looking for signs that chemical pollution is compromising the animals’ immune systems, such as the seals that caught H3N8 bird flu in 2012.
A related project on global chemical pollution is the International Pellet Watch, led by Prof. Hideshige Takada of the Tokyo University of Agriculture and Technology. Chemical pollution accumulates in plastic pellets in oceans and other waterways. International Pellet Watch collects pellets found on beaches around the world. Analyzing these pellets helps create a map of global chemical pollution. International Pellet Watch is collaborating with Handoh to form a better understanding of the global spread of chemical pollution, comparing the pellet data to Handoh’s computer modeling. If you live near a coast, you can help by finding pellets and sending them to International Pellet Watch.
Here is the full abstract of the talk:
The so-called global environmental problems are a manifestation of adverse effects of the interactions between humanity and nature. Some of the problems are attributed to a chemical imbalance in the Earth system. Marine pollution is such an example. Excessive inputs of particular chemicals (of both natural and anthropogenic origins) into the oceans could trigger marine pollution. In order to better understand and characterize the chemical imbalance and its relation to Global Catastrophic Risk (GCR), we discuss the following two case studies with particular reference to the recently-emerged Planetary Boundaries (PBs) paradigm: phosphorus biogeochemical cycles and chemical pollution caused by persistent organic pollutants (POPs).
The biggest concern for phosphorus may be an oceanic, biogeophysical threshold resulting in massive eutrophication, and more importantly, an oceanic anoxic event (OAE) in which low ocean oxygen concentrations result in massive species extinctions. A modeling study suggested a sustained increase of terrestrial phosphorus flows into the oceans could trigger an OAE, though significant uncertainty remains. There may not be enough phosphorus available to trigger an OAE, while the depletion of phosphorus reserves may be a more serious problem for humanity than OAE. Human dimensions of phosphorus impacts are addressed.
Similarly for phosphorus, chemical pollution has been identified as one of the PBs, but the control variable has not yet been determined. Chemical pollution is commonly understood to have mainly aggregative effects, with localized pollution poisoning nearby humans and other organisms. However, chemical pollution can also have systemic effects, both because the chemicals can spread around the world and because their local impacts can have systemic consequences such as disruptions to markets for products that become contaminated with chemical pollutants. Using Finely-Advanced Transboundary Environmental model (FATE), which is capable of predicting the exposure of several POPs, such as polychlorinated biphenyls (PCBs), to marine organisms, and a compiled data set on mass disease and mortality events of higher trophic-level marine mammals, we critically assess the response of an ecological integrity to environmental risk associated with POPs.
The presentation was hosted online via Skype, with slides shown in Prezi. There were some technical difficulties experienced due mainly to the Skype call host having an unreliable internet connection. We apologize to the attendees inconvenienced by this. Attendees included Dave Denkenberger, an energy efficiency engineer also working on global catastrophic risk, Anne Riederer of the Blacksmith Institute, which works on global chemical pollution issues, Seth Baum and Grant Wilson of GCRI, Jianhua Xu of GCRI and Peking University, and one other attendee.
[1] Rockström J et al. (2009) Planetary boundaries: Exploring the safe operating space for humanity. Ecology and Society 14(2):32 and A safe operating space for humanity. Nature 461:472-475.
[2] A tenth boundary was proposed in Running SW (2012) A measurable planetary boundary for the biosphere. Science, 337(6101):1458-1459.
[3] For an excellent overview, see Cordell D et al. (2009) The story of phosphorus: Global food security and food for thought. Global Environmental Change 19(2) 292–305.
[4] Handoh IC and Lenton TM (2003) Periodic mid-Cretaceous oceanic anoxic events linked by oscillations of the phosphorus and oxygen biogeochemical cycles. Global Biogeochemical Cycles 17:1092.
