Australia's leading science body has reissued its climate change booklet in a bid to improve public understanding of the contentious subject.
The Australian Academy of Science was prompted to update the information based on new research and public questions since its original release in 2010.
Most available material is either too technical for the lay reader and usually omits some of the basics, such as how scientists know humans are causing global warming and what future projections are based on, said Steven Sherwood, a climate scientist at the University of NSW.
"There is so much misinformation or confusing information out there, that we thought it would be nice to gather in one place an accessible explanation," Professor Sherwood said.
About 97 per cent of scientists who study the climate accept that humans are having an impact, with carbon dioxide – mostly emitted from humans burning fossil fuels – the primary driver.
"Even though carbon dioxide is not the only influence on climate, over the long term it will have such a large effect, it has to be brought under control no matter what else we do," Professor Sherwood said.
The academy report notes global carbon dioxide emissions rose at an average annual rate of 3.2 per cent between 2000 and 2012, at the top end of previous projections. These emissions, though, will have to start falling at a pace between 5.5 and 8 per cent for the planet to have a 50-50 chance of keeping temperature increases to within 2 degrees of pre-industrial levels.
World leaders will gather in Paris in December to thrash out a global climate treaty aimed at reducing carbon emissions beyond 2020. Countries, including Australia, are expected to announce their targets by the end of next month.
The heads of Britain's three main political parties agreed at the weekend to phase out all coal-fired power plants unless their emissions can be captured.
The academy report notes average surface warming had slowed since 2001 despite rising carbon emissions but said decadal variability in how oceans and the atmosphere exchange heat meant extra warmth had been absorbed by the seas. Other changes such as the increasing incidence of heat extremes, shrinking Arctic sea ice – its thickness dropping 30 per cent in 30 years – and rising sea levels had all continued unabated.
It is well known that the greenhouse effect is important for sustaining life on Earth – temperatures would be 33 degrees cooler without it. Perhaps less well known is the role rising temperatures have on concentrations of water vapour, a key greenhouse gas.
"When global average atmospheric temperatures rise, global water vapour concentrations increase, amplifying the initial warming through an enhanced greenhouse effect," the report says. "[T]his feedback approximately doubles the sensitivity of climate to human activities."
"For Australia, a warmer future will likely mean that extreme precipitation is more intense and more frequent, interspersed with longer dry spells," the report says.
By the end of the century, a high temperature event that would now occur only once in every 20 years would be occurring annually or once every two years on our current emissions trajectory, the academy says.
While societies and nations will face varying challenges to cope with climate change, many natural ecosystems are likely to face extinction.
Native animals that depend on cooler mountain habitats, for instance, will be particularly vulnerable. Scientists examining the fate of 50 species in the Wet Tropics bioregion in north Queensland found they would be all but wiped out with a 5-degree temperature increase.