Update: Joint PCIC & PICS Briefing on Recent IPCC Report Release

Just hours ago, PCIC and the Pacific Institute for Climate Solutions hosted a special briefing for members of the public and media, on the recently released Physical Science Basis section of the IPCC's 5th Assessment Report (AR5). In addition to the roughly 160 attendees at the Wosk Centre for Dialogue, in Vancouver, 345 people tuned in via webcast to hear about the latest findings shared in the IPCC report and what these mean for the province of BC.

PCIC Director and Vice Chair of the IPCC’s Working Group I, Dr. Francis Zwiers, spoke first, introducing the rigorous and transparent drafting process of the report that was just released. He explained how the drafting process involves hundreds of climate scientists compiling the most important findings from thousands of articles in the peer-reviewed literature into a concise, distilled summary of our current understanding of the Earth's climate system that is subject to multiple rounds of careful review.

Dr. Greg Flato from the Canadian Centre for Climate Modelling and Analysis then spoke about selected findings from the report. Among these, he noted the close agreement between climate model output and observations down to spatial scales smaller than continents, which forms a part of the detection and attribution literature. In addition, he discussed the increase of atmospheric greenhouse gas concentrations and the consequent anthropogenic warming of the climate system, decrease in sea ice and increase in ocean acidity. He also covered projections of the future climate assuming various atmospheric greenhouse gas concentrations in which we see further warming of the atmosphere and ocean, and further reductions in Arctic sea ice cover (for more information, read the summary of the main findings of the report: Briefing Headline Statements (IPCC)). He was followed by Dr. Zwiers, who detailed the changes to BC's climate that we have already observed, including significant warming over BC's winter and summer seasons. He also discussed projected changes to BC's climate, assuming a moderate emissions scenario, which included further warming in the winter and summer as well as changes to the hydrology of interior river basins. While changes to BC's temperature were clear in both the observations and projections, changes to precipitation in the winter and summer could not be discerned with the same confidence (for a brief summary of these changes to BC's climate, read the Briefing Factsheet (PCIC)).

In the question and answer period, Dr. Flato noted that the different pathways of atmospheric greenhouse gas concentrations diverge near the middle of the century and Dr. Zwiers offered the climate-exacerbated spread of the mountain pine beetle as an example of an impact that we have already seen here in BC (PCIC scientists have recently authored two papers on the impacts of climate change on BC's forests, see here for more). When asked if there were any surprises that arose in the report, Dr. Flato said that there are few real surprises in the report, because it draws from findings that have already been published in journals and because the findings of the current report are in line with the findings of the previous IPCC reports. Dr. Zwiers added that our understanding and confidence in estimates of climate sensitivity had strengthened. The authors also discussed the eleventh chapter in the report, dedicated to decadal predictions, that finds that, over large regions of the planet and in the global mean, predictions of average temperature exhibit positive skill. The authors offered an example of the challenges faced in this undertaking: though changes to the Atlantic Meridional Overturning Circulation can be predicted, this did not necessarily translate to predictable temperature changes over land. When asked about what scenario to look at if we overshoot even those scenarios used by the IPCC that lead to the greatest concentrations, Dr. Zwiers noted that the scenarios can be viewed in terms of time rather than simply emissions. Looked at this way, a projection for the 2100s that assumes a certain amount of carbon dioxide in the atmosphere can be read as a projection for the 2070s, under the assumption of a greater amount of carbon dioxide in the atmosphere.

Climate Change 2013: The Physical Science Basis, the contribution of Working Group 1 to the IPCC's 5th Assessment Report is available online. The related Summary for Policymakers is also available online.