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Disposing of Fossil Fuel CO2

It is expected that by the end of the century, global average surface temperatures will have risen by a further 1.5-4°C, depending on emissions pathway. To avoid ‘dangerous’ climate change and the occurrence of undesirable and rapid and/or discontinuous state transitions in the Earth system (known loosely as ‘tipping points’), many authors and international bodies are calling for efforts to limit the temperature rise to a maximum of 2°C. However, efforts to secure the necessary reductions in CO2 emissions have so far been mostly unsuccessful and a recent study showed that it was unlikely that even ambitious CO2 reduction targets could prevent an eventual 2°C temperature rise.

Proposals have thus been advanced to capture CO2 from power stations or even directly frp, the air using ‘artificial trees’. The technologies for both already exist, albeit currently at unacceptable cost for direct air capture. However, aside from a few pilot studies sequestering CO2 in petroleum reservoirs to also enhance oil recovery, we do not seem to be anywhere near ready to dispose of CO2 in geological formations on the scale required to avert dangerous climate change. Why not the deep ocean? Sequestration of CO2 in the deep ocean appears to have become unpalatable, akin to the ‘70s and ‘80s dumping of nuclear waste at sea. Yet on time scales of 1000-10000 years, the ‘resting place’ of over 90% of CO2 release to the atmosphere is the deep ocean. The advantage of transferring CO2 directly to the deep ocean is that the degree of acidification of surface waters and hence marine biological impacts will be lessened. But are we sufficiently confident in our understanding of the ocean carbon cycle and its circulation to ‘put our money where our mouth is’ and inject captured CO2 into the deep sea?

In this lecture, Andy Ridgwell will introduce the primary marine carbon cycle processes which act to neutralize fossil fuel CO2 emitted to the atmosphere and their characteristic timescales. I will discuss how these can be utilized with a view to the sequestration of CO2 in the ocean, touch on how the marine carbon cycle (and hence the efficiency of CO2 sequestration) may be impacted by a changing climate and ocean circulation, and hence question our current understanding of oceans and climate.

View this presentation online


Andy Ridgwell, University of Bristol


Andy Ridgwell is Royal Society University Research Fellow and head of the 'Bristol Research Initiative for the Dynamic Global Environment' in the School of Geographical Sciences, University of Bristiol. Although in practice spending most of his time tending to the every need of 7 cats, his research addresses fundamental questions surrounding the past and future controls on atmospheric CO2 and the role of feedbacks in the climate system. His weapon of choice in this endeavour is the Earth System Climate Model.