Averting a climate catastrophe won't be cheap, but it will be affordable as long as countries act urgently to set the wheels of a low-carbon transition into motion, the United Nations declared yesterday.
The report from the Intergovernmental Panel on Climate Change (IPCC) found greenhouse gas emissions steadily on the rise, growing more quickly between 2000 and 2010 than in any of the three previous decades. That's despite the global economic crisis, the creation of carbon markets and reams of city- and state-level policies worldwide aimed at curbing carbon.
If the world hopes to avert the worst impacts of warming and cut emissions 40 to 70 percent by midcentury, the next 15 years will be critical. After that, the report warns, options become more limited and the costs rise dramatically. But the good news, the panel found, is that the price of current solutions is "relatively modest" and governments are increasingly preparing to tackle the challenge.
"So many of the technologies that will help us fight climate change are far cheaper, more readily available and better performing than they were when the last IPCC assessment was released less than a decade ago," Secretary of State John Kerry said in a statement. "This report makes very clear we face an issue of global willpower, not capacity."
The report is the third and final in a series from the United Nations' climate science body detailing the physical evidence behind global warming, the hazards it poses to ecosystems and vulnerable populations and, finally, the range of solutions. Released yesterday in Berlin, it details about 1,200 scenarios for keeping emissions in check from wind and solar development to new car and building efficiency standards.
Global cooperation is essential
But none of them, IPCC Chairman Rajendra Pachauri warned, can be brought about without "an unprecedented level" of global cooperation.
"Effective mitigations will not be achieved if individual nations advance their interests independently," he said. "The high-speed mitigation train would need to leave the station soon, and all of global society would have to get on board."
In fact, the report comes at a key moment for international cooperation. Nations have agreed to establish a new global agreement on climate change at the end of 2015 with all countries for the first time playing a role in lowering emissions. Yet that process is riddled with divisions between rich and poor nations, and many involved in the IPCC process said those rifts spilled over into the negotiations over the report's summary for policymakers.
The United States, for example, objected to language pointing to the need for massive financial contributions from rich to poor countries. Developing nations chafed at an implication that they might soon have to take on a greater role in cutting carbon. A judgment call that the 1997 Kyoto Protocol "has not been as successful as intended" was watered down to read merely that the current treaty "offers lessons" toward achieving global goals.
And a section exploring the ethical issues surrounding how much burden nations of different levels of emissions and wealth should bear offered no concrete conclusions about the fairest way to divide up the job.
"We're operating in a much more complex landscape internationally than we were the last time countries negotiated," said Jennifer Morgan, director of the Climate and Energy Program at the World Resources Institute and an IPCC review editor for the chapter on international cooperation.
Harvard University economist Robert Stavins, a lead coordinating author for the same chapter, said the report reinforces the U.N. Framework Convention on Climate Change as the primary forum for developing a new deal, but also points to "serious action" happening in groups like the U.S.-led Major Economies Forum, the G-20 and bilateral agreements.
In order to keep global temperatures from rising beyond 2 degrees Celsius over preindustrial levels -- the United Nations' accepted limit for preventing the worst impacts of climate change -- nations will need to stabilize the concentration of CO2 in the atmosphere at 450 parts per million by the end the century. The concentration is currently around 400 ppm.
"None of this is going to happen on its own. Public policy is going to be required," Stavins said. "International cooperation is necessary. It's not just advisable, it's necessary."
Future options will be expensive
But the window for affordable action is closing fast. If nations are unable to lower emissions to between 30 billion and 50 billion metric tons by 2030 -- a 10 to 45 percent reduction from current levels -- the world will need to rely on carbon capture and storage technology to keep concentrations at an adequate level, said Leon Clarke, a coordinating lead author of the report's chapter on mitigation strategies.
"If you really delay ... you're banking on having to go with this one technology in the second half of the century and take on much more aggressive action," said Clarke, a senior scientist at the Joint Global Change Research Institute in College Park, Md.
But, he added, if the world keeps its carbon emissions under 50 billion metric tons per year, "it's an easier road from there on out."
If emissions aren't significantly reduced in the next couple of decades, scenarios show that the world will likely rely on the burning of biomass -- trees, agricultural waste and other plant matter -- for electricity, and storing the carbon dioxide it emits. This would lead to "negative emissions" because trees that support the development of biomass also absorb CO2 through photosynthesis. Therefore, biomass is considered carbon-neutral and the carbon capture would lead to an overall deficit in emissions.
"It provides a bit more flexibility for a more radical transformation," said Steven Rose, a lead author of the report and a scientist at the Electric Power Research Institute.
The concept of carbon neutrality is debated in the scientific community because not all biomass reduces emissions over the long term. The use of leftovers from the forestry industry destined for the landfill is more sustainable that using whole, large trees, for example.
Policymakers should not consider carbon capture as the only solution, said Clarke. But other options, reducing reliance on fossil fuels, will be limited if they don't act now.
"It's true that it's a useful technology, but it's definitely not true that all of the scenarios reaching that goal rely on [carbon dioxide removal]," Clarke said.
Emissions from forests and land use drop
While most sectors -- electricity, transportation, and industry, for example -- are expected to see CO2 emissions increase, emissions from land use, agriculture and forests is the only area that will see a decrease, according to the report.
"We're planting more trees and we're cutting down fewer trees; we're degrading forests less," said Pete Smith, a professor of soils and global change at the University of Aberdeen in Scotland and a coordinating lead author of the report. International efforts to conserve forests for biodiversity will provide benefits to help control climate change, he added.
Bioenergy, the generation of electricity and fuels from plant matter, plays a "critical role" in cutting carbon emissions, although the scientific debate on the overall impact remains unresolved, wrote the authors. There are also concerns over biofuels' effects on water resources, biodiversity and human communities, say the authors (see related story).
Reducing Emissions from Deforestation and Forest Degradation, a U.N.-backed mechanism that would pay countries to keep forests standing, is a promising effort, but there is little scientific evidence to support its benefits, say the authors.
Meanwhile, the growth in renewable energy technologies is another silver lining. The energy supply sector is the top contributor to global emissions and remains on track to double or even triple by 2050, according to the report. New coal-fired power in the developing world is the largest contributor to this increase, it notes.
In the near term, fuel switching from coal to natural gas could lower the sector's emissions. But even the relatively lower emissions level of natural gas depends on a number of caveats such as power plant efficiency and, extended over a longer time frame, carbon capture and storage.
"From an energy perspective, the growth of gas is a big deal," said James Edmonds, Battelle fellow with the Pacific Northwest National Laboratory and co-author of the energy systems chapter of the report. "From a climate perspective, maybe less so." Gas reduces carbon emissions when it displaces coal, he said, but raises them when it displaces renewables or nuclear power.
Emissions from buildings gain notice
The report also devotes an entire chapter to buildings, which make up 34 percent of global final energy use, leading to 8.8 gigatons of direct and indirect carbon dioxide emissions, according to the draft summary.
"That's their relevance to the problem," said Christopher Pyke, vice president for research at the U.S. Green Building Council and co-author of the buildings chapter. "The flip side of that is that buildings are regarded to have some of the most cost-effective greenhouse gas mitigation strategies of any sector."
In the time since the last assessment report in 2007, Pyke acknowledged that much of the fundamental understanding of how buildings influence emissions is the same, but now there is a large body of demonstrations, including offices that have net zero energy consumption, passive energy standards and home retrofits.
Even with billions of square feet of new real estate under construction in countries like India and China, efficiency measures like better insulation and low-energy lighting could slow and even reduce emissions from buildings, according to the draft report summary.
Doing this will require voluntary efficiency standards to drive the global construction and retrofit market, as well as robust measurement and validation to ensure that double-glazed windows and smart thermostats are truly paying off.
"We have to understand that we have to manage these efficiency technologies across their entire life cycle," Pyke said. "When you build a home, you're building a thing that's going to last 100-plus years in the United States. Even though they will individually be small, those emissions will add up."
Put together, the costs reaching that 450 ppm goal by the century's end entail a median global consumption loss of 4.8 percent, the report finds. Ottmar Edenhofer, co-chairman of one of the IPCC working groups, said that does not mean the global community must sacrifice economic growth. The cost estimates also exclude the co-benefits of reining in emissions, he noted.
"We are clearly arguing that achieving these goals is a huge institutional challenge. We are not saying this is a free lunch. But we are saying this is a lunch worthwhile to buy," Edenhofer said. "It does not cost the world to save the planet."
Reporters Umair Irfan, Nathanael Massey and Stephanie Paige Ogburn contributed.