Anthropocene.2023.pdf

Who owns the Anthropocene? For geoscientists, the timescale of Earth’s history rivals the periodic table in terms of scientific importance It has taken centuries of stratigraphic work: • matching up major rock units around the world • placing them in order of formation Geologists carve up Ear...

Who owns the Anthropocene? For geoscientists, the timescale of Earth’s history rivals the periodic table in terms of scientific importance It has taken centuries of stratigraphic work: • matching up major rock units around the world • placing them in order of formation Geologists carve up Earth’s 4.5 billion years of history on the basis of stratigraphy, that is evidence contained in layers of • rock • ocean sediments • ice cores • lake cores • other geological deposits A hierarchy of decision making: 1) Sub-Commission gathers evidence on a given time interval makes recommendation to -> 2) International Commission of Stratigraphy reviews the evidence makes recommendation to -> 3) International Union of Geological Sciences At every step, decisions are made based on majority vote. To be accepted as a new formal unit: ¡ the geological signal in the given strata must be “large, clear and distinctive” ¡ the unit must be “useful as a formal term to the scientific community”. The base of every unit is defined by a ‘Golden Spike’: Global Boundary Stratotype Section and Point (GSS) Ediacaran period 635-541 Ma Flinders Ranges, South Australia Techofossils on mudflat, River Thames Estuary ¡ The term is not yet an official unit in the Geological Time Scale. ¡ In 2019, the Anthropocene Working Group within the SubCommission on Quaternary Stratigraphy has voted that: The Anthropocene should become a formal chronostratigraphic unit defined by a Global Boundary Stratotype Section and Point (GSSP) Waters et al. Earth-Science Reviews, 2018 Paleo-environmental archives and their stratigraphic signals In virtually all environments, there is an increase in abundance of radionuclides from nuclear bomb testing in the early 1950s: 239-plutonium 137-cesium 14-carbon (‘bomb’ carbon) ¡ This is broadly coincident with a shift towards more negative δ13C values. ¡ Using this evidence would put the base of the Anthropocene in the mid 20th century. Waters et al. Earth-Science Reviews, 2018 ¡ Debate rages on because the onset of human influence on our planet is time-transgressive Gibbard et al. 2021, Episodes - Journal of Int. Geoscience • determines the state of knowledge on climate change • reports are neutral, policy-relevant but not policy-prescriptive • 195 member countries 2023 IPCC Report 2021: Climate Change -The Physical Science Basis ¡ most significant global climate agreement to date ¡ > 190 countries are signatories ¡ governments set their own targets (“nationally determined contributions”) ¡ 1st stock assessment is taking place Nov 30 to Dec 12, 2023: Countries assess their progress toward implementing the agreement (Cop 28) IPCC Report 2023: Summary for Policy Makers ¡ experts agree that the current commitments made under Paris Agreement are not sufficient ¡ Nevertheless, the agreement is achievement of international diplomacy. ¡ In 2021, the Canadian government inked a new goal into legislation committing Canada to hit net-zero emissions by 2050. The Right Kind Climate Optimism Hannah Ritchie, Vox 2023 The Right Kind Climate Optimism pessimistic optimistic changeable ‘The future will be better if we work hard to change it’ ‘We are doomed and need to take extreme action to protect ourselves’ not changeable ‘The future will be better; it will all work out fine’ ‘We are doomed and there is nothing we can do’ Hannah Ritchie, Vox 2023 2.6 Quaternary Ice Age This is it folksJ Completed: A 4.6 Billion Year Long Hike Assign-3 Test 3 due Dec 2, 11:59pm Saturday Dec 9, 8:30 am PETM, 2nd half Pleistocene Anthropocene Test 2 make up Saturday Dec 9, 8:30 am Snowball Earth Cretaceous PETM, 1st