Biogeochemical processes and ecosystem function in changing polar systems and their global impacts (BIOPOLE)

Climate change is threatening two key ecosystem services provided by the ocean for humankind: food and storage of atmospheric carbon. The polar regions are major influences on both but are also experiencing the most dramatic and rapid changes. A better understanding of the factors affecting how nutrients are supplied and biologically processed in the ocean is needed to assess the future risk to quantify the dependence of the Earth system, and humanity, on this essential global function that supports global productivity and fisheries. Key nutrients, such as nitrogen (N) and phosphorus (P), are not evenly distributed across the global ocean but are in excess in the polar regions from where they are exported to lower latitudes by ocean circulation. Living matter is produced through combining N, P and carbon (C) (and other minor elements) in a ratio that is more or less the same in most regions of the global ocean. However, the ratios found in the polar regions are substantially different. This is because, firstly, polar nutrients come from a diversity of sources (glaciers, sea-ice, rivers and other seas). Secondly, the polar ecosystem processes these nutrients and carbon in distinct ways. This results in i) a nutrient surplus, which is exported from the polar oceans and supports productivity globally, and ii) the transport of carbon from the atmosphere into deep waters distant from the atmosphere. The pressing issue is that rapid climatic change at the poles is changing both the supply of nutrients and the processing capacity of their ecosystems. This threatens not only the marine food stocks on which humanity depends but also the biological drawdown of C in the oceans, a critical regulator of global climate. Our ability to fully characterise and predict this threat is limited by inadequate representation of polar biogeochemical and ecosystem processes in Earth System Models (ESMs). BIOPOLE represents and links together many of the major environmental research institutes in the UK, who will work with national and international partners to address this problem. We propose an ambitious combination of focussed observations, novel analyses and computer simulations to radically improve our ability to measure, understand and predict how nutrient supply and C storage in the polar regions will be affected by climate change. BIOPOLE will further identify and quantify the wider global impacts to ocean productivity and fisheries. We will sample and collect data at both poles to take a full Earth system perspective of this problem. The latest experimental and observational techniques will delineate C and nutrient processing by the unique polar communities. It will include the use of novel autonomous technologies to collect data over longer periods and greater areas than can be achieved by ships alone. Global modelling will be informed by the new understanding generated and used alongside other modelling approaches to better quantify the role that polar oceans play in sustaining global oceanic primary productivity and fish stocks, and to predict future trends. Climate change is proceeding faster at the poles than any other region, resulting in sea-ice loss and glacial melting. There is a clear urgency in understanding the full biogeochemical and ecosystem level implications of these changes for the polar regions themselves and for the wider Earth system. As ice retreats, the fragile and globally significant ecosystems that are exposed require international protection, which depends on building a strong body of scientific evidence through co-ordinated polar science. Direct outputs from the ocean resulting from ocean productivity have been valued at $6.9trn, while that of the capacity of the oceans to absorb C is $4.3trn. The uncertainty in how climate change will impact these roles remains large, requiring both scientific and economic evaluation, and presenting a pressing challenge for both science and society.