What is climate change?Climate change is what happens when greenhouse gases (such as carbon dioxide and methane) trap more heat in the earth's surface. The earth is naturally insulated by the gases in the atmosphere, which for tens of thousands of years have kept the earth's temperature relatively stable. Heat comes from the sun. Most of it is trapped by the gases in the atmosphere, while some is reflected back into space. Carbon dioxide and other greenhouse gases trap more heat, causing the earth's temperature to increase. When we burn fossil fuels and cut down forests, the result is that greenhouse gases are released into the atmosphere. This causes climate change. Over the last one hundred or so years, we humans have been releasing more and more greenhouse gases into the atmosphere. Total global carbon dioxide emissions increased 70 per cent between 1970 and 2004, and are rising at an increasing rate. Their annual increase jumped from an average 1.1 per cent for 1990–1999 to more than three per cent for 2000–2004. The growth rate of emissions since 2000 has exceeded even the most pessimistic projections of the Intergovernmental Panel on Climate Change (IPCC). The carbon dioxide (CO2) level in the atmosphere is the highest concentration in the last 800,000 years and probably in the last twenty million years, at 387 parts per million (ppm). The serious part of the problem is not just the change to our climate, but the fast pace of change. In the past million years, such a large increase in carbon dioxide has never taken less than 1000 years. Climate change is happening faster than at any other time in recent history.
Find our more at the Department of Climate Change, the Bureau of Meteorology or the Union of Concerned Scientists. What are the effects of climate change?Climate scientists are telling us that if we don't start reducing the amount of greenhouse gases we emit, we will see a global increase in temperature of up to 6.4 degrees Celsius by the end of the century. By 2030, climate scientists are telling us we will see an increase of around 1 degree Celsius. This may not sound like much, but there is no such thing as "small" warming. We are already seeing serious consequences in Australia and in different regions around the world. We are facing significant increases in droughts and risk of bushfires in some regions of Australia, floods and storm surges in others. The Murray Darling Basin, already close to collapse, will be put under even greater pressure. The Great Barrier Reef, currently suffering from coral bleaching, will be devestated. Biodiversity will suffer, with many species - both flora and fauna - facing extinction. What are tipping points?Tipping points are the point of no return, where dangerous climate change disrupts the climatic balance and causes a permanent shift in the climate. Some tipping points are so serious that they can cause a feedback loop, increasing the pace and severity of climate change. The most well documented and known tipping point is the melting of the Arctic ice sheet. The Arctic sea ice is at its lowest recorded levels ever, and scientists predict that before 2020, there will be no more summer sea ice. Rising temperatures are also causing the boreal forests to die, removing one of the planet's important carbon sinks. Tipping points are important to discussions for climate change, because they increase the risks associated with dangerous change. We need to return to a safe climate World leaders will be meeting in Copenhagen in December this year to negotiate a new Kyoto-style international agreement. Many of these politicians are basing their policies on outdated science, calling for a stabilisation of carbon dioxide at 450 parts per million. This is intended to limit global average temperature increases to no greater than 2 degrees Celsius. Such a temperature increase would likely tip us over the edge into dangerous and irreversible climate change. There are an increasing number of climate scientists are saying that 450 ppm is much to high, and that to have a safe climate we need to aim for between 280-325 ppm. We have a climate emergency
Scientists tell us that stopping global warming is urgent - we have just a few years to turn around the growth of greenhouse gas emissions in order to avoid the worst effects. The good news is that we can achieve these emissions reductions with effective national policies and international treaties. We must insist that businesses and governments join individuals around the world to greatly increase energy efficiency, widely adopt renewable energy, and commit to stopping climate change Success is possible, but we need your help.
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