{"title":"Biogeochemistry and Climate","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0003","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0003","url":null,"abstract":"This chapter focuses on tools for climate research: biogeochemical observations and models. It discusses physical climate observations, such as temperature and humidity, and in situ observations of atmospheric composition. Turning these into reliable climate records appears to be non-trivial. The chapter describes how isotopes are used to get insight into biogeochemical processes. A special category of observations is biogeochemical proxy observations, used to gain insight into geological processes when no direct observations are possible. The example of climate proxy observations, such as those obtained via ice cores, is described. Models are increasingly used to gain insight into sensitivity of climate to changes in the forcing. Earth system modelling has become increasingly complex over the last two decades, including often detailed biogeochemical processes in the ocean and on land. The parametrization of these remains an important research subject. Inverse modelling is being used to identify sources and sinks of greenhouse gases.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125945708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Climate Variability, Climate Change and Earth System Sensitivity","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0002","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0002","url":null,"abstract":"This chapter addresses climate variability and climate sensitivity. Understanding climate variability is important for estimating how future climate will respond to changes in the greenhouse gas concentration in the atmosphere. The chapter approaches climate sensitivity as Earth system sensitivity. This makes it possible to investigate sensitivity at both current and geological timescales. Climate change is examined in terms of geological-scale variability, glacial variability and centennial-scale variability. The chapter starts by distinguishing between slow (geological, ice sheets) processes and fast (anthropogenic) processes, where the slow processes may provide boundary constraints to the faster processes. It first analyses Cenozoic temperature variability and then examines the periodical variations in carbon dioxide and temperature that occurred during the glacial–interglacial cycles in the Pleistocene. It concludes by discussing the fundamental changes in the atmosphere that have arisen as a result of both the burning of fossil fuel and the change in land use by humans.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130507355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Aerosols and Climate","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0005","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0005","url":null,"abstract":"The chapter describes the important role aerosols may have played in the past and are still playing in today’s climate, discussing aerosol distribution, aerosol–climate interaction, aerosol–radiation interaction, aerosol–cloud interaction and aerosol–surface interaction. The biogeochemical aspects are illustrated using the CLAW hypothesis about feedback of dimethylsulphide on climate, and the role that volatile organic carbons may play in shaping today’s climate. Aerosol sources and sinks are shown and it is clear that a substantial part today originates from humans. The aerosols may interact with radiation through scattering and absorption and with clouds to change the availability of cloud condensation nuclei. The basic physics of these interactions are described. The role of volcanic explosions and dust is elucidated and, particularly, the role of dust and associated iron in glacial–interglacial transitions is discussed.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114749425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Physics and Dynamics of the Oceans","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0007","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0007","url":null,"abstract":"This chapter focuses on the physics and dynamics of the ocean. It describes the variability of salinity and surface temperature, as well as the vertical temperature structure of the ocean, with the thermocline separating the variable top layer from the deeper ocean. It then describes the key forces in the ocean, as well as the geostrophic balance due to the Coriolis force and density differences. It derives the equations for the change of velocity with depth, the Ekman flow. Barotropic flow and baroclinic flow are elucidated and the general circulation of the ocean, with gyres and the effect of vorticity on their structure, is shown. The thermohaline circulation of the ocean with surface flow and returning deep ocean flows is described. Next, a simple model is used to show how salinity interacts with the thermohaline flow. Finally, as an example of ocean–land interaction, the El Niño phenomenon is described.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129454807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Nitrogen Cycle and Climate","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0011","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0011","url":null,"abstract":"The nitrogen cycle is described, together with its denitrification and nitrification processes, including the Anammox process. The importance of human intervention through the Haber–Bosch process is shown by identifying the tremendous growth of agricultural food production for a growing world population. The processes of emission of nitrous oxide from the ocean and land are described. The role of reactive nitrogen in cascading through land water into the ocean, where it provides eutrophication in coastal areas, is also described, as is the role of nitrogen in aerosol formation. The geological record of nitrogen cycling is then discussed in relation to Earth’s oxygenation. The impact of nitrogen on the carbon cycle is also discussed.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114414534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Hydrological Cycle and Climate","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0008","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0008","url":null,"abstract":"Water is a key part of the Earth system and interacts with climate through a variety of mechanisms. The chapter initially describes the effect of atmospheric moisture on the lapse rate and then discusses cloud formation and the main global reservoirs and fluxes, including precipitation, and discharge into the oceans. Atmospheric transport of water vapour, together with its relation to precipitation, is then discussed. It is shown that meridional transport can occur with a few very strong events, through atmospheric rivers. The difference between evaporation over the ocean and that over land is shown, with the help of data from Earth observation satellites, and the recycling of water is shown to depend very much on locality. Finally, the importance of frozen water on climate is described, using the recent decrease in Arctic sea ice, and the variability in ice sheet extent and consequent sea levels during the Last Glacial Maximum.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121351119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Methane Cycling and Climate","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0010","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0010","url":null,"abstract":"The chapter describes the mechanisms by which methane is produced in anaerobic environments. Various methane sources and sinks, both natural (e.g. wetlands) and anthropogenic (e.g. landfills, agriculture, fires), are described. The decomposition of organic material in the soil is described as a continuum within the soil matrix, rather than a separation into labile and stable pools. The different pathways of methane production under anaerobic conditions—the acetate pathway and the hydrogen pathway—are described. The roles of wetlands, water bodies, permafrost and clathrate in storing and emitting methane are elucidated. At the geological scale, the chapter discusses the role of methane as a greenhouse gas in providing a habitable climate under a fainter sun (the faint sun paradox), in glacial–interglacial transitions and in the current anthropogenic perturbation. Future methane emissions, global warming potential and the sensitivity of the important methane stores to climate change are also discussed.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115052780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Physics and Dynamics of the Atmosphere","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0006","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0006","url":null,"abstract":"This chapter describes the basic physics and thermodynamics of the atmosphere, starting from the ideal gas law and the hydrostatic equation, from which the lapse rate in the troposphere is derived. The effect of atmospheric moisture on the lapse rate is identified and the Clausius–Clapeyron equation giving the saturated humidity is derived. The effect of moisture on adiabatic vertical transport is shown. Then, the three-dimensional equations of motion are derived in vector form. From these, geostrophic balance and the thermal wind equations are derived. This, with the Coriolis force, gives the physical description of the atmospheric circulation. The driving force behind circulation is identified as the energy difference between the tropics and the extratropics. This is driven by radiation differences, including, at large geological scale, the Milankovitch cycles. Finally, circulation as a three-cell system per hemisphere, and the development of weather systems such as cyclones, are described.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125679498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Future of Climate Change","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0013","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0013","url":null,"abstract":"The role of adaptation and mitigation to climate change is described using the concept of planetary boundaries. The future evolution of the main reservoirs of carbon is described. The role of the land and ocean sink, the permafrost feedback and ocean acidification is described. The challenge to keep Earth’s temperature below 1.5 °C or 2.0 ºC is discussed. As this will involve large amounts of negative emission technologies, such as carbon capture and storage, this may be hard to achieve, as an analysis of their potential and environmental costs shows. Geoengineering has a separate of difficult problems to cope with, which makes the application non-trivial. Decarbonization of societies is discussed and an outline given for a transition path towards a carbon-free society.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122900279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Phosphorus, Sulphur, Iron, Oxygen and Climate","authors":"H. Dolman","doi":"10.1093/OSO/9780198779308.003.0012","DOIUrl":"https://doi.org/10.1093/OSO/9780198779308.003.0012","url":null,"abstract":"This chapter describes the important nutrient cycles of phosphorus, sulphur, iron and oxygen. The pre-industrial phosphorus cycle is described, as is its current perturbation through human use. Phosphorus is a non-renewable resource, so it is expected to run out soon. At the geological timescale, the importance of weathering is shown using the example of the rise of the Himalayas and its interaction with the carbon cycle. The iron cycle is also important, as iron is carried far by dust and is thought to have played a major role in glacial–interglacial transitions. The sulphur cycle is also tightly related to oxygen, as analysis of the geological record shows. Recent developments in measuring oxygen variations in the atmosphere and in ice cores have shown that, at the 0.5 million-year timescale, the geological thermostat appears to work and that current levels are declining as a result of fossil fuel burning.","PeriodicalId":305899,"journal":{"name":"Biogeochemical Cycles and Climate","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130361476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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