The science of climate change

Climate change is one of the most formidable challenges of our time. The science is clear. The danger is very real. The stakes are high. We must act.

The Climate Institute's job is to find solutions.

What is climate change?

Rising emissions of carbon dioxide (CO2) and other greenhouse gases are trapping more heat in the atmosphere and oceans — rapidly changing the global climate. Add to that, as the oceans absorb more CO2 they become more acidic, threatening to undo marine food chains. CO2 is released when we burn fossil fuels — such as coal, gas and oil — or when forests are cut down. 

View our Carbon 101 and Dangerous Degrees booklets for more information. You can also listen to a podcast narrated by renowned climate scientist Dr Graeme Pearman and Andrew Demetriou, CEO of the Australian Football League, both Board Members of The Climate Institute.

Dangerous milestones

Ream after ream of data show that global warming is well and truly happening.

NASA and the US National Ocean and Atmospheric Agency (NOAA) recently confirmed that 2015 was the hottest year on record. Between 1880 and 2015, sixteen of the hottest years have occurred since 1998. Today, the average global temperature is 0.9°C higher than the 20th-Century average.

In March 2015, the world hit a dangerous milestone when the average concentration of CO2 in the air surpassed 400 parts per million (ppm), according to NOAA. (Earlier, in 2013, Hawaii’s Mauna Loa atmospheric observatory detected CO2 over 400 ppm—now it’s global.) This is 40 per cent higher than CO2 levels before the Industrial Revolution started in the mid-18th Century and higher than at any time in human history. 

Since the 1880s, the world’s oceans have become 30 per cent more acidic and have risen by about 20 centimetres. Sea levels continue to rise.

The last time CO2 levels were this high was around three million years ago, during the Pliocene. The world then was very different: average global temperatures were at least 3°C higher than temperatures just before the Industrial Revolution; Arctic temperatures were higher by as much as 16°C; sea levels were more than 25 metres higher. Today, a rapid return to Pliocene conditions would be catastrophic.

Australian impacts

Australia is already feeling the effects of climate change. Every decade since the 1970s has been warmer than the last. 2013 was Australia’s hottest year on record; 2015 the fifth hottest, while eight of the 10 warmest years on record have occurred since 2002. 

Across Australia, rainfall patterns are shifting. The south is getting dryer, with significantly reduced rainfall in winter and spring. While in the north the risk of torrential downpours and severe floods is going up. The risk of fire-weather conditions is rising in the south-east, and, overall, droughts are likely to become more frequent and more intense.

In its Annual Climate Statement 2015, the Bureau of Meteorology says that last year was 0.83°C above the 1961–1990 Australian average. In May, one of the record-strongest El Niño events became established. September 2015 was the third-driest September on record nationally. Record warmth was detected in the Pacific and Indian Oceans. Northern and central parts of the country were hit by a record hot spell in March, while large parts experienced severe and significant extreme weather events.

The bigger picture

The last report of the Intergovernmental Panel on Climate Change (IPCC) confirmed what every other report since 1990 had predicted: the world is warming, fast.

The human fingerprint is all over climate change, which threatens to undo decades of development, undermine peace and security, and impose a rising toll on human health and the natural world.

Without “substantial and sustained reductions” in carbon pollution, says the IPCC synthesis report, the world faces “further warming and long-lasting changes… increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.”

Some further warming is inevitable and Australia must prepare for a changing climate. But, by reining in and reversing emissions, as well as investing smartly and strongly in adaptation, we still have a good shot at avoiding the worst predictions. The task now is to manage the unavoidable and avoid the unmanageable.

Learn more

The web abounds with sites on climate change. Here are some we rely on for rigorous, scientifically sound analysis and insight:

Why a rise of only a few degrees in the average global temperature risks our prosperity, security, and health.
Dangerous Degrees
This primer covers carbon jargon and explains the concepts behind the zero emissions economy.
Carbon 101 Cover
Creative Fellow Michael Hall’s photos represent the tragic reality of climate extremes.
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