September 23, 2020

Summer is back. Plus Climate Change fingerprints.

  • Vancouver Island Inland Sections Forecast - No watches or warnings in effect.

    Forecast Issued 05:00 AM PDT Wednesday 23 September 2020 - Wednesday: Rain. Amount 15 to 25 mm. Becoming windy late this morning. High 19. UV index 1 or low. Wednesday night: Showers. Amount 10 to 15 mm. Windy early this evening. Low 12. Thursday: Showers. Amount 10 to 15 mm. High 16. UV index 1 or low. Thursday night: Showers. Low 11. Friday: Periods of rain. High 18. Friday night: Rain. Low 10. Saturday: Periods of rain. High 20. Saturday night: Rain. Low 11. Sunday: Rain. High 17. Sunday night: Cloudy with 60 percent chance of showers. Low 12. Monday: Cloudy with 60 percent chance of showers. High 18. Monday night: Cloudy periods. Low 11. Tuesday: A mix of sun and cloud. High 21.

It is going to feel like full on summer on our final full week before the Equinox and start of Fall (which is at 1:44PM on the 22nd).

It is a tale of the jetstream once again. Our great arbiter of all things weather on our coast will be bent way to the North of us by Wednesday, which should give us some of our hottest temperatures of the summer (low thirties) and may be record breaking for some areas.
(our all time record for September is 35C in 1988)

Here is the jet on Wednesday:
20130909-070221.jpg

The bottom portion of the kink is forecast to break off and turn into a cutoff low that will swirl into our area on Sunday or so. We shall see if that brings any precipitation or perhaps more thunderstorms.

2012 Climate Change/Anthropogenic Global Warming Fingerprints
When people talk Climate Change they generally mean humanities affect on our climate. The way we are affecting of course, Global Warming by the addition of CO2 to the atmosphere. So Anthropogenic Global Warming (AGW for short) means Global Warming caused by Humanity.

Reuters reported in August:

Drafts seen by Reuters of the study by the U.N. panel of experts, due to be published [this month], say it is at least 95 percent likely that human activities – chiefly the burning of fossil fuels – are the main cause of warming since the 1950s.

That is up from at least 90 percent in the last report in 2007, 66 percent in 2001, and just over 50 in 1995, steadily squeezing out the arguments by a small minority of scientists that natural variations in the climate might be to blame.

So that is the cause. We are the cause.

Causation is one thing, but because the earth is such a complex system, pinning down current effects solely to AGW is hard. Scientists are researching it, and publishing the results. Here is a published, peer reviewed (large PDF), assessment of extreme weather events in 2012 and whether they were caused, or made worse, by us through AGW.

Eighteen assessments were done on twelve different extreme weather events in 2012 by 78 scientists.A good summary is here by weather historian Christopher C. Burt.

1. U.S. Heat Wave of July 2012
(AGW likely to have played a role)

2. U.S. Heat Wave of March-May 2012
(AGW likely to have played a role)

3. Hurricane Sandy
(AGW did not play a role in the storm itself but may make such storms more destructive in the future due to AGW-driven sea rise)

4. September 2012 Arctic Sea Ice Minimum
(AGW played a role although a severe Arctic storm in August 2012 was also a contributing factor)

5. February 2012 Western European Cold Wave
(AGW probably not a factor)

6. Extreme Rainfall Variation in Europe Summer of 2012
(AGW may have played a role along in combination with several other factors)

7. Record Winter Drought on Iberian Peninsula 2011-2012
(AGW most likely played a role “modulated” by the NAO phase)

8. Rainfall Deficits in Eastern Kenya and Southern Somalia 2012 and 2003-2012
(not clear what, if any, role AGW played)

9. North China Floods of 2012
(not clear what, if any, role AGW played)

10. Heavy Rainfall in Southwestern Japan in 2012
(AGW unlikely to have played a role)

11. Heavy Rainfall over Eastern Australia in March 2012
(AGW unlikely to have played a role although warming ocean temperatures a factor)

12. Two-day Extreme Rainfall Event in Golden Bay, New Zealand during December 2011
(AGW may have played a role in so far as increased moisture in the atmosphere)

CITATION FOR COMPLETE REPORT: Peterson,, T.C., M.P. Hoerling, P.A. Stott and S. Herring, Eds., ‘Explaining Extreme Events of 2012 from a Climate Perspective’. Bulletin of the American Meteorological Society, Vol. 94 (9), S1-S74.. Report is here.