Events & Courses

Time and location:

The event commences at 19:00hrs and will be held virtually via Zoom

Event description:

The Anthropocene, the concept that humans now dominate geological processes, originated with Paul Crutzen, working as part of the Earth System science community, in 2000. Since 2008, this concept has been tested as a potential formal stratigraphic unit distinct from the Holocene, and a considerable array of evidence has been assembled to suggest that it has geological reality, and that the boundary might be most conveniently placed around the mid-20th century. The Anthropocene community is now searching for geological sections that could represent a GSSP (Global Boundary Stratotype Section and Point) – a ‘Golden Spike’. The candidates include Antarctic ice cores, and Canadian and Chinese Lakes for example. The ‘geological’ evidence includes: widespread novel ‘mineral’ particles, including plastics and fly ash; ‘rocks’ such as concrete and ceramics; chemostratigraphic indicators such as changes to carbon and nitrogen isotopes, persistent organic pollutants and artificial radionuclides; and the biostratigraphical traces of species invasions, extinctions and modifications. Aside from these we have unprecedentedly rapid increases in climate drivers such as carbon dioxide and methane, which have risen to levels beyond anything known from the Quaternary. Their rate of rise continues to increase and is leading to rises in both temperature and sea level. However, temperature rise and sea level rise are not directly linked (1:1) to rises in greenhouse gases, because (a) it takes time for ice to absorb enough heat to melt , and (b) as long as ice is present, albedo remains high. Nevertheless, the rates of temperature and sea level rise are accelerating. Both have departed from their respective long-term Holocene trends, but neither has yet exceeded maximum Quaternary interglacial levels, although temperature is currently near this limit. It is highly likely that the Anthropocene world will be marked by warmer-than-Quaternary climates and high sea levels for many millennia, with the scale and rate of change largely depending on greenhouse gas emissions over this century. Stopping emissions will not stop global warming, because (i) the oceans contain 90% of the heat from global warming and will continue to emit heat to keep the ocean and atmosphere in balance; (ii) continuation of present warmth (even without further warming) will melt more ice and raise sea level further; (iii) the rise in sea level will increase the area available for evaporation, providing more greenhouse gas in the form of water vapour; (iv) continuation of present warmth will also melt permafrost, releasing CO2 and CH4 from decomposing organic remains on land and on the seabed. It therefore seems likely that without negative carbon emissions (getting us back to 350 ppm CO2, the level of 1988), it will be difficult to avoid extensive climate change. Politicians have yet to appreciate this paradox, seemingly believing that ceasing emissions is enough.

Speaker:

Dr. Colin Summerhayes is a marine geochemist and oceanographer carrying out research on past global climate change. He has a special interest in the climates of icy regions, which has taken him to Antarctica 7 times, to the Arctic and to mountain areas like the Alps. He holds the position of Emeritus Associate at the Scott Polar Research Institute of Cambridge University. Colin is a member of the international working group developing the case for naming the Anthropocene as a new unit of geological time. He has published several books including “Oceanography: an Illustrated Guide”(1996), “Antarctic Climate Change and the Environment”(2009), “Earth’s Climate Evolution”(2015), “The Anthropocene as a Geological Time Unit”(2019), and “Paleoclimatology: from Snowball Earth to the Anthropocene”(2020). Prior to joining Scott Polar, Colin worked in senior positions as a researcher and/or science manager in academia, government, the UN, and industry (including both BP and EXXON). He is a past President of the international Society for Underwater Technology, and a past Vice President of the Geological Society of London. He lives in Guildford, and spends his summers playing lawn bowls.