Durban, South Africa—Yesterday, before an audience of more than 100 environmental ministers gathered at the opening “high level segment” plenary of the Durban Climate Change Conference, U.N. Secretary-General Ban Ki-Moon flatly declared, “We are nearing the ‘point of no return,’ and we must pull back from the abyss." The “abyss” against which the Secretary-General warned is a future average global temperature increase higher than 2 degrees Celsius (3.6 degrees Fahrenheit).
What's so terrible about exceeding those two degrees, and where did that figure come from? The 2°C baseline is based on climate models that project increases in greenhouse gases produced chiefly by burning fossil fuels will soon commit humanity to this much extra warming.
In political terms, the 2°C figure derives from the 2010 Cancun Agreements in which member countries to the United Nations Framework Convention on Climate Change officially recognized “that deep cuts in global greenhouse gas emissions are required according to science.” How deep? They should be deep enough “to hold the increase in global average temperature below 2°C above preindustrial levels.” In addition, the Cancun Agreements resolved that this target should reviewed by 2015 with the idea that it could be lowered to cutting greenhouse gas emissions even further with goal of holding the increase in global average temperature below 1.5°C. Keep in mind that it is generally thought that average global temperatures have already increased by 0.8°C in the last 100 years.
“The world has an ever narrowing window of time to stay within the 2 degrees scenario,” asserted Achim Steiner, executive director of the United Nations Environment Program. “If we allow the United States to set the framework for negotiations from here to 2020, we can wave goodbye to 2 degrees,” warned Tim Gore of Oxfam. Nicholas Stern, lead author of the notorious Stern Review on the Economics of Climate Change, said “The numbers for climate change are very clear—if we want to remain below 2 degrees the reductions in greenhouse gas emissions have to be radical.”
In order to meet this goal, many activists are arguing that global emissions of greenhouse gases must peak by 2015 and begin falling thereafter. A number of analyses have been presented at the conference to underpin these dire assertions. For example, United Nations Environment Program (UNEP) executive director Achim Steiner formally handed his agency’s report, Bridging the Emissions Gap, over to a South African deputy minister for the environment.
The UNEP report calculates that under a business-as-usual scenario the world would be emitting 56 billion tons of greenhouse gases annually by 2020. That would represent additional emissions of 23 billion tons per year. A new study in Nature Climate Change just reported this week that the world’s carbon emissions rose an unprecedented 5.9 percent in 2010 to 9 billion tons (equivalent to 33 billion tons of carbon dioxide).
In order to stay on an emissions trajectory that would keep temperatures from rising more than 2°C, UNEP calculates that countries should not be emitting more than 44 billion tons of greenhouse gases by 2020 and that emissions should drop sharply thereafter reaching 21 billion tons by 2050. However, UNEP claims that even if countries actually honor their Cancun pledges to cut their greenhouse gas emissions, it won't be enough. The world will be emitting between 11 and 6 billion tons more than is consistent with the 2°C goal, resulting in what is generally referred to in U.N.-speak as the “ambition gap.” Parties at the climate change negotiations are constantly excoriated for their lack of “ambition,” i.e. for not commiting to cut their greenhouse gas emissions even more deeply than they’ve already agreed to do.
The UNEP report asserts that its computer models show that “there is abundant evidence that emission reductions of between 14 and 20 [billion tons] of CO2 equivalent are possible by 2020 and without any significant technical or financial breakthroughs needed.” The UNEP analysis looks at implementing various energy efficiency improvements, deploying of solar and wind energy production technologies, burning vast quantities of biomass, mandating various land use changes, and so forth. The report estimates that it will cost between $50 and $100 to cut one ton of carbon dioxide emissions. Since the report says that no financial breakthroughs are needed to cut 14 to 20 billion tons that would imply spending an additional $1.4 to $2 trillion.
A complementary report, World Energy Outlook 2011 (WEO), was just issued by the International Energy Agency (IEA). The WEO analysis also takes staying below the 2°C mark as its goal. The IEA argues that this goal can be achieved by keeping atmospheric levels of carbon dioxide from rising to more than 450 parts per million (ppm). The current level is 394 ppm. “Unless we change course by 2017…, all of our energy infrastructure after 2017 must be zero carbon,” asserted IEA Executive Director Maria van der Hoeven at a press conference on Tuesday.
Van der Hoeven was largely reprising the WEO study’s conclusion that “four-fifths of the total energy-related CO2 emissions permitted to 2035 in the 450 Scenario are already locked-in by existing capital stock, including power stations, buildings and factories.” Without immediate stringent efforts to reduce global carbon dioxide emissions, the IEA report suggests that the world will have to stop building new coal or gas-fired electricity generation plants and stop adding to the world’s petroleum-powered vehicle fleet in only five more years. That is, if people wanted to stay below the 2°C mark.
The WEO assumes that efficiency improvements will account for half of the additional reductions in emissions required for average global temperature to remain below 2°C. In other words, emissions will be lower because people will be using substantially less energy. The IEA may be overlooking the controversial energy efficiency “rebound effect.”[PDF] It turns out that people and industries don’t cut their energy use by the amount equal to the efficiency gains. One example might be people driving their energy efficient automobiles more or leaving their new LED lights on longer since they are cheaper to fuel. As University of Manitoba environmental scientist Vaclav Smil has pointed out, "Historical evidence shows unequivocally that secular advances in energy efficiency have not led to any declines of aggregate energy consumption."
Another thought experiment about the economic challenges posed by deep cuts in carbon dioxide emissions was offered by Paul Simpson, the CEO of the Carbon Disclosure Project. Right now global GDP is around $60 trillion and the world emits roughly 30 billion tons of carbon dioxide. By 2030, world GDP will likely be over $120 trillion and, if countries don’t take action to limit them, emissions would exceed 60 billion tons. Simpson suggested that in order to keep the average global temperature from exceeding 2°C emission levels in 2030 should be just 20 billion tons. One way to think about this is that in 2030 every ton of carbon dioxide emitted must yield four to five times more economic value than a ton being emitted today.
Achieving this goal implies that the world’s economy must decarbonize at a rate of around 6 percent per year for the next 20 years. An analysis done in 2009 for the Copenhagen Consensus Center by McGill University economists Isabel Galiana and Christopher Green found that the world’s economy has been decarbonizing at a rate of just 1.3 percent [PDF] per year for the last 30 years.
A new report issued this week by Climate Interactive (a collaboration between MIT’s Sloan School of Management and the Ventana Systems consultancy) also found that to achieve the 2°C goal, the world economy must decarbonizes at a 5.8 percent rate, more than quadrupling the historical rate of 1.3 percent. But it gets worse, according to the Climate Interactive analysis, if countries wait to impose stringent emissions reductions until after 2020; decarbonization would have to rise to 8 percent per year. Interestingly, the latest reports note that in 2010 global carbon intensity actually increased by 0.6 percent rather than falling.
Obviously, a lot of brain and computer power have been devoted to calculating the suite of “ambitious” industrial policies needed to meet these emissions trajectories. In their models, the analysts and most of the folks here at the conference clearly see the climate “abyss” yawning before the world. But how much should we rely on prominent well-meaning energy experts to accurately discern the future?