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Unforced Variations: Aug 2021

Filed under: — group @ 2 August 2021

This month is IPCC month – the Sixth Assessment Report from Working Group 1 is out on Monday August 9. We’ll have some detailed comments once it’s out, but in the meantime, feel free to speculate widely (always considering that IPCC is restricted to assessing existing literature…).

Open thread – please stick to climate science topics.

Climate adaptation should be based on robust regional climate information

Climate adaptation steams forward with an accelerated speed that can be seen through the Climate Adaptation Summit in January (see previous post), the ECCA 2021 in May/June, and the upcoming COP26. Recent extreme events may spur this development even further (see previous post about attribution of recent heatwaves). 

To aid climate adaptation, Europe’s Climate-Adapt programme provides a wealth of resources, such as guidance, case studies and videos. This is a good start, but a clear and transparent account on how to use the actual climate information for adaptation seems to be missing. How can projections of future heatwaves or extreme rainfall help practitioners, and how to interpret this kind of information? 

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Rapid attribution of PNW heatwave

Summary: It was almost impossible for the temperatures seen recently in the Pacific North West heatwave to have occurred without global warming. And only improbable with it.

It’s been clear for at least a decade that global warming has been in general increasing the intensity of heat waves, with clear trends in observed maximum temperatures that match what climate models have been predicting. For the specific situation in the Pacific NorthWest at the end of June, we now have the first attribution analysis from the World Weather Attribution group – a consortium of climate experts from around the world working on extreme event attribution. Their preprint (Philip et al.) is available here.

Trends in Tmax globally
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Forced Responses: July 2021

Filed under: — group @ 2 July 2021

A new bi-monthly open thread for climate solutions discussions. Climate science threads go here.

Unforced Variations: July 2021

Filed under: — group @ 2 July 2021

This month’s open thread for climate science. Probably a good time to discuss attribution for extreme heat, wildfires, hurricane intensity and intense precipitation.

Unforced Variations: Jun 2021

Filed under: — group @ 2 June 2021

This month’s open thread for climate science. Start of the meteorological summer, official hurricane season (outlook), the final stretches of the IPCC AR6 review process and a rare conjunction of Father’s Day and the summer solstice. Please stay on topic.

Why is future sea level rise still so uncertain?

Filed under: — gavin @ 12 May 2021

Three new papers in the last couple of weeks have each made separate claims about whether sea level rise from the loss of ice in West Antarctica is more or less than you might have thought last month and with more or less certainty. Each of these papers make good points, but anyone looking for coherent picture to emerge from all this work will be disappointed. To understand why, you need to know why sea level rise is such a hard problem in the first place, and appreciate how far we’ve come, but also how far we need to go.

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Forced Responses: May 2021

Filed under: — group @ 2 May 2021

A bimonthly open thread on climate solutions. Perhaps unsurprisingly this is always the most contentious comment thread on the site, but please try and be constructive and avoid going off on wild tangents.

Unforced Variations: May 2021

Filed under: — group @ 1 May 2021

This month’s open thread for climate science topics.

Nenana Ice Classic 2021

Filed under: — gavin @ 30 April 2021

And…. it’s that time again. The clock stopped on the Nenana ice classic this afternoon (April 30, 12:50pm AT). This is pretty much on trend and unsurprising given the relatively slightly cool winter in Alaska. The jackpot on offer this year was $233,591 but will likely be shared among several winners. This year’s ‘break up’ is a little odd, since the ice moved sufficiently to trigger the clock, but not enough to actually topple the tripod (which is still visible as this is being written (9pm ET) – Update 10:30pm ET: gone now though!). But, the rules are the rules…

Nenana Ice Classic break-up dates since 1917.

The trends in the break up date is about 8 days earlier per century (±4), estimated over the whole record, but substantially faster over the last 50 years (16 ± 12 days/century, 95% CI).

Other phenological records show similar trends, notably the longest cherry blossom record from Kyoto which dates back to 9th Century, and which had a record earliest peak bloom this year and a clear trend over the last few decades:

Kyoto Cherry Blossom trends (graph from Statista)

Feel free to link to your favorite such record in the comments…