23 September 2013: The twelfth session of the Intergovernmental Panel on Climate Change (IPCC) Working Group I (WGI-12) opened in Stockholm, Sweden. Over a four-day meeting, the WG is expected to finalize its findings on the physical science basis of climate change as part of the Fifth Assessment Report (AR5).

During the opening ceremony, statements were made by the WGI Co-Chairs Thomas Stocker and Dahe Qin, IPCC Chair Rajendra Pachauri, Halldór Thorgeirsson, UN Framework Convention for Climate Change (UNFCCC) Secretariat, on behalf of UNFCCC Executive Secretary Christiana Figueres, and the Swedish Environment Minister Lena Ek. Michel Jarraud, Secretary-General, World Meteorological Organization (WMO), and Achim Steiner, Executive Director, UN Environment Programme (UNEP), also addressed the Panel via video-recorded messages. Many of the speakers highlighted the increased scientific evidence of climate change, and the important role of the IPCC in informing the UN climate change negotiations working towards a new agreement by 2015.

Delegates then began to discuss, line-by-line, the Summary for Policy Makers of the WGI report, including the introductory section, as well as text following that section on observed changes in the climate system. Many modifications were suggested by delegates to add clarity, readability, and precision to the draft text. During lunchtime, delegates heard several scientific presentations on the language the IPCC uses to communicate uncertainty, temperature change, and changes in the cryosphere and oceans.

The IPCC WG I assesses the physical scientific aspects of the climate system and climate change. The main topics assessed by WG I include: changes in greenhouse gases (GHG) and aerosols in the atmosphere; observed changes in air, land and ocean temperatures, rainfall, glaciers and ice sheets, oceans and sea level; historical and paleoclimatic perspective on climate change; biogeochemistry, carbon cycle, gases and aerosols; satellite data and other data; climate models; climate projections, causes and attribution of climate change. [IISD RS Meeting Coverage] [Meeting Website] [Thorgeirsson’s Statement] [WMO Press Release]