The latest on climate change from IPCC

Submitted by Arthur Dahl on 4. November 2014 - 1:50

The latest on climate change from IPCC

report by Arthur Dahl

The Intergovernmental Panel on Climate Change (IPCC) completed the work on its Fifth Assessment Report with the approval of the Synthesis Report in Copenhagen on 1 November 2014. On 3 November I was able to attend a presentation of the most important findings of the report during four hours at the University of Bern, Switzerland, by the Chair of the IPCC, the Co-Chairs of Working Group I and key contributors to the report, in the presence of the Swiss Minister for the Environment, Transportation, Energy and Communication.

The new Synthesis Report combines the content of the three Working Group reports I (the physical science basis), II (impacts, vulnerabilities and adaptation) and III (mitigation of climate change) into an integral perspective and emphasizes cross-cutting issues. Over 800 scientists have worked for 5 years and reviewed thousands of scientific papers and petabytes of data to update the best available science on climate change as the basis for government action through the UN Framework Convention on Climate Change meeting in Lima in December and in Paris next year.

The language of this report is the strongest ever. "Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems. Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen. Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century. In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate."

"Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks. Surface temperature is projected to rise over the 21st century under all assessed emission scenarios. It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions. The ocean will continue to warm and acidify, and global mean sea level to rise. Climate change will amplify existing risks and create new risks for natural and human systems. Risks are unevenly distributed and are generally greater for disadvantaged people and communities in countries at all levels of development. Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases."

It is worth emphasizing that the quotes above are based on the best scientific literature and have been reviewed word by word and agreed as accurate by all the governments in the IPCC.

Some of the new conclusions are quite striking. The past three decades have all been successively warmer. It is the oceans that have been absorbing 90% of the heat, raising ocean temperatures. Climate change impacts are already under way. Greenhouse gas emissions have accelerated since 2000 and are higher than they have ever been in the earth's history. Of a total carbon budget for greenhouse gases of 790 gigatonnes of carbon, we had already emitted 515 by 2011, leaving only 275 remaining before we overshoot the 2°C limit. The window for action is rapidly closing, and we must have a carbon-neutral economy by the end of the century, with a major reduction in carbon emissions of 40-70% already by 2050. Without mitigation, we face a very high risk of severe, widespread, and irreversible impacts globally. In their language, this means a greater than 95% confidence limit. The impacts already attributed to climate change show how sensitive human and natural systems are. For example, they say there is no way to save coral reefs (my own scientific specialty), even with only 2°C of warming.

We have the technologies to make the transition, and it would cost only 0.06% of global GDP annually, much less than the costs of a rapidly changing climate and rising seas. There appear overall to be strong economic and social benefits from the transition, but obviously the fossil fuel and transport parts of the economy would lose out and will resist any change.

On the human side, climate change will amplify existing risks and create new ones, and these risks are not evenly distributed. The report redefines vulnerability as a propensity and predisposition to experience harm. Human inequalities drive vulnerabilities to climate change. It is marginalized groups, by gender, race, class or ethnicity, in every society, that will suffer the most.

One of the significant innovations in the 5th Assessment has been the inclusion for the first time of the ethical dimension, especially in chapter 3 of the Working Group III report. Prof. John Broome of the University of Oxford, one of the authors of this part of the report, emphasized at the meeting that climate change is an ethical problem. People, mostly the wealthy, who generate greenhouse gases, harm other people, especially the poor, while delaying mitigation shifts the burden to future generations. Policy makers who must pick among options must make ethical judgements, and while the IPCC is not prescriptive, it has provided a framework for these judgements. Economics also makes moral judgements, like having enough life boats on a ship in the unlikely event that it sinks. In the case of climate change, the science shows similar events with a low probability but very high consequences.

Prof. Broome explained that morality or ethics can take two perspectives, and raise a series of relevant questions. The first perspective is what is owed to people, their rights and duties, generally labeled as justice or equity. For example, how should the burden of action be shared? How should we respond to the injustice to the poor? How do we consider historical responsibility?

The second perspective is one of values, promoting good and preventing harm, making the world a better place. How do we ensure the well-being of people? How do we protect the natural value of species and ecosystems? What is our responsibility for cultural values? Beyond this, how can different values be combined, be aggregated, or weighed against each other? How do we weigh the well-being of future generations against those being asked to sacrifice now? Money has a different value for the poor and the rich, with the same amount allowing one to educate a child, and the other to have a night out. This is ignored in most cost-benefit analysis, which thus systematically discriminates against the poor.

As the Synthesis Report puts it: "Effective decision making to limit climate change and its effects can be informed by a wide range of analytical approaches for evaluating expected risks and benefits, recognizing the importance of governance, ethical dimensions, equity, value judgments, economic assessments and diverse perceptions and responses to risk and uncertainty." Let us hope that the politicians acknowledge their ethical responsibility.

You can download the Synthesis Report summary for policy makers of 40 pages at

Last updated 11 December 2014