Anthropocene Handout PDF

lesson 9: the Anthropocene -let’s review what we learned about the active and changing Earth -global warming seems to be occurring at an unprecedented rate -humans are almost certainly the cause of this rapid warming owing to greenhouse gas emissions -we h...

lesson 9: the Anthropocene -let’s review what we learned about the active and changing Earth -global warming seems to be occurring at an unprecedented rate -humans are almost certainly the cause of this rapid warming owing to greenhouse gas emissions -we have other impacts on the Earth’s climate and environment: ocean acidification, extinctions, e? t h e Ant h ropocen pollution, Add land modification -are we entering a new geological epoch: the Anthropocene? 1   The p refix “ mean an Earth is an incredibly old, s “hum thro” anthro an”. e dynamic, and complex system p.g. relatin ogenic mea , g n from h to or resul s uman tin Are we entering a geological activit g y epoch where humans are the dominant influence on Earth’s climate and environment? “The Anthropocene” First, let’s look at what have we learned about global change… “the Blue Marble”; photo from Apollo 17, 1972 1. The Earth is a complex and dynamic system vs. 3 2. The Earth’s lithosphere is active and constantly changing 4 3. Earth is incredibly old, and humans are vanishingly small in this time span 5 4. Natural geo-hazards affect us, and may (or may not) be changing 6 5. We are dependent on non-renewable resources from the Earth 7 6. We need petroleum from the Earth, but there are consequences 8 7. Earth’s climate is currently changing: greenhouse gases and global warming 9 8. Earth has gone through major swings in climate—this is natural 10 9. the Anthropocene Over the course of the 1990s, scientists in particular worked to catalog the global changes in the atmosphere, the \ hydrosphere, the biosphere, and the lithosphere that made the world a physically different place than it had been in centuries past. In 2000, atmospheric chemist and Nobel Laureat Paul Crutzen teamed up with biologist Eugene Stoermer to suggest that humanity’s impact on the earth’s atmosphere was significant enough to constitute a new geological epoch the “anthropocene”. [from: Howe, 2017. Making Climate Change History. pg 282] h ropocen e? t h e Ant Add see also: the “great acceleration” https://www.slideshare.net/owengaffney/great-acceleration 9. the Anthropocene Over the course of the 1990s, scientists in particular worked to catalog the global changes in the atmosphere, the \ hydrosphere, the biosphere, and the lithosphere that made the world a physically different place than it had been in centuries past. In 2000, atmospheric chemist and Nobel Laureat Paul Crutzen teamed up with biologist Eugene Stoermer to suggest that humanity’s impact on the earth’s atmosphere was significant enough to constitute a new geological epoch the “anthropocene”. [from: Howe, 2017. Making Climate Change History. pg 282] h ropocen e? t h e Ant Add see also: the “great acceleration” https://www.slideshare.net/owengaffney/great-acceleration some effects humans have had on the Earth system 1. climate forcing from greenhouse gas emissions the “hockey stick” graph “increase in atmospheric carbon dioxide over the past 60 years is about 100 times faster than previous natural increases” (Lindsay 2019. climate.gov) [ipcc.ch]  - essentially, current global warming is happening much faster than it did compared to the warming interglacial events over the past million years - humans could witness a warming of 4 degrees C over 110 years; normally this warming would take 5000 years according to climate records - (that is probably a high estimate for the amount of warming; this is still debated…) NOAA Climate.gov - greenhouse gas concentration left natural trend about 8,000 years ago (time of onset of cattle and wet rice farming) - warming may have started ~15,000 yrs ago extinction of mammoths by human hunting resulted in growth of birch trees Doughty et al. 2010. Biophysical feedbacks between the Pleistocene megafauna extinction and climate: Rudiman, 2005. Plows, plagues, and petroleum The first human induced global warming? GRL ‐ 2. depletion of non-renewable resources e.g., “peak oil” theory: conventional sources of crude oil globally have reached or will soon reach their maximum production capacity, and will diminish quickly (this does not include non-conventional sources such as oil sands, shale gas/fracking operations) —with production of readily available oil reaching a peak and declining, crude prices will rise and remain high In 195 So is the Earth running out of oil? 6, M. propo Ki sed “p ng Hubbert estima ea ted a p k oil” and Red line is Hubbert prediction for US. eak in ~2000 Green lines are actual US production 3. ocean acidification and heating “The ocean has absorbed enough carbon dioxide to lower its pH by 0.1 units, a 30% increase in acidity.” Extra CO (Lindsay 2019. NOAA climate.gov) ocean 2 is absor bed in [aside: pH from 8.21 to 8.1; scale is logarithmic] s, lead carbo i n nic ac g to H+ (w id hich lo and free wers p H) coral bleaching in Australian Great Barrier Reef [pbs.org] 4. current extinction “Although extinction is a natural phenomenon, it occurs at a natural ‘background’ rate of about one to five species per year. Scientists estimate we're now losing species at up to 1,000 times the background rate, with literally dozens going extinct every day.” [biologicaldiversity.org] from Carrington. Earth’s sixth mass extinction under way... The Guardian, 10 July 2017 [theguardian.com] 5. garbage and plastic in oceans [oceanhealthindex.org] - pollution of groundwater and surface waters ex: Bexfield et al. 2019. Hormones and pharmaceuticals in groundwater used as a source of drinking water across the United States. Environ. Sci. Technol., vol 53, pg 2950-2960. 6. engineering and agriculture “Agriculture and excavations shape the landscape more than rivers and glaciers.” Nature news, 07 March 2005 “Concrete: the most destructive material on Earth” e-top…! i t over- th The Guardian, 25 Feb 2019 This i s a b “A pressure-controlled water tank in Kusakabe, “The Three Gorges Dam on the Yangtze River, China, Japan, constructed to protect Tokyo against is the largest concrete structure in the world.” floodwaters” [theguardian.com] [theguardian.com]  e.g., Natural vs. artificial shoreline My cottage on Carson Lake how geologists may define the “Anthropocene” h ow t h e ge o lo gical - geologic boundaries ratified based on one specific location This is uilt GSSP (global stratotype section and point = “golden spike”) timescale was b 65 ratified, most based on fossils (all but very recent ones) ex: base of Ordovician ratified in 2001 using first appearance of a conodont species at a [Waters et al. 2018] location in Newfoundland [stratigraphy.org] still, stratigraphic determination of ‘Anthropocene’ requires something unique in the sedimentary record - likely candidate: Plutonium 239 from above-ground nuclear tests starting in 1952 (detectable world-wide) [Waters et al. 2015] The marker site for the Anthropocene: Crawford Lake, Ontario - a committee convened by the International Commission on Stratigraphy chose this site from among 12 sites globally as the GSSP (“golden spike”) for the Anthropocene - Crawford Lake has annual sediment layers and is a protected public site - human habitation for 100s of years (indigenous settlements going back to 13th century) chemical and biological record at Crawford Lake; red line marks 1952 sediment cored from Crawford Lake [Waters et al. 2018] [Krueger & McCarthy 2016] So is there a new geological epoch called the Anthropocene? - No - the proposal was voted down (by a wide margin) in March 2024 by various governing bodies specializing in stratigraphy that define the formal geological time scale of Earth - e.g., some concerns raised by the IUGS (International Union of Geological Sciences): - anthropogenic effects on Earth long predate the mid-20th century - too short a time to be certain (less than a human lifetime) vs. other events spanning thousands/millions of years - are anthropogenic events spatially/temporally variable? IUGS: “Anthropocene as a concept will continue to be widely used not only by Earth and environmental scientists, but also by social scientists, politicians and economists, as well as by the public at large. As such, it will remain an invaluable descriptor in human-environment interactions. But it will not be recognised as a formal geological term but will more usefully be employed informally in future discussions of the anthropogenic impacts on Earth’s climatic and environmental systems.” Welcome to the Anthropocene (maybe…)! 28