2014 CLIMATE AND ENERGY LOW CARBON FRAMEWORKS CO UNDERSTANDING 2 CARBON BUDGETS A carbon budget can be defined as a tolerable quantity of greenhouse gas emissions that can be emitted in total over a specified time. The budget needs to be in line with what is scientifically required to keep global warming and thus climate change “tolerable.” FAST FACTS: WHAT IS A CARBON BUDGET? WHY DO WE NEED GREENHOUSE GASES With industrialisation A carbon budget can be defined as a tolerable quantity of A CARBON BUDGET? from the mid-1700s on, human activity has greenhouse gas emissions that can be emitted in total over released increasing a specified time. The budget needs to be in line with what is According to the scientific Intergovernmental Panel on Climate amounts of green- house gases into the scientifically required to keep global warming and thus climate Change, for the planet to have a 50% chance of avoiding a dangerous atmosphere. These are change “tolerable.” Carbon budgeting should not be confused with global average temperature rise of 2 degrees Celsius (2 °C) or more 50% the gases that trap heat, leading to global warm- the use of targets, thresholds or caps to set emissions reduction above pre-industrial levels, greenhouse gas concentrations must ing, which is causing goals. stabilise at 450 ppm CO2e. This will be very tough to achieve, but climate change. The gases is still possible. As at April 2012, globally we are already at 396.18 CHANCE accumulate in the air over Scientists have tracked how much of emissions leads to how much OF AVOIDING DANGEROUS time, and get more and ppm1, so there is no time to lose. The average global temperature has GLOBAL TEMPERATURE RISE rise in temperature, and what impact higher temperatures have on more concentrated in the already increased by 0.8 °C over the past century, most of that since atmosphere, trapping the climate. If we want to avoid the worsening impacts of climate more and more heat. the 1970s.2 change, the temperature has to stay within limits, and so we The most common greenhouse gas released cannot emit more than a certain amount of emissions. This is our 1From the website co2now.org, by human activity is Africa is set to get much hotter than the global average. If globally global carbon budget. It is a global budget because emissions from accessed on 5/6/2012 carbon dioxide (CO ), 2 we continue emitting as we are, studies project that “by mid- which is emitted when anywhere on earth go into the atmosphere we all share. 2USA National Academies’ we make cement, burn century the South African coast will warm by around 1–2 °C, and A budget is a finite limit to the amount of emissions we can allow National Research Council wood and use fossil fuels 2011 publication Advancing the interior by around 2–3 °C; after 2050, warming is projected to such as gas, coal or oil. ourselves before we are locked into catastrophic climate change. But the Science of Climate Change, 3 Another major green- reach around 3–4 °C along the coast, and 6–7 °C in the interior” . the way in which we use our carbon budget is up to us to decide. cited in the Living Planet house gas is methane Report 2012, by the Zoological The consequences of such temperature increases in South Africa (CH ) from livestock farts, 4 For example, we could use our emissions allowance to improve Society of London, Global 4 rubbish landfills and Footprint Network, European can be found in government and independent research . rotting things. Different roads for private cars, or we could use it to create public transport Space Agency and WWF, greenhouse gases have infrastructure. Or focus on developing minerals beneficiation rather released May 2012 (www. Many argue that aiming for 450 ppm is too high. WWF and other different global warming wwf.org.za/media_room/ organisations say that humanity cannot allow our emissions to and hence climate change than accelerating mining. To stay within budget, a rise in emissions publications/lpr, accessed impacts. from one activity or country will require emissions to fall in another; 31/7/2012) increase the average global temperature by more than 1.5 °C. To be able to compare and an “overspend” in one year will require greater cuts in emissions 3From government’s Cooler would be better, but by now is unlikely to be possible. the emissions of these November 2010 National Hotter than that and the climate tips over into conditions that we gases, they are converted in future years. We can make choices about the timing and use of Climate Change Response to a common basis called emissions, but not all choices are feasible, desirable or affordable. Green Paper will find it very hard to survive in, particularly people with few carbon dioxide equivalent 4 resources. The longer we delay cutting emissions, or if our cuts are (written CO e). Shorthand For example South 2 We speak about “spending our carbon budget”, but note that we talk of “carbon emis- Africa’s Second National insignificant, the more dramatic our actions will need to be and sions”. a carbon budget is not an amount of money. It is an amount of Communication under the the heavier the price we pay – not only in conventional economic greenhouse gases. It is an answer to the question: How much more UNFCCC 2011 (at www.sanbi. org /sites/default/files/ terms, but in human suffering, and destruction of the ecosystems of these gases can we afford to emit, before life on earth as we know documents/ documents/ sasnc201111.pdf ), South which support life. it becomes impossible? African Risk and Vulnerability Atlas (at www.rvatlas.org) 2 3 WHAT IS THE GLOBAL CARBON HOW CAN WE BUDGET AS REQUIRED BY DIVIDE THE GLOBAL SCIENCE? CARBON BUDGET FAIRLY BETWEEN 5Sharing the Effort Under a Global 5 Carbon Budget, a 2009 study WWF A study commissioned by WWF from Ecofys chose to set the desired International commissioned from concentration limit at 400 ppm CO e, so as to have a better chance COUNTRIES? Ecofys, written by Niklas Höhne 2 and Sara Moltmann (66% likelihood) of staying below 2 °C of global warming. The We have a carbon budget for the whole planet because 6For a better chance than 66%, study translates this ppm limit into a global carbon budget for the there is one shared atmosphere. But economic activity other researchers put the budget causing emissions is located within countries, sectors, at 700 Gt CO2e to have a 70% period 1990–2100. (1990 was chosen as the start year because the chance of staying within the 2 Kyoto Protocol allows for emission reduction targets against 1990 companies and other collectives, and that is where °C limit: “Decision support for we can change our global emissions. There are many international climate policy – the emissions levels.) PRIMAP emission module”, a ways to divide the budget up among countries, but 2011 paper by J.E.M.S. Nabel, J. The study concludes that collectively we can emit no more than the cumulative budget cannot change substantially. If Rogelj, C.M. Chen, K. Markmann, we relax on the emissions coming from one country, D.H. Gutzmann, M. Meinshausen, about 1 600 Gt CO e over the period 1990–2100. We have already published in Environmental 2 another country needs to reduce its emissions to Modelling and Software Issue 26 emitted a significant portion of this global carbon budget in the last compensate. 7 6 From The Emissions Gap Report 20 years, leaving us with about 870 Gt CO2e from 2009–2100. After The remaining carbon budget is a scarce resource, of 2010, by the United Nations Environmental Programme that we need to approach no net emissions. that needs to be divided fairly between countries. (UNEP) Issues that come into the debate about how to do this If we divide this total budget up per year, globally we can emit include: • responsibility for historical emissions • state on average 9.5 Gt CO2e per year for the 91 years from 2009. This is of economic development and the right to be able to about 20% of our current annual global emissions. If we continue develop to a certain level • size of population and per our current global 47 Gt CO e emissions per year7, we will use up our capita emissions • financial, technological and other 2 capacity to reduce emissions. These issues are the remaining budget by about 2030. subject of political negotiations between countries. This cube shows how much space a tonne of CO2 takes up at sea level pressure. So-called “developed” countries that have been FAST FACTS: (www.energyrace.com/commentary/what_does_a_ton_of_co2_look_like/, accessed 16/9/2011) industrialised for longer have historically been MEASURING EMISSIONS emitting the greenhouse gases that have built up to An amount of greenhouse gases is measured in tonnes: today’s concentrations in the atmosphere. Developing • 1 megatonne (Mt) = 1 000 000 tonnes countries motivate that they should still be allowed to • 1 gigatonne (Gt) = 1 000 000 000 tonnes emit to continue their economic development, at least up to a certain threshold. There is also debate about The concentration of greenhouse gases in the atmosphere is measured in parts per million (ppm): of every million molecules in the air, how many whether there should be convergence in terms of a are CO2e molecules. The more tonnes of emissions we add, the higher the global per capita carbon allowance, where everyone concentration becomes. This is like dissolving more and more spoonfuls of ends up with the same per capita allowance; or sugar in a cup of tea.