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This will take months to read, but the headline topic of equilibrium climate sensitivity comes as a surprise to me. I was not expecting the big jump from 1.5 to 2.5C on the lower bound. A.4.4 The equilibrium climate sensitivity is an important quantity used to estimate how the climate responds to radiative forcing. Based on multiple lines of evidence, the very likely range of equilibrium climate sensitivity is between 2°C (high confidence) and 5°C (medium confidence). The AR6 assessed best estimate is 3°C with a likely range of 2.5°C to 4°C (high confidence), compared to 1.5°C to 4.5°C in AR5, which did not provide a best estimate. SPM pg. 14

If 8/6 ends up being the minimum that would be epic indeed.

The long awaited Assessment Report 6 from the IPCC Working Group 1 regarding the Physical Science Basis Report has been released. https://www.ipcc.ch/report/ar6/wg1/

Some sea ice coupled GCMs did show that the 2020's could be a stall decade, but definitely not a recovery. I don't even know how a recovery could be possible considering the planetary energy imbalance is sitting at close to +0.9 W/m2 right now. And it might even be increasing at that. And given that environmental conditions this year should have promoted higher sea ice extent/area and yet we're still well below average is rather telling. Recovery is a pipe dream.

RSS matches RATPAC better. https://www.ncdc.noaa.gov/sotc/upper-air/201813 The claim that UAH matches radiosondes better comes from Dr. Spencer and Dr. Christy themselves. They also use IGRA as their radiosonde data source. The IGRA website warms users against using their dataset for long term trend analysis. How can you know that UAH (or any dataset for that matter) is "true" and thus a gold standard?

One thing that confused me a couple of years ago is the increase in outgoing longwave radiation (OLR). I naively thought that GHGs would reduce OLR and that's what creates the Earth Energy Imbalance (EEI). That is what happens initially. But...the warming that results from a positive EEI leads to feedbacks like the cloud feedback. If the cloud feedback is positive then Earth's albedo will drop and the absorbed shortwave radiation (ASR) will also increase. Because EEI = OLR - ASR there two ways for the planet to achieve energy balance after a positive EEI perturbation. The first is if OLR increases (temperature increase). The second is if ASR decreases (albedo increase). The fact that we observe an increase in OLR while EEI itself continues to increases is a tell that ASR is increasing which means albedo is decreasing. This is consistent with the hypothesis that the cloud feedback is positive. Donohoe et al 2014 has a pretty good explanation for the counter-intuitive OLR increase when the climate system is acted on by increases in GHG. See figure 1c and 1d for how the OLR and ASR respond to pulses of GHG forcing. It is interesting to note that most (not all) global circulation models actually predict this behavior. DeWitte & Clerbaux 2018 point out that OLR is indeed increasing and attribute this to "cloud thinning".

The low was 104 and the high was 130. I think that might qualify as the warmest day ever observed anywhere in the world.

It's still above 2010, 2012, and 2016. But it is below 2017, 2018, 2019, and 2020.

Perfect. Thanks. Excluding 2021 the mean was 104F (40C) with a standard deviation of 3.0F (1.7C). The z-score for 121F (49.6C) is thus 5.6 implying a recurrence interval of 1-in-10,000,000 years. Including 2021 the mean is 105F (40.5C) with a standard deviation of 5.1F (2.8C). The z-score for 121F (49.6C) is thus 3.1 implying a recurrence interval of 1-in-1200 years. Clearly this was an astonishingly rare event in statistical terms.

While we were all distracted by the historic Pacific Northwest Heatwave of 2021 the 5-day daily extent in the NH dropped below 2020 for this date. It is now the 4th lowest for this date.

So the old Canadian record was 113F (45.0C) in 1937 and the new record is 121F (49.6C) in 2021. Let's say the recurrence interval on the 113F is 50 years and the mean annual Tmax is say 102F with a standard deviation of 5.4F for an annualized z-score of 2.0 (1-in-50 years). Using the mean of 102 +/- 5.4F (1-sigma) the annualized z-score on the 121F would be 3.5 (1-in-5,000 years). Obviously that was just a back-of-the-envelope estimation without any hard data. I have no idea how far off that 102 +/- 5.4F figure is; could be a lot. If someone can supply the annual Canadian Tmax values we can compute the real mean and standard deviation and then just plug all of that into a z-score calculator and get the real recurrence interval for the 121F. My bet...the real recurrence interval from rigorous statistical analysis will be at least several hundred years and probably over a thousand and maybe even approaching the 5000 year figure I guesstimated above.

William Reid is partnering with Chris Burt on this. Reid's blog has a lot more information and is up-to-date through 2020. It is my understanding that they are (or were) preparing a publication to be submitted to WMO. I am unsure of the status on that. I do know this isn't the first time Burt has gotten a record dismissed by the WMO so he's no stranger to the process. http://stormbruiser.com/chase/2020/11/23/death-valleys-134f-record-temperature-study-part-one/

I hope we see a statistical analysis similar to the one we got for the 2020 Siberian Heatwave after this is all said and done. I'd really like to know how this stacks up statistically. I did see the tweet above regarding 500mb heights approaching a 5-sigma event implying a recurrence interval of over 4000 years. Clearly this is an unusual event.

Hunter 2003 concluded that the 1841 to 2002 rise was +1 mm/yr at that benchmark site in Tasmania. This is composed of +0.8 mm/yr rise wrt to the marking plus +0.2 mm/yr when accounting for isostatic uplift of the land. No analysis was made regarding acceleration at this site though. Anyway, this is consistent with broader sea level over this 160 year period.

Here is a GR2Analyst volume render of the tornado at its peak. It's still the most impressive looking volume I have seen from any tornado.

This is not just another perspective on climate change. It is factually incorrect in the same way claims of table top cold fusion and n-rays are incorrect. This is egregious enough that it rises to the level of disinformation. Let me correct some factually incorrect information I heard in this video. Note that this may not be an exhaustive list, but I did my best to spot each misleading, misinformation, or disinformation (most of it) tidbit. ** Disinformation: Nature has produced 97% of the 400 ppm of CO2 in the atmosphere. Fact: Humans pumped nearly 330 ppm of CO2 into the atmosphere. Of this 330 ppm pumped into the atmosphere nature buffered about 195 ppm for us in the land and ocean leaving 135 ppm in the atmosphere. Humans are responsible for 32% of the CO2 currently in the atmosphere and 100% of the rise from 280 to 415 ppm. And if Mother Nature hadn't lent a helping hand we'd actually be responsible for almost 55% of the 610 ppm that would have occurred had 195 ppm not been buffered. The mistake the commentator in the video makes is that they conflate carbon emission in units of ppm/yr or GtC/yr (4% human, 96% natural) with carbon mass ppm or GtC (without the /yr part). A ~4% increase in inflow flux to the atmosphere with only a ~2% increase in outflow flux over many years will add up rather quickly. Sources: Global Carbon Project - Friedlingstein 2020 ** Disinformation: Sea level is not rising by more than 1 mm/yr. Fact: Sea level is rising by about 3.5 mm/yr now and it has accelerated in recent decades. Sources: Dangendorf 2019, and NASA Vital Signs Page, and IPCC SROCC ** Disinformation: Solar activity explains the warming observed today. Fact: Solar activity peaked in 1958 and has been flat to even declining ever since. This happened during a period when the warming became most acute. Furthermore like all main sequence stars the Sun brightens with age yet the Earth has cooled and even entered into the on-going Quaternary Ice Age since the Eocene Climate Optimum 55 MYA. Sources: SORCE - Kopp 2011 and NASA Vital Signs Page, and Berkeley Earth, and Gough 1981, and various sources. ** Disinformation: Scientists concluded that CO2 has no warming potential. Fact: CO2's warming potential was convincingly demonstrated in the 1800's. The first climate models appeared in the 1800's and even CO2's climate sensitivity was first estimated prior to 1900. Even Arrhenius' 1908 calculation (which is said to be quite laborious) of 4C at 2xCO2 is considered be a reasonable prediction even today. Sources: Tyndall 1861, Arrhenius 1896, Chamberlin 1897, Chamberlin 1899, Arrhenius 1908, Pekeris 1929, Callendar 1938, Callendar 1949, Plass 1956 (a, b, and c), Callendar 1961, Manabe 1961, Manabe 1967, Budyko 1969, Sellers 1969, Charney 1979, Ramanathan 1985, Hansen 1988, Myhre 1998, Schmidt 2010, IPCC AR5 WG1 Sherwood 2020, and the list goes on and on and on. I haven't even scratched the surface on all of the lines of evidence confirming over and over again that CO2 puts a positive radiative force on the planet. ** Misinformation: A Sun driven cooling period is imminent. Fact: Not even a solar grand minimum will reverse global warming. The current Earth Energy Imbalance is +0.8 W/m^2. A solar grand minimum might put about -0.3 W/m^2 of force on the planet. Cumulative CO2 forcing alone is +2.0 W/m^2 with another +1.7 W/m^2 expected if concentrations hit 560 ppm. There have been a few sun driven cooling prediction in the last few decades. Obviously none of them panned out. Source: Schuckmann 2020, and Myhre 1998, and Owens 2017, and Anet 2013, and SORCE - Kopp 2011 ** Misleading: CO2 levels have been this high in the past. Fact: Yeah, like more than a million years ago. And note that high CO2 levels in the past were required to offset the lower solar luminosity. 600 MYA the solar forcing was -12 W/m^2 relative to today. CO2 levels would have had to been around 4,000 ppm just to maintain an offset of +12 W/m^2 to balance the lower solar flux. CO2 is an essential piece of the puzzle in solving the faint young Sun problem, the PETM, other hyperthermal events, magnitude of the glacial cycles, etc. Source: GEOCARB III - Berner 2001 and Gough 1981, and NASA Vital Signs Page

The book Merchants of Doubt has a good rundown of how the rhetoric and strategies are echoed across multiple public interest topics. In fact, many players in the space offered their services across the gambit of these topics ranging from DDT and environmental harm to the link between smoking and cancer to climate change among other topics.

Fundamentals....yes. Details...no. And by "settled" we mean in the same way anything in science is settled. It doesn't mean we have perfect knowledge or understanding. We never will. But we do know enough to draw conclusions with high confidence. There is a lot of uncertainty on the climate sensitivity. There is a lot of uncertainty on the attribution on individual climate forcing agents. There is a lot of uncertainty on regional effects. There is a lot of uncertainty on a variety of aspects of climate change. But we know that the planet is warming and that humans play a significant role. That part is settled.

Great post. And welcome to AmericanWx. I'll add some commentary of my own. The Charney sensitivity is most closely related to the fast-feedback equilibrium climate sensitivity (ECS). It is important to note that slow-feedbacks are often omitted from the ECS estimates you often see. Generally speaking fast-feedbacks are those that complete in < 150 years. Slow-feedbacks include those that longer than 150 years to complete like would be the case for Greenland and Antarctic ice sheets and some carbon cycle processes. Sherwood 2020 - An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence is great comprehensive study that I suspect will be referenced heavily by AR6. The 1-sigma and 2-sigma envelopes for 2xCO2 is 2.6 - 3.9C and 2.3 - 4.7C respectively. Official Link: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019RG000678 Free Copy: https://climateextremes.org.au/wp-content/uploads/2020/07/WCRP_ECS_Final_manuscript_2019RG000678R_FINAL_200720.pdf

Does Koonin present a model of the climate system in his book that makes predictions from 1880-present that are better than say CMIP5 or CMIP6? General relativity and quantum mechanics disagree by 120 orders of magnitude regarding the cosmological constant. It is called the worst prediction in all of science. But I trust you still feel that GR and QM are settled enough to continue relying on GPS to get you where you need to go or on MRI to diagnose a potentially serious medical issue you might have in the future. No? Fine grained details regarding AGW are still heavily debated, but the fact that the planet is warming and that humans have played a significant role is about as settled as anything can get in science.

I didn't make the chart. Nick Stokes did. I'm guessing he downloaded the netcdf files and did a lot of manual stuff on his side. He also just mentioned something else last night...50 of the 68 members in Dr. Spencer's graph come from CanESM5 which runs very hot. It appears that KNMI does not yet have all of the CMIP6 data yet.

I'm really trying to be patient with Dr. Spencer. Afterall he and Dr. Christy did pioneer satellite measurements of tropospheric temperatures which is useful. But he just keeps posting misleading articles. http://www.drroyspencer.com/2021/04/an-earth-day-reminder-global-warming-is-only-50-of-what-models-predict/ Here he says the warming is only 50% what models predict. That's not true at all. This post is misleading at best because even though the graph is labeled as "Sea Surface Temperature" he's actually comparing observed SSTs with modeled air temperature. The problem...the atmosphere warms faster than the sea surface. Nick Stokes kindly created a graph in which observed SSTs are compared correctly with modeled SSTs. Note that "tas" is air temperature and "tos" is sea surface temperature. Is modeling perfect? Nope. Is it as bad as Dr. Spencer claims? Not even close.

JTWC estimated its minimum central pressure at 888mb. JMA at 895mb. This shatters the record for the most intense cyclone prior to May 1st and is in the elite top 20 highest wind speeds at any time of year. https://weather.com/storms/hurricane/news/2021-04-16-typhoon-surigae-philippines-forecast BTW...this was a well forecasted cyclone. Both the GFS and ECMWF had been consistently showing a low 900's intensity at least 5 days out.

The latest JMA advisory is 895mb.