Global carbon budget – experts respond

Carbon dioxide emissions, the main contributor to global warming, are set to rise again in 2014 – reaching a record high of 40 billion tonnes, according to a new global stock-take.

Credit: Eric Schmuttenmaer (Flickr)
Credit: Eric Schmuttenmaer (Flickr)

A 2.5 per cent projected rise in burning fossil fuels is revealed by the Global Carbon Budget 2014, an analysis published in the journal Earth System Science Data Discussions.

This means that the future global ‘carbon budget’ of 1,200 billion tonnes – calculated as the total upper limit international governments can afford to emit without pushing temperatures higher than 2°C above pre-industrial levels – is likely to be used up within 30 years, just one generation from now.

The report comes ahead of the United Nations New York Climate Summit, where representatives from countries around the world, including New Zealand, will seek to catalyse action on climate change.

Coinciding with the Global Carbon Budget publication, a series of comments, reviews and editorials have also been published by Nature Geoscience and Nature Climate Change.

The latest update from the Ministry for the Environment shows that New Zealand currently contributes more than 75 million tonnes of carbon dioxide, more than double its emissions in 1990.

The SMC has collected the following expert commentary. Feel free to use these quotes in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476;

Prof David Frame, Director of the Climate Change Research Institute, Victoria University Wellington, is co-author of a commentary article in the Nature Geoscience special issue. He comments:

“Our commentary emphasises the way the cumulative emissions approach can help reshape the negotiations around the main feature of the problem: the unavoidable need for major emitters to reduce emissions of carbon dioxide.

“In the short-term this may make some parts of the negotiations harder; but in the long-run it makes negotiators focus on the parts of the problem that matter most.”

Dr Jim Salinger, Climate Researcher and Visiting Scientist at the Institute of Biometeorology, National Research Council, Italy, comments:

“The latest papers show that it is critical that we have robust international and national climate policy in place immediately. Living in the belief ‘that we can ramp down emissions mid -century’ and prevent damaging climate change is comparable to commencing saving for your retirement when you are 55 – it will be virtually impossible. Germany is leading the way with huge investments in wind and solar renewables to such an extent that these technologies are now cost-effective compared with fossil fuels.

“New Zealand must share by becoming leaders in converting electricity production to virtually 100% renewable, and radically reducing transport emissions using electric technologies. As this country did in 1989 by pioneering the negotiations and signing of the Montreal Protocol on Protection of the Ozone Layer, it is time 25 years later to become a world leader again.”

Prof Martin Manning, Climate Change Research Institute, Victoria University Wellington, comments:

“CO2 is the dominant cause of climate change and this very thorough analysis has produced the most detailed budget for the global carbon cycle going back to 1750. It also shows that during 2014 we can now expect another 40 billion tonnes of CO2 to be emitted into the atmosphere, with more than 90% of that due to use of fossil fuels. This is pushing CO2 higher than it has been at any time over the last two million years and heading back to a very different world where sea level was also higher, by about 20 meters.

“This review shows that about 30% of the CO2 emitted into the atmosphere is going into vegetation and soil while another 27% is being taken up by the oceans, but the remainder adds to the greenhouse effect in the atmosphere and a significant fraction will stay there for thousands of years.

“A very detailed carbon budget shows that the biggest relative change since the 1960s has been a 190% increase in fossil fuel emissions of CO2, whereas deforestation has decreased. The amount of CO2 being taken up by the ocean has also increased, but only by 140%, and the uptake by vegetation by even less at 60%. So it is clear that natural processes for balancing the carbon cycle cannot keep up with this rapid rise in CO2 emissions.

“Per capita emissions in China have roughly doubled in the last ten years and are now slightly more than the EU, but they are still less than in New Zealand and only about half that in the USA. Also roughly 5% of all CO2 emissions are for products made in developing countries and exported to developed countries.

“It is clear that increasing CO2 has already gone more than half way to warming the Earth by 2°C and the known reserves of fossil fuels are far more than we can use to have any confidence in keeping to this target. So continued prospecting for more oil or gas can only be justified if it were to replace coal and be used for just a short period while much more rapid uptake of renewable energy occurs.”

Our colleagues at the UK Science Media Centre also collected the following commentary:

Prof Myles Allen, Head of the Climate Dynamics Group at the University of Oxford, said:

“It is depressing that the immediate reaction to the news we have a limited carbon pie is discussion of how countries can slice it up. We didn’t save the Ozone layer by rationing deodorant.

“What we will need, to meet any carbon budget dwarfed by vast reserves of highly profitable fossil fuels, is CCS. Countries that claim to take this problem seriously should be requiring their fossil fuel suppliers to sequester a steadily increasing fraction of the fossil carbon they sell to ensure we stick to the two degree carbon budget. This wouldn’t need any international negotiations (which is presumably why the idea is of no interest to international negotiators), but it would solve the climate problem.”

Professor Sybil Seitzinger, Executive Director of the International Geosphere-Biosphere Programme, said:

“Since 2008, China has been the world’s largest emitter of carbon dioxide. It now accounts for 28% of emissions, with the US accounting for 14% and Europe 10%. What is remarkable this year is that China’s per capita emissions outstripped Europe’s for the first time. Moreover, China’s emissions now exceed the US and Europe’s emissions combined. This is an interesting trend and shows the important role China will play in addressing the climate challenge.”

Dr Grant Allen, Atmospheric physicist at the University of Manchester, said:

“These studies go so far in indicating the effects of emissions, but they do not sufficiently take into account the rate of emission of CO2.

“We cannot simply measure cumulative emissions and predict surface temperature as it is emission rate, not total emissions, that govern the concentration of CO2 in the atmosphere. And that’s important because it is the concentration of CO2 that governs temperature.

“I disagree with the statement in one of the studies that rate is not important and that cumulative emission is directly related to temperature – the physics of that statement are just wrong. The faster we emit CO2, the greater the warming effect.

“Cumulative emissions are, at best, a blunt tool for policy makers. Instead the focus should be on reducing the rate at which we pump CO2 into the atmosphere as quickly and efficiently as possible – something I think we can all agree on.”

Dr Miles Seaman, Member of Sustainability Group at the Institution of Chemical Engineers, said:

“The dilemma of matching the dynamics of our increasingly well founded predictions of the effect of climate change and the ability of the institutional structures at both national and international level to respond appropriately are well illustrated by these two positions.

“Of course we know that it will not be easy to establish a workable and equitable basis for restricting carbon emissions on a worldwide basis. There are too many entrenched positions, particularly among the “advanced” nations and national groupings (e.g. the European Commission) to see a way forward which will deliver solutions to operating very low carbon economies. The know-how to do this is well within our grasp inasmuch as knowing that current engineering can deliver these solutions if incentivised to do so.

“But whilst we are on the rack of macroeconomic ‘policy’ which depends on growth unconstrained by resource limitations such solutions will not emerge. However there is some dim light at the end of the tunnel when we see what is happening in the emerging economic powers. From a western point of view, the breathtaking transformations taking place, particularly in China, together with the technological capacity which has brought this about illustrate the likely role that these actors will play in producing a physical dynamic to meet the challenges that have thwarted the current ‘rich’ world.

“If the current political paralysis is not overcome by the obvious need for action, we may find that the game is being played on a much larger field than we currently contemplate.”

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

“If this were a bank statement it would say our credit is running out.

“We’ve already burned through two-thirds of our global carbon allowance and avoiding dangerous climate change now requires some very difficult choices. Not least of these is how a shrinking global carbon allowance can be shared equitably between more than 7 billion people and where the differences between rich and poor are so immense.

“As governments draft and debate their plans for a post-2020 international climate change agreement, how to avoid this looming ‘carbon crunch’ must be at the top of the agenda.”

Dr Chris Huntingford, of the UK Centre for Ecology and Hydrology, said:

“Climate research findings are often difficult to interpret, even by other researchers. The United Nations do a good job with their reports summarising information on global warming, but even these run to thousands of pages.

“What the authors of these new papers achieve are two very clear statements. First greenhouse gas emissions are still rising, despite many calls for the opposite to happen in order to lessen the risk of unwelcome climatic impacts. Second, if country-based emission quotas are to ever be implemented, then what constitutes an algorithm to achieve this needs significant debate. Should such quotas be based on existing fossil fuel use, country population levels, or some combination?”

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

“These studies refine the IPCC numbers and give us roughly 30 years until we emit the trillionth tonne of carbon dioxide and pass the two degrees of warming threshold.

“Warming is currently around 0.8 C since pre-industrial times. This means that over the next decades the world could be expected to warm by around 0.4 C per decade – twice as fast as anything seen in the historical record.

“Any rebound from the pause in global temperature change would add to this, so the warming rate could be even stronger. On the other hand, if the world doesn’t warm as we expect, we climate scientists may have serious egg on our face. I would prefer that to be the case; but I fear the climate scientists may be right.”