1,721,016 research outputs found
Geoengineering the climate: an overview and update
No full textThe climate change that we are experiencing now is caused by an increase in greenhouse gases due to human activities, including burning fossil fuels, agriculture and deforestation. There is now widespread belief that a global warming of greater than 2°C above pre-industrial levels would be dangerous and should therefore be avoided. However, despite growing concerns over climate change and numerous international attempts to agree on reductions of global CO2 emissions, these have continued to climb. This has led some commentators to suggest more radical ‘geoengineering’ alternatives to conventional mitigation by reductions in CO2 emissions. Geoengineering is deliberate intervention in the climate system to counteract man-made global warming. There are two main classes of geoengineering: direct carbon dioxide removal and solar radiation management that aims to cool the planet by reflecting more sunlight back to space. The findings of the review of geoengineering carried out by the UK Royal Society in 2009 are summarized here, including the climate effects, costs, risks and research and governance needs for various approaches. The possible role of geoengineering in a portfolio of responses to climate change is discussed, and various recent initiatives to establish good governance of research activity are reviewed. Key findings include the following. — Geoengineering is not a magic bullet and not an alternative to emissions reductions. — Cutting global greenhouse gas emissions must remain our highest priority. (i) But this is proving to be difficult, and geoengineering may be useful to support it. — Geoengineering is very likely to be technically possible. (i) However, there are major uncertainties and potential risks concerning effectiveness, costs and social and environmental impacts. — Much more research is needed, as well as public engagement and a system of regulation (for both deployment and for possible large-scale field tests). — The acceptability of geoengineering will be determined as much by social, legal and political issues as by scientific and technical factors.Some methods of both types would involve release of materials to the environment, either to the atmosphere or to the oceans, in areas beyond national jurisdiction. The intended impacts on climate would in any case affect many or all countries, possibly to a variable extent. There are therefore inherent international implications for deployment of such geoengineering methods (and possibly also for some forms of research), which need early and collaborative consideration, before any deployment or large-scale experiments could be undertaken responsibly
Fishing effort control: could it work under the common fisheries policy?
No full textThe system of managing fisheries under the CFP using TACs and quotas has not been sufficiently effective, and is no longer adequate. Direct control of fishing effort has always been a possible alternative, but has not been implemented except in special cases because of the difficulties of measuring and comparing the fishing effort of different vessels and fishing gears, and ensuring fair sharing of the resources available. I suggest that both of these problems can be overcome by adopting a scheme based on uniform pro rata adjustments to individual vessel entitlements to fishing effort, based on track records, and thus also maintaining the important principle of relative stability. Such a scheme is well adapted to a system of regional management of the fisheries, could be effectively enforced using satellite monitoring, and should be seriously considered as an alternative to TACs and quotas in the CFP after 2002
Bifurcations of the thermohaline circulation in a simplified three-dimensional model of the world ocean and the effects of inter-basin connectivity
No full textA coarse-resolution, global, three-dimensional, idealised model of the world ocean, based on the thermocline equations, is described. It is demonstrated that, at suitable resolution, such a model can be integrated for hundreds or thousands of millenia, and could therefore form a component of an earth system model designed to investigate climate change on these time scales. As in other ocean models, the thermohaline circulation is found to exhibit multiple stable states. The bifurcation structure of the model has been explored, as a function of surface saline forcing, and is found to depend on the inter-basin connectivity, the topography, and the form of the imposed wind forcing
Geoengineering the climate: science, governance and uncertainty
No full textGeoengineering, or the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change, has been suggested as a new potential tool for addressing climate change. Efforts to address climate change have primarily focused on mitigation, the reduction of greenhouse gas emissions, and more recently on addressing the impacts of climate change—adaptation. However, international political consensus on the need to reduce emissions has been very slow in coming, and there is as yet no agreement on the emissions reductions needed beyond 2012. As a result global emissions have continued to increase by about 3% per year (Raupach et al. 2007), a faster rate than that projected by the Intergovernmental Panel on Climate Change (IPCC) (IPCC 2001)7 even under its most fossil fuel intensive scenario (A1FI8) in which an increase in global mean temperature of about 4°C (2.4 to 6.4°C) by 2100 is projected (Rahmstorf et al. 2007). The scientifi c community is now becoming increasingly concerned that emissions will not be reduced at the rate and magnitude required to keep the increase in global average temperature below 2°C (above pre-industrial levels) by 2100. Concerns with the lack of progress of the political processes have led to increasing interest in geoengineering approaches. This Royal Society report presents an independent scientifi c review of the range of methods proposed with the aim of providing an objective view on whether geoengineering could, and should, play a role in addressing climate change, and under what conditions
A comparison of no-take zones and traditional fishery management tools for managing site-attached species with a mixed larval pool
No full textNo-take zones (NTZs) can generate higher larval production by sessile, sedentary and site-attached species per unit area than in exploited areas, and may increase recruitment and yield compared to status quo management. Whilst NTZs may be considered an essential part of optimal management, few studies have specifically compared the effects of NTZs with those of correctly applied gear and effort controls.A yield-per-recruit (YPR) population model, based on the sedentary abalone Haliotis laevigata, was used to compare the effects of management by minimum landing size (MLS), effort limitation and NTZs, either singularly or in combination. Initially, a minimum basic YPR model was used. Three additional assumptions were sequentially added to the model to see if they affected conclusions drawn from the model. The additional assumptions were the inclusion of: (i) a length–fecundity relationship; (ii) an age-dependent natural mortality function; and (iii) mortality of undersized individuals due to fishery operations. In the absence of undersized mortality caused by fishing, under virtually all conditions the population is best managed with a combination of MLS and effort control, without any NTZs. For simulations that included mortality of undersized individuals in the fished area, under nearly all circumstances NTZs were considered an essential part of optimal fishery management, and management incorporating NTZs greatly increased the sustainable yield that could be taken
Modelling the timing of plankton production and its effect on recruitment of cod (Gadus morhua)
No full textThe match–mismatch hypothesis, which relates timing of plankton production to recruitment of fish, is difficult to test for a number of reasons, not least of which is lack of adequately resolved spatial and seasonal data for matching information on fish larvae and their food. Spatial, seasonal, and interannual variability of water-column stratification, primary production, and copepod egg production can be modelled, but do such models adequately represent features of interannual variability that affect survival of fish larvae? Information on the timing and location of cod larvae in the Irish Sea and at Iceland is used to identify target areas for which long-term hindcasts of plankton production are made using a one-dimensional model of water-column stratification and production of chlorophyll and copepod eggs, driven by hourly meteorological data. Hindcast spring chlorophyll and nitrate values for Faxa Bay (Iceland) in 1966 correspond well with observations. Hindcast interannual variability in Calanus egg production appears to have a significant effect on cod recruitment in the Irish Sea and at Iceland. While the conclusions from such a limited study must be tentative, they suggest that local meteorological forcing, in areas where cod larvae occur, exerts an effect on their survival, owing to the match between plankton production and larval feeding
- …
