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Subtropical gyre (STG) depth and strength are controlled by wind stress curl and surface buoyancy forcing1,2. Modern hydrographic data reveal that the STG extends to a depth of about 1 km in the Northwest Atlantic, with its maximum depth defined by the base of the subtropical thermocline. Despite the likelihood of greater wind stress curl and surface buoyancy loss during the Last Glacial Maximum (LGM)3, previous work suggests minimal change in the depth of the glacial STG4. Here we show a sharp glacial water mass boundary between 33° N and 36° N extending down to between 2.0 and 2.5 km-approximately 1 km deeper than today. Our findings arise from benthic foraminiferal δ18O profiles from sediment cores in two depth transects at Cape Hatteras (36-39° N) and Blake Outer Ridge (29-34° N) in the Northwest Atlantic. This result suggests that the STG, including the Gulf Stream, was deeper and stronger during the LGM than at present, which we attribute to increased glacial wind stress curl, as supported by climate model simulations, as well as greater glacial production of denser subtropical mode waters (STMWs). Our data suggest (1) that subtropical waters probably contributed to the geochemical signature of what is conventionally identified as Glacial North Atlantic Intermediate Water (GNAIW)5-7 and (2) the STG helped sustain continued buoyancy loss, water mass conversion and northwards meridional heat transport (MHT) in the glacial North Atlantic.
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Cubierta de Hielo , Agua de Mar , Movimientos del Agua , Océano Atlántico , Modelos Climáticos , Foraminíferos/aislamiento & purificación , Sedimentos Geológicos/parasitología , Golfo de México , Historia Antigua , Calor , Agua de Mar/análisis , Agua de Mar/química , VientoRESUMEN
In this study, we synthesize terrestrial and marine proxy records, spanning the past 620 ky, to decipher pan-African climate variability and its drivers and potential linkages to hominin evolution. We find a tight correlation between moisture availability across Africa to El Niño Southern Ocean oscillation (ENSO) variability, a manifestation of the Walker Circulation, that was most likely driven by changes in Earth's eccentricity. Our results demonstrate that low-latitude insolation was a prominent driver of pan-African climate change during the Middle to Late Pleistocene. We argue that these low-latitude climate processes governed the dispersion and evolution of vegetation as well as mammals in eastern and western Africa by increasing resource-rich and stable ecotonal settings thought to have been important to early modern humans.
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Evolución Biológica , Cambio Climático/historia , El Niño Oscilación del Sur/historia , África , Historia Antigua , HumanosRESUMEN
Time is divided by geologists according to marked shifts in Earth's state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Here we review the historical genesis of the idea and assess anthropogenic signatures in the geological record against the formal requirements for the recognition of a new epoch. The evidence suggests that of the various proposed dates two do appear to conform to the criteria to mark the beginning of the Anthropocene: 1610 and 1964. The formal establishment of an Anthropocene Epoch would mark a fundamental change in the relationship between humans and the Earth system.
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Cronología como Asunto , Ambiente , Geología/métodos , Actividades Humanas/historia , Agricultura/historia , Atmósfera/química , Dióxido de Carbono/análisis , Historia del Siglo XV , Historia del Siglo XVI , Historia del Siglo XVII , Historia del Siglo XVIII , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Industrias/historia , Dinámica Poblacional , Factores de TiempoRESUMEN
The Lancet Countdown: tracking progress on health and climate change is an international, multidisciplinary research collaboration between academic institutions and practitioners across the world. It follows on from the work of the 2015 Lancet Commission, which concluded that the response to climate change could be "the greatest global health opportunity of the 21st century". The Lancet Countdown aims to track the health impacts of climate hazards; health resilience and adaptation; health co-benefits of climate change mitigation; economics and finance; and political and broader engagement. These focus areas form the five thematic working groups of the Lancet Countdown and represent different aspects of the complex association between health and climate change. These thematic groups will provide indicators for a global overview of health and climate change; national case studies highlighting countries leading the way or going against the trend; and engagement with a range of stakeholders. The Lancet Countdown ultimately aims to report annually on a series of indicators across these five working groups. This paper outlines the potential indicators and indicator domains to be tracked by the collaboration, with suggestions on the methodologies and datasets available to achieve this end. The proposed indicator domains require further refinement, and mark the beginning of an ongoing consultation process-from November, 2016 to early 2017-to develop these domains, identify key areas not currently covered, and change indicators where necessary. This collaboration will actively seek to engage with existing monitoring processes, such as the UN Sustainable Development Goals and WHO's climate and health country profiles. The indicators will also evolve over time through ongoing collaboration with experts and a range of stakeholders, and be dependent on the emergence of new evidence and knowledge. During the course of its work, the Lancet Countdown will adopt a collaborative and iterative process, which aims to complement existing initiatives, welcome engagement with new partners, and be open to developing new research projects on health and climate change.
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Cambio Climático , Salud Global , Política de Salud , Conservación de los Recursos Naturales , Biomarcadores Ambientales , HumanosAsunto(s)
Congresos como Asunto , Conservación de los Recursos Energéticos/legislación & jurisprudencia , Conservación de los Recursos Energéticos/tendencias , Calentamiento Global/prevención & control , Objetivos , Cooperación Internacional/legislación & jurisprudencia , Conservación de los Recursos Energéticos/economía , Conservación de los Recursos Energéticos/estadística & datos numéricos , Calentamiento Global/economía , Calentamiento Global/legislación & jurisprudencia , Inversiones en Salud/economía , Inversiones en Salud/legislación & jurisprudencia , Energía Nuclear/economía , Energía Nuclear/legislación & jurisprudencia , Energía Nuclear/estadística & datos numéricos , Paris , Sector Privado/economía , Asociación entre el Sector Público-Privado/economía , Asociación entre el Sector Público-Privado/tendencias , Energía Renovable/economía , Energía Renovable/legislación & jurisprudencia , Energía Renovable/estadística & datos numéricos , TemperaturaAsunto(s)
Salud Infantil , Cambio Climático , Salud Global , Enfermedades Transmisibles/epidemiología , Conservación de los Recursos Naturales , Atención a la Salud/métodos , Calor Extremo/efectos adversos , Abastecimiento de Alimentos/estadística & datos numéricos , Política de Salud , Humanos , Cooperación Internacional , Desnutrición/epidemiología , Tiempo (Meteorología)RESUMEN
Episodes of environmental stability and instability may be equally important for African hominin speciation, dispersal, and cultural innovation. Three examples of a change from stable to unstable environmental conditions are presented on three different time scales: (1) the Mid Holocene (MH) wet-dry transition in the Chew Bahir basin (Southern Ethiopian Rift; between 11 ka and 4 ka), (2) the MIS 5-4 transition in the Naivasha basin (Central Kenya Rift; between 160 ka and 50 ka), and (3) the Early Mid Pleistocene Transition (EMPT) in the Olorgesailie basin (Southern Kenya Rift; between 1.25 Ma and 0.4 Ma). A probabilistic age modeling technique is used to determine the timing of these transitions, taking into account possible abrupt changes in the sedimentation rate including episodes of no deposition (hiatuses). Interestingly, the stable-unstable conditions identified in the three records are always associated with an orbitally-induced decrease of insolation: the descending portion of the 800 kyr cycle during the EMPT, declining eccentricity after the 115 ka maximum at the MIS 5-4 transition, and after â¼ 10 ka. This observation contributes to an evidence-based discussion of the possible mechanisms causing the switching between environmental stability and instability in Eastern Africa at three different orbital time scales (10,000 to 1,000,000 years) during the Cenozoic. This in turn may lead to great insights into the environmental changes occurring at the same time as hominin speciation, brain expansion, dispersal out of Africa, and cultural innovations and may provide key evidence to build new hypotheses regarding the causes of early human evolution.
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Distribución Animal , Evolución Biológica , Clima , Evolución Cultural , Especiación Genética , Hominidae/fisiología , Animales , Ambiente , Etiopía , Sedimentos Geológicos/análisis , Humanos , Kenia , Lagos/análisis , Modelos Teóricos , PaleontologíaRESUMEN
Global health, population growth, economic development, environmental degradation, and climate change are the main challenges we face in the 21st century. However, because the academics, non-governmental organisations, and policy makers in these specialties work within separate communities, our understanding of the associations between them is restricted. We organised an international symposium in May, 2011 in London, UK, for academics and technical experts from population, developmental, and environmental science to encourage debate and collaboration between these disciplines. The conference provided the impetus for this Review, which describes, in historical context, key events and fundamental intercommunity debates from the perspectives of population, development, and climate change communities. We consider the interconnections between population, development, and climate change and their effects on health, including new analysis of longstanding debates, and identify opportunities for effective collaboration on shared goals.
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Congresos como Asunto , Salud Global , Crecimiento Demográfico , Cambio Climático , Conducta Cooperativa , Desarrollo Económico , Contaminación Ambiental , Humanos , LondresAsunto(s)
Cambio Climático , Estado de Salud , Salud Pública/tendencias , Contaminación del Aire/prevención & control , Cambio Climático/economía , Enfermedades Transmisibles/epidemiología , Desastres , Electricidad , Abastecimiento de Alimentos , Salud Global/tendencias , Empleos en Salud , Planificación en Salud/economía , Humanos , Rayos Infrarrojos , Cooperación Internacional , Desnutrición/etiología , Salud Materna , Medición de Riesgo/tendencias , TrabajoAsunto(s)
Cambio Climático , Salud Global , Política de Salud , Cambio Climático/economía , Conservación de los Recursos Energéticos , Contaminación Ambiental/prevención & control , Organización de la Financiación , Planificación en Salud/economía , Investigación sobre Servicios de Salud , Humanos , Política , Salud Pública , Energía Renovable , Informe de InvestigaciónAsunto(s)
Monitoreo del Ambiente/instrumentación , Agricultura Forestal/estadística & datos numéricos , Nave Espacial , Árboles/crecimiento & desarrollo , Clima Tropical , Secuestro de Carbono/fisiología , Conservación de los Recursos Naturales/métodos , Conservación de los Recursos Naturales/estadística & datos numéricos , Agricultura Forestal/economía , Árboles/metabolismoRESUMEN
Food security and healthy ecosystems are placed in jeopardy by poor potassium management. Six actions may prevent declines in crop yield due to soil potassium deficiency, safeguard farmers from potash price volatility and address environmental concerns associated with potash mining.
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Ecosistema , Potasio , Suelo , Minería , Seguridad AlimentariaRESUMEN
The transition from a humid green Sahara to today's hyperarid conditions in northern Africa ~5.5 thousand years ago shows the dramatic environmental change to which human societies were exposed and had to adapt to. In this work, we show that in the 620,000-year environmental record from the Chew Bahir basin in the southern Ethiopian Rift, with its decadal resolution, this one thousand year long transition is particularly well documented, along with 20-80 year long droughts, recurring every ~160 years, as possible early warnings. Together with events of extreme wetness at the end of the transition, these droughts form a pronounced climate "flickering", which can be simulated in climate models and is also present in earlier climate transitions in the Chew Bahir environmental record, indicating that transitions with flickering are characteristic of this region.
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Anthropogenic climate change is affecting people's health, including those with neurological and psychiatric diseases. Currently, making inferences about the effect of climate change on neurological and psychiatric diseases is challenging because of an overall sparsity of data, differing study methods, paucity of detail regarding disease subtypes, little consideration of the effect of individual and population genetics, and widely differing geographical locations with the potential for regional influences. However, evidence suggests that the incidence, prevalence, and severity of many nervous system conditions (eg, stroke, neurological infections, and some mental health disorders) can be affected by climate change. The data show broad and complex adverse effects, especially of temperature extremes to which people are unaccustomed and wide diurnal temperature fluctuations. Protective measures might be possible through local forecasting. Few studies project the future effects of climate change on brain health, hindering policy developments. Robust studies on the threats from changing climate for people who have, or are at risk of developing, disorders of the nervous system are urgently needed.
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Cambio Climático , Enfermedades del Sistema Nervioso , Humanos , Enfermedades del Sistema Nervioso/epidemiologíaAsunto(s)
Cambio Climático , Modelos Teóricos , Incertidumbre , Simulación por Computador , Política PúblicaRESUMEN
The last 35 years have been a period of intense and continuous international negotiations to deal with climate change. During the same period of time humanity has doubled the amount of anthropogenic carbon dioxide in the atmosphere. There has, however, been progress and some notable successes in the negotiations. In 2015, at COP21 of the United Nations Framework Convention on Climate Change, 196 countries adopted the Paris Agreement stating that they would limit global temperatures to well below 2°C above pre-industrial levels and would pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels. The first review of the Paris Agreement was at COP26 in Glasgow with many countries pledging to go to net zero emissions by the middle of the century. But currently these pledges, if fulfilled, will only limit the global average temperature to between 2.4°C and 2.8°C. At COP27 in Egypt the core agreements from the Glasgow Climate Pact were maintained and countries finally agreed to set up a loss and damage facility - although details of who will provide the finance and who can claim are still be to be worked out. This article reviews the key moments in the history of international climate change negotiations and discusses what the key objectives are for future COP meetings.
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Climate justice is not just a financial transaction to protect the environment. It needs to be seen as the protection of the most vulnerable in society after centuries of resource exploitation. African countries disproportionately face impacts of climate change on their environments, their economies, their resources and their infrastructure. This leads to greater vulnerability and increased exposure to the negative effects of a changing climate. In this article, we highlight the importance of climate justice and its role within the United Nations negotiations, and ultimately in concrete action. We discuss current climate impacts across key sectors in the African region, with a focus on health, infrastructure, food and water scarcity, energy and finance. All sectors are affected by climate change. They are interconnected and under threat. This triggers a ripple effect, where threats in one sector have a knock-on effect on other sectors. We find that the current set of intergovernmental institutions have failed to adequately address climate justice. We also contend that a siloed approach to climate action has proven to be ineffective. As we head towards the next set of negotiations (COP27), this paper argues that the economic and social conditions in Africa can be addressed through financial and collaborative support for adaptation and localised solutions, but that this will only be achieved if climate justice is prioritised by the decision makers. This needs to include a global-scale transition in how climate finance is assessed and accessed. Climate justice underpins real, effective and sustainable solutions for climate action in Africa.