Progress in global environmental change     

W. Neil Adger  Katrina Brown  Declan Conway 《Global Environmental Change》2010,20(4):547-549

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Future cereal production in China: The interaction of climate change,water availability and socio-economic scenarios   总被引：4，自引：0，他引：4  

Xiong Wei  Conway Declan  Lin Erda  Xu Yinlong  Ju Hui  Jiang Jinhe  Holman Ian  Li Yan 《Global Environmental Change》2009,19(1):34-44

Food production in China is a fundamental component of the national economy and driver of agricultural policy. Sustaining and increasing output to meet growing demand faces significant challenges including climate change, increasing population, agricultural land loss and competing demands for water. Recent warming in China is projected to accelerate by climate models with associated changes in precipitation and frequency of extreme events. How changes in cereal production and water availability due to climate change will interact with other socio-economic pressures is poorly understood. By linking crop and water simulation models and two scenarios of climate (derived from the Regional Climate Model PRECIS) and socio-economic change (downscaled from IPCC SRES A2 and B2) we demonstrate that by the 2040s the absolute effects of climate change are relatively modest. The interactive effects of other drivers are negative, leading to decreases in total production of ?18% (A2) and ?9% (B2). Outcomes are highly dependent on climate scenario, socio-economic development pathway and the effects of CO₂ fertilization on crop yields which may almost totally offset the decreases in production. We find that water availability plays a significant limiting role on future cereal production, due to the combined effects of higher crop water requirements (due to climate change) and increasing demand for non-agricultural use of water (due to socio-economic development). Without adaptation, per capita cereal production falls in all cases, by up to 40% of the current baseline.By simulating the effects of three adaptation scenarios we show that for these future scenarios China is able to maintain per capita cereal production, given reasonable assumptions about policies on land and water management and progress in agricultural technology. Our results are optimistic because PRECIS simulates much wetter conditions than a multi-model average, the CO₂ crop yield response function is highly uncertain and the effects of extreme events on crop growth and water availability are likely to be underestimated.  相似文献   

An imaging survey of a uniform sample of brightest cluster galaxies and intracluster light     

Parimal Patel  S. Maddox  Frazer R. Pearce  A. Aragón-Salamanca  E. Conway 《Monthly notices of the Royal Astronomical Society》2006,370(2):851-883

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The effect of wave generation on HXR bremsstrahlung spectra from flare thick-target beams     

Haydock  E.L.  Brown  J.C.  Conway  A.J.  Emslie  A.G. 《Solar physics》2001,203(2):355-369

Fast electrons in the solar atmosphere are detected by their hard X-ray bremsstrahlung and by type III radio bursts caused by ‘bump-on-tail’ plasma wave generation. This paper investigates empirically the effect of wave generation on the HXR spectrum. Purely collisional propagation of an electron beam generates a bump in the distribution function, due to stopping of low-velocity electrons. The consequent positive gradient means there is a possibility of wave generation, production of type III radio bursts, and energy redistribution of the electron beam. We have represented this relaxation parametrically and calculated the global bremsstrahlung HXR emission spectrum. We show that for a range of relaxed forms, with different local electron spectral shapes, the bremsstrahlung spectrum integrated over the whole target is identical in shape to the purely collisionally evolved beam. Our results show that spatially integrated HXR spectral measurements would be unable to distinguish between the presence or absence of relaxation effects. Only spatially resolved hard X-ray spectra, such as anticipated from the HESSI mission, will be able to remove this ambiguity in HXR diagnostics of beam relaxation.  相似文献   

Vertical distribution of fish eggs and larvae in the Irish Sea and southern North Sea   总被引：4，自引：1，他引：4  

Conway  D. V. P.; Coombs  S. H.; Smith  C. 《ICES Journal of Marine Science》1997,54(1):136-147

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Les radiotélescopes: Émile-Jacques Blum: Presses Universitaires de France. 1972. 128 pp. 3.95 F.fr.     

R.G Conway 《Planetary and Space Science》1973,21(7):1271-1272

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Influence of upper air conditions on the Patagonia icefields   总被引：1，自引：1，他引：0  

L.A. Rasmussen  H. Conway  C.F. Raymond 《Global and Planetary Change》2007,59(1-4):203

Upper-air conditions archived in the NCEP-NCAR Reanalysis have been used to investigate changes in precipitation and snowfall over the Patagonia icefields during 1960–99. Apparently, whereas total precipitation has not changed, warming has caused a decrease in the amount falling as snow. Precipitation at a site is taken to be proportional to the product of the relative humidity and the component of the wind in a particular critical direction, both at 850 hPa ( 1400 m) at a point over the ocean to the west of the icefields; whether it falls as rain or snow is assumed to depend on whether the temperature at the elevation of the site is above or below + 2 °C. The critical direction is assumed to be 270°, which is perpendicular to the north–south trending Andes and is also the prevailing wind direction in this zone of strong westerlies. Because of the scarcity of precipitation records on or near the icefields, the constant of proportionality cannot be determined, so the investigation is limited to examining relative changes in those upper air variables. Warming at 850 hPa has been 0.5 °C over the 40 years, both winter and summer, with the effects that it has: (1) shifted from snow to rain 5% of the precipitation, the total of which has changed little, and (2) increased annual melt in the ablation areas by 0.5 m w.e. The icefields have been losing mass since at least 1870, so this 40-year trend represents only an acceleration of the longer-term trend of adjusting to climate change since the Little Ice Age.  相似文献   

Palaeoecological investigations towards the reconstruction of the post-glacial environment at Lough Doo,County Mayo,Ireland     

Michael O'connell  Frazer J. G. Mitchell  Peter W. Readman  Terence J. Doherty  Declan A. Murray 《第四纪科学杂志》1987,2(2):149-164

Results of palaeoecological studies involving pollen analytical, chemical and palaeomagnetic investigations on a 3 m core from Lough Doo, NE County Mayo, are presented. The record, which commences shortly after 7000 BP, shows a sharp Alnus expansion coinciding with a decline in Pius at 6400 BP, an elm decline taking place in the context of severe soil erosion and the final decline of Pinus occurring as the chemical record indicates onset of severe reducing conditions in the catchment. Pine becomes extinct at or shortly before 3200 BP in the context of increased farming activity and the expansion of blanket bog in the adjacent upland areas. A later feature (c. 1880 BP) is the expansion of Taxus to 7.1% of total pollen. On the basis of the palynological evidence, it is concluded that there were no major Neolithic Landnam phases, which contrasts sharply with the evidence for widespread woodland clearance and the laying out of extensive and regular field systems in the northern coastal part of County Mayo. In the upper part of the core a severe inversion of ¹⁴C dates is recorded. On the basis of the palaeomagnetic and pollen evidence this began at c. 1500 BP and is considered to have been initiated in the context of woodland clearance and a renewal in farming activity.  相似文献   

The optical jet in 3C 31 on 15 arcsec scales     

J. H. Croston  M. Birkinshaw  E. Conway  R. L. Davies 《Monthly notices of the Royal Astronomical Society》2003,339(1):82-86

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NGC7538 Irs1 N: Modeling a Circumstellar Maser Disk     

M. Pestalozzi  M. Elitzur  J. Conway  R. Booth 《Astrophysics and Space Science》2005,295(1-2):231-236

We present an edge-on Keplerian disk model to explain the main component of the 12.2 and 6.7 GHz methanol maser emission detected toward NGC7538-IRS1N. The brightness distribution and spectrum of the line of bright masers are successfully modeled with high amplification of background radio continuum emission along velocity coherent paths through a maser disk. The bend seen in the position–velocity diagram is a characteristic signature of differentially rotating disks. For a central mass of 30M, suggested by other observations, our model fixes the masing disk to have inner and outer radii of 270 and 750 AU.  相似文献