09 July 2014

Climate change - what next?

Options Magazine, Summer 2014: How IIASA research and the IPCC’s Fifth Assessment Report are changing the narrative on climate change mitigation, impacts, and adaptation.



Whatever happens in Paris and other current policy processes, negotiators will base much of their talks on the new IPCC Fifth Assessment Report (AR5) released in 2013 and 2014. The report provides a wealth of information, not only on the physical science of climate change, but also on the benefits that climate policy could have for the environment, human health, and economic development, as well as the potential impacts and risks of climate change.

IIASA research played an important role in the new report, particularly in Working Groups II and III, which focus respectively on climate change impacts and mitigation. Nineteen IIASA researchers contributed to the AR5 as authors or reviewers. Countless IIASA publications were also cited in the report.

IIASA Director General and CEO Professor Dr. Pavel Kabat says, “IIASA’s systems analysis approach is key for addressing global problems such as climate change. The IPCC’s Fifth Assessment Report incorporates this viewpoint even more than previous reports.” 

“The IPCC AR5 clearly demonstrates that adaptation and mitigation are becoming more urgent. Any further delays in avoiding dangerous climate change render our actions more difficult and costlier,” says IIASA Deputy Director General and Deputy CEO Professor Dr. Nebojsa Nakicenovic, a lead author on the new report.

“Stabilization of climate change at two degrees will bring huge potential co-benefits for human development and well-being. It will also avoid exceeding planetary boundaries, such as ocean acidification and biodiversity loss,” he adds.

Climate change affects us all

“Nobody on this planet is going to be untouched by the impacts of climate change,” IPCC chair Rajendra Pachauri said at the launch of the IPCC WGII report in March 2014.

One big question is where and how climate change will affect human beings. IIASA research with the Potsdam Institute for Climate Impacts Research has brought a new clarity to that question, in part through a unique model intercomparison project, ISI-MIP. The project results, published in a special issue of the journal Proceedings of the National Academy of Sciences, showing that the impacts of climate change could be greater than expected in areas ranging from water availability, health, and agriculture, provided important evidence for the new IPCC report.

A shift towards climate risk management

The AR5 also brings a change in thinking on adaptation strategies, reflecting new evidence on climate-related impacts and strategies for risk management. “The fifth assessment report essentially takes a risk‑management approach, which lays out potential risks from a warming climate across natural and social systems, the potential for adaptation, as well as the limits to adaptation,” says Reinhard Mechler, a lead author on Working Group II report’s technical summary and Chapter 17, which focuses on the economics of climate adaptation.

“This focus on risk represents a fundamental shift in thinking, which should lead to better informing decisions on mitigation as well as adaptation,” says Mechler.

Mechler and researcher s in IIASA’s Risk, Policy, and Vulnerability Program were authors on the IPCC’s 2012 special report, “Managing the Risks of Extreme Disaster,” which provided a new focus on risk management that fed into the AR5. The report showed that climate change will not only lead to rising sea levels and temperature, but also increases the risks from extreme weather. It also identified a need for increased efforts to help communities and countries adapt to the growing risks of extreme weather, linked to human-caused climate change. Mechler says, “The thinking developed in that report was crucial for AR5. It gave scientists a much better understanding of risk and risk management.”

“We are not doomed”

While much of the IPCC report focuses on better cataloging the potential dangers of climate change, the Working Group III report on climate change mitigation brought a much more expansive view of the possibilities for action.

“We are not doomed,” says IIASA researcher Volker Krey, a lead author of the report. “If we want to limit climate change, there are a number of possible ways to do this.”

The IIASA-led 2012 Global Energy Assessment (GEA), for example, provided 41 pathways for energy systems transitions that would allow the world to limit climate change to the 2°C target, while also bringing energy to people currently living without access to clean modern energy, and cutting air pollution worldwide.

The GEA also provided the groundwork for research on the multiple co-benefits of climate action, showing that climate policies would also improve energy security and reduce the health burden of air pollution. The GEA was a key input into AR5, with 40 GEA authors contributing as lead authors to the IPCC report. But even with all these possibilities and benefits of climate action, in the real world, climate agreements have proven difficult to conclude. So IIASA researchers have also begun to examine in detail what could happen without a climate deal.

Recent research from the IIASA Energy program shows that in the absence of such a global agreement, voluntary pledges for emissions reductions to 2030 are far below what they need to be in order to meet climate targets. While it could still be possible to reduce emissions starting from a higher level in 2030, it would become far more difficult and expensive, and the options for mitigation decrease. “There is not much time to fundamentally change the system,” says IIASA Energy Program Director Keywan Riahi. “Delays will not only increase the cost significantly, but would also require a global energy transformation at a pace that will be historically unprecedented.”

Another study showed that technologies for removing carbon from the atmosphere may become necessary. For example, bioenergy with Carbon Capture and Storage (CCS) could be used to limit climate change in the future. However, relying on CCS is a risky choice, the researchers say, because it has not been proven to work at large scale, and it may prove politically unpopular in some countries or regions. “CCS could buy us time,” says Krey. “But what if it doesn’t work? It’s a risky strategy.” With the new report in hand, negotiators in Paris will have thousands of pages of evidence pushing them toward action, as well as clear guidance about potential outcomes of their action. What happens will ultimately depend on politics, and on public opinion in the IPCC member countries. But the links between climate, policy, and socioeconomics are becoming ever clearer.

A look ahead

The research in the Fifth Assessment Report is already old news to the researchers who worked on it. They are already well into work on a new framework that will streamline the IPCC reporting process and better integrate the work between different disciplines, which began with the Representative Concentration Pathways used in AR5, and is continuing with the development of the Shared Socioeconomic Pathways (SSPs).

The SSPs are five scenarios that provide different explanations of how the future will develop. But unlike previous scenarios used by the IPCC, the SSPs provide a consistent set of assumptions, across academic fields, which researchers can use to provide input to their models, whether they are examining wheat yield in Africa or the future availability of drinking water in Africa. Three different research communities are working together to develop the SSPs: climate modelers, who focus on physical science, integrated assessment modelers, who examine the connections between economics and policy, and experts in impacts, adaptation, and vulnerability, all of which are represented in IIASA research programs.

Text by Katherine Leitzell

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Last edited: 11 September 2014


Nebojsa Nakicenovic

Distinguished Emeritus Research Scholar Transformative Institutional and Social Solutions Research Group - Energy, Climate, and Environment Program

Keywan Riahi

Program Director and Principal Research Scholar Energy, Climate, and Environment Program

Principal Research Scholar Integrated Assessment and Climate Change Research Group - Energy, Climate, and Environment Program

Principal Research Scholar Pollution Management Research Group - Energy, Climate, and Environment Program

Principal Research Scholar Sustainable Service Systems Research Group - Energy, Climate, and Environment Program

Reinhard Mechler

Research Group Leader and Senior Research Scholar Systemic Risk and Resilience Research Group - Advancing Systems Analysis Program

Volker Krey

Research Group Leader and Principal Research Scholar Integrated Assessment and Climate Change Research Group - Energy, Climate, and Environment Program

Principal Research Scholar Sustainable Service Systems Research Group - Energy, Climate, and Environment Program

Options Summer 2014


Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change

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