While the presence of life is persistent, its diversity is always changing. If we had a time-lapse camera trained on our planet for the last four billion years, we would see continents changing their shape and jostling each other; forests expanding and contracting as icecaps and glaciers wax and wane; species rising in dominance and disappearing in extinction; the atmosphere itself changing in thickness and composition.
These changes are impossible to watch, of course, because they happen in geological time scales, the time it takes for rocks to form and erode away. The new development in planetary history is that global change is now happening in human time scales, within our lifetimes.
“Climate change is variation in either the mean state of the climate or in its variability, persisting for an extended period, typically decades or longer. It encompasses temperature increase (global warming), sea-level rise, changes in precipitation patterns and increased frequencies of extreme events. Each of these phenomena can impact on biological diversity. In fact climate change is one of the major threats to biodiversity.”
The Convention on Biological Diversity
Life as we know it – indeed, the development of human societies - has flourished because the earth’s climate has remained relatively stable for a long period of time. The earth’s climate has been relatively stable since the last Ice Age ended 10,000 years ago, perhaps the most stable interglacial period for 400,000 years (IPCCa 2001).
The earth’s climate is regulated by the natural greenhouse effect, created by an atmosphere containing greenhouse gases like carbon dioxide and methane that trap heat from the sun. The heat regulation provided by the atmosphere depends on the concentration of these gases.
The global heat balance has been changed by human use of fossil fuels such as coal and oil, which release greenhouse gases when burned. By depending on the combustion of fossil fuels for energy and transport, humans are creating an extra blanket around the earth, an additional ‘unnatural’ greenhouse effect. The present atmospheric CO2 concentration has not been exceeded during the past 420,000 years, and likely not during the past 20 million years (IPCCa 2001).
Global warming is a reality already with us. The 1990s were the warmest decade on record, about 0.6 of a degree celcius (°C) warmer than 100 years ago. Australia has warmed by 0.7 °C between 1910 – 1999, with most of this increase occurring since 1950 (CSIRO, 2001).
Small changes in global average temperature have a major impact on nature. The global average temperature during the last Ice Age 10 to 20,000 years ago, which created vast areas under ice and glaciers, was only 8–10°C cooler than today (Hadley Centre, 1999).
Similarly, we can expect increases in the global average temperature of a few degrees will have dramatic changes on local environments and climatic conditions.
By 2030, average annual temperatures in Australia will be between 0.4 – 2.0°C higher than in 1990, and by 2070 it will be between 1 – 6°C warmer (CSIRO 2001). These are dramatic changes, and they are predicted to occur within our lifetimes (see map opposite).
This wide range of warming in the CSIRO scenarios reflects uncertainty about the levels of human greenhouse emissions in the future and how quickly the atmosphere responds to greater gas levels. We can however be certain that the current warming trend will continue, at rates much faster than normal.
Animals and plants are showing us that climate change is happening:
Where animals and plants are able to live depends largely on the climate. As climate changes, scientists are seeing changes in animal abundance and
distribution; changes in body size, development, and genetics; and shifts in the timing of events, such as breeding. Some wildlife are moving away from their usual habitats as the climate warms, seeking to maintain their preferred climate by moving towards the polar regions and higher altitudes (IPCCb, 2001).
The Inter-governmental Panel on Climate Change (IPCC), the world’s scientific think-tank, says that “for animals that are exhibiting significant large-scale patterns of changes, the most consistent explanation is recent climatic change.” Two out of every three international scientific studies into the impacts of climate on plants, insects, amphibians, reptiles, birds and mammal species show new and significant climate-driven changes (IPCCb, 2001).
Throughout the world, just a few of the changes that are occurring now include:
These changes are impossible to watch, of course, because they happen in geological time scales, the time it takes for rocks to form and erode away. The new development in planetary history is that global change is now happening in human time scales, within our lifetimes.
“Climate change is variation in either the mean state of the climate or in its variability, persisting for an extended period, typically decades or longer. It encompasses temperature increase (global warming), sea-level rise, changes in precipitation patterns and increased frequencies of extreme events. Each of these phenomena can impact on biological diversity. In fact climate change is one of the major threats to biodiversity.”
The Convention on Biological Diversity
Life as we know it – indeed, the development of human societies - has flourished because the earth’s climate has remained relatively stable for a long period of time. The earth’s climate has been relatively stable since the last Ice Age ended 10,000 years ago, perhaps the most stable interglacial period for 400,000 years (IPCCa 2001).
The earth’s climate is regulated by the natural greenhouse effect, created by an atmosphere containing greenhouse gases like carbon dioxide and methane that trap heat from the sun. The heat regulation provided by the atmosphere depends on the concentration of these gases.
The global heat balance has been changed by human use of fossil fuels such as coal and oil, which release greenhouse gases when burned. By depending on the combustion of fossil fuels for energy and transport, humans are creating an extra blanket around the earth, an additional ‘unnatural’ greenhouse effect. The present atmospheric CO2 concentration has not been exceeded during the past 420,000 years, and likely not during the past 20 million years (IPCCa 2001).
Global warming is a reality already with us. The 1990s were the warmest decade on record, about 0.6 of a degree celcius (°C) warmer than 100 years ago. Australia has warmed by 0.7 °C between 1910 – 1999, with most of this increase occurring since 1950 (CSIRO, 2001).
Small changes in global average temperature have a major impact on nature. The global average temperature during the last Ice Age 10 to 20,000 years ago, which created vast areas under ice and glaciers, was only 8–10°C cooler than today (Hadley Centre, 1999).
Similarly, we can expect increases in the global average temperature of a few degrees will have dramatic changes on local environments and climatic conditions.
By 2030, average annual temperatures in Australia will be between 0.4 – 2.0°C higher than in 1990, and by 2070 it will be between 1 – 6°C warmer (CSIRO 2001). These are dramatic changes, and they are predicted to occur within our lifetimes (see map opposite).
This wide range of warming in the CSIRO scenarios reflects uncertainty about the levels of human greenhouse emissions in the future and how quickly the atmosphere responds to greater gas levels. We can however be certain that the current warming trend will continue, at rates much faster than normal.
Animals and plants are showing us that climate change is happening:
Where animals and plants are able to live depends largely on the climate. As climate changes, scientists are seeing changes in animal abundance and
distribution; changes in body size, development, and genetics; and shifts in the timing of events, such as breeding. Some wildlife are moving away from their usual habitats as the climate warms, seeking to maintain their preferred climate by moving towards the polar regions and higher altitudes (IPCCb, 2001).
The Inter-governmental Panel on Climate Change (IPCC), the world’s scientific think-tank, says that “for animals that are exhibiting significant large-scale patterns of changes, the most consistent explanation is recent climatic change.” Two out of every three international scientific studies into the impacts of climate on plants, insects, amphibians, reptiles, birds and mammal species show new and significant climate-driven changes (IPCCb, 2001).
Throughout the world, just a few of the changes that are occurring now include:
- 22 of 35 non-migratory European butterfly species have shifted northwards by 35 – 240 km this century (Hughes 2000).
- The only two vascular plant species in Antarctica have increased in numbers between 1964 and 1990 when there have been warmer summers and milder winters (Hughes 2000).
- Changes in migration patterns of birds have been noted in Europe, North America and Latin America (IPCCb 2001).
- Populations of Adelies Penguins, which inhabit pack ice, have decreased by 22 percent as sea ice has declined; Chinstrap Penguins, which prefer open water, have increased by more than 400 percent (IPCCb 2001).
- The massive climate-related coral bleaching event of 1998 destroyed about 16 percent of coral reefs of the world in 9 months (Wilkinson, 2000).
- A rise in surface sea temperatures of 0.8°C over 42 years was accompanied by a decline in zooplankton abundance of 70 per cent over 20 years, and further up the food chain, a decline in Sooty Shearwater abundance by 90 per cent (more than 4 million birds) (Hughes, 2000).
