Climatic Window Research Articles

Climate impact response functions as impact tools in the tolerable windows approach

A critical issue for policymakers in defining mitigationstrategies for climate change is the availability ofappropriate evaluation tools. The development of climate impactresponse functions (CIRFs) is our reaction to this challenge.CIRFs depict the response of selected climate-sensitive impactsectors across a wide range of plausible futures. They consist ofa limited number of climate-change-related dimensions andsensitivities of sector-specific impact models. The concept ofCIRFs is defined and the procedure to develop them is presented.The use of climate change scenarios derived from various GCMexperiments and the adopted impact assessment models areexplained.The CIRFs presented here consider climate change impacts onnatural vegetation, crop production, and water availability. Theyare part of the ICLIPS integrated assessment framework based onthe tolerable windows approach. CIRFs can be applied both in`forward' and in `inverse' mode. In the latter, they help totranslate thresholds for climate impacts perceived by stakeholders(so-called impact guardrails) into constraints for climatevariables (so-called climate windows). This enables the results ofdetailed impact models to be incorporated into intertemporallyoptimizing integrated assessment models, such as the ICLIPS model.

Climate impact response functions for terrestrial ecosystems

We introduce climate impact response functions as a means for summarizing and visualizing the responses of climate-sensitive sectors to changes in fundamental drivers of global climate change. In an inverse application, they allow the translation of thresholds for climate change impacts (‘impact guard-rails’) into constraints for climate and atmospheric composition parameters (‘climate windows’). It thus becomes feasible to specify long-term objectives for climate protection with respect to the impacts of climate change instead of crude proxy variables, like the change in global mean temperature. We apply the method to assess impacts on terrestrial ecosystems, using the threat to protected areas as the central impact indicator. Future climate states are characterized by geographically and seasonally explicit climate change patterns for temperature, precipitation and cloud cover, and by their atmospheric CO2 concentration. The patterns are based on the results of coupled general circulation models. We study the sensitivity of the impact indicators and the corresponding climate windows to the spatial coverage of the analysis and to different climate change projections. This enables us to identify the most sensitive biomes and regions, and to determine those factors which significantly influence the results of the impact assessment. Based on the analysis, we conclude that climate impact response functions are a valuable means for the representation of climate change impacts across a wide range of plausible futures. They are particularly useful in integrated assessment models of climate change based on optimizing or inverse approaches where the on-line simulation of climate impacts by sophisticated impact models is infeasible due to their high computational demand.

Dendroécologie comparée du sapin blanc (Abies alba) et de l'épicéa commun (Picea abies) dans une vallée alpine de France

A comparative dendroecological study was carried out in an alpine valley of France (Haute-Tarentaise, Savoie) to analyze the climatic influence on the radial growth of the silver fir (Abies alba Mill.) and the Norway spruce (Picea abies Karst.). Ten populations were sampled at three altitudes on two exposures (North and South). For each population, a chronology of ring-width indices was standardized with a 7-year weighted moving average and with a residue chronology by autoregressive modelling. Then, correlation functions were calculated between growth indices standardized with both methods and climate with an iterative process (bootstrap). The climatic window used here covers 3 years, with mean monthly data of precipitation and temperature. The summer is the most important period for the spruce, which shows a transition along the altitude. This species is successively sensitive to drought at the lower level (year n of ring formation), sensitive to the previous hot summer (n - 1) at the intermediate level, and sensitive to the cold the same year (n) at the upper level. Fir growth is favoured by a rainy previous summer (n - 1) and a hot summer n at the highest altitude on northern slopes, with a difference between northern and southern slopes stronger than for spruce. The interspecific comparison reveals that the fir uses soil water more efficiently and is thermophile, whereas the spruce is more sensible to summer drought. The influence of the year preceding ring formation appears with both methods of standardization and seems to show a real physiological effect.

The Portavadie dry dock, west Scotland: a case history of the geotechnical aspects of its construction

Summary The paper discusses the construction of a dry dock in western Scotland designed for the fabrication of offshore concrete oil production platforms. The project involved the excavation of some 830 000 m 3 of soft material and rock from a tidal inlet to a base level between 11 and 13 m below Chart Datum. The construction period was limited through the necessity to meet a climatic window for float out. The progress achieved and the organizational relationships of the project are described. The site investigations prior to commencement of the site work were limited. These and the subsequent investigations carried out during the course of the works are described. The authors also discuss methods of construction, and show how certain aspects of these and the original designs were modified as the work proceeded.