Theory proposes that increased environmental stochasticity negatively impacts population viability. Thus, in addition to the directional changes predicted for weather parameters under global climate change (GCC), the increase in variance of these parameters may also have a negative effect on biodiversity. As a case study, we assessed the impact of interannual variance in precipitation on the viability of an Asiatic wild ass (Equus hemionus) population reintroduced in Makhtesh Ramon Nature Reserve, Israel. We monitored the population from 1985 to 1999 to determine what environmental factors affect reproductive success. Annual precipitation during the year before conception, drought conditions during gestation, and population size determined reproductive success. We used the parameters derived from this model to assess population performance under various scenarios in a Leslie matrix type model with demographic and environmental stochasticity. Specifically, we used a change in the precipitation regime in our study area to formulate a GCC scenario and compared the simulated dynamics of the population with a no-change scenario. The coefficient of variation in population size under the global change scenario was 30% higher than under the no-change scenario. Minor die-offs (> or = 15%) following droughts increased extinction probability nearly 10-fold. Our results support the idea that an increase in environmental stochasticity due to GCC may, in itself, pose a significant threat to biodiversity.

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The impact of increased environmental stochasticity due to climate change on the dynamics of asiatic wild ass.

1. The Queensland Conservation Council Inc (QCC) has requested me to provide an expert report of the likely ecological impacts of global warming and climate change on the Wet Tropics World Heritage Area, Australia. My letter of instructions is attached as Appendix 1.

2. This report has been prepared in response to that request for use in an objections hearing concerning an open-cut coal mine in the Queensland Land and Resources
Tribunal. The mine is an extension of the Newlands Coal Mine, 129 km west of Mackay, known as the “Newlands Wollombi No. 2 Project”. I am instructed that the mining, transport and use of the coal from the mine will produce greenhouse gas emissions contributing to global warming and climate change estimated to be 84.0 million tonnes of carbon dioxide equivalent. The contribution of these emissions to global warming and climate change is a matter for other witnesses. My evidence concerns the likely impacts of global warming and climate change on the Wet
Tropics World heritage Area and the rainforest biodiversity contained within the area of which the emissions from the mine the subject of this objection are a contributing factor.

Miguel Ortega Huerta

Papers

Will climate change catch us off guard