Free Radicals – science and sustainability news from the Powerhouse Museum, Sydney

IPCC predictions of the impact of temperature changes on humanity

Climate change is a hotly debated issue in Australia and around the world. The Intergovernmental Panel on Climate Change (IPCC) publishes regular reports that review the scientific evidence for climate change.
According to the IPCC:
• The Earth has warmed by more than 0.7°C over the last century
• It is more than 90% certain that this warming is due to human emissions of greenhouse gases like carbon dioxide and methane
• These emissions come from burning fossil fuels for energy and transport, from clearing forests, from agriculture and from industrial processes
• If we keep emitting greenhouse gases, the Earth will continue to warm and Australia is likely to experience more heatwaves, bushfires and intense storms, rising sea levels, water supply problems and loss of iconic species and ecosystems like the Great Barrier Reef

From 7-18 December 2009, representatives from almost every country will meet in Copenhagen, Denmark to decide what to do about climate change at an international level. One of the main issues they will discuss is what targets the world should set to reduce greenhouse gas emissions by 2020.

What would you do?

Option 1: Do nothing
The IPCC says that if we do nothing to change our ways, temperatures could increase by more than 6°C this century, hundreds of millions of people will run out of water, more than 40% of species will become extinct and coastal flooding due to sea level rise will affect millions of people. The Garnaut Climate Change Review in Australia found that the impacts on human civilisation and ecosystems would be catastrophic and that the cost would exceed 8% of Australia’s gross domestic product (GDP) by the end of the century. In rough terms, this is equivalent to every Australian losing $85 per week. Climate change would continue to accelerate beyond our ability to control it.
But some people disagree and don’t believe that climate change is really happening, or that it is really caused by humans. They argue that we don’t need to do anything about climate change and can continue business as usual. Is this what you believe?

Option 2: Reduce emissions by up to 15%
The Australian Government has committed to reduce emissions by 5% by 2020. It would increase this target to 15% if countries like the United States and European countries take on similar targets and other major economies (like China) agree to limit their emissions. Households would need to pay an extra $7 per week on energy bills to help achieve this target, but low and middle-income households will receive direct cash assistance from the government to cope with higher bills.
If other countries take similar action, the Earth would probably be on track for a temperature increase of 3 to 4°C by the end of the century. This level of warming would create major economic and environmental damage, with up to 30% of species becoming extinct, the likely loss of the Great Barrier Reef and destruction of about 30% of coastal wetlands. At these temperatures, there is a risk of triggering feedback mechanisms that would lead to unstoppable climate change.

Australia (unconditional), the United States is currently considering legislation for a target in this range but it has not yet passed the Senate, South Korea, New Zealand

Option 3: Reduce emissions by 16-25%
In May, the Australian Government announced that it would increase Australia’s 2020 emission reduction target to 25% if the world agrees to an ambitious global deal to stabilise greenhouse gases in the atmosphere at 450 parts per million or less. Households would need to pay an extra $11 per week on energy bills to help achieve this target, but low and middle-income households would receive direct cash assistance from the government to cope with higher bills.
A global deal along these lines could limit temperature rise to 2 to 2.5°C by the end of the century. There would still be significant economic and environmental impacts from this amount of warming but some of the catastrophic impacts would probably be avoided and the risk of unstoppable climate change would be reduced. However, many climate change experts think that a global deal like this one is unlikely unless rich countries like Australia commit to even stronger targets.

Australia (with conditions), European Union (unconditional)

Option 4: Reduce emissions by more than 25%
If Australia committed to reduce its emissions by more than 25% by 2020 it would be one of the strongest targets of any country, alongside the commitments made by the European Union, Japan and Brazil. If rich countries like Australia commit to reduce emissions by more than 25% then an ambitious global deal to limit temperature rise to less than 2°C becomes feasible. Many scientists believe that a 2°C temperature rise is the safe limit that should not be exceeded, allowing us to avoid most of the worst impacts of climate change.
To achieve a reduction in emissions of more than 25%, households would need to pay more than an extra $11 per week on energy bills, but low and middle-income households would most likely still receive direct cash assistance from the government to cope with higher bills.

European Union (with conditions), Norway, Japan, United Kingdom, Brazil, Indonesia

We look forward to your comments.

Sources
Commonwealth Treasury 2008, Australia’s low pollution future: The economics of climate change mitigation.
Garnaut, R 2008, The Garnaut Climate Change Review, Cambridge University Press.
Intergovernmental Panel on climate Change 2008, Fourth Assessment Report, Cambridge University Press.

Prepared by: Dr Chris Riedy, Research Director, Institute for Sustainable Futures, University of Technology, Sydney

Links:
CSIRO breifing at the Australian science Media Centre Nov 19 2009
And the same as reported by the ABC
Australian Government “Climate Change Science” information book
Intergovernmental Panel on Climate Change (IPCC)