|Abstracts on Global Climate Change|
A new study of the Mediterranean outflow, air-sea interactions, and meddies using multisensor data
Yan, XH Jo, YH Liu, WT He, MX
JOURNAL OF PHYSICAL OCEANOGRAPHY 36:4 691-710
Previous studies of the Mediterranean Sea outflow and meddies (O&M) were limited by the poor spatial and temporal resolution of conventional in situ observations as well as the confinement of satellite observations to the ocean’s surface. Accordingly, little is known about the formation and transport of meddies and the spatial and temporal variation of O&M trajectories, which are located, on average, at a depth of 1000 m. However, a new remote sensing method has been developed by the authors to observe and study the O&M through unique approaches in satellite multisensor data integration analyses. Satellite altimeter, scatterometer, infrared satellite imagery, and XBT data were used to detect and calculate the trajectories and the relative transport of the O&M (January 1993-December 2002). Two experiments [covering 199395: A Mediterranean Undercurrent Seeding Experiment (AMUSE) and Structures des Echanges MerAtmosphere, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE)] and XBT temperature measurements were used to directly validate the method presented herein. The monthly mean features derived from floats and XBTs for multiple meddies and the results of the presented method were significantly correlated based on a statistical chi-square test. In addition, the complex singular value decomposition method was used to identify the propagating features and their phase speeds. It was found that saltier water from the Mediterranean Sea was transported into the North Atlantic Ocean over the Strait of Gibraltar in boreal spring and summer relative to boreal autumn and winter. Streamfunctions using altimetry, and time-frequency energy distributions using the Hilbert-Huang transform, were computed to evaluate the meddy interactions with the sea surface variation. Since the O&M play a significant role in carrying salty water from the Mediterranean Sea into the Atlantic, such new knowledge about their trajectories, transport, and life histories is important to the understanding of their mixing and interaction with North Atlantic water. This may lead to a better understanding of the global ocean circulation and global climate change.
Long-term demographic fluctuations in an orchid species driven by weather: implications for conservation planning
Pfeifer, M Wiegand, K Heinrich, W Jetschke, G
JOURNAL OF APPLIED ECOLOGY 43:2 313-324
1. Management decisions are increasingly based on matrix models intended to predict the long-term fate of endangered species. However, certain elements of these models, such as life-state transition probabilities (vital rates), are difficult to parameterize and their values may vary depending on external conditions such as weather. Details of how weather might influence population performance are rare, yet necessary to assess the effects of global climate change on a species’ distribution. 2. Based on a 26-year data set of a population of Himantoglossum hircinum in a nature reserve in Germany, variations of life-history traits and vital rates were studied. Matrix analysis was used to identify the most important life-state transitions for population growth. Multiple linear regression was used to quantify the response of population traits and vital rates to changing weather conditions. 3. Population size increased exponentially and density effects could not be observed. Flowering plants and large plants had the highest and second highest reproductive value, respectively. The population’s finite rate of increase fluctuated strongly among years; life-history traits varied strongly and were interlinked, thereby violating the assumptions of matrix modelling in a population viability analysis. 4. Some vital rates and the population growth rate showed a trend over the total period. A certain and sometimes large amount of that variability could be attributed to variability of weather conditions, with warmer winter conditions favouring population performance. Prediction of population size was fairly accurate within a time frame of 10 years, but size class structure was not. 5. Synthesis and applications. Matrix modelling proved to be unreliable for predicting long-term population dynamics, despite the long-term data set used for matrix construction. This can be explained by weather-dependent variability of vital rates driving population dynamics. A minimum study period of 4 years is necessary to produce relevant information for model development. Our study emphasizes the need for critical evaluation of management decisions based only on single short-term studies and for studies covering longer time intervals than 2-3 years.
Pied Flycatchers Ficedula hypoleuca travelling from Africa to breed in Europe: differential effects of winter and migration conditions on breeding date
Both, C Sanz, JJ Artemyev, AV Blaauw, B Cowie, RJ Dekhuizen, AJ Enemar, A Javinen, A Nyholm, NEI Potti, J Ravussin, PA Silverin, B Slater, FM Sokolov, LV Visser, ME Winkel, W Wright, J Zang, H
ARDEA 94:3 511-525
In most bird species there is only a short time window available for optimal breeding due to variation in ecological conditions in a seasonal environment. Long-distance migrants must travel before they start breeding, and conditions at the wintering grounds and during migration may affect travelling speed and hence arrival and breeding dates. These effects are to a large extent determined by climate variables such as rainfall and temperature, and need to be identified to predict how well species can adapt to climate change. In this paper we analyse effects of vegetation growth on the wintering grounds and sites en route on the annual timing of breeding of 17 populations of Pied Flycatchers Ficedula hypoleuca studied between 1982-2000. Timing of breeding was largely correlated with local spring temperatures, supplemented by striking effects of African vegetation and NAO. Populations differed in the effects of vegetation growth on the wintering grounds, and on their northern African staging grounds, as well as ecological conditions in Europe as measured by the winter NAO. In general, early breeding populations (low altitude, western European populations) bred earlier in years with more vegetation in the Northern Sahel zone, as well as in Northern Africa. In contrast, late breeding populations (high altitude and northem and eastern populations) advanced their breeding dates when circumstances in Europe were more advanced (high NAO). Thus, timing of breeding in most Pied Flycatcher populations not only depends upon local circumstances, but also on conditions encountered during travelling, and these effects differ across populations dependent on the timing of travelling and breeding.
Carbon flows and carbon use in the German anthroposphere: An inventory
Uihlein, A Poganietz, WR Schebek, L
RESOURCES CONSERVATION AND RECYCLING 46:4 410-429
Today, global climate change is one of the most urgent environmental problems. The atmospheric concentration of carbon dioxide (CO2) has to be stabilised by significant reductions of CO, emissions in the next decades to keep the expected temperature rise within tolerable borders. Efforts exceeding the implemented measures to reduce CO2 emissions in Germany are desirable. An important precondition for such measures is a scientific-based inventory of the sources, sinks, and use of carbon. In this paper, we present CarboMoG, i.e. Carbon Flow Model of Germany. CarboMoG is a carbon flow model covering carbon flows, carbon sources and sinks in Germany and the German anthroposphere, showing concurrent energy and non-energy use of carbon sources. The model consists of seven modules in German anthroposphere following the German classification of economic sectors. Carbon flows to and from atmosphere and lithosphere as well as imports and exports were included into the model. The model comprises roughly 220 material flows determined based on material flow procedures for the base year 2000. Main sources of carbon are fossil energy carriers from lithosphere and uptake Of CO2 by crops (52% resp. 48% of all carbon sources). The model calculations show that import of energy carriers dominates total carbon import to Germany (82%). Total non-energy use of carbon in Germany is significantly higher than energy use (386 Mt C and 230 Mt C, resp.). Carbon throughput of Industry is greatest (about 224 Mt C input), followed by Energy (about 129 Mt C input). Agriculture and Forestry & Industry show the highest figure for non-energy use of carbon, energy use of carbon is largest in the Energy sector. Emissions Of CO2 to atmosphere account for 94% of carbon flows to sinks in Germany. Carbon accumulates in German anthroposphere 5 Mt C in 2000. (c) 2005 Elsevier B.V. All rights reserved.
Climate sensitivity to ocean dimethylsulphide emissions
Gunson, JR Spall, SA Anderson, TR Jones, A Totterdell, IJ Woodage, MJ
GEOPHYSICAL RESEARCH LETTERS 33:7 -
The production of dimethylsulphide (DMS) by ocean phytoplankton is hypothesized to form part of a feedback process on global climate. Changes in the DMS flux to the atmosphere cause changes to aerosols for cloud formation, leading to changes in the amount of radiation reaching the ocean, and hence on the planktonic production of DMS. This hypothesis has been investigated using a coupled ocean-atmosphere general circulation model (COAGCM) that includes an ocean ecosystem model and an atmospheric sulphur cycle. Ocean DMS concentrations are parameterised as a function of chlorophyll, nutrient and light. The results of several sensitivity experiments are presented showing significant global climate change responses to perturbations in ocean DMS production. A small negative feedback from climate change onto ocean DMS production is found and the implications are discussed.
Carbon sequestration in two Brazilian Cerrado soils under no-till
Bayer, C Martin-Neto, L Mielniczuk, J Pavinato, A Dieckow, J
SOIL & TILLAGE RESEARCH 86:2 237-245
A considerable proportion of the 200 million hectares of the Brazilian Cerrado is suitable for annual crops but little is known about the effects of tillage on the C dynamics of Cerrado soils. We evaluated the role of two representative Cerrado Oxisols (350 and 650 g clay kg(-1)) as sources or sinks of atmospheric C when managed under three tillage systems (conventional tillage (CT), reduced tillage (RT), and no-till (NT)) in 8- and 5-year long-term experiments. A literature review was also carried out and the mean C sequestration rates in no-till soils of tropical and subtropical regions of Brazil were calculated and compared with values for soils from temperate regions of the world. The original C stocks in 0-20 cm layer of soils under native Cerrado were higher in the clayey (54.0 Mg ha(-1)) than in the sandy clay loam soil (35.4 Mg ha(-1)), suggesting a higher physical stability of organic matter associated with variable clay minerals in the clayey Oxisol. The original C stocks of the native Cerrado soils appear not to have decreased after 23 years of conventional tillage in the sandy clay loam Oxisol, except when the soil had been subjected to erosion (15% loss of C), or after 25 years in the clayey Oxisol. Compared to conventionally tilled soil, the C stocks in no-till sandy clay loam Oxisol increased by 2.4 Mg ha(-1) (C sequestration rate = 0.30 Mg ha(-1) year(-1)) and in the clayey Oxisol by 3.0 Mg ha(-1) (C sequestration rate = 0.60 Mg ha(-1) year(-1)). The mean rate of C sequestration in the no-till Brazilian tropical soils was estimated to be 0.35 Mg ha(-1) year(-1), similar to the 0.34 Mg ha(-1) year(-1) reported for soils from temperate regions but lower than the 0.48 Mg ha(-1) year(-1) estimated for southern Brazilian subtropical soils. Considering the large area (about 70 million hectares) of the Cerrado which is currently used and potentially available for cropland, the adoption of no-till systems could turn the Cerrado soils into a significant sink for atmospheric C and contribute to the mitigation of global climate change. (C) 2005 Elsevier B.V. All rights reserved.
Migration Watch: an Internet survey to monitor spring migration in Britain and Ireland
Baillie, SR Balmer, DE Downie, IS Wright, KHM
JOURNAL OF ORNITHOLOGY 147:2 254-259
The arrival patterns of summer visitors to Britain and Ireland were monitored from 2002 to 2004 using large numbers of birdwatching lists collected by Migration Watch, an Internet-based survey. Records were only accepted from registered observers, and procedures for data validation were implemented. We show here how data on the frequency of occurrence from birdwatching lists can be analysed to estimate the timing and duration of the migration period. Aerial insectivores showed clear species-specific arrival patterns, with sand martins arriving first, followed in succession by swallows, house martins and finally swifts. Wheatears showed two peaks of arrivals, one for the British population and one for passage migrants from Greenland. The progression of arrivals from south to north and variation in arrival timing between years were also demonstrated. The method offers considerable potential for studying migration phenology at large spatial scales, and within Britain and Ireland it is now being applied throughout the year within the BTO/RSPB/BWI BirdTrack project. It could potentially be implemented at a continental scale, at which it would provide an important tool for measuring the growing impacts of global climate change on bird populations.
Above- and belowground net primary production in a temperate mixed deciduous forest
Newman, GS Arthur, MA Muller, RN
ECOSYSTEMS 9:3 317-329
Our current ability to detect and predict changes in forest ecosystem productivity is constrained by several limitations. These include a poor understanding of belowground productivity, the short duration of most analyses, and a need for greater examination of species- or community-specific variability in productivity studies. We quantified aboveground net primary productivity (ANPP) over 3 years (1999-2001), and both belowground NPP (BNPP) and total NPP over 2 years (2000-2001) in both mesic and xeric site community types of the mixed mesophytic forest of southeastern Kentucky to examine landscape variability in productivity and its relation with soil resource [water and nitrogen (N)] availability. Across sites, ANPP was significantly correlated with N availability (R-2 = 0.58, P = 0.028) while BNPP was best predicted by soil moisture content (R-2 = 0.72, P = 0.008). Because of these offsetting patterns, total NPP was unrelated to either soil resource. Interannual variability in growing season precipitation during the study resulted in a 50% decline in mesic site litter production, possibly due to a lag effect following a moderate drought year in 1999. As a result, ANPP in mesic sites declined 27% in 2000 compared to 1999, while xeric sites had no aboveground production differences related to precipitation variability. If global climate change produces more frequent occurrences of drought, then the response of mesic sites to prolonged moisture deficiency and the consequences of shifting carbon (C) allocation on C storage will become important questions.
A comparative analysis of woody biomass and coal for electricity generation under various CO2 emission reductions and taxes
Gan, JB Smith, CT
BIOMASS & BIOENERGY 30:4 296-303
Mitigating global climate change via CO2 emission control and taxation is likely to enhance the economic potential of bioenergy production and utilization. This study investigated the cost competitiveness of woody biomass for electricity production in the US under alternative CO2 emission reductions and taxes. We first simulated changes in the price of coal for electricity production due to CO2 emission reductions and taxation using a computable general equilibrium model. Then, the costs of electricity generation fueled by energy crops (hybrid poplar), logging residues, and coal were estimated using the capital budgeting method. Our results indicate that logging residues would be competitive with coal if emissions were taxed at about US$25 Mg-1 CO2, while an emission tax US$100Mg(-1) CO2 or higher would be needed for hybrid poplar plantations at a yield of 11.21 dry Mg ha(-1)yr(-1) (5 dry tons ac(-1)yr(-1)) to compete with coal in electricity production. Reaching the CO2 emission targets committed under the Kyoto Protocol would only slightly increase the price of fossil fuels, generating little impact on the competitiveness of woody biomass. However, the price of coal used for electricity production would significantly increase if global CO2 emissions were curtailed by 20% or more. Logging residues would become a competitive fuel source for electricity production if current global CO2 emissions were cut by 20-30%. Hybrid poplar plantations would not be able to compete with coal until emissions were reduced by 40% or more. (c) 2005 Elsevier Ltd. All rights reserved.