Impact of Elevated Atmospheric CO₂ on Biodiversity: Mechanistic Population-Dynamic Perspective

Abstract

Biodiversity is characteristically defined on three levels: genetic diversity, species diversity and ecosystem diversity. In this paper I consider the impact of elevated CO₂ and associated climate change on the biodiversity of terrestrial systems at the species level.

I attempt to understand the impact of a rapidly changing physical environment mechanistically. The direct impact of elevated CO₂ is emphasised. A changing physical environment will cause behavioural and physiological responses in organisms that will affect population dynamics and interspecific relationships. In the short term, extinctions will occur via the direct interaction of species with their changing environment. Species exposed to new diseases, and species dependent on mutualists or keystone species that become extinct or change geographical range, may become extinct rapidly through interactions with other species. I hypothesise that the effect of environmental change on competitive interactions will play a minor role in causing declines in biodiversity.

Existing literature on the impact of climate change on terrestrial ecosystems emphasises the way in which ecosystems and species should track suitable climates across the landscape. Here I argue that each species will be affected in one, or a combination, of the following ways: range change to track shifting climate zones, tolerating the environmental change, microevolutionary change, and extinction.