Question 18:
What are the potential impacts of
climate change?
The effects of climate change are already being felt by natural systems in many places. Glaciers in both
the northern and southern hemispheres are shrinking, permafrost is thawing, growing seasons are
lengthening and animals are shifting their ranges to higher and cooler ground.
While increases in intense rainfall events and heatwaves have happened in some regions, there is no
clear global trend in smaller-scale severe weather events such as tornadoes, hail or dust storms.
Tropical cyclones have increased in intensity since 1970, although there is no clear trend in their
numbers. Climate models indicate that further increases in greenhouse gases will lead to continued
global warming, more heatwaves, fewer frosts, less snow and a rise in sea level. Rainfall over most
parts of the world may increase, but some places in the mid-latitudes, including parts of Australia,
may become drier. Vulnerable natural systems, such as alpine fauna and coral reefs, are likely to
suffer most as a result of climate change.
The world's poor and disadvantaged people and developing countries are likely to be affected much
more than developed countries, which have the capacity to adapt to climatic changes. Projections for
the 21st century suggest:
- More heatwaves could result in heat stress and heat-related deaths in humans and livestock,
and damage to crops. The risk of bushfires is likely to increase in some areas.
- Fewer cold and frosty days would reduce cold stress and cold-related deaths in humans and
livestock, and reduce frost damage, but may extend the range of pests and diseases. Yields of stone
fruit such as apricots and nectarines in some locations may be reduced due to inadequate chilling.
- More intense and sporadic rainfall (including from tropical cyclones) would increase flooding and
associated loss of life, property and productivity. It would also affect soil erosion and pollution of
rivers and oceans.
- More frequent or intense droughts would increase loss of crops, livestock, fisheries and wildlife,
and decrease river flows and water quality.
- Changes in rainfall patterns and reduced soil moisture in parts of Australia could reduce water
supplies for agriculture, domestic and industrial uses, energy generation and biodiversity.
- The net effect of climate change on plant growth is dependent on interactions between carbon
dioxide, temperature, nutrients and rainfall. High carbon dioxide concentrations and longer growing
seasons due to higher temperatures increase plant productivity. However, reductions in rainfall and
increased risk of drought would decrease plant growth as seen during 2002-3 and 2006-7.
- Like agricultural systems, Australia's natural forests may benefit from a carbon dioxide-enriched
atmosphere, but the gains may be offset or even nullified by the impact of rising temperatures.
Plantation forestry, however, may be able to adapt to changing climate conditions through
management practices.
- In tropical rainforests, even a modest degree of warming is likely to significantly harm high altitude
rainforest flora and fauna. In woodland ecosystems in south-western Australia, modest warming
may harm most frog and mammal species.
- Projected global warming will contribute additional stress to coral reefs around the world due to
ocean warming (causing coral bleaching), stronger tropical cyclones, sea level rise and higher levels
of carbon dioxide which may reduce coral growth rates.
- All natural systems are vulnerable to invasion by exotic species. Disturbance by climate change is
likely to increase vulnerability by increasing the stress on established vegetation. Warmer conditions
will increase the likelihood of pests and diseases from tropical and sub-tropical Australia spreading
southward. Some weeds may benefit from climate change and from reduced competition as
unfavourable conditions weaken native species and perhaps crops.
- Less snow and a shorter snow season appear likely, threatening alpine ecosystems.
Greater investment in snow-making will be needed by the ski industry.
Further details are available from:
Climate change: an Australian guide to the science and potential impacts
(www.greenhouse.gov.au/science/guide)
Intergovernmental Panel on Climate Change Climate Change 2007: Impacts, Adaptation and
Vulnerability” WGII Chapter 11 www.ipcc.ch/
