This is the Executive Summary of a report produced by the membership of the Anthropocene Working Group as part of a submission to the Subcommission on Quaternary Stratigraphy to seek formalisation of the Anthropocene as an epoch of geological time. It summarises the content of two reports and their associated appendices which provide a background to: the history of usage of the term Anthropocene, when the proposed epoch started, the characterisation of the Anthropocene geological deposits and their stratigraphic value, the recognition of the Anthropocene in different sedimentary environments, the rank and duration of the Anthropocene, the proposed Global boundary Stratigraphic Section and Point and supporting Standard Auxiliary Boundary Sections.

This part of the Anthropocene Working Group (AWG) submission proposes that the base of the Anthropocene should be defined as series/epoch, terminating the Holocene Series/Epoch with a single Crawfordian stage/age using a Global boundary Stratotype Section and Point (GSSP) in an annually varved Crawford Lake core, Ontario, Canada, defined at 17.5 cm in core CRA23-BC-1F-B at the base of the dark lamina in a varve deposited in 1952 CE, at the level where the primary marker shows a rapid increase in 239+240Pu concentrations (coinciding with a globally recognisable, isochronous signal of the first above-ground thermonuclear tests). Secondary markers, determined in precisely correlated core closely adjacent to the proposed GSSP host, include a marked increase in 14C values and in spheroidal carbonaceous particles (SCPs), increased heavy metal concentrations, a decline in δ15N values, a marked change in phytoplankton assemblages and declines in elm (Ulmus) pollen and in non-arboreal pollen. The submission also provides descriptions of three proposed Standard Auxiliary Boundary Stratotypes (SABSs), in cores extracted from marine anoxic sediments of Beppu Bay (Japan), in Sihailongwan Maar Lake (China) and in the Śnieżka Peatland (Poland) and eight reference sections located in cores extracted from marine anoxic sediments in the Baltic Sea, from coral bioherms off Australia and in the Gulf of Mexico, from an Antarctic ice core, from San Francisco Estuary and nearby lake (USA), in a speleothem from northern Italy and a section in urban anthropogenic deposits in Austria. This ubiquity of signals verifies that the Anthropocene can be widely delineated as a sharply distinctive chronostratigraphic unit in diverse terrestrial and marine depositional environments, and reflects a major Earth System change that will have geologically lasting consequences.

The Anthropocene Working Group (AWG) has concluded that the Anthropocene represents geological reality and should be linked with the plethora of stratigraphic proxies that initiate or show marked perturbations at around the 1950s, and should be defined using a Global boundary Stratotype Section and Point (GSSP). We propose formalizing the Anthropocene as series/epoch, terminating the Holocene Series/Epoch with a single Crawfordian stage/age. The GSSP should be located at the level where the primary marker shows a rapid increase in 239+240Pu concentrations (coinciding with a globally recognisable, isochronous signal of the first above-ground thermonuclear tests). The stratigraphic signature of the Anthropocene comprises: a) lithostratigraphic signals, including many new proxies, such as synthetic inorganic crystalline mineral-like compounds, microplastics, fly ash and black carbon, in addition to direct modification through human terraforming of landscape and indirect influences on sedimentary facies through drivers such as climate change; b) chemostratigraphic signals including inorganic and organic contaminants and isotopic shifts of carbon and nitrogen; c) fallout from above-ground nuclear weapons testing; d) stratigraphic effects of climate warming, sea-level rise and ocean acidification; and e) biostratigraphic signals, especially range and abundance changes characterised by unprecedented rates and extents of non-native species introductions, increased population and species extinction and extirpation rates. These correlative markers are present in many kinds of geological deposits around the world. This ubiquity of signals verifies that the Anthropocene can be widely delineated as a sharply distinctive chronostratigraphic unit in diverse terrestrial and marine depositional environments, and reflects a major Earth System change that will have geologically lasting consequences. As background, the Anthropocene was suggested as a new epoch by Paul Crutzen in 2000. The AWG was established in 2009 by the Subcommission on Quaternary Stratigraphy to examine the evidence for the potential inclusion of the Anthropocene in the International Chronostratigraphic Chart (ICC) and, if warranted, to formulate a definition and proposal. Various suggested start dates were considered, and the mid-20th century was found to be the only one associated with an extensive array of effectively globally isochronous geological markers reflecting the ‘Great Acceleration’ of population, industrialization and globalization. Alternative interpretations of the Anthropocene, including as an informal ‘event’, were considered in detail by the AWG and found to be inconsistent with the stratigraphic evidence.

One could argue for a pragmatic approach to analyze the pros and cons of each proposal, along the lines of what Richard A. Falk did back in 1973 in relation to the situation in Vietnam. More recently, a simulation of trial of Monsanto’s activities took place in 2016–2017 in the Hague. The Monsanto International Tribunal enabled five eminent judges to hear testimonies from victims coming from all around the world, in order to examine the consequences of the activities of the multinational agrochemical company Monsanto in the light of international law. A similar approach applied to a selection of representative cases would help fine-tune a draft definition, which might eventually collect enough political support to lead to international negotiations and result in some exciting new legal developments such as an amendment of the Rome Statute or the negotiation of a new MEA. If the road could be long, the growing level of environmental awareness, combined with the pressure civil society which keeps exerting toward change and environmental sustainability, might help remove some of

Built water infrastructure impacts the balance of services provided by a river and its flow regime. Impacts on both commercial and subsistence activities should be considered in water management decision-making. Various methods used to define mandatory minimum environmental releases do not account for the inherent and often complex trade-offs and synergies which must be considered in selecting a balance of ecosystem and engineered services. This paper demonstrates the value and use of optimised many-objective trade-off analysis for managing resource-systems providing diverse and sometimes competing services. Using Kenya's Tana River basin as a demonstration it shows controlled releases from multi-reservoir systems can be optimised using multiple performance metrics, representing individual provisioning ecosystem and engineered services at different locations and relating to different time periods. This enables better understanding the interactions between natural and built assets, and selecting river basin interventions that appropriately trade-off their services. Our demonstration shows prioritising Kenya's statutory minimum environmental 'reserve' flows degrades flood-related provisioning services. Low overall flow regime alteration correlates negatively with consistency of hydropower generation, but positively with other provisioning services.

The advent of anthropogenic global warming and widespread modification of the climate, landscape and environment has brought humans to the fore as a formidable force of nature. The terrestrial and aquatic environment of the East African region is sensitive to a variety of global, regional and local stresses. The geological materials along East Africa coasts, lakes and peats are excellent archives of environmental and climatic changes. The study of their sedimentary records has contributed to our understanding of global environmental and ecosystem changes induced by anthropogenic activities associated with the "Anthropocene", the proposed new geological epoch in Earth history. Humans have occupied East Africa for thousands of years, but until about 300 years ago, their impact on the environment was localized and transitory. The impacts intensified during the 19th century due to rapid population growth and extension and intensification of agriculture that was largely driven by colonists; during this period, the overprinting of natural environmental changes by humans is clear, marked by significant changes in sedimentation, sediment properties, and lake water quality as a consequence of land and water degradation and overexploitation of terrestrial and aquatic ecosystem goods and services. Related impacts include changes in terrestrial and aquatic ecosystems and associated biodiversity losses. There have been temporal and spatial lags in the changes, depending on locality, but there is a widespread convergence of these effects from the mid-1900s, support the Anthropocene Working Group's proposed date of 1950 as the start of the Anthropocene.

Non-technical summaryThe El Niño event in 2015/2016 was one of the strongest since at least 1950. Through surveys and interviews with key informants, we found businesses in the capital cities of Zambia, Botswana and Kenya experienced major disruption to their activities from El Niño related hydroelectric load shedding, water supply disruption and flooding, respectively. Yet, during the 2015/2016 El Niño, fluctuations in precipitation were not extreme considering the strength of the El Niño event. Results therefore highlight that even fairly moderate precipitation anomalies can contribute to major disruption to economic activity. Addressing the risk of disruption – and supporting the private sector to adapt – is a development priority.

Since 2009, the Working Group on the ‘Anthropocene’ (or, commonly, AWG for Anthropocene Working Group), has been critically analysing the case for formalization of this proposed but still informal geological time unit. The study to date has mainly involved establishing the overall nature of the Anthropocene as a potential chronostratigraphic/geochronologic unit, and exploring the stratigraphic proxies, including several that are novel in geology, that might be applied to its characterization and definition. A preliminary summary of evidence and interim recommendations was presented by the Working Group at the 35th International Geological Congress in Cape Town, South Africa, in August 2016, together with results of voting by members of the AWG indicating the current balance of opinion on major questions surrounding the Anthropocene. The majority opinion within the AWG holds the Anthropocene to be stratigraphically real, and recommends formalization at epoch/series rank based on a mid-20th century boundary. Work is proceeding towards a formal proposal based upon selection of an appropriate Global boundary Stratotype Section and Point (GSSP), as well as auxiliary stratotypes. Among the array of proxies that might be used as a primary marker, anthropogenic radionuclides associated with nuclear arms testing are the most promising; potential secondary markers include plastic, carbon isotope patterns and industrial fly ash. All these proxies have excellent global or near-global correlation potential in a wide variety of sedimentary bodies, both marine and non-marine.

We assess the scale and extent of the physical technosphere, defined here as the summed material output of the contemporary human enterprise. It includes active urban, agricultural and marine components, used to sustain energy and material flow for current human life, and a growing residue layer, currently only in small part recycled back into the active component. Preliminary estimates suggest a technosphere mass of approximately 30 trillion tonnes (Tt), which helps support a human biomass that, despite recent growth, is ~5 orders of magnitude smaller. The physical technosphere includes a large, rapidly growing diversity of complex objects that are potential trace fossils or ‘technofossils’. If assessed on palaeontological criteria, technofossil diversity already exceeds known estimates of biological diversity as measured by richness, far exceeds recognized fossil diversity, and may exceed total biological diversity through Earth’s history. The rapid transformation of much of Earth’s surface mass into the technosphere and its myriad components underscores the novelty of the current planetary transformation.

Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An integration of the two approaches provides powerful insights into the nature and significance of contemporary changes to Earth. From both perspectives, the Earth has been pushed out of the Holocene Epoch by human activities, with the mid‐20th century a strong candidate for the start date of the Anthropocene, the proposed new epoch in Earth history. Here we explore two contrasting scenarios for the future of the Anthropocene, recognizing that the Earth System has already undergone a substantial transition away from the Holocene state. A rapid shift of societies toward the UN Sustainable Development Goals could stabilize the Earth System in a state with more intense interglacial conditions than in the late Quaternary climate regime and with little further biospheric change. In contrast, a continuation of the present Anthropocene trajectory of growing human pressures will likely lead to biotic impoverishment and a much warmer climate with a significant loss of polar ice.

Groundwater is used extensively in the Central Kenya Rift for domestic and agricultural demands. In these active rift settings groundwater can exhibit high fluoride levels. In order to address water security and reduce human exposure to high fluoride in drinking water, knowledge of the source and geochemical processes of enrichment are required. A study was therefore carried out within the Naivasha catchment (Kenya) to understand the genesis, enrichment and seasonal variations of fluoride in the groundwater. Rocks, rain, surface and groundwater sources were sampled for hydrogeochemical and isotopic investigations, the data was statistically and geospatially analyzed. Water sources have variable fluoride concentrations between 0.02-75 mg/L. 73% exceed the health limit (1.5mg/L) in both dry and wet seasons. F(-) concentrations in rivers are lower (0.2-9.2mg/L) than groundwater (0.09 to 43.6 mg/L) while saline lake waters have the highest concentrations (0.27-75 mg/L). The higher values are confined to elevations below 2000 masl. Oxygen (δ(18)O) and hydrogen (δD) isotopic values range from -6.2 to +5.8‰ and -31.3 to +33.3‰, respectively, they are also highly variable in the rift floor where they attain maximum values. Fluoride base levels in the precursor vitreous volcanic rocks are higher (between 3750-6000 ppm) in minerals such as cordierite and muscovite while secondary minerals like illite and kaolinite have lower remnant fluoride (<1000 ppm). Thus, geochemical F(-) enrichment in regional groundwater is mainly due to a) rock alteration, i.e. through long residence times and natural discharge and/or enhanced leakages of deep seated geothermal water reservoirs, b) secondary concentration fortification of natural reservoirs through evaporation, through reduced recharge and/or enhanced abstraction and c) through additional enrichment of fluoride after volcanic emissions. The findings are useful to help improve water management in Naivasha as well as similar active rift setting environments.

Biospheric relationships between production and consumption of biomass have been resilient to changes in the Earth system over billions of years. This relationship has increased in its complexity, from localized ecosystems predicated on anaerobic microbial production and consumption to a global biosphere founded on primary production from oxygenic photoautotrophs, through the evolution of Eukarya, metazoans, and the complexly networked ecosystems of microbes, animals, fungi, and plants that characterize the Phanerozoic Eon (the last ∼541 million years of Earth history). At present, one species, Homo sapiens, is refashioning this relationship between consumption and production in the biosphere with unknown consequences. This has left a distinctive stratigraphy of the production and consumption of biomass, of natural resources, and of produced goods. This can be traced through stone tool technologies and geochemical signals, later unfolding into a diachronous signal of technofossils and human bioturbation across the planet, leading to stratigraphically almost isochronous signals developing by the mid‐20th century. These latter signals may provide an invaluable resource for informing and constraining a formal Anthropocene chronostratigraphy, but are perhaps yet more important as tracers of a biosphere state that is characterized by a geologically unprecedented pattern of global energy flow that is now pervasively influenced and mediated by humans, and which is necessary for maintaining the complexity of modern human societies.

Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the Earth system through the stratigraphic record. The appearance of manufactured materials in sediments, including aluminum, plastics, and concrete, coincides with global spikes in fallout radionuclides and particulates from fossil fuel combustion. Carbon, nitrogen, and phosphorus cycles have been substantially modified over the past century. Rates of sea-level rise and the extent of human perturbation of the climate system exceed Late Holocene changes. Biotic changes include species invasions worldwide and accelerating rates of extinction. These combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs.

In situ monitoring of water dates to Pharaonic Egypt and remained the primary means of observation into the later part of the 20th century. Monitoring networks have declined ([ 1 ][1]–[ 4 ][2]) since the 1980s because of budgetary constraints and political instabilities. This decline paradoxically

We evaluate the boundary of the Anthropocene geological time interval as an epoch, since it is useful to have a consistent temporal definition for this increasingly used unit, whether the presently informal term is eventually formalized or not. Of the three main levels suggested - an 'early Anthropocene' level some thousands of years ago; the beginning of the Industrial Revolution at similar to 1800 CE (Common Era); and the 'Great Acceleration' of the mid-twentieth century - current evidence suggests that the last of these has the most pronounced and globally synchronous signal. A boundary at this time need not have a Global Boundary Stratotype Section and Point (GSSP or 'golden spike') but can be defined by a Global Standard Stratigraphic Age (GSSA), i.e. a point in time of the human calendar. We propose an appropriate boundary level here to be the time of the world's first nuclear bomb explosion, on July 16th 1945 at Alamogordo, New Mexico; additional bombs were detonated at the average rate of one every 9.6 days until 1988 with attendant worldwide fallout easily identifiable in the chemostratigraphic record. Hence, Anthropocene deposits would be those that may include the globally distributed primary artificial radionuclide signal, while also being recognized using a wide range of other stratigraphic criteria. This suggestion for the Holocene-Anthropocene boundary may ultimately be superseded, as the Anthropocene is only in its early phases, but it should remain practical and effective for use by at least the current generation of scientists. (C) 2014 Elsevier Ltd and INQUA.

The Great Lakes of East Africa are among the world’s most important freshwater ecosystems. Despite their importance in providing vital resources and ecosystem services, the impact of regional and global environmental drivers on this lacustrine system remains only partially understood. We make a systematic comparison of the dynamics of the bio-optical and thermal properties of thirteen of the largest African lakes between 2002 and 2011. Lake surface temperatures had a positive trend in all Great Lakes outside the latitude of 0° to 8° south, while the dynamics of those lakes within this latitude range were highly sensitive to global inter-annual climate drivers (i.e. El Niño Southern Oscillation). Lake surface temperature dynamics in nearly all lakes were found to be sensitive to the latitudinal position of the Inter Tropical Convergence Zone. Phytoplankton dynamics varied considerably between lakes, with increasing and decreasing trends. Intra-lake differences in both surface temperature and phytoplankton dynamics occurred for many of the larger lakes. This inter-comparison of bio-optical and thermal dynamics provides new insights into the response of these ecosystems to global and regional drivers.