Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Nature Climate Change: Action by 2020 key for limiting climate change

Limiting climate change to target levels will become much more difficult to achieve, and more expensive, if action is not taken soon, according to a new analysis from IIASA, ETH Zurich, and NCAR

This is a joint press release from the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria, ETH Zurich in Switzerland, and the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.

Limiting climate change to target levels will become much more difficult to achieve, and more expensive, if action is not taken soon, according to a new analysis from IIASA, ETH Zurich, and NCAR.

The new paper, published today in Nature Climate Change, explores technological, policy, and social changes that would need to take place in the near term in order to keep global average temperature from rising above 2°C, a target supported by more than 190 countries as a global limit to avoid dangerous climate change. This study for the first time comprehensively quantifies the costs and risks of greenhouse gas emissions surpassing critical thresholds by 2020. The findings of the study are particularly important given the failure of the recent climate negotiations in Doha to decide to increase mitigation action before 2020.

The authors show that the 2°C target could still be reached even if greenhouse gas emissions are not reduced before 2020, but only at very high cost, with higher climate risks, and under exceedingly optimistic assumptions about future technologies. The more emissions are reduced in the near term, the more options will be available in the long run and, by extension, the cheaper it will be to reach international climate targets.

"We wanted to know what needs to be done by 2020 in order to be able to keep global warming below two degrees Celsius for the entire twenty-first century," says Joeri Rogelj, lead author of the paper and researcher at ETH Zurich. The team of researchers analyzed a large array of potential scenarios for limiting global temperature rise to 2 °C above preindustrial levels, a target set by international climate agreements.

Projections based on current national emissions pledges suggest that global carbon dioxide equivalent (CO2e) emissions will reach 55 gigatons (billion metric tons, Gt) or more per year in 2020, up from approximately 50 Gt today. At such levels, it would still be possible to reach the 2°C target in the long term, though it would be more difficult and expensive than if near-term emissions were lower.

For instance, nuclear power would need to remain on the table as a mitigation option, or people would need to quickly adopt advanced technology strategies, including electric vehicles and highly efficient energy end-use technologies such as appliances, buildings, and transportation. Meanwhile, coal-fired power plants would need to be rapidly shut down and replaced with other energy sources. IIASA Energy Program Leader Keywan Riahi, who also worked on the study, says, "You would need to shut down a coal power plant each week for ten years if you still wanted to reach the two-degree Celsius target."

"If we want to keep as many options open as possible, we should aim to reduce global emissions to 41 to 47 gigatons of carbon dioxide equivalent per year by 2020", says Rogelj. According to the study, the only way to meet the long-term temperature target without carbon capture and storage is to ensure that emissions fall within this near-term range.

"What we do over the next eight years really determines the feasibility and choices that we have in the long term," says Riahi. "Some of these options for policies and technological change are still choices, such as phasing out nuclear power. We lose these choices if we overshoot certain thresholds."

The study goes beyond previous analyses by directly assessing how high emissions in 2020 can go before the long-term target of 2 °C is no longer attainable. "Under some conditions, the two-degree target is feasible even if we don't reduce emissions at all by 2020," says co-author Brian O'Neill, of the National Center for Atmospheric Research in Boulder, Colorado. "But if we allow for the possibility that some technologies may not pan out, or are overly costly or have undesirable consequences, then emissions reductions have to start this decade."

"Our analysis shows that we are very dependent on key technologies like carbon capture and storage and on land-consuming measures like afforestation and the cultivation of crops for biofuel production," says Rogelj. "If we want to become less dependent on massive implementation of these technologies to make it below two degrees Celsius, we need to reduce emissions by 2020 and use energy more efficiently."

The study highlights the importance of reducing energy demand and improving efficiency as perhaps the most effective way to mitigate climate change this decade, echoing previous work from IIASA and others (Global Energy Assessment, 2012). In scenarios with lower energy demand growth, the researchers find a much greater chance that global temperatures would not rise more than 2 °C, with much more flexibility in the methods and technologies required to reduce greenhouse gases.

"Fundamentally, it's a question of how much society is willing to risk," says IIASA energy researcher David McCollum, another study co-author. "It's certainly easier for us to push the climate problem off for a little while longer, but if we do that, then we risk that certain mitigation options may not ultimately be available in the long run. What's more, from the perspective of the global climate system, continuing to pump high levels of emissions into the atmosphere over the next decade only increases the risk that we will overshoot the two-degree target."

Rogelj, J., D.L. McCollum, B.C. O'Neill, and K. Riahi. 2012. 2020 emissions levels required to limit warming to below 2 _C. Nature Climate Change. doi:10.1038/NCLIMATE1758

Embargo Information
Journalists should seek to credit the relevant Nature publication as the source of stories covered. For more information on Nature's embargo policy, please see the Nature Web site:


ETH Zurich:

Joeri Rogelj, Institute for Atmospheric and Climate Science
Phone +41 44 632 82 79
Claudia Naegeli, Media Relations
Phone :+41 44 632 41 41
Email :
Keywan Riahi, IIASA Energy Program Leader
Phone: +43(0) 2236 807 491
David McCollum, Research Scholar, Energy Program
Phone +43(0) 2236 807 586
Katherine Leitzell, IIASA Communications:
Phone: +43(0) 2236 807 316 or
Brian O'Neill, Leader, NCAR Integrated Assessment Modeling Group
Phone: +1 303.497.8118
About IIASA:
IIASA is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policy makers to shape the future of our changing world. IIASA is independent and funded by scientific institutions in Africa, the Americas, Asia, Oceania and Europe.

About ETH Zurich:

ETH Zurich has come to symbolise excellent education, groundbreaking basic research and applied results that are beneficial for society as a whole. Founded in 1855, ETH Zurich has more than 17,000 students from approximately 80 countries, 3,700 of whom are doctoral candidates. Today, it offers researchers an inspiring environment and students a comprehensive education as one of the world's leading universities for technology and the natural sciences. 21 Nobel Laureates have studied, taught or conducted research at ETH Zurich, underscoring the excellent reputation of the institute.

About NCAR:

The National Center for Atmospheric Research (NCAR) is a US federally funded research and development center devoted to service, research and education in the atmospheric and related sciences. The National Science Foundation is NCAR's primary sponsor, with significant additional support provided by other U.S. government agencies, other national governments and the private sector.

Katherine Leitzell | EurekAlert!
Further information:

More articles from Earth Sciences:

nachricht Oasis of life in the ice-covered central Arctic
24.10.2016 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>