Tuesday, February 4, 2014

Scientific workshop concludes there is no proof of a link between Arctic climate change and the polar jet stream

A report published today from a recent international workshop on the polar jet stream and Arctic climate change concludes that the observational "record is too short to rigorously/statistically provide sufficient scientific proof [of a linkage between them]. Consequently there is still skepticism and uncertainty in these areas." The workshop also concludes that IPCC climate models are unable to adequately model changes in the jet stream or polar vortex to be used in support of a link.

Of course, this doesn't stop irresponsible climate alarmists such as Michael Mann, Jennifer Francis, Heidi Cullen, Jeff Masters, and John Holdren from claiming in the media that such a linkage has been proven and is responsible for jet stream dips of the polar vortex, as a convenient excuse to blame recent record cold events on Mann-made global warming.

Excerpts from the workshop report:

Main scientific findings are as follows: 

* Arctic/mid-latitude linkages will be a major topic for the next decade because of the emergence of Arctic climate changes, known as Arctic amplification, and their impact on hemispheric weather and potential for improved seasonal forecasting. However, sorting causality and attribution of linkages is difficult between Arctic forcing and changes in mid-latitude chaotic flow. While evidence increasingly supports increased variability and the possibility of linkages from observed extremes during the last 5-10 years, the record is too short to rigorously/statistically provide sufficient scientific proof. Consequently there is still skepticism and uncertainty in these areas. Most studies have relied on correlation of reanalyses or model output; research needs to move to more mechanistic studies as a way forward. There is a need to look at forcing beyond just sea ice and snow to a full suite of possible factors. 

* Model studies are still rather weak in their support of linkages, especially the climate models that were used in the CMIP5 effort. Using CMIP5 output as an argument that linkages are not present is not a valid argument that linkages are not found in the real world. Increased resolution and examination of multiple individual ensemble members (as opposed to averaging model output across members) is expected to provide a way forward. There needs to be a better understanding of climate-model biases in response to Arctic sea-ice loss, and a clearer attribution of the recent sea-ice decline as well as of extreme weather events. Climate models seem unable to capture the recently observed highly-amplified jet-stream wave pattern, neither do they well represent the stratospheric polar vortex, but a more concerted model and attribution focus on high latitudes would help. 

At this stage, the linkage mechanisms are uncertain, but their potential importance is difficult to overstate. Having summarized the present state of knowledge, we need to identify the most fruitful way forward in this rapidly progressing research field, and identify sources of uncertainty in the conceptual models outlined below.


Report Available from Northern Hemisphere Polar Jet Stream Linkages Workshop

Contributed by James E. Overland and Edward Hanna

The Northern Hemisphere polar jet stream and links with Arctic climate change IASC/CliC/IMO/NOAA Workshop was held on 13-15 November 2013 at the Icelandic Met Office in Reykjavik, Iceland. The workshop was successful with 33 scientists who have recently worked on jet stream and Arctic linkages issues. The workshop consisted of summary talks and extensive time for discussion during the sessions and during breaks and meals provided by IMO.  Iceland provided this group of meteorologists and oceanographers with some outstanding weather:  a major storm followed by snow. The agenda and list of participants are provided at the end.  We appreciated the major support of IASC and CliC, and the hospitality of our hosts at IMO.

Download the workshop report. You can also view and download presentations and watch the FrostBytes produced here.
Related:

Papers finding climate models are unable to simulate the Polar Vortex

1 comment:

  1. http://www.climate.gov/news-features/event-tracker/us-temperature-extremes-and-polar-jet-stream

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