Climate change is an extended change in the average state of the climate or a change in its variability, persisting for decades or longer. Climate change may include temperature increases (global warming), sea-level rises, changes in rainfall patterns and more extreme weather events such as droughts or cyclones.
Climate changes generally occur on a geological timescale and are not noticed over a human lifetime. However, scientists tell us that climate change is now occurring at an alarming rate within our lifetimes. Even small changes in average global temperatures will have a major impact on natural environments. It is estimated that there is a 20 year time lag between the emission of greenhouse gases and their effects on climate change. Thus, we are now experiencing changes caused by emissions 20 years ago. Any reduction in emissions will probably not be detectable for another 20 years and until then the effects of climate change will continue to increase.
Climate change is becoming a major threat to the biodiversity of the World Heritage Area. It can make the impacts of other threats much worse. Current modelling predicts that even minimal global warming of one degree may have significant effects. Global warming could decrease the habitat of many endemic vertebrate species which live in the cooler upland and montane rainforests, leaving only isolated pockets of rainforest for them to live in. It is predicted that seven frog species, five mammal species, three bird species and three skink species would lose over half their present habitat with only a 1ºC temperature increase.
As well as habitat changes, increased temperatures will physiologically affect some animals. Raised cloud levels are likely to change water cycles and affect some frogs and skinks. Seasonal changes may change plant reproduction and fire regimes. Increased sea levels, cyclones and flooding may drastically affect coastal ecosystems.
Climate change may cause ecosystem disturbance, alter water and fire regimes and increase vulnerability to invasion by feral animals, weeds and pathogens. Wet Tropics ecosystems that are already fragmented and disrupted are less able to adapt to any changes wrought by global warming.
The neighbouring Great Barrier Reef World Heritage Area is also threatened by climate change. Increases in water temperatures from 2ºC to 6ºC will have severe implications for the health of coral reefs, fisheries and coastal ecosystems which are shared with the Wet Tropics World Heritage Area.
The Wet Tropics Management Authority produced a special climate change report as its State of the Wet Tropics Report in 2008. The report detailed the impacts of climate change on the Wet Tropics World Heritage Area and suggested responses to mitigate the potential damage to the Area and its fauna and flora. Download the detailed report: Climate Change in the Wet Tropics: Impacts and Responses (2008)
In 2003 the Rainforest Cooperative Research Centre produced a report on the impacts of climate change on the Wet Tropics. You can download a copy of the report here: Environmental Crisis: Climate Change and Terrestrial Biodiversity in Queensland.
