November 14, 2016

expert reaction to the Global Carbon Budget analysis for 2016

Publishing in the journal Earth System Science Data a group of scientists have described their modelling of carbon dioxide emissions and their distribution – known as the global carbon budget.

Prof. Chris Rapley, Professor of Climate Science at UCL, said:

“It is encouraging that actions taken by nations that acknowledge the risks and realities of climate change – notably China – are taking effect, and that the rate of human carbon emissions have flatlined over the last few years. However, despite the rate having steadied, we are collectively still adding CO2 to the atmosphere. As a result its concentration continues to rise.

“To combat climate change risk, the rate needs to fall to zero so that the concentration flatlines. Worryingly, the reductions pledged to by Nations under the Paris agreement are not sufficient to achieve this. This puts seriously at risk our breaching the 2C ‘safe’ guardrail.

“So efforts need to be redoubled not just to maintain the current welcome trend in emissions, but to achieve significant and sustained reductions as soon as possible in the future. In this respect, recent statements by the US President-Elect on climate change, green technology and the use by the USA of fossil fuels are deeply troubling.”

Prof. Myles Allen, Professor of Geosystem Science at the University of Oxford, said:

“It is encouraging that global carbon dioxide emissions from fossil fuel use have remained stable for a second year running, because it shows it is possible to grow the world economy without increasing emissions. But, of course, we need to do more than that: to stabilise climate, we need to reduce net carbon dioxide emissions to zero, meaning any residual emissions (from countries run by climate change deniers, for example) will need to be compensated for by active CO2 removal.

“So the challenge is very clear. Global human-induced warming since pre-industrial times is now about 1 degree, so if we want to reach net zero emissions by the time this warming reaches 1.5 degrees, we need to reduce emissions, on average, by 20% of today’s value for every tenth of a degree of warming from now on. Or if the goal is 2 degrees, then 10% for every tenth of a degree and so on. This isn’t a policy, it’s just a fact.

“Right now, a tenth of a degree of warming takes only 6-8 years or so, so 20% per tenth of a degree means about 3% per year, or emissions decreasing at about the same rate they have been increasing since 2000. That sounds challenging, but not impossible: we needed to buy stuff and build stuff to increase emissions at this rate, so by buying and building different stuff, we could reduce them at a similar rate.

“But the longer we put off reducing emissions, the higher the chances we will have to take the very expensive step of abandoning stuff we have already bought or built. None of these simple facts is affected by recent political developments: I very much hope the people responsible for investing my pension understand this.”

Dr Emily Shuckburgh, Deputy Head of Polar Oceans at the British Antarctic Survey, said:

“The amount of carbon dioxide that we can emit before a level of warming is locked in can be seen as a carbon budget. Like a household budget, without careful planning it can easily be blown. The more carbon dioxide we emit now, the faster we will have to reduce our emissions later to stay within the budget – and we may find that the speed of cuts then required is unachievable, even with new technologies.

“It is welcome news that the growth in emissions has stalled while global economic growth has continued: that demonstrates change is possible. Nevertheless, at the present rate of fossil fuel use and deforestation we are on course to exhaust the entire carbon budget for 2°C within the next twenty to thirty years, with the budget for 1.5°C of warming being exhausted even sooner. If the worst of climate change impacts are to be averted, everyone from governments to individuals needs to step up their efforts to reduce emissions. Time is short now; for our futures and those of our children and grandchildren, it is vital that this message is understood around the world.”

Prof. David Reay, Professor of Carbon Management at the University of Edinburgh, said:

“This could be the turning point we have hoped for. Ever since the industrial revolution our global carbon emissions have been tightly bound to economic growth. To tackle climate change those bonds must be broken and here we have the first signs that they are at least starting to loosen.

“The demise of coal has been key. It may have produced seismic changes in US politics, but it has also helped cut the carbon intensity of global energy production. To avoid the worst impacts of climate change these emissions now need to plummet. The real Houdini work of freeing our economies from carbon has only just begun.”

Prof. Piers Forster, Professor of Climate Change at the University of Leeds, said:

“These data are intriguing. They reveal the first green shoots of success for global climate policy. Ever since the industrial revolution, economic growth has come at the cost of burning more fossil fuels but for the first time last year the world economy grew without a corresponding rise in emissions.

“Climate mitigation policies around the world are beginning to deliver. Hopefully emissions have peaked. There is also a lesson for the incoming US administration here – you don’t need coal to drive economic growth.”

Prof. Richard Betts, Head of Climate Impacts Research at the Met Office Hadley Centre, said:

“This has been an important year for carbon cycle science. After a steady increase in recent years, CO2 concentrations suddenly rose fast in 2016. The El Nino weakened the land carbon sink, so more emissions from fossil fuel burning and deforestation remained in the air. This illustrates the importance of the regular, systematic Global Carbon Budget – it is crucial that we keep track of how the carbon cycle is responding to our interference.”

*Global Carbon Budget 2016 by Corinne Le Quéré et al. published in Earth System Science Data on Monday 14 November 2016. 

Declared interests

None declared