What is the effect of climate change on biodiversity?

You can intuitively sense that climate change will have significant effects on biodiversity, a term that represents the collective plants and animals in any location. Because it is only obvious that most, if not every, living organisms will be affected by changes in climate.

But what is the breadth and depth of such effects on our biodiversity?

What should be of concern to us is that, even small changes in average temperatures can have a significant effect upon ecosystems, partly because of their inter-connected nature. This inter-connected nature means that the loss of one species can have knock-on effects upon a range of ecosystem functions and could result in extinctions on scales larger than the extinction of dinosaurs 65 million years ago.

To estimate the effect of climate change on species, scientists use what they call a climatic envelope, which is the range of temperatures, rainfall and other climate-related parameters in which a species currently exists.

As the climate warms, the geographic location of such climatic envelopes will shift significantly, possibly even to the extent that species can no longer survive in their current locations. They need to migrate.

In many cases, however, such migration might not be possible because of unfavourable environmental parameters, geographical or human-made barriers, and competition from species already in an area. In addition, today’s change is occurring rapidly, giving many marine organisms too little time to adapt or migrate.

Thus, those species with restricted or narrow climatic envelopes and limited ability to migrate are most likely to suffer in the face of rapid climate change.

For instance, the mountain pygmy possum is particularly vulnerable to a loss of habitat linked to climate change. The lizard is another species that researchers say is far more susceptible to climate-warming extinction than previously thought, as many species live right at the edge of their thermal limits.

The following is a list of threats to biodiversity from various components of climate change:

• Temperature Spikes – There is evidence that a number of animal species are physiologically vulnerable to temperature spikes.
• Increase in Frequency of Extreme Events – Quick changes in intensity, frequency and extent of disturbances such as fire, cyclone, drought and flood will place existing vegetation under stress and favour species able to rapidly colonise denuded areas. In many cases this will mean the spread of alien ‘weed’ species and negative effects on many indigenous species.
• Changes in Rainfall – Even minor changes in rainfall patterns could have major impacts on wildlife. Many freshwater and other aquatic species (frogs, waterbirds, turtles) are at risk because of a change in water quality and quantity.
• Ocean Effects –An increase in CO2 absorption by oceans results in a decrease in the ocean’s pH, which in turn affects the survival of many marine organisms such as corals. In addition, warmer waters could adversely affect the growth of algae such as phytoplankton. Some ocean species are highly vulnerable because their distribution is limited to shallow coastal and estuarine waters in regions such as southern Australia and New Zealand. Species in habitats that are exposed to large changes in ocean conditions and have limited scope to avoid these changes.
• The Ice Effect – Whole species assemblages adapted to life on top of or under ice could be affected. So it is not the iconic polar bear at the top of that food chain alone that is at risk.

What all the above highlight is the breadth and width of ecosystem and biodiversity effects owing to global warming and climate change – simply put, the effects are vast!