University of East Anglia

About: University of East Anglia is a education organization based out in Norwich, Norfolk, United Kingdom. It is known for research contribution in the topics: Population & Climate change. The organization has 13250 authors who have published 37504 publications receiving 1669060 citations. The organization is also known as: UEA.

Precipitation measurements and trends in the twentieth century

Abstract: Concern about anthropogenic climate change has heightened the need for accurate information about spatial and temporal variations in precipitation at the Earth’s surface. Large-scale precipitation estimates can be derived from either surface gauge measurements or by satellite remote sensing, both of which have shortcomings. Gauge measurements provide information about trends and variability of monthly precipitation throughout the entire twentieth century, but because of the lack of data from most ocean regions, this information is representative of only about 25–30% of the Earth’s surface. In contrast, satellite (especially multi-platform) measurements provide spatially complete coverage at monthly to subdaily resolution, but do not extend back beyond 1974. Merged gauge–satellite datasets maximize (and minimize) the relative benefits (and shortcomings) of each source type. While these merged products only extend back to 1979, their importance will grow as we move into the new century. Precipitation gauge data indicate that global land precipitation (excluding Antarctica) has increased by about 9 mm over the twentieth century (a trend of 0.89 mm/decade), which is relatively small compared with interannual and multi-decadal variability. Within this century-long trend, global precipitation exhibits considerable variability on decadal time-scales, with departures of up to 40 mm from the century mean of about 950 mm. Regionally, precipitation has increased over most land areas, with the exception of tropical North Africa, and parts of southern Africa, Amazonia and western South America. The dominant mode of interannual variability in global and

Economic analysis for ecosystem service assessments

Abstract: The paper seeks to contribute to the expanding literature on ecosystem service assessment by considering its integration with economic analyses of such services. Focussing upon analyses for future orientated policy and decision making, we initially consider a single period during which ecological stocks are maintained at sustainable levels. The flow of ecosystems services and their contribution to welfare bearing goods is considered and methods for valuing resultant benefits are reviewed and illustrated via a case study of land use change. We then broaden our time horizon to discuss the treatment of future costs and benefits. Finally we relax our sustainability assumption and consider economic approaches to the incorporation of depleting ecological assets with a particular focus upon stocks which exhibit thresholds below which restoration is compromised.

Prevention of growth of potentially dense phytoplankton populations by zooplankton grazing, in the presence of zooplanktivorous fish, in a shallow wetland ecosystem

Abstract: In two linked, shallow, freshwater basins, phytoplankton densities in summer were very different. Hudsons Bay supported a large stand of water lilies, and the adjacent open water was clear with chlorophyll a concentrations generally 100 pg*literl. Hudsons Bay water, in bioassays, could support great phytoplankton growth in summer and did so in spring and fall. The period of clear water coincided with the presence of the lily stand. Zooplankton populations were of rotifers and small-bodied Cladocera in Hoveton Great Broad, but mostly of Cladocera, including large-bodied individuals of plantassociated species, in Hudsons Bay. Zooplanktivorous fish were present and there was evidence of feeding by them in both basins. Coexistence with fish of the large, apparently efficiently grazing Cladocera in Hudsons Bay depended on provision of daytime refuges for the Cladocera among the lilies, and grazing was greatest in the adjacent open water at night. Grazing control was helped by a hydrological regime which favored small and rapidly growing phytoplankters, rather than inedible colonial forms with slow growth. Weed-associated grazers may be important in maintaining the dominance of aquatic plants in shallow lakes which would otherwise more rapidly become dominated by phytoplankton as nutrient loading increased.

Eemian interglacial reconstructed from a Greenland folded ice core

Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.