Global warming
The Conservation Threat of Global Warming
Global warming will cause problems for many ecosystems and species. We must plan for the consequences and try to curb emissions.
 Global sea temperatures from the past 1000 years, reconstructed from ice-cores (Source Hughes, 2000). |
What is Global Warming?
Planet earth has become about 0.5o C warmer and the sea level has risen 10 cm in the last century. The best scientific evidence suggests that this warming is a consequence of increased greenhouse gas emissions, and that the planet will continue to warm and the seas to rise. By 2050, the planet will be between 1.5 and 4.5o C warmer than now, and by 2100, the sea may be 95 cm higher than now. These trends will not stop, but are likely to continue for centuries.
The Threat in the NT
The changes that will occur in regional climate are complex and poorly understood. It is thought that monsoonal Australia will probably receive more rain, but less frequent cyclones. Two consequences that can be reasonably well predicted are a rise in sea level, and that for most species, the climatic envelope that defines their range will migrate toward higher latitudes and higher altitudes. There is now an increasing body of evidence that these migrations have already begun in areas all over the world.
 Land below 10 m above sea level (in black) near Darwin |
Sea level rises may have a large effect in the NT because so much of the land is low lying and the tidal reaches of the rivers so long. Salt water will intrude further up rivers, and the estuarine floodplains may become inundated by the sea. In Kakadu National Park, it is estimated that more than 20% of the park is at risk of inundation because it lies below 10 m above sea level.
The climatic envelope defining where particular species live will change. There is relatively little topographic relief in the NT, so there is little scope for species to move altitudinally. In order to adapt to these changing conditions, the species themselves must be able to migrate. For many plant species and the less mobile animals, climatic changes may occur too quickly for dispersal to keep up with. Also, species will only be able to migrate if there are no barriers in their path. The nature of a barrier differs among species, but for some, a road would be impossible to cross, while for many others, a large expanse of cleared agricultural land would be a practical barrier. The threat of global warming requires large north-south corridors of native vegetation be retained. It is also likely that some of the species occurring in conservation reserves created today will not occur there in the future. Thus, it is sensible to be able to re-design the reserve network as the biota moves.
It is likely that the climate envelope required by some species will disappear altogether as has been predicted in simulations of the impact of changed climatic regions on selected Australian species. For example, it is predicted that the climatic envelope of the endangered Kowari (Dasyuroides byrnei) may be eliminated in the NT.
 Will floodplains like this soon be in the sea? |
What can we do?
We cannot now make global warming go away. All we can do is slow its progress and try to prevent some of the worst impacts. The actions that are needed are:
- Australia and the NT should strive to reduce greenhouse gas emissions. Since the 1995 Kyoto international protocol was established to reduce gas emissions, Australia has increased emissions by more than 10%.
- Clearing of native vegetation should be minimised as it is a major source of greenhouse gas emissions.
- There are some things we can all do: take fewer trips on planes; be more energy efficient at home (solar water heating, better insulation etc); drive smaller cars or use public transport; eat less meat (20% of Australia's emissions are from agriculture, mostly from cattle and sheep production).
- Establish a representative reserve system that includes corridors for migration of species' climatic envelopes.
- In the future we will probably have to actively move species that cannot migrate themselves, which will require a huge effort.
Further Reading
There are a number of websites in Australia dealing with global warming. Try the Australian Greenhouse Office, or the NT Greenhouse Office. For non-government perspectives visit the Australian Conservation Foundation.
