• Scientists offer insights into climate-change conference
The upcoming Paris Climate Change Conference hosted by the United Nations is aimed at achieving a global agreement on fighting climate change.
Adeshola Ore

24 Nov 2015 - 1:08 PM  UPDATED 24 Nov 2015 - 2:06 PM

The upcoming Paris Climate Change Conference hosted by the United Nations is aimed at achieving a global agreement on fighting climate change.

The hope is to implement action that will limit global warming to two degrees Celsius over pre-industrial levels.

An online briefing by the Adelaide-based Australian Science Media Centre, featuring climate scientists and policy experts, has offered insights into the talks.

Adeshola Ore reports.

From 30 November, representatives from nearly 200 countries will gather in Paris for the 12-day United Nations conference on climate change.

The Australian Science and Media Centre says it is being hailed as the most likely to achieve a legally binding global climate agreement in over 20 years of UN negotiations.

University of New South Wales visiting fellow Professor Stefan Rahmstorf says the increasing carbon dioxide concentration in the atmosphere shows action is critical.

"It is now much higher than it has been at any time in at least one million years. That much we know from the ice core drilling in Antarctica. And we also know that this increase is entirely caused by human activities -- mainly, the burning of fossil fuels. We know that, for example, because the amount that we see increasing in the atmosphere is actually only half as much as we have emitted through our smokestacks."

Professor Rahmstorf says the scale of the warming is greater than would be expected with current carbon dioxide levels.

"That is because carbon dioxide is not the only greenhouse gas that is increasing in the atmosphere due to human activities. There are several other greenhouse gases that also add to the greenhouse effect. And if you look at the total sum of everything that humans are contributing to climate change, then that adds up pretty well exactly to the warming that is observed over the last decades."

Frank Jotzo is director of the Centre for Climate Economics and Policy at the Australian National University.

Dr Jotzo says he believes the Paris talks will have an impact on how countries can work together.

"The fundamental aspect of really having developing countries and developed countries on the same page, so there's no fundamental distinction anymore on the nature of commitments made by developed or developing countries, is a real fundamental breakthrough on what we have there, compared to the earlier situation where developing countries insisted on developed, rich countries doing everything."

A key aim of the conference is to limit global warming to two degrees Celsius over pre-industrial levels.

Professor Rahmstorf says he believes it is critical to limit the rise in global temperatures.

"What we can hope for, by stopping global warming at two degrees, is that we stop a further acceleration of sea-level rise. But there will be sea level rise for many centuries to come."

But the director of the Climate Change Research Centre at the University of New South Wales, Professor Steven Sherwood, says naming a safe level for global warming and emissions is problematic.

"We don't really know. There isn't any safe amount of CO2 that we can emit. The idea that we can go a certain distance and be safe and, after that, unsafe doesn't really have any basis. And there probably are tipping points out there, but the uncertainty in the science is such that we don't know where they lie. And, indeed, people who study the ice sheets, the West Antarctic Ice Sheet and the Greenland Ice Sheet, some of them are saying that we've already passed tipping points and set into motion changes that, over time, over centuries, will lead to metres of sea level rise."

Each country that will attend the talks submits a nationally determined contribution to reducing climate change.

Professor Rahmstorf says, while the combined pledges will have some impact, they still leave gaps in achieving the goal of limiting the temperature rise to two degrees.

"By themselves, these pledges will not be enough, even if implemented as promised. So that's why a crucial component of a Paris climate agreement will have to be that these pledges will be reviewed at regular intervals and, if needed, strengthened."