by Judith Curry
A fascinating look at the how the deliberations in Stockholm influenced the final IPCC AR5 WG1 Summary for Policy Makers
The iisd is a reporting service for environment and development negotiations. They provide fascinating context and details regarding the negotiations last week in Sweden: Summary of the 12th session of Working Group I (WGI) of the Intergovernmental Panel on Climate Change (IPCC) and the 36th session of the IPCC.
Below are excerpts related to topics under recent discussion:
Via a video message, WMO Secretary-General Michel Jarraud highlighted that the improved knowledge on anthropogenic contribution to climate change forms the basis for mitigation and adaptation action. Noting the strengthened evidence on temperature increase, sea level rise, glacier melt, and extreme weather events, Jarraud said that the work of WGI is also central to the negotiations towards a climate agreement in 2015. He welcomed the special attention the IPCC has given to the socio-economic aspects of climate change, for example of monsoon rains and El Niño.
Via a video message, UNEP Executive Director Achim Steiner underscored that, while the science keeps evolving, the great challenge of climate change demands new policies in all sectors. In the context of the UNFCCC working towards a new agreement in 2015, Steiner highlighted that the work of the IPCC is important for better understanding both what is happening in the climate system and the benefits of climate action in terms of new jobs, markets and opportunities for the green economy.
Halldór Thorgeirsson, on behalf of UNFCCC Executive Secretary Christiana Figueres, stressed that AR5 goes further to meet the needs of the UNFCCC than previous assessments. He also highlighted the ongoing review process under the UNFCCC of the agreed 2ºC upper limit for global temperature rise.
Lena Ek, Minister for the Environment, Sweden, welcomed participants, recalling the 40th anniversary of the International Conference on the Human Environment in Stockholm celebrated in 2012. She underscored that the effects of climate change can already be seen in the Nordic countries, and announced the launch of “The New Climate Economy” initiative on 24 September 2013 in New York.
OBSERVED CHANGES IN THE CLIMATE SYSTEM: On the headline statement, which states that warming of the climate system is unequivocal and, since 1950, many of the observed changes are unprecedented over decades to millennia, Saudi Arabia said the statement was “alarmist,” urged qualifying the terms “unequivocal” and “unprecedented,” requested using the year 1850 instead of 1950, and called for a reference to slowed warming over the past 15 years.
Germany, Australia, Chile, Spain, Fiji, New Zealand, the US, Saint Lucia, Tanzania, Mexico, Slovenia, the UK and others supported the statement as presented, with Germany pointing out that AR4 concluded almost the same. Canada pointed out that factors other than warming will be the emphasis in the future. The Russian Federation proposed “changing,” rather than warming of the climate system. After some discussion, Saudi Arabia agreed to accept the statement as presented.
Atmosphere: Addressing the keynote statement to the sub-section, Germany, supported by Belgium and Ireland, argued for an opening sentence singling out the fact that the first decade of the 21st century has been the warmest decade since 1850. The WG Co-Chairs and CLAs suggested focusing on 30-year time periods due to the multi-decadal nature of global warming. Canada proposed adding the word “successively” for the sentence to read that: “Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.” This language was supported by the CLAs, Slovenia, the US, Austria, the Netherlands, New Zealand, and Trinidad and Tobago, and eventually accepted.
Extensive discussion took place throughout the week on text on global temperature increase both in plenary and informal consultations. The text initially referred to both: global mean temperature increase during the period 1901-2012, and temperature change between 1850-1900 and 1986-2005. Debate revolved around, inter alia: reference years used; whether to discuss these two concepts in a single bullet point, which, some said, would lead to confusion among policy makers; placement of text on temperature change; and use of the term “pre-industrial.” The US cautioned against mixing information from trends with information from differences between time periods, and suggested two separate bullet points. While some countries called for using the period 1850-1900, the CLAs clarified regional trends were sparse prior to 1901, and noted the availability of three datasets for the period 1880-2012, and one going back to 1850 for global temperature.
On temperature change between 1850-1900 and 1986-2005, Canada, supported by Belgium and the US, proposed providing context for the two time periods, referring to the former as the early instrumental period, and the latter as the AR5 reference period used for projections. Delegates debated at length whether to place this text in the observations or in the projections section. Delegates also discussed whether to use the term “pre-industrial” for the period 1850-1900, with some countries suggesting this would lead to confusion as in other places, “pre-industrial” refers to 1750.
After a series of informal consultations, compromise text was introduced, which included two bullet points in the observations section, one relating to a linear trend in global temperature increase of 0.85°C over the period 1880 and 2012, when multiple datasets exist, and another, on regional trends for 1901-2012. The group also agreed to insert text into the chapeau of the section on future climate change, which, among other things, clarifies that considering observed changes between different periods is necessary to place projections in historical context.
On lower rates of warming in the last 15 years, there was broad agreement on the underlying science as well as on the importance of addressing the phenomenon in the SPM, given the media attention to this issue. A lengthy discussion occurred regarding how to communicate the underlying scientific explanation clearly and in an accessible manner to policy makers to avoid sending a misleading message.
Germany, supported by Belgium, Luxembourg and others, suggested adding that the rates of warming were higher in the preceding 15-year period. Norway noted that only periods of 30 years are sufficient to draw conclusions about rates of temperature change as defined in the glossary of the report. The US, with Belgium, Luxembourg and others, proposed adding that the rate of warming since the late 1990s is very sensitive to the choice of a start year, referring to a strong El Niño effect in 1997-1998. The latter suggestion was taken on board in a slightly modified form.
The US, with Brazil, further suggested adding actual estimates of the rate of warming for 15-year periods using different starting years, to which a CLA responded that this was not evaluated in the underlying assessment. During informal consultations, CLAs did calculations in response to the suggestion by the US, and a related footnote was subsequently approved by the WG noting that “trends for 15-year periods starting in 1995, 1996 and 1997 are 0.13 (uncertainty interval: 0.02 to 0.24), 0.14 (0.03 to 0.24), and 0.07 (-0.02 to 0.18) ºC per decade, respectively.”
Concerning text on the Medieval Climate Anomaly, Belgium and Ireland underscored that this phenomenon was regional in nature, unlike global warming in late 20th century, and suggested clarifying language to reflect this. Canada, supported by Norway, raised the issue of the Arctic experiencing a greater increase in surface temperature than globally, and text on this was introduced in other parts of the SPM.
Evaluation of Climate Models: Participants debated extensively the text dealing with simulated and observed trends in global mean surface temperature in the long and short term. Co-Chair Stocker emphasized the need to address discussions currently taking place among policy makers regarding the past 10-15 years and said that “now is the time for the IPCC to make a statement to the outside world.” The US said that a period of 10-15 years is too short for model evaluation. The most contentious point concerned differences between simulated and observed short-term trends. The US, Austria, Saudi Arabia, the Russian Federation, Germany, Belgium and others supported reference to 10-15-year periods in general. China maintained that reference should only be made to the past 15 years. Informal consultations did not result in agreement, and the Co-Chair proposed, and China accepted, a compromise to include in parenthesis “e.g., 1998-2012.”
On the explanation of the observed reduction in the surface warming trend over the period 1998-2012, Saudi Arabia strongly urged incorporating language from the Technical Summary on models overestimating the warming trend. The CLAs advised against including this statement in the SPM, noting that: the research is currently inconclusive; overestimation of the models is too small to explain the overall effect and not statistically significant; and it is difficult to pinpoint the role of changes in radiative forcing in causing the reduced warming trend, with Co-Chair Stocker referring to this issue as an “emerging science topic.”
Switzerland proposed including the language suggested by Saudi Arabia, together with an explanation of the level of confidence. Germany questioned the adequacy of that language. The suggestion by Saudi Arabia was incorporated in the SPM text.
On Thursday morning, Germany and the UK said that their objections were not noted the previous evening when a sentence on overestimates in some models introduced by Saudi Arabia was adopted. Saudi Arabia, supported by Sudan, expressed grave concerns in opening up agreed text, emphasizing that “we are in dangerous waters,” while Sudan added that opening up agreed text raises the issue of equal treatment of countries. No changes were made to the text.
Quantification of Climate System Responses: On equilibrium climate sensitivity, several delegations, including Australia, the Netherlands and others, noted that the message that the lower limit of the assessed “likely” range of climate sensitivity is less than the 2°C in the AR4 can be confusing to policy makers and suggested noting it is the same as in previous assessments. The CLAs explained that comparison to each of the previous IPCC assessments would be difficult, and new language was developed adding that the upper limit of the assessed range is the same as in AR4.
On GHG metrics, the text was endorsed by Austria, the Netherlands, Slovenia and New Zealand, and opposed by Brazil, who called for informal consultations, explaining this was one of the most important issues in AR5 for his delegation due to different policy implications of the choice between Global Warming Potential and Global Temperature Potential as a metric. A revised text was developed by an informal group and accepted approved by the WG.
Detection and Attribution of Climate Change: In drafting the keynote message, the UK suggested adding a sentence that explicitly notes increased evidence of anthropogenic influence since the AR4. This was supported, with several different wording suggestions, by Slovenia, Switzerland, Canada, Fiji, Saint Lucia and Germany, and opposed by Saudi Arabia. A contact group developed a proposal that included text suggested by the UK.
Canada proposed including Arctic warming in the context of explaining warming of continental regions, and additional language was developed.
JC comment: not sure what to say here, other than that this is very high-level motivated sausage making indeed. But how do they claim they are policy neutral?