Speaking at CEDA’s climate change review event in Adelaide, Professor Howden, Australian National University Climate Change Institute Director, outlined key findings from the latest IPCC (Intergovernmental Panel on Climate Change) report, on which he was an editor. 

The report addresses two specific objectives of the Paris Climate Change agreement. The first was to keep temperatures below two degrees above pre-industrial levels – the agreement that Australia has signed – and an aspirational target to keep temperatures below 1.5 degrees. 

It involved 91 authors, 137 contributing authors, drew on around 6000 studies and spans hundreds of pages, making it one of the largest science policy activities ever undertaken. 

Professor Howden said at current levels we have 10-14 years until we use up our ‘carbon budget’ before global temperatures reach 1.5 degrees above pre-industrial levels. 

“If we want to stay below 1.5 degrees, what that carbon budget says is that we have to make our emissions decline by about 45 per cent by 2030, and then effectively net zero by 2050,” Professor Howden said. 

“If we want to stay below two degrees, it’s a little bit more lenient; we need to have about 20 per cent reduction by 2030, but effectively net zero by 2075 … when we’re producing 42 billion tons a year, that’s a huge task.”

Professor Howden said results from the study show there was almost zero chance that global warming was not caused by human influence.

“In fact, there’s less than a one in 100,000 chance that it’s not due to human influence. So, there’s no wriggle room here to say that we’re not causing this,” he said. 

Professor Howden said after levelling off for three or four years, emissions are increasing again. 

“Here in Australia, even though we’ve got our emission targets of 26 to 28 per cent reduction by 2030, our emissions are going up … they’ve gone up the last few years, they’ll go up about two per cent this year,” he said. 

“We’re going in the wrong direction. It’s not as though we’re even starting the journey to emission reductions, we’re still heading in the wrong direction.”

Professor Howden said Australia is also losing ground against other nations, including China, in clean energy technology. While China is carving out a space for itself in the emerging world, Australia seems to have forgotten how to do it and blown opportunities to be world leaders in renewable energy. 

“That’s one of the things that really annoys me, the opportunities that have gone missing because of political stances on this issue,” he said. 
 
The IPCC report also examined the impacts of climate change of 1.5 degrees warming versus two degrees on areas such as biodiversity and extreme weather events.
 
“For a range of them – fisheries, the Arctic, biodiversity, corals – the picture is looking grim, even before we get to two degrees. And remembering two degrees is the high-end Paris target,” Professor Howden said. 

“And even at 1.5 degrees there’s significant risks for various systems. So, the message coming from the science community is that, even though 1.5 or two degrees doesn’t sound much, in fact, it matters a lot.

“We see impacts on weather extremes and impacts on sea level rise. 

“The difference between 1.5 and two, is small by the end of the century, but if you carry that out to multi-century timescales it’s several metres’ difference between 1.5 and two degrees. 

“Roughly speaking, it’s about 10 metres of sea level rise per degree in the long term. So, if you go up half a degree it’s five metres. And to put that in context, Tuvalu or Kiribati are only three metres above sea level. That’s the highest point on those places, so they go under.”

Discussing the economics of climate change, Professor Howden said a recent University of Melbourne study noted a two degree rise scenario against four degrees by the end of this century was worth an estimated $17 trillion. 

Another study has placed a social cost of $US417 on a ton of carbon released into the atmosphere. 

“These are really big numbers, and so if you think about the arguments in Australia about a $20 carbon tax, well, if that’s what’s needed to solve it, $20, versus $417, that’s a good deal,” Professor Howden said. 

He said the IPCC report showed it was possible to reduce our greenhouse gas emissions and have synergies with Sustainable Development Goals too. 

However, things will need to change significantly for Australia to continue down the path of 1.5 or two degrees. 

“Our current national commitments in Australia and globally are nowhere near adequate,” he said. 

“Those emission reduction goals are nowhere near adequate to take us to 1.5 or two. They’re more consistent with 3.5 or maybe even four degrees.

“Our current goals in Australia are 26 to 28 per cent (emissions reduction). We have to go to about 45 per cent by 2030, and we have to go to net zero by 2050 to be consistent with 1.5. We’re nowhere near that at a national level.

“If we’re to do that sort of thing across the nation and across the globe, it’s going to require changes in every aspect of society; whether it’s food production, or housing systems, or our transport systems, or our waste management systems, all of those things are going to have to be included, because they all produce greenhouse gas emissions; not just marginal change but often transformational change in those different systems.”

He said the IPCC report does reveal some good news. 

“We are producing less greenhouse gas per dollar GPD. Our cars are getting more efficient, our energy systems are getting more efficient,” he said. 

However, he said, we need a lot more ambition and need to take fast action.