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There are multiple lines of evidence that corroborate the anthroprogenic hypothesis in the context of CO2. The atmospheric C13/C12 ratio is declining. Fossil carbon is C13 depleted because it was formed by biomass that primarily uses C3 carbon fixation photosynthesis which prefers C12. The atmospheric C14/C12 ratio had been declining up until the bomb spike. Fossil carbon is C14 depleted because C14 is radioactive with a half life of 5700 years. The atmospheric C14/C12 ratio since the bomb spike is not declining at a rate that can be explained without human C14 depleted emissions. The atmospheric O2 ratio is declining. Fossil carbon is released primarily via combustion which forms via C + O2 --> CO2. Ocean pH is declining. Ocean pH is declining fastest at the surface. Mass accounting of human emissions of carbon match the carbon mass increase in the carbon cycle (atmosphere, hydrosphere, and biosphere). The trajectory and timing of human emissions of carbon match the trajectory and timing of carbon increases in the carbon cycle (atmosphere, hydrosphere, biosphere). There is no known increase in carbon source flux or decrease in carbon sink flux that is entirely naturally modulated that has appeared since the industrial era. There are large changes in source and sink fluxes that are unquestionably tied to anthroprogenic actions. These include fossil fuel combustion, cement production, land use changes, etc. Yes. CO2 has been much higher in the past. That's how we know that natural factors can modulate its concentration too.

And as the effectiveness of the GHE increases so too does the temperature near the surface of Earth increase all other things being equal. Any other outcome would violate the 1LOT, 2LOT, or other laws of physics. And yes...one signature of the GHE is a reduced diurnal temperature range. Another even more compelling signature of the GHE is the cooling of the stratosphere simultaneous with the warming of the troposphere and hydrosphere. That's the "trapping" effect in action. Heat accumulates on one side of the GHG layer and depletes on the other side. Make no mistake...adding CO2 (and other gas species) to the atmosphere WILL result in a positive radiative forcing component. It WILL put upward pressure on Earth's energy imbalance. It WILL put a warming tendency on the planet. This is a certainty.

Earth's surface and lower atmosphere emit in a portion of the EM spectrum called the "atmospheric window" or sometimes "infrared window". This is a non-contiguous band in which photons have a free escape trajectory. Certain polyatomic gas species (like CO2, CH4, CFCs, etc.) have vibration modes that are excited by the atmospheric window. In the presence of these molecules photons which would have otherwise had a free escape to space are now captured by the molecule. One of two things happens with this captured energy. 1) The molecule can "thermalize" it by using its induced dipole moment to accelerate and collide with neighboring molecules. In this manner the energy is used to increase the temperature in the vicinity of that molecule. 2) The molecule can relax its induced dipole moment by remitting a new photon. This new photon is emitted in a random direction with roughly 50% having downward trajectories. It is precisely because there is no special force that would cause a significant preference on the trajectory of the emission that some of these new photons and the energy they carry will proceed toward the surface as downwelling longwave radiation. Both of these processes act to impede the transmission of radiant energy to space and enhance the transmission of radiant energy toward the surface. A positive energy imbalance develops in the geosphere. It is the decrease in transmission to space and increase in transmission back toward the surface that is being referred to by "trapping heat". And "trapping heat" is a perfectly reasonable and quite intuitive description of the processes involved. The analogy I frequently give to people is that of your home with a furnace and insulation. The insulation does not provide energy to your home nor does it act as a source of energy. That is the role of the furnace and its fuel source. The insulation augments the furnace by allowing your home to achieve a higher equilibrium temperature than would otherwise be possible. It does this by impeding the transmission of energy produced by the furnace to the outside. It "traps" the energy inducing an energy imbalance that cause it to accumulate inside your home. This accumulation occurs until a new equilibrium is achieved. Although there are subtle and important differences worth discussing the analogy is conceptually similar to how the GHE works in the atmosphere on a planetary scale. The point...the word "trap" is used to mean a positive energy imbalance which is exactly what happens in both the GHE and inside your home. Anytime you add a thermal barrier to a system with an energy source that energy will ALWAYS be "trapped" by the barrier. The anthroprogenic emission of CO2 caused 100% of the increase from 280 to 410 ppm. In other words 130 of the 410 ppm or 32% of the total concentration was caused by anthroprogenic actions. That is a significant portion of the whole. The atmospheric window is on the order of 40 W/m^2. An increase from 280 to 410 ppm is able to close off 5.35 * ln(410/280) = 2.0 W/m^2 of that window. A +2.0 W/m^2 radiative force may seem small relative to the 240 W/m^2 emitted to space but at a sensitivity of 1.0C per W/m^2 that would represent a +2.0C change in lower troposphere temperature. That is a significant change. It is the primary cause of the warming today. And it makes perfect sense. No other theory even comes remotely close in its ability to explain present day warming. It is about as settled as anything in science can be. csnavy says it best...there are so many nails in this coffin there probably isn't enough room to drive in another. The body of scientific evidence comes to a different conclusion than you. In fact, you may unwittingly be betting your life, like many do, on the GHE and the trapping of heat if you work in an environment monitored by NDIR sensors. And the radiometers onboard the GOES-R satellites (among others) exploits the GHE every minute of every day to detect water vapor which like most polyatmoic gas species is a GHG. In fact the GOES-R radiometer even has the "CO2 channel" that exploits CO2's minor absorption line near 13.3 um (not be confused with its primary GHE interaction near the 15 um band) to produce some of those great satellite products we've all come to love. All of this because CO2 and other polyatmoic gas species "trap" radiant energy. To be honest...scientific understanding of this "trapping" behavior is likely better understood than many other physical concepts you take for granted like say gravity. I have no interest in mocking you or anyone. I do, however, have an interest in making sure everyone including you understands what science actually says regarding the matter.

Clearly there are circumstances that are causing the PHL site to warm but not the Chester County site. There could be various reasons for this including the obvious urban heat island effect. While most urban sites are no longer experiencing significant increases in urban heating there are, of course, many location (both in the US and worldwide) that are. Scientists who develop and maintain datasets that publish a global mean surface temperature (GMST) are well aware of the urban heat island effect and take necessary steps to make sure it is not biasing the warming trends either way. It is also a very misunderstood topic by laypeople. Many people have the mistaken belief that the UHI effect on the GMST warming trend can only ever be positive and is always increasing. This couldn't be further from the truth. Berkeley Earth did an analysis a few years ago and determined that the UHI effect may actually be biasing global mean surface warming trends too low for the post-WWII era, albeit by a small amount. "We observe the opposite of an urban heating effect over the period 1950 to 2010, with a slope of -0.10 ± 0.24°C/100yr (2σ error) in the Berkeley Earth global land temperature average."

No need to do any of that. Just download the radar data from the NCEI site I linked to above. You will need to run the GRUtils.exe app to convert the data into rv3x files so that GRL3 can load them up. Even better...buy GR2Analyst and download the L2 volume files conveniently from Amazon and drag-n-drop them directly onto GR2A.

I believe you drag-n-drop them onto GRLevel3.

Alright...this got brought up in a local weather forum I participate in. Anybody have any ideas of what phenomenon would cause the feature in this satellite loop. Keep your eye on the outer band east of the eye. An anomaly shows up at a towering thunderstorm in this outer band and races inward toward the eye. This anomaly occurs between 21:00 and 22:00Z and shows up in water vapor, longwave, and visible imagery. Make sure you expand the video to full screen for easy viewing. https://imgur.com/GcQo3Nm

There was a pretty sharp loss the last 2 days. This brings the daily extent below 2019 as of 8/20 per NSIDC. The 5-day average is still in 3rd place for this date.

No need to save them off. They are available on the NCEI website. https://www.ncdc.noaa.gov/has/HAS.FileAppRouter?datasetname=7000&subqueryby=STATION&applname=&outdest=FILE If you have a level II viewer like GR2Analyst you can find the volumes here. https://s3.amazonaws.com/noaa-nexrad-level2/index.html

Probably. Yes. There is an incredibly detailed and lengthy write up by William Reid and Christopher Burt regarding the matter. The investigation is still on-going, but unless something has changed it is my understanding that this will eventually be presented to the WMO for official review. The following is a lengthy 8-part series summarizing the state of the investigation through March 2020 from William Reid. http://stormbruiser.com/chase/2013/08/29/death-valleys-134f-record-temperature-study-part-one/ You can review a considerably more consolidated summary on Christopher Burt's blog. https://www.wunderground.com/blog/weatherhistorian/an-investigation-of-death-valleys-134f-world-temperature-record.html

I believe they had been publishing 2.0-4.5C per 2xCO2 in previous publications and then widen it to 1.5-4.5C for AR5.

Unfortunately I cannot find a copy of this newly published study that isn't behind a paywall. But it is said that it supports a 2035 target for the first ice-free summer according to news articles. https://www.nature.com/articles/s41558-020-0865-2

Hmm...maybe this is my misunderstanding but I was under the impression that sea ice would tend to cling to the northern coast of Greenland for decades to come and possibly through the remainder of this century even during the summer. But after seeing the substantial reductions in this area in 2020 I'm now obviously questioning that assumption. I was also an advocate of more moderate estimates of the first "ice-free" summer tending to favor 2050 or so. Again...I'm starting to question my position in this regard as well.

Gotcha. Thanks. That's helpful. I try to lurk as much as I can on the Arctic Sea Ice Forum. Sea ice is such a complicated beast to understand.

I'm still trying to learn the ins and outs of Arctic sea ice. I've gotten a pretty good understanding of some of the things that negatively affect the ice. What was the pattern like in July and August of 2012?

ERA 2mT reanalysis is +0.627 for May. This is the warmest May on record. https://climate.copernicus.eu/surface-air-temperature-may-2020

NCEP/NCAR 2mT reanalysis was -0.08C from April to May. UAH's TLT product doesn't always move in tandem with the surface temperature. In fact, it often moves in the opposite direction. BTW...I just recently learned that UAH's TLT product is actually derived from their MT, TP, and LS products. Specifically the weighting is LT = 1.538*MT + -0.548*TP + 0.01*LS. I've mentioned this before, but I wonder how much the stratospheric cooling is contaminating their TLT product. https://www.drroyspencer.com/wp-content/uploads/APJAS-2016-UAH-Version-6-Global-Satellite-Temperature-Products-for-blog-post.pdf

That's pretty cool. Which reanalysis dataset are you using?

Here is an update of the CMIP5 vs observation comparison as of March/2020. CarbonBrief

That's what the GISS group wanted to do. Other groups use different baselines. All it does is to make a baseline from which the anomalies are computed. You can pick any baseline you want. It can be an entirely arbitrary decision. It does not change the ranking of the years, the warming trend, or the structure of the graph chubbs posted.

That April 2020 update from UAH brings their trend up one notch to +0.14C/decade now. For comparison Berkeley Earth is +0.19C/decade, RSS is +0.21C/decade, and ERA is +0.19C/decade over the same time period.

One thing to take note of with this event is that the big 3 global models are all robust with thermodynamic and kinematic environment even with the low levels. 4 consecutive SREF runs show a 90 contour surrounded by an expansive 75 contour on the tornado ingredients product even though the event is more than 48 hours away. CIPS analog guidance has 3 high risk days in the list including 2007-03-01, 2010-04-24, and yes 2011-04-27 is there too.

You guys beat me to it. I was just going to post the SREF tornado ingredients product myself. A 90 contour at F72 is rare indeed.

The globals (GFS, UKMET, and ECMWF) have the high risk style look to them. And there's already a 60 contour showing up on the SREF tornado ingredients product. That's pretty high for the FH81 frame. There's not a whole of lot data to constrain this event at this point in time. I'm usually pretty conservative when guessing at the risk outlooks...sometimes too much so...but yeah, if tonight's global runs are not materially different than today then I too would not be surprised by a D3 moderate from the SPC tomorrow.

UAH also recorded another increase in stratospheric temperatures. If history is any guide then that means further troposphere cooling is around the corner. The leading hypothesis for stratospheric warming is still wildfire smoke.