Abstracts on Global Climate Change

Aug 2006

Modelling dispersal of a temperate insect in a changing climate

Walters, RJ Hassall, M Telfer, MG Hewitt, GM Palutikof, JP


We construct a novel individual-based random-walk model to assess how predicted global climate change might affect the dispersal rates of a temperate insect. Using a novel approach we obtained accurate field measurements of daily movements for individuals over time to parameterize our model. Males were found to move significantly further on average than females. Significant variation in movement was evident among individuals; the most dispersive individuals moved up to five (females) and seven (males) times as far on average as the least dispersive individuals. Mean relative daily movement of both males and females were exponentially related to maximum daily temperature recorded within the grass sward. Variability, both within and among individuals, in relative daily movement was incorporated into the model using gamma probability distributions. Resultant dispersal functions for seasonal movement are predicted to be highly leptokurtic, which agrees well with observations from the field. Predictions of the model suggest that for populations at the polewards edge of the current range an increase of 3-5 degrees C in daily maximum temperature may increase the proportion of long-distance dispersers (those characterized as comprising the top 0.1 % of furthest dispersing individuals under local conditions experienced during the 1963-1990 period) by up to 70%.

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An optimised method for the extraction and analysis of lipid biomarkers from stalagmites

Blyth, AJ Farrimond, P Jones, M


Lipid compositions preserved in stalagmites have significant potential for use in reconstruction of global climate change and regional vegetation cover, but the low organic content of stalagmites poses a problem both for clean extraction and for obtaining a high temporal resolution in palaeoenvironmental records. Here, we present an acid digestion method optimised for cleanliness and maximum lipid recovery. The use of acid digestion and hydrolysis improves lipid yields not only by releasing organic matter trapped within individual calcite crystals, but also by allowing access to the chemically-bound pool of lipids, particularly acidic compounds such as alkanoic acids, hydroxy acids, and alkanedioic acids. The technique also considerably reduces contamination problems in comparison to conventional soxhlet extraction. (c) 2006 Elsevier Ltd. All rights reserved.

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Monitoring coral bleaching using a colour reference card

Siebeck, UE Marshall, NJ Kluter, A Hoegh-Guldberg, O

CORAL REEFS 25:3 453-460

Assessment of the extent of coral bleaching has become an important part of studies that aim to understand the condition of coral reefs. In this study a reference card that uses differences in coral colour was developed as an inexpensive, rapid and non-invasive method for the assessment of bleaching. The card uses a 6 point brightness/saturation scale within four colour hues to record changes in bleaching state. Changes on the scale of 2 units or more reflect a change in symbiont density and chlorophyll a content, and therefore the bleaching state of the coral. When used by non-specialist observers in the field (here on an intertidal reef flat), there was an inter-observer error of I colour score. This technique improves on existing subjective assessment of bleaching state by visual observation and offers the potential for rapid, wide-area assessment of changing coral condition.

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Long-term cosmic ray intensity variation and part of global climate change, controlled by solar activity through cosmic rays

Dorman, LI


In this paper, we investigate properties long-term variations in galactic cosmic ray intensity as an important possible link in the connection between solar activity variation and global climate change. There are two main aims of the paper: (1) to estimate how solar activity influences on galactic CR long-term variations, what are the relative role in this influence of convection-diffusion modulation and drift modulation and (2) to estimate the expected part of global climate change which may be caused by the influence of solar activity cycle on climate through 11- and 22-year cosmic ray variations. (c) 2006 Published by Elsevier Ltd on behalf of COSPAR.

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Rapid fluctuation of alkenone temperature in the southwestern Okhotsk Sea during the past 120 ky

Harada, N Ahagon, N Sakamoto, T Uchida, M Ikehara, M Shibata, Y


Sea-ice expansion in the Okhotsk Sea in winter is sensitively affected by global warming and cooling. Regionally, the southwestern Okhotsk Sea is closely linked to climate change in East Asia, including Japan, because the cold sea surface temperature (SST) in the southwestern Okhotsk Sea influences directly the development of the Okhotsk atmospheric high-pressure system, and the activated Okhotsk high causes cold climatic conditions in northern Japan. Therefore, environmental change in the Okhotsk Sea indicates two-way interactions as a sensitive mirror reflecting global climate change and as a driving force of regional climate change. To better understand how surface environmental changes in the Okhotsk Sea can influence climate change in East Asia, SSTs were estimated in the southwestern Okhotsk Sea for the past 120 ky with millennial to centennial time resolution using the long-chain unsaturated alkyl ketone (alkenone) thermometer. The alkenone temperature, which corresponds to the SST to 20 in depth in autumn, showed repeated abrupt changes at a centennial timescale, especially during the last glacial period, 20-60 ky before present (BP). The alkenone temperature changed concurrently with changes from interstadials (warm events) to stadials (cold events) in the delta O-18 record of the ice cores from Greenland, although some interstadials could not be identified in the alkenone temperature record. A wavelet power spectrum analysis showed that a periodicity of about 8 ky was prominent during 10-90 ky BP, and a 4- to 5-ky cycle was characteristic during 30-40 ky BP in the alkenone temperature records. These periodicities were both similar and dissimilar to those in the Polar Circulation Index, which is based on the atmospheric circulation intensity at high latitudes, as recorded by major-ion concentrations in GISP2. Both the similarity and dissimilarity imply that the SST in the southwestern Okhotsk Sea is controlled mainly by the atmosphere-ocean circulation system in the Northern Hemisphere; however, the relationship between the SST in the Okhotsk Sea and the climate in the Greenland is not linear. Anomalously high alketione temperatures occurred repeatedly in the glacial period. These warm alkenone temperature episodes would have had multiple causes. In particular, high alkenone temperatures during the last glacial maximum (LGM) have been reported previously for locations near this study site. More investigations are necessary to understand what happened in the Okhotsk Sea and in adjacent seas at the time of the LGM. (C) 2006 Elsevier B.V. All rights reserved.

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Effects of environmental hypercapnia on animal physiology: A C-13 NMR study of protein synthesis rates in the marine invertebrate Sipunculus nudus

Langenbuch, M Bock, C Leibfritz, D Portner, HO


Global climate change is associated with a progressive rise in ocean CO2 concentrations (hypercapnia) and, consequently, a drop in seawater pH. However, a comprehensive picture of the physiological; mechanisms affected by chronic CO2 stress in marine biota is still lacking. Here we present an analysis of protein biosynthesis rates in isolated muscle of the marine invertebrate Sipunculus nudus, a sediment dwelling worm living at various water depths. We followed the incorporation of 13 C-labelled phenylalanine into muscular protein via high-resolution NMR spectroscopy. Protein synthesis decreased by about 60% at a medium pH of 6.70 and a consequently lowered intracellular pH (pHi). The decrease in protein synthesis rates is much stronger than the concomitant suppression of protein degradation (60% versus 10-15%) possibly posing a threat to the cellular homeostasis of structural as well as functional proteins. Considering the progressive rise in ocean CO2 concentrations, permanent disturbances of cellular protein turnover might seriously affect growth and reproductive performance in many marine organisms with as yet unexplored impacts on species density and composition in marine ecosystems. (c) 2006 Elsevier Inc. All rights reserved.

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