Climate Change and Tropical Biodiversity

In this review article, Brodie et al. expose a different approach to looking at the effects of global climate change on tropical biodiversity. An abundant amount of literature does, in fact, address the direct effects of climate change on biodiversity in the tropics. Brodie et al. argue, however, that while these efforts are extremely important and notable for current and future conservation efforts, little attention is devoted to perhaps a no-less considerable factor – how does climate change impact synergistic interactions between humans and tropical environments.

In other words, climate change affects the environment, which contributes to a multitude of changes in humans’ interaction with that environment – this interaction change is, in turn, a huge factor to be considered when evaluating topical biodiversity impacts resulting from climate change. Brodie et al. address several synergistic impacts of climate change, particularly relating to human land use behavior.

They present findings indicating that increased temperatures in the tropics may not always be detrimental to biodiversity in the tropics – in fact, sometimes temperature increases are beneficial to biodiversity, such as in the case of the Paleocene-Eocene Thermal Maximum event.

The human element here, in combination with increasing temperatures, is the focal point for potential biodiversity exacerbation. Furthermore, increasingly severe dry seasons caused by climate change further deepen the impacts of human land-use change on tropical forest biodiversity. In longer dry seasons, the economic feasibility of logging and forest olonization could very well increase, leading to the disappearance of ‘remote’ tropical areas that were once inaccessible to humans due to wetter climate. In this way, successive drying indirectly (or directly through human land use) leads to increased forest vulnerability. The negative effects of increased forest vulnerability would quickly spill over to impacting wildlife as well. A crucial factor mentioned here is how human land-use change dramatically increases tropical forest vulnerability to fire.

Large bodies of research shows that logged or fragmented forests are far more susceptible to fires than are intact ones, supporting the team’s argument. The group also goes as far as predicting that the synergistic interactions between drying, forest disruption and the increased incidence of anthropogenic fires might result in a massive replacement of Amazonian forests by savannahs or secondary forests in the coming century, creating a runaway climatic warming process.

The research group doesn’t shy away from discussing the economics of this global predicament, and how societal and global financial pressures can magnify changes in land-use and consequently negative impacts on tropical environments. Crop-based biofuel production has increased rapidly in recent years, along with a rising demand for food. This requires a substantial expansion of agricultural land in the tropics, which tends to come at the expense of intact forests.

Brazilian farmers, for instance, have increased the burning of forests and woodlands in recent years to expand soy production as a consequence of generous Federal subsidies to promote ethanol production. Lastly, Brodie et al. make general suggestions for what needs to be done if the world doesn’t want to see tropical environments disappear altogether. Halting perverse agricultural subsidies for biofuel production is one strategy they discuss, as well diverting agricultural expansion from intact forests to areas that have already been cleared or degraded.

They further call for a renewed focus on ecological connectivity between forests and protected areas, so as to reduce susceptibility to fires as well as allow for better potential for wild-life range shift in situations of habitat loss. These are all noble calls for action, but they probably are slightly idealistic in today’s world. Most people are motivated by profits and capital advancement first, and about the environment second (probably farther down than second). One can only hope that the world will reach a realization point before it does a crucial ecological tipping point.