If the world continues down its current carbon-spewing course, global temperatures will hit a staggering 4.8 degrees Celsius above preindustrial levels by the end of the century, with potentially disastrous consequences for humanity, ecosystems and sustainable development, according to a new report by the U.N. Intergovernmental Panel on Climate Change (IPCC).
The report, "Climate Change 2014: Mitigation of Climate Change," is the third of three Working Group Reports, which make up the IPCC's fifth Assessment Report on climate change. Produced by 235 authors from 58 countries, the report analyzed close to 1,200 climate scenarios investigating the economic, technological and institutional requirements for meeting global climate goals.
Based on this analysis, the report found that stabilizing global temperature rise at 2 degrees Celsius over preindustrial temperatures—the limit considered by many scientists to be safe — will require lowering greenhouse gas emissions (GHG) by as much as 70 percent compared to 2010 numbers by mid-century and reaching near-zero emissions by 2100.
Between 2000 and 2010, global GHG emissions increased by the equivalent of 10 billion tons of carbon dioxide (CO2), the report says. Half of all human CO2 emissions between 1750 and 2010 have occurred in the last 40 years. Mashable recently reported that the amount of CO2 in Earth’s atmosphere has, for the first time, exceeded 402 parts per million (ppm) -- higher than at any time in at least the past 800,000 years. CO2 is one of the longest-lived GHGs, which means the emissions that have and continue to pump into the atmosphere will remain there for centuries.
Scenarios show that to have a likely chance of limiting the increase in global mean temperature to 2 degrees Celsius means lowering global greenhouse gas emissions by 40 to 70 percent compared with 2010 by mid-century -- and to near-zero by the end of this century. Ambitious mitigation may even require removing carbon dioxide from the atmosphere. IPCC says scientific literature confirms that even less ambitious temperature goals would still require similar emissions reductions.
“Climate policies in line with the 2 degrees Celsius goal need to aim for substantial emission reductions,” said Ottmar Edenhofer, one of the three co-chairs of IPCC Working Group III. “There is a clear message from science: To avoid dangerous interference with the climate system, we need to move away from business as usual.”
But don’t freak out just yet. Many fast actions for addressing climate change are proving to be more affordable than previously imagined, IPCC says. For example, actions to improve energy efficiency through new building codes and vehicle efficiency standards can significantly reduce emissions without harming people's quality of life. A recent report by the American Council for an Energy-Efficient Economy (ACEEE) found that energy efficiency programs aimed at reducing energy waste cost utilities only about 3 cents per kilowatt hour, while generating the same amount of electricity from sources such as fossil fuels can cost two to three times more.
Renewable energy technologies, such as wind and solar, are becoming cheaper to produce and deploy.
Estimates of the economic costs of mitigation vary widely, IPCC says. In business-as-usual scenarios, consumption grows by 1.6 to 3 percent per year. Ambitious mitigation would reduce this growth by around 0.06 percentage points a year. However, the underlying estimates do not take into account economic benefits of reduced climate change.
The IPCC report also emphasizes the importance of quickly addressing emissions sources, which can reduce warming while producing co-benefits for human health and ecosystem impacts. Several recent studies have shown that addressing short-lived climate pollutants (SLCPs), including black carbon soot, methane, tropospheric ozone and hydrofluorocarbons, can produce significant near-term climate benefits while also improving human health, food security and energy security.
"Cutting short-lived climate pollutants [SLCPs] could cut the current rate of climate change in half by 2050, while preventing more than 2.4 million air-pollution related deaths a year and avoiding around 35 million tons of crop losses annually," said Durwood Zaelke, president of the Institute for Governance and Sustainable Development. "Cutting SLCPs is one of the best ways to reduce impacts over the next 50 years and beyond."
Fast mitigation and co-benefits are particularly high where currently legislated and planned air pollution controls are weak, the IPCC report says.
"We have the technologies to cut the short-lived pollutants today," Zaelke added. "This includes phasing down HFCs under the Montreal Protocol and using other complementary initiatives such as the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants, the only global effort focusing on these pollutants."
In the United States, President Barack Obama’s Climate Action Plan has finally established some semblance of a comprehensive national climate change strategy. Some of the policies outlined in the plan, such as the Environmental Protection Agency’s impending carbon rules for existing power plants, could achieve even greater GHG reductions than previously thought — and at less cost. This is a good start, but much more needs to be done. Even if the U.S. one day achieves carbon neutrality, it will all be for naught if emerging economies such as India and China continue to spout CO2.
Global warming is, after all global warming.
Image Credit: Flickr Daryl Mulvihill
Based in San Francisco, Mike Hower is a writer, thinker and strategic communicator that revels in driving the conversation at the intersection of sustainability, social entrepreneurship, tech, politics and law. He has cultivated diverse experience working for the United States Congress in Washington, D.C., helping Silicon Valley startups with strategic communications and teaching in South America. Connect with him on LinkedIn or follow him on Twitter (@mikehower)