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Instrumental Record

River Ice break-up trends 2022

4 May 2022 by Gavin 5 Comments

As in previous years, the spring break-up of river ice on the Tanana River at Nenana and the Yukon River at Dawson City in Canada (new! h/t Ed Wiebe), is a great opportunity to highlight phenology that indicates that the planet is in fact reacting to the ongoing global warming. As we’ve done in previous years, the Nenana dates can be plotted and show a clear trend towards earlier break-ups (by about 8 days/century over the whole record, or 13 days/century since 1975).

Nenana Ice Classic break up dates since 1917.

2022 was on trend, and in 2014, I noted that May 3rd was the most likely date given the trends until then.

Dawson City in the Yukon is about 250 miles east of Nenana which is close enough for the seasonal anomalies in climate to be quite highly correlated. So one might expect that the break-up dates would be similarly correlated… and indeed they are:

Break up dates at Nenana and Dawson City

The ice at Dawson breaks up on average 3.8 days later than the ice at Nenana (5.1 days this year), but the correlation between the two series is an impressive 0.82. There have been 15 times the ice went out within 24 hours of each other and in 1963 they broke up less than 3 minutes apart! The trends are likewise very similar 7.7±3.8 days/century for Nenana, compared to 6.5±3.1 days/century since 1917. This pretty much puts paid to the occasional claim of the urban heat island in Fairbanks affecting the water and causing the trend.

[Update: I misunderstood the Yukon river break up website, and erroneously stated that the break-up was on May 2nd. It was not. I’ll update this again when it has. Apologies.]

[Update II: The Yukon river ice broke up on May 7, and I’ve updated the graph and text.]

Filed Under: Climate impacts, Climate Science, Instrumental Record Tagged With: nenana, yukon

Digital Twinge

28 Apr 2022 by Gavin 6 Comments

A couple of weeks ago the EU announced that they were funding a project called DestinE (Destination Earth) to build ‘digital twins’ of the Earth System to support policy making and rapid reaction to weather and climate events.

While the term ‘digitial twin’ has a long history in the engineering world, it’s only recently been applied to Earth System Modeling, and is intended (I surmise, as does Bryan Lawrence) to denote something more than the modeling of either weather or climate that we’ve been doing for years. But what exactly? And is it an achievable goal or just a rebranding effort of things that are happening anyway?

[Read more…] about Digital Twinge

Filed Under: Climate impacts, Climate modelling, Climate Science, climate services, Featured Story, Instrumental Record Tagged With: cloud computing, DestinE, digital twin

Issues and Errors in a new Scafetta paper

30 Mar 2022 by Gavin 38 Comments

Earlier this week, a new paper appeared in GRL by Nicola Scafetta (Scafetta, 2022) which purported to conclude that the CMIP6 models with medium or high climate sensitivity (higher than 3ºC) were not consistent with recent historical temperature changes. Since there have been a number of papers already on this topic, notably Tokarska et al (2020), which did not come to such a conclusion, it is worthwhile to investigate where Scafetta’s result comes from. Unfortunately, it appears to emerge from a mis-appreciation of what is in the CMIP6 archive, an inappropriate statistical test, and a total neglect of observational uncertainty and internal variability.

[Read more…] about Issues and Errors in a new Scafetta paper

References

  1. N. Scafetta, "Advanced Testing of Low, Medium, and High ECS CMIP6 GCM Simulations Versus ERA5‐T2m", Geophysical Research Letters, vol. 49, 2022. http://dx.doi.org/10.1029/2022GL097716
  2. K.B. Tokarska, M.B. Stolpe, S. Sippel, E.M. Fischer, C.J. Smith, F. Lehner, and R. Knutti, "Past warming trend constrains future warming in CMIP6 models", Science Advances, vol. 6, 2020. http://dx.doi.org/10.1126/sciadv.aaz9549

Filed Under: Climate modelling, Climate Science, Featured Story, Instrumental Record, Scientific practice Tagged With: CMIP6, Scafetta

Another dot on the graphs (Part II)

2 Feb 2022 by Gavin

We have now updated the model-observations comparison page for the 2021 SAT and MSU TMT datasets. Mostly this is just ‘another dot on the graphs’ but we have made a couple of updates of note. First, we have updated the observational products to their latest versions (i.e. HadCRUT5, NOAA-STAR 4.1 etc.), though we are still using NOAA’s GlobalTemp v5 – the Interim version will be available later this year. Secondly, we have added a comparison of the observations to the new CMIP6 model ensemble.

[Read more…] about Another dot on the graphs (Part II)

Filed Under: Climate modelling, Climate Science, Instrumental Record, IPCC

Another dot on the graph

15 Jan 2022 by Gavin

So last week was the annual release of the temperature records from NASA, NOAA and Berkeley Earth. The Copernicus ERA5 data was released a few days ago, and the HadCRUT data will follow soon. Unlike in years past, there is no longer any serious discrepancy between the records – which use multiple approaches for the ocean temperatures, the homogenization of the weather stations records, and interpolation.

Depending on the product, 2021 was either the 5th, 6th or 7th warmest year, but in all cases, it is part of the string of warm years (since 2015) that have all been more than 1ºC warmer than the late 19th C.

[Read more…] about Another dot on the graph

Filed Under: Aerosols, Climate Science, Communicating Climate, El Nino, Greenhouse gases, Instrumental Record

A Tale of Two Hockey Sticks

9 Aug 2021 by mike

Two decades ago, the so-called “Hockey Stick” curve, published in 1999 by me and my co-authors (Mann, Bradley and Hughes, 1999), was featured in the all-important “Summary for Policy Makers” (SPM) of the 2001 IPCC Third Assessment report. The curve, which depicted temperature variations over the past 1000 years estimated from “proxy data such as tree rings, corals, ice cores, and lake sediments”, showed the upward spiking of modern temperatures (the “blade”) as it dramatically ascends, during the industrial era, upward from the “handle” that describes the modest, slightly downward steady trend that preceded it.

The Hockey Stick became an icon in the case for human-caused climate change, and I found myself at the center of the contentious climate debate (I’ve described my experiences in “The Hockey Stick and the Climate Wars”).

Featured two decades later now in the AR6 SPM is a longer Hockey Stick with an even sharper blade. And no longer just for the Northern Hemisphere, it now covers the whole globe. The recent warming is seen not only to be unprecedented over the past millennium, but tentatively, the past hundred millennia.

Side-by-side comparison of the (left) original Mann et al (1999) “Hockey Stick” reconstruction as featured in the Summary for Policy Makers of the IPCC 3rd Assessment report (2001) and the (right) longer, sharper “Hockey Stick” as featured in the Summary for Policy Makers of the IPCC 6th Assessment report (2021).

The relevant statements in the SPM and Technical Summary are:

A.2.2 Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years (high confidence). Temperatures during the most recent decade (2011–2020) exceed those of the most recent multi-century warm period, around 6500 years ago13 [0.2°C to 1°C relative to 1850– 1900] (medium confidence). Prior to that, the next most recent warm period was about 125,000 years ago when the multi-century temperature [0.5°C to 1.5°C relative to 1850–1900] overlaps the observations of the most recent decade (medium confidence). {Cross-Chapter Box 2.1, 2.3, Cross-Section Box TS.1}

SPM AR6

Global surface temperature has increased by 1.09 [0.95 to 1.20] °C from 1850–1900 to 2011–2020, and the last decade was more likely than not warmer than any multi-centennial period after the Last Interglacial, roughly 125,000 years ago.

Cross Section Box TS.1

As the new IPCC report lays bare (you can find my full commentary about the new report at Time Magazine), we are engaged in a truly unprecedented and fundamentally dangerous experiment with our planet.

References

  1. M.E. Mann, R.S. Bradley, and M.K. Hughes, "Northern hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations", Geophysical Research Letters, vol. 26, pp. 759-762, 1999. http://dx.doi.org/10.1029/1999GL900070

Filed Under: Climate Science, Greenhouse gases, Instrumental Record, IPCC, Paleoclimate

We are not reaching 1.5ºC earlier than previously thought

9 Aug 2021 by group

Guest commentary by Malte Meinshausen, Zebedee Nicholls, and Piers Forster

Of all the troubling headlines emerging from the release of the Intergovernmental Panel on Climate Change (IPCC) WG1 report, one warning will surely dominate headlines in the next days and weeks: Earth is likely to reach the crucial 1.5℃ warming limit in the early 2030s.

In 2018, the IPCC Special Report on 1.5C warming  stated in its summary for policy makers that the world was likely to cross the 1.5℃ threshold between 2030 and 2052, if current warming trends continue. 

In this latest AR6, a more comprehensive assessment was undertaken to estimate when a warming level of 1.5℃ might be reached. As a result, some early media reports suggest 1.5ºC warming is now anticipated 10-years earlier than previously assumed (AFR, THE TIMES). 

We want to explain here why that is not backed up by a rigorous comparison of the SR1.5 and AR6 reports. In fact, the science in the previous SR1.5 report and the new AR6 report are remarkably consistent.

[Read more…] about We are not reaching 1.5ºC earlier than previously thought

Filed Under: Climate impacts, Climate modelling, Climate Science, Instrumental Record, IPCC

The IPCC Sixth Assessment Report

9 Aug 2021 by group

Climate scientists are inordinately excited by the release of a new IPCC report (truth be told, that’s a bit odd – It’s a bit like bringing your end-of-(seven)-year project home and waiting anxiously to see how well it will be received). So, in an uncharacteristically enthusiastic burst of effort, we have a whole suite of posts on the report for you to read.

  • AR6 of the Best. Half a dozen takeaways from the report from Gavin
  • New (8/13): Sea Level Rise in AR6 from Stefan
  • A Tale of Two Hockey Sticks by Mike
  • #NotAllModels discusses the use (and mis-use) of the CMIP6 ensemble by Gavin
  • We are not reaching 1.5ºC earlier than previously thought from guest authors Malte Meinshausen, Zebedee Nicholls and Piers Forster
  • New (8/12): Deciphering the SPM AR6 WG1 Code by Rasmus
  • New (8/12): A deep dive into the IPCC’s updated carbon budget numbers from guest author Joeri Rogelj

If/when we add some more commentary as we digest the details and we see how the report is being discussed, we’ll link it from here. Feel free to discuss general issues with the report in the comments here, and feel free to suggest further deep dives we might pursue.

Filed Under: Climate impacts, Climate modelling, Climate Science, Communicating Climate, Greenhouse gases, In the News, Instrumental Record, IPCC, Paleoclimate, Sea level rise

Rapid attribution of PNW heatwave

7 Jul 2021 by group

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
[Read more…] about Rapid attribution of PNW heatwave

Filed Under: Climate impacts, Climate modelling, Climate Science, heatwaves, Instrumental Record, statistics

Nenana Ice Classic 2021

30 Apr 2021 by Gavin

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…

Filed Under: Climate Science, Instrumental Record

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