Weather to disperse? Evidence that climatic conditions influence vertebrate dispersal

1. Dispersal is regarded as critical to the stability of existing populations and the spread of invading species, but empirical data on the effect of travelling conditions during the transfer phase are rare. We present evidence that both timing and distance of ex-natal dispersal in buzzards (Buteo buteo) are strongly affected by weather. 2. Dispersal was recorded more often when the wind changed to a more southerly direction from the more common westerly winds, and when minimum temperatures were lower. The effect of wind direction was greatest in the winter and minimum temperature was most important in the autumn. Poor weather did not appear to initiate dispersal. 3. Dispersal distance was most strongly correlated with maximum temperature during dispersal and wind direction in the following 5-day period. Combined with the sex of the buzzard these three variables accounted for 60% of the variation in dispersal distance. 4. These results are important for conservationists who manage species recovery programs and wildlife managers who model biological invasions.

A statistical mechanical approach for the computation of the climatic response to general forcings

The climate belongs to the class of non-equilibrium forced and dissipative systems, for which most results of quasi-equilibrium statistical mechanics, including the fluctuation-dissipation theorem, do not apply. In this paper we show for the first time how the Ruelle linear response theory, developed for studying rigorously the impact of perturbations on general observables of non-equilibrium statistical mechanical systems, can be applied with great success to analyze the climatic response to general forcings. The crucial value of the Ruelle theory lies in the fact that it allows to compute the response of the system in terms of expectation values of explicit and computable functions of the phase space averaged over the invariant measure of the unperturbed state. We choose as test bed a classical version of the Lorenz 96 model, which, in spite of its simplicity, has a well-recognized prototypical value as it is a spatially extended one-dimensional model and presents the basic ingredients, such as dissipation, advection and the presence of an external forcing, of the actual atmosphere. We recapitulate the main aspects of the general response theory and propose some new general results. We then analyze the frequency dependence of the response of both local and global observables to perturbations having localized as well as global spatial patterns. We derive analytically several properties of the corresponding susceptibilities, such as asymptotic behavior, validity of Kramers-Kronig relations, and sum rules, whose main ingredient is the causality principle. We show that all the coefficients of the leading asymptotic expansions as well as the integral constraints can be written as linear function of parameters that describe the unperturbed properties of the system, such as its average energy. Some newly obtained empirical closure equations for such parameters allow to define such properties as an explicit function of the unperturbed forcing parameter alone for a general class of chaotic Lorenz 96 models. We then verify the theoretical predictions from the outputs of the simulations up to a high degree of precision. The theory is used to explain differences in the response of local and global observables, to define the intensive properties of the system, which do not depend on the spatial resolution of the Lorenz 96 model, and to generalize the concept of climate sensitivity to all time scales. We also show how to reconstruct the linear Green function, which maps perturbations of general time patterns into changes in the expectation value of the considered observable for finite as well as infinite time. Finally, we propose a simple yet general methodology to study general Climate Change problems on virtually any time scale by resorting to only well selected simulations, and by taking full advantage of ensemble methods. The specific case of globally averaged surface temperature response to a general pattern of change of the CO2 concentration is discussed. We believe that the proposed approach may constitute a mathematically rigorous and practically very effective way to approach the problem of climate sensitivity, climate prediction, and climate change from a radically new perspective.

Geodetic mass balance of Azarova glacier, Kodar Mountains, eastern Siberia, and its links to observed and projected climatic change

The Kodar Mountains in eastern Siberia accommodate 30 small, cold-based glaciers with a combined surface area of about 19 km2. Very little is known about these glaciers, with the first survey conducted in the late 1950s. In this paper, we use terrestrial photogrammetry to calculate changes in surface area, elevation, volume and geodetic mass balance of the Azarova Glacier between 1979 and 2007 and relate these to meteorological data from nearby Chara weather station (1938-2007). The glacier surface area declined by 20±6.9% and surface lowered on average by 20±1.8 m (mean thinning: 0.71 m a-1) resulting in a strongly negative cumulative and average mass balance of -18±1.6 m w.e. and -640±60 mm w.e.a-1 respectively. The July-August air temperature increased at a rate of 0.036oC a-1 between 1979 and 2007 and the 1980-2007 period was, on average, around 1oC warmer than 1938-1979. The regional climate projections for A2 and B2 CO2 emission scenarios developed using PRECIS regional climate model indicate that summer temperatures will increase in 2071–2100 by 2.6-4.7°C and 4.9-6.2°C respectively in comparison with 1961–1990. The annual total of solid precipitation will increase by 20% under B2 scenario but decline by 3% under A2 scenario. The length of the ablation season will extend from July–August to June-September. The Azarova Glacier exhibits high sensitivity to climatic warming due to its low elevation, exposure to comparatively high summer temperatures, and the absence of a compensating impact of cold season precipitation. Further summer warming and decline of solid precipitation projected under the A2 scenario will force Azarova to retreat further while impacts of an increase in solid precipitation projected under the B2 scenario require further investigation.

Assessment of projected changes in upland environments using simple climatic indices

Climate controls upland habitats, soils and their associated ecosystem services; therefore, understanding possible changes in upland climatic conditions can provide a rapid assessment of climatic vulnerability over the next century. We used 3 different climatic indices that were optimised to fit the upland area classified by the EU as a Severely Disadvantaged Area (SDA) 1961–1990. Upland areas within the SDA covered all altitudinal ranges, whereas the maximum altitude of lowland areas outside of the SDA was ca. 300 m. In general, the climatic index based on the ratio between annual accumulated temperature (as a measure of growing season length) and annual precipitation predicted 96% of the SDA mapped area, which was slightly better than those indices based on annual or seasonal water deficit. Overall, all climatic indices showed that upland environments were exposed to some degree of change by 2071–2100 under UKCIP02 climate projections for high and low emissions scenarios. The projected area declined by 13 to 51% across 3 indices for the low emissions scenario and by 24 to 84% for the high emissions scenario. Mean altitude of the upland area increased by +11 to +86 m for the low scenario and +21 to +178 m for the high scenario. Low altitude areas in eastern and southern Great Britain were most vulnerable to change. These projected climatic changes are likely to affect upland habitat composition, long-term soil carbon storage and wider ecosystem service provision, although it is not yet possible to determine the rate at which this might occur.

Climatic and oceanic associations with daily rainfall extremes over southern Africa

Changes in climate variability and, in particular, changes in extreme climate events are likely to be of far more significance for environmentally vulnerable regions than changes in the mean state. It is generally accepted that sea-surface temperatures (SSTs) play an important role in modulating rainfall variability. Consequently, SSTs can be prescribed in global and regional climate modelling in order to study the physical mechanisms behind rainfall and its extremes. Using a satellite-based daily rainfall historical data set, this paper describes the main patterns of rainfall variability over southern Africa, identifies the dates when extreme rainfall occurs within these patterns, and shows the effect of resolution in trying to identify the location and intensity of SST anomalies associated with these extremes in the Atlantic and southwest Indian Ocean. Derived from a Principal Component Analysis (PCA), the results also suggest that, for the spatial pattern accounting for the highest amount of variability, extremes extracted at a higher spatial resolution do give a clearer indication regarding the location and intensity of anomalous SST regions. As the amount of variability explained by each spatial pattern defined by the PCA decreases, it would appear that extremes extracted at a lower resolution give a clearer indication of anomalous SST regions.

Global responses of terrestrial productivity to contemporary climatic oscillations

The terrestrial biosphere is subjected to a wide range of natural climatic oscillations. Best known is the El Niño–southern oscillation (ENSO) that exerts globally extensive impacts on crops and natural vegetation. A 50-year time series of ENSO events has been analysed to determine those geographical areas that are reliably impacted by ENSO events. Most areas are impacted by changes in precipitation; however, the Pacific Northwest is warmed by El Niño events. Vegetation gross primary production (GPP) has been simulated for these areas, and tests well against independent satellite observations of the normalized difference vegetation index. Analyses of selected geographical areas indicate that changes in GPP often lead to significant changes in ecosystem structure and dynamics. The Pacific decadal oscillation (PDO) is another climatic oscillation that originates from the Pacific and exerts global impacts that are rather similar to ENSO events. However, the longer period of the PDO provided two phases in the time series with a cool phase from 1951 to 1976 and a warm phase from 1977 to 2002. It was notable that the cool phase of the PDO acted additively with cool ENSO phases to exacerbate drought in the earlier period for the southwest USA. By contrast in India, the cool phase of the PDO appears to reduce the negative impacts of warm ENSO events on crop production.

Testing the sustainability and sensitivity to climatic change of terrace agricultural systems in the Peruvian Andes: a pilot study

The results of an integrated geoarchaeological and palaeoecological pilot study of a prehistoric agricultural terrace and nearby mire basin are presented. They reveal two stages of terrace construction for the cultivation of Zea mays during the Middle Horizon (615–695 AD) and late, Late Intermediate Period (1200–1400 AD). These stages were strongly associated with evidence for vegetation succession, destabilisation and erosion of the surrounding landscape, and changes in mire surface wetness. The reasons for agricultural terrace abandonment and/or reconstruction are uncertain, with only circumstantial evidence for climatically induced agricultural change.

Timing and climatic imprint of Greenland interstadials recorded in stalagmites from Northern Turkey

A 50 kyr-long exceptionally well-dated and highly resolved stalagmite oxygen (δ 18O) and carbon (δ 13C) isotope record from Sofular Cave in northwestern Turkey helps to further improve the dating of Greenland Interstadials (GI) 1, and 3–12. Timing of most GI in the Sofular record is consistent within ±10 to 300 years with the “iconic” Hulu Cave record. Larger divergences (>500 years) between Sofular and Hulu are only observed for GI 4 and 7. The Sofular record differs from the most recent NGRIP chronology by up to several centuries, whereas age offsets do not increase systematically with depth. The Sofular record also reveals a rapid and sensitive climate and ecosystem response in the eastern Mediterranean to GI, whereas a phase lag of ∼100 years between climate and full ecosystem response is evident. Finally, results of spectral analyses of the Sofular isotope records do not support a 1,470-year pacing of GI.

Complex latitudinal variation in the morphology of the kleptoparasitic spider Argyrodes kumadai associated with host use and climatic conditions

We examined complex geographical patterns in the morphology of a kleptoparasitic spider, Argyrodes kumadai, across its distributional range in Japan. To disentangle biotic and abiotic factors underlying morphological variation, latitudinal trends were investigated in two traits, body size and relative leg length, across separate transition zones for host use and voltinism. Statistical analyses revealed complex sawtooth clines. Adult body size dramatically changed at the transition zones for host use and voltinism, and exhibited a latitudinal decline following the converse to Bergmann’s cline under the same host use and voltinism in both sexes. A similar pattern was observed for relative leg length in females but not in males. A genetic basis for a part of observed differences in morphology was supported by a common-garden experiment. Our data suggest that local adaptation to factors other than season length such as resource availability (here associated with host use) obscures underlying responses to latitude.