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PubMed2002

Future projections for Mexican faunas under global climate change scenarios.

Global climates are changing rapidly, with unexpected consequences. Because elements of biodiversity respond intimately to climate as an important driving force of distributional limitation, distributional shifts and biodiversity losses are expected. Nevertheless, in spite of modelling efforts focused on single species or entire ecosystems, a few preliminary surveys of fauna-wide effects, and evidence of climate change-mediated shifts in several species, the likely effects of climate change on species' distributions remain little known, and fauna-wide or community-level effects are almost completely unexplored. Here, using a genetic algorithm and museum specimen occurrence data, we develop ecological niche models for 1,870 species occurring in Mexico and project them onto two climate surfaces modelled for 2055. Although extinctions and drastic range reductions are predicted to be relatively few, species turnover in some local communities is predicted to be high (>40% of species), suggesting that severe ecological perturbations may result.

Algorithms↗
PubMed2002

Allele frequency shifts in response to climate change and physiological consequences of allozyme variation in a montane insect.

Rapid changes in climate may impose strong selective pressures on organisms. Evolutionary responses to climate change have been observed in natural populations, yet no example has been documented for a metabolic enzyme locus. Furthermore, few studies have linked physiological responses to stress with allozyme genotypic variation. We quantified changes in allele frequency between 1988 and 1996 at three allozyme loci (isocitrate dehydrogenase, Idh; phosphoglucose isomerase, Pgi; and phosphoglucomutase, Pgm) for the leaf beetle Chrysomela aeneicollis in the Bishop Creek region of the Sierra Nevada of California (2900-3300 m). Beetles often experience high daytime (> 32 degrees C) and extremely low nighttime (< -5 degrees C) temperatures during summer. Bishop Creek weather station data indicated that conditions were unusually dry before 1988, and that conditions were cool and wet during the years preceding the 1996 collection. We found directional changes in allele frequency at Pgi (11% increase in the Pgi-1 allele), but not at Idh or Pgm. We also found that physiological response to thermal extremes depended on Pgi genotype. Pgi 1-1 individuals induced expression of a 70-kD heat shock protein (HSP) at lower temperatures than 1-4 or 4-4 individuals, and 1-1 individuals expressed higher levels of HSP70 after laboratory exposure to temperatures routinely experienced in nature. Survival after nighttime laboratory exposure to subzero temperatures depended on gender, previous exposure to cold, and Pgi genotype. Females expressed higher levels of HSP70 than males after exposure to heat, and recovery by female Pgi 1-1 homozygotes after exposure to cold (-5 degrees C) was significantly better than 1-4 or 4-4 genotypes. These data suggest that the cooler climate of the mid-1990s may have caused an increase in frequency of the Pgi-1 allele, due to a more robust physiological response to cold by Pgi 1-1 and 1-4 genotypes.

Animals↗
PubMed2004

A review of indicators of climate change for use in Ireland.

Impact indicators are systems/organisms, the vitality of which alters in response to changes in environmental condition. The indicators assessed in this review fall within the impact category of the driver-pressure-state-impact-response (DPSIR) framework. Instrumental records have shown unequivocal changes in climatic conditions over the past 30 years at a global level but impact indicators allow these changes to be monitored at a finer resolution. Our main aim was to review sets of indicators of climate change currently used in various countries and to make recommendations for their use in the Irish environment. We review a preliminary set of climate change impact indicators in five sectors: agriculture; plant and animal distribution patterns; phenology; palaeoecology and human health. Currently, the most effective impact indicators of climate change have proved to be phenological observations of tree developmental stages. The strongest factor limiting the use of indicators is the lack of long-term data sets from which a climatic signal can be extracted.

Agriculture↗
PubMed2003

Climate change and habitat destruction: a deadly anthropogenic cocktail.

Climate change and habitat destruction are two of the greatest threats to global biodiversity. Lattice models have been used to investigate how hypothetical species with different characteristics respond to habitat loss. The main result shows that a sharp threshold in habitat availability exists below which a species rapidly becomes extinct. Here, a similar modelling approach is taken to establish what determines how species respond to climate change. A similar threshold exists for the rate of climate change as has been observed for habitat loss-patch occupancy remains high up to a critical rate of climate change, beyond which species extinction becomes likely. Habitat specialists, especially those of relatively poor colonizing ability are least able to keep pace with climate change. The interaction between climate change and habitat loss might be disastrous. During climate change, the habitat threshold occurs sooner. Similarly, species suffer more from climate change in a fragmented habitat.

Adaptation, Physiological↗
PubMed1998

A common-sense climate index: is climate changing noticeably?

We propose an index of climate change based on practical climate indicators such as heating degree days and the frequency of intense precipitation. We find that in most regions the index is positive, the sense predicted to accompany global warming. In a few regions, especially in Asia and western North America, the index indicates that climate change should be apparent already, but in most places climate trends are too small to stand out above year-to-year variability. The climate index is strongly correlated with global surface temperature, which has increased as rapidly as projected by climate models in the 1980s. We argue that the global area with obvious climate change will increase notably in the next few years. But we show that the growth rate of greenhouse gas climate forcing has declined in recent years, and thus there is an opportunity to keep climate change in the 21st century less than "business-as-usual" scenarios.

Climate↗
PubMed2006

Effects of food abundance, density and climate change on reproduction in the sparrowhawk Accipiter nisus.

The reproductive success of predators depends on abiotic environmental conditions, food abundance and population density, and food abundance, density and their interactions may respond to changes in climatic conditions. Timing of reproduction by five of the eight numerically most common prey of the sparrowhawk Accipiter nisus advanced significantly since 1971, during a period of temperature increase. There was no evidence that mean laying date or any other reproductive parameter of sparrowhawks changed consistently during the study period 1977-1997. Laying date advanced and percentage of unsuccessful female sparrowhawks decreased with beech mast in the current year, an index of food abundance for avian prey. Mean laying date of sparrowhawks was advanced in warmer springs, and although mean clutch size was not larger in warm than in cold springs, mean brood size of successful pairs and breeding success increased in such springs, showing that sparrowhawks enjoyed a fitness gain when reproducing early. The timing of sparrowhawk reproduction with respect to the peak in abundance of fledgling prey increased, from a good match between mean timing of fledging by prey and maximum demand for food by the predator in 1977, to reproduction occurring later than the peak in fledging prey availability in 1997. The size of the breeding population of sparrowhawks was not predicted by mean spring temperature, the size of the breeding population the previous year or beech mast crop. The size of the post-breeding population was predicted by size of the breeding and post-breeding population the previous year and by the proportion of unsuccessful females the current year. These findings imply that sparrowhawks did not respond to change in climate, although climate changed the timing of reproduction by the main prey species.

Animals↗
PubMed2000

Quantifying the uncertainty in forecasts of anthropogenic climate change

Forecasts of climate change are inevitably uncertain. It is therefore essential to quantify the risk of significant departures from the predicted response to a given emission scenario. Previous analyses of this risk have been based either on expert opinion, perturbation analysis of simplified climate models or the comparison of predictions from general circulation models. Recent observed changes that appear to be attributable to human influence provide a powerful constraint on the uncertainties in multi-decadal forecasts. Here we assess the range of warming rates over the coming 50 years that are consistent with the observed near-surface temperature record as well as with the overall patterns of response predicted by several general circulation models. We expect global mean temperatures in the decade 2036-46 to be 1-2.5 K warmer than in pre-industrial times under a 'business as usual' emission scenario. This range is relatively robust to errors in the models' climate sensitivity, rate of oceanic heat uptake or global response to sulphate aerosols as long as these errors are persistent over time. Substantial changes in the current balance of greenhouse warming and sulphate aerosol cooling would, however, increase the uncertainty. Unlike 50-year warming rates, the final equilibrium warming after the atmospheric composition stabilizes remains very uncertain, despite the evidence provided by the emerging signal.

Journal Article↗
PubMed2003

Prediction of climate change effects of fish communities in the Mackinaw River watershed, Illinois, USA.

As part of an integrated assessment of multiple sector impacts produced by predicted changes in climate we have integrated a set of models, which provide predictions of fish populations under changing flow and temperature regimes. The core of the approach is the U. S. Fish and Wildlife Service Physical Habitat Simulation Model (PHABSIM). PHABSIM estimates habitat conditions based on flow, which are life stage specific. The output from PHABSIM is used to model fish populations, considering both flow and a temperature threshold, which affects spawning date. Water temperatures were modelled based on air temperature. The resulting assessment tool provides the means to evaluate the effect of multiple stressors produced by climate change scenarios. The model has been used to estimate smallmouth bass (Micropterus dolomieui) populations for representative reaches of the Mackinaw River, Illinois. The model has been used to illuminate population effects of changing flow and temperature under historical climate/weather conditions, as well as under climate change scenarios. The integrated models in the assessment tool have provided a useful addition to watershed management, improving our capacity to evaluate natural resources impact at temporal scales typical of climate change, and management response systems.

Animals↗
PubMed2002

The influence of land-use change and landscape dynamics on the climate system: relevance to climate-change policy beyond the radiative effect of greenhouse gases.

Our paper documents that land-use change impacts regional and global climate through the surface-energy budget, as well as through the carbon cycle. The surface-energy budget effects may be more important than the carbon-cycle effects. However, land-use impacts on climate cannot be adequately quantified with the usual metric of 'global warming potential'. A new metric is needed to quantify the human disturbance of the Earth's surface-energy budget. This 'regional climate change potential' could offer a new metric for developing a more inclusive climate protocol. This concept would also implicitly provide a mechanism to monitor potential local-scale environmental changes that could influence biodiversity.

Agriculture↗
PubMed2004

Quantification of modelling uncertainties in a large ensemble of climate change simulations.

Comprehensive global climate models are the only tools that account for the complex set of processes which will determine future climate change at both a global and regional level. Planners are typically faced with a wide range of predicted changes from different models of unknown relative quality, owing to large but unquantified uncertainties in the modelling process. Here we report a systematic attempt to determine the range of climate changes consistent with these uncertainties, based on a 53-member ensemble of model versions constructed by varying model parameters. We estimate a probability density function for the sensitivity of climate to a doubling of atmospheric carbon dioxide levels, and obtain a 5-95 per cent probability range of 2.4-5.4 degrees C. Our probability density function is constrained by objective estimates of the relative reliability of different model versions, the choice of model parameters that are varied and their uncertainty ranges, specified on the basis of expert advice. Our ensemble produces a range of regional changes much wider than indicated by traditional methods based on scaling the response patterns of an individual simulation.

Journal Article↗
PubMed2006

Challenges of climate change: an Arctic perspective.

Climate change is being experienced particularly intensely in the Arctic. Arctic average temperature has risen at almost twice the rate as that of the rest of the world in the past few decades. Widespread melting of glaciers and sea ice and rising permafrost temperatures present additional evidence of strong Arctic warming. These changes in the Arctic provide an early indication of the environmental and societal significance of global consequences. The Arctic also provides important natural resources to the rest of the world (such as oil, gas, and fish) that will be affected by climate change, and the melting of Arctic glaciers is one of the factors contributing to sea level rise around the globe. An acceleration of these climatic trends is projected to occur during this century, due to ongoing increases in concentrations of greenhouse gases in the Earth's atmosphere. These Arctic changes will, in turn, impact the planet as a whole.

Animals↗
PubMed2004

Population response to climate change: linear vs. non-linear modeling approaches.

BACKGROUND: Research on the ecological consequences of global climate change has elicited a growing interest in the use of time series analysis to investigate population dynamics in a changing climate. Here, we compare linear and non-linear models describing the contribution of climate to the density fluctuations of the population of wolves on Isle Royale, Michigan from 1959 to 1999. RESULTS: The non-linear self excitatory threshold autoregressive (SETAR) model revealed that, due to differences in the strength and nature of density dependence, relatively small and large populations may be differentially affected by future changes in climate. Both linear and non-linear models predict a decrease in the population of wolves with predicted changes in climate. CONCLUSIONS: Because specific predictions differed between linear and non-linear models, our study highlights the importance of using non-linear methods that allow the detection of non-linearity in the strength and nature of density dependence. Failure to adopt a non-linear approach to modelling population response to climate change, either exclusively or in addition to linear approaches, may compromise efforts to quantify ecological consequences of future warming.

Age Factors↗
PubMed2006

Impact of climate change on health: what is required of climate modellers?

The potential impacts of climate change on human health are significant, ranging from direct effects such as heat stress and flooding, to indirect influences including changes in disease transmission and malnutrition in response to increased competition for crop and water resources. Development agencies and policy makers tasked with implementing adaptive strategies recognize the need to plan for these impacts. However at present there is little guidance on how to prioritize their funding to best improve the resilience of vulnerable communities. Here we address this issue by arguing that closer collaboration between the climate modelling and health communities is required to provide the focused information necessary to best inform policy makers. The immediate requirement is to create multidisciplinary research teams bringing together skills in both climate and health modelling. This will enable considerable information exchange, and closer collaboration will highlight current uncertainties and hopefully routes to their reduction. We recognize that climate is only one aspect influencing the highly complex behaviour of health and disease issues. However we are optimistic that climate-health model simulations, including uncertainty bounds, will provide much needed estimates of the likely impacts of climate change on human health.

Environmental Health↗
PubMed2006

Variation in the sensitivity of organismal body temperature to climate change over local and geographic scales.

Global climate change is expected to have broad ecological consequences for species and communities. Attempts to forecast these consequences usually assume that changes in air or water temperature will translate into equivalent changes in a species' organismal body temperature. This simple change is unlikely because an organism's body temperature is determined by a complex series of interactions between the organism and its environment. Using a biophysical model, validated with 5 years of field observations, we examined the relationship between environmental temperature change and body temperature of the intertidal mussel Mytilus californianus over 1,600 km of its geographic distribution. We found that at all locations examined simulated changes in air or water temperature always produced less than equivalent changes in the daily maximum mussel body temperature. Moreover, the magnitude of body temperature change was highly variable, both within and among locations. A simulated 1 degrees C increase in air or water temperature raised the maximum monthly average of daily body temperature maxima by 0.07-0.92 degrees C, depending on the geographic location, vertical position, and temperature variable. We combined these sensitivities with predicted climate change for 2100 and calculated increases in monthly average maximum body temperature of 0.97-4.12 degrees C, depending on location and climate change scenario. Thus geographic variation in body temperature sensitivity can modulate species' experiences of climate change and must be considered when predicting the biological consequences of climate change.

Animals↗
PubMed2003

The economics of abrupt climate change.

The US National Research Council defines abrupt climate change as a change of state that is sufficiently rapid and sufficiently widespread in its effects that economies are unprepared or incapable of adapting. This may be too restrictive a definition, but abrupt climate change does have implications for the choice between the main response options: mitigation (which reduces the risks of climate change) and adaptation (which reduces the costs of climate change). The paper argues that by (i) increasing the costs of change and the potential growth of consumption, and (ii) reducing the time to change, abrupt climate change favours mitigation over adaptation. Furthermore, because the implications of change are fundamentally uncertain and potentially very high, it favours a precautionary approach in which mitigation buys time for learning. Adaptation-oriented decision tools, such as scenario planning, are inappropriate in these circumstances. Hence learning implies the use of probabilistic models that include socioeconomic feedbacks.

Adaptation, Psychological↗
PubMed2001

Range shifts and adaptive responses to Quaternary climate change.

Tree taxa shifted latitude or elevation range in response to changes in Quaternary climate. Because many modern trees display adaptive differentiation in relation to latitude or elevation, it is likely that ancient trees were also so differentiated, with environmental sensitivities of populations throughout the range evolving in conjunction with migrations. Rapid climate changes challenge this process by imposing stronger selection and by distancing populations from environments to which they are adapted. The unprecedented rates of climate changes anticipated to occur in the future, coupled with land use changes that impede gene flow, can be expected to disrupt the interplay of adaptation and migration, likely affecting productivity and threatening the persistence of many species.

Adaptation, Physiological↗
PubMed1989

Preparing for climate change.

There is a distinct probability that humankind is changing the climate and at the same time raising the sea level of the world. The most plausible projections we have now suggest a rise in mean world temperature of between 1 degree Celsius and 2 degrees Celsius by 2030--just 40 years hence. This is a bigger change in a smaller period than we know of in the experience of the earth's ecosystems and human societies. It implies that by 2030 the earth will be warmer than at any time in the past 120,000 years. In the same period, we are likely to see a rise of 15-30 centimeters in sea level, partly due to the melting of mountain glaciers and partly to the expansion of the warmer seas. This may not seem much--but it comes on top of the 12-centimeter rise in the past century and we should recall that over 1/2 the world's population lives in zones on or near coasts. A quarter meter rise in sea level could have drastic consequences for countries like the Maldives or the Netherlands, where much of the land lies below the 2-meter contour. The cause of climate change is known as the 'greenhouse effect'. Greenhouse glass has the property that it is transparent to radiation coming in from the sun, but holds back radiation to space from the warmed surfaces inside the greenhouse. Certain gases affect the atmosphere in the same way. There are 5 'greenhouse gases' and we have been roofing ourselves with them all: carbon dioxide concentrations in the atmosphere have increased 25% above preindustrial levels and are likely to double within a century, due to tropical forest clearance and especially to the burning of increasing quantities of coal and other fossil fuels; methane concentrations are now twice their preindustrial levels as a result of releases from agriculture; nitrous oxide has increased due to land clearance for agriculture, use of fertilizers, and fossil fuel combustion; ozone levels near the earth's surface have increased due mainly to pollution from motor vehicles; and chlorofluorocarbons (CFCs) have been released in great quantities through their use in aerosol sprays, refrigerator fluids, and insulating foams. We can get rid of CFCs and curb the pollutants generating ozone, but it will be difficult to put the brake on either methane or nitrous oxide. And the reduction in carbon dioxide emissions will demand major changes in energy policy as well as action to slow deforestation. It appears that we are already committed to rising temperatures and sea levels. The question is by how much, in which areas? A number of things can be done to prepare for these changes: Governments must recognize that there is a problem; Better models must be worked out, especially to define where the greatest impacts from climate change and sea level rise will hit; Reference scenarios must be developed to see what the impacts are likely to be in ecological, agricultural, social and economic terms; Every country should develop "avoidance strategies" to minimize risk (for example, by not building on land likely to be flooded); We must cut down on the amount of greenhouse gases released into the atmosphere from human activities, by eliminating CFCs and adopting energy conservation programs and other measures to minimize CO2 release; Global agreements to protect the atmosphere are needed.

Climate↗
PubMed2005

Climate change threats to plant diversity in Europe.

Climate change has already triggered species distribution shifts in many parts of the world. Increasing impacts are expected for the future, yet few studies have aimed for a general understanding of the regional basis for species vulnerability. We projected late 21st century distributions for 1,350 European plants species under seven climate change scenarios. Application of the International Union for Conservation of Nature and Natural Resources Red List criteria to our projections shows that many European plant species could become severely threatened. More than half of the species we studied could be vulnerable or threatened by 2080. Expected species loss and turnover per pixel proved to be highly variable across scenarios (27-42% and 45-63% respectively, averaged over Europe) and across regions (2.5-86% and 17-86%, averaged over scenarios). Modeled species loss and turnover were found to depend strongly on the degree of change in just two climate variables describing temperature and moisture conditions. Despite the coarse scale of the analysis, species from mountains could be seen to be disproportionably sensitive to climate change (approximately 60% species loss). The boreal region was projected to lose few species, although gaining many others from immigration. The greatest changes are expected in the transition between the Mediterranean and Euro-Siberian regions. We found that risks of extinction for European plants may be large, even in moderate scenarios of climate change and despite inter-model variability.

Biodiversity↗