Statement on Tropical Cyclones and Climate Change Purpose: “The Sixth Workshop was attended by 125 delegates from 34 different countries and regions. The Statement has been requested by WMO leadership and many heads of National Meteorological and Hydrological Services so they can respond to questions from the media, and also to assist in advising their governments on future activities and how to respond to climate change effects”.

Sequence of events Henderson Sellers et al., Bams: 1998 IWTC-5: Decision made to prepare background material for updated statement 2005: Papers by Emanuel and by Webster et al. Record hurricane season, Hurricane Katrina November 2005: TMRP Committee TC2, Climate Change Impacts on Tropical Cyclones, was re- formed to respond to these events February 2006: A Statement on Tropical Cyclones and Climate Change presented to CAS-14.

Procedure to produce current document Starting point –Working Group Reports for all of Topic 4 of this Workshop (Climate variability and Seasonal Prediction of TC’s) –Working Group Report 4.2: Knutson et al., Possible relationships between climate change and cyclone activity –The February 2006 Statement –Henderson Sellers et al., Bams: 1998 John McB developed a document, based entirely on these sources. Then a week of high volume s with a smaller subgroup to refine and modify (Emanuel, Landsea, Knutson, Chan, C-Y Lam) Special Session on last Friday night –Expose the Statement to Emanuel, Holland in presence of Gray, Klotzbach, Landsea etc. –Draw ideas and comments from the floor to make the statement representative of the views of this entire workshop (not just the researchers –Two new major points came out of the Friday meetingIWTC-5: Decision made to prepare background material for updated statement Extensive rewrite, discussion and traffic over the past weekend.

Components of the Science A) Observed warming of oceans B) Is the observed ocean warming due to anthropogenic increases of greenhouse gases C) Is there a detectable signal of increases in tropical cyclone activity in the observational record D) If the climate warms, what will be the impact on tropical cyclone behaviour We, the IWTC community, are the appropriate community to make a statement on c) d). We are not the appropriate experts to discuss or make a statement on a), b).

AGENDA Read Executive Summary –Discussion Read other key paragraphs –Discussion Read paragraphs on –Reconnaissance: Discussion –Uniformity: Discussion Recommendations within the document –Discussion Recommendations about the document –Discussion

Recommendations about the document Small group with appropriate technical knowledge to redraft paras on reconnaissance and on uniformity That this Workshop endorses the Statement as being an outcome of the workshop Request that WMO sends statement to heads of all NHMS Request that either WMO or this Workshop release it publicly through a press release That we (Project TC2) send it to BAMS and request they publish it as an outcome of this meeting That WMO/AREP place the Statement prominently on the WMO website

J.mcbride bom.gov.au