I think they do pretty well, considering the complexity of the system. Mean climate statistics have been improving with each generation. The biggest challenges relate mostly to small scale convection (e.g., thunderstorms).
At 2:23 the image shows variability in tree ring width from side to side. If one is working on an early tree ring sample do they have the full diameter or just "one side" of it, I wonder.
I did not hear how you calculate temperature from tree rings? Which I understand is what lead to the "Hockey Stick" using these proxies of prior temperature. These tree rings then in modern day do not match with actual records. Therefore there must be something wrong with the "Hockey Stick" ??
History of the climate model? Son, there is no mention of Milankovitch in your school textbooks?! I'm sorry that they condemned you to eternal darkness at such a young age.
What I want to know is why scientists don't use antarctic ice core data to determine co2 levels beyond 800 000 years ago, when we know the antarctic ice sheet formed 34 million years ago. Only the accuracy of timing beyond 800 000 years is lost, but we still know that since in all the ice core data there wasn't an instance with co2 levels beyond 300ppm, this means there wasn't an elevated co2 level up to 34 millions ago either, contradicting the unreliable proxies. And since we now could adjust the proxies with that information, it would mean the co2 levels were estimated too high even beyond 34 million years ago. Finally, given that crustaceans never all went extinct, since they appeared 500 million years ago, but they can't exist without sufficient carbonate, which is disappearing with the acidification of the oceans right now, that again, we were never in a co2/methane regime like we are now, ever since animal life appeared basically. We can't lose ocean life, that would be terminal I think. So my suggestion would be no more new fossil projects, write off everything that's still in the ground and untapped (until maybe a thousand years later when we feel like preventing an ice age). Make existing production expensive by a phased in massive tax over 10 years, so nobody is going to buy new ice vehicles much longer 22:21 yes I don't buy the linear correlation of O18 with temperature. It's not going to be linear and depend on a bunch of other variables. 27:11 I think it is very dangerous to 'estimate' that co2 was much higher back then based on some random co2 models from a few people. In my mind there is absolutely no way to estimate the turnover in biomass and the amount of biomass that has decomposed back into the atmosphere..I mean seriously go pound sand. All we know about co2 for sure is the antarctic ice core record and that one is clear as hell: do not go over 300 ppm. And yes nobody talks about the sun having been much weaker back then (according to same models I take it) which means you can't take elevated co2 levels at face value. In any case this 'co2 was higher nothing happened' is gaslighting.
What is wrong with the feedback loop claimed for CO2? Big question is how then does glacial maxima terminate and how does interglacial terminate if CO2 is a major factor. That CO2 lags both termination means that CO2 concentration is the effect and not the cause. Otherwise, it would either be that we are stuck at warm temperatures or we are stuck at the bottom of a glacial maxima. If ever CO2 has any effects, it is too small to be the driver of global temperature.
Tom Gallagher from Calgary University explains the climate record quite accurately using the continental drift theory and carbonic acid cycle. CO2 doesn’t play any significant roll in his theory but it is quite compelling.
The CO2 warming theory leaves out the role of carbonic acid in the climate cycle. The other factor missing is the Beryllium-7 paleo data that recorded the suns effect on climate which along with water vapor and clouds explains the climate record quite well. Climate scientists need to remove the CO2 goggles so that they can see the real drivers of climate.
A couple suggestions: Where is the W/m2 change due to the greening of the earth from CO2 fertilization? There is also no discussion about the decreasing effect of CO2 infrared emission as concentration increases or quantification of CO2 saturation level in the energy absorption and emission band.
The hockey stick handle based on dendrological records is not accurate to any degree whatsoever. It shouldn’t even be shown as resembling anything factual related to global temperatures.
Tree ring records cannot be used to recreate temperature records. Precipitation is the primary cause of tree ring thickness. Temperature has very little influence on tree ring thicknesses. Droughts and temperature are not well correlated.
The discussion on sea surface height anomaly don't take into account the effect of wind thas can displace water : by geostrophic way, if you put a westely wind over the ocean at mid-latitudes, you will induce an se surface height gradient. No T or S effects here.
28:00 I've always learned that Ekman induced vertical motions was basically a low-level effect, so the presentation here is a bit weird i think. To understand vertical motions in the free atmosphere, you have to look at something other than Ekman things.
Modelling is a great tool but only after a level of certainty about the parameters have been reached. In physics some known factors can be easily established by sheer experience and real live data observations. However, in regards to climate only a very limited amount of parameters are certain. Complicated by a dynamic interactive non equilibrium system one could say with absolute certainty that no model or series of models can be relied upon, not even an average even if they all agree. If the underlying premise or assumption is wrong the outcome is as well. So, if you assume the greenhouse gas theory is right in ALL your models All of them will more or less point to the same thing. Since everyone seems to be focused on Co2 maybe it is best to start the models without that and see how they level up to real time measurements. A lot better than they currently do would be my assumption
Climate sensitivity to CO2? Any statement about this is simply that but not a statement of fact. Ergo, highly speculative and uncertain especially given the amounts of CO2, its saturation and frequency response. And guess what? The more you zoom in the less certain it becomes. Unfortunately the whole climate discussion in terms of political policies hangs on this one element.
Upwards radiation fr the surface is clearly very small as it will be drowned out by convection and conduction to a lesser extend. Another point is that the influence of greenhouse gasses is ( as standard) overstated. I understand you need to connect both upwards radiation and greenhouse gasses in order to make your calculations work. However, convection usually trumps radiation as does conduction. Furthermore, the oceans play a bigger role than the Earth's surface in regulating energy transfer. Overall, H2O which includes clouds and water vapour completely dwarfs anything Co2 might do both in its frequency spectrum and saturation points in light of greenhouse gasses which is of course a misnomer but anyway. The assumptions about greenhouse gasses are always stated as if they are fact. I see them more as speculation just like the use of the SB law. It assumes the Earth as a blackbox but both the Earth and the atmosphere do not fit into the SB straightjacket as far as i can see. It seems, pun intended, rather...forced.
Hello, at 4:15 why pressure surfaces under the warming arent affected ? I would say that the increase of volume of the layer that is warmed would push down on the surfaces below and distord them?
47:57 No, snow and water are near-perfect blackbody absorbers. They have an emissivity of near 1, similar to the others. I call that a paradox, but is it true. (I also have the solution).
Near perfect? Blackbody physics require a vacuum which is obviously not the case on Earth. To simply ignore that part of the SB law is rather convenient for yr argument but goes against it fr a scientific viewpoint. I think yr argument has more to do with albedo..
Very poor explanation on the role of H2O as a greenhouse gas! In fact understates the role of water vapor in the atmosphere, which as a molecule is 10x stronger at being excited by infra-red than CO2. H2O makes up 3% of the total atmospheric gases (Nitrogen is 75%, Oxygen 20%), CO2 makes up just 0.04%.
Considered irrelevant. Only way to remove water vapor is to freeze it. Which means geoengineering has proceeded along CO2 removal or sunlight diminishment already
Hello I'm afraid I can't reflect the opinions of the others who commented here. I watched the first lecture which was predictable by it's nature, no surprise there but suddenly in this second lecture we dive into black body radiation which is something of a heavy concept especially if you haven't come across it before. Furthermore, the equations just dumped in front of the students, myself included, seem almost to shock and put people off. There is no real explanation of the black body radiation and the ensuing calculations are almost completely unhelpfu because they aren't shown, a fail in an exam I might add. So we went from being put to sleep in the first lecture and part of this one, to being thrown under the bus in this one. Sorry but it just makes me so angry when people who are supposed to be teaching others do this.
If you don't mind me saying so, the concepts invoked here are supposed to be familiar to any high-school student following a scientific curriculum. There's no need to demonstrate such simple calculations (I remind you that the course assumes some basic notions). For example, calculating the energy emitted by the sun : - Surface area of a sphere: 4πR² - With a radius of 700,000 km: 4*3.14*700,000,000² = 6.15*10^18 m². Take Stefan's formula with T=5770K, sigma = 5.670400*10^-8 and multiplying by the area gives: (5.670400*10^-8)*(6.15*10^18)*(5770^4) = 3.86*10^26 Watts (rounded off) An exercise I used to do in high school.
Hi Paul, this is a great video that clearly walks through a problem I've been struggling to wrap my head around. I do have a question on your statement that the kinematic method "tends not to be used" because of inaccuracies in measuring the ageostrophic wind. This is confusing to me because I think it's still very much the case that both ECMWF & the WRF model use the kinematic method as the basis for their omega calculations. Do you mean instead that the kinematic method is rarely used for deriving realistic vertical velocity estimates based off observations? It seems to me like it would still be a viable way of calculating vertical velocity on gridded model output fields. Is this a correct interpretation?
Yes, it's rarely used for deriving realistic vertical velocity estimates based off of observations. When it comes to the models, horizontal velocities are known to many digits of accuracy, and so losing one digit of accuracy from the kinematic method is justifiable.
Any IPCC accord is garbage. World politicians have run out of ways to raise revenue the normal way so now they want to tax consumption of some good so they can redistribute to the poor & claim Nobels for their goodness. Not that it gets to the poor anyway. But this is what is fact. Given the narrative of the greens that co2 is a bad gas, you must then in carbon markets maintain the producer of such on the market in order to tax their revenues. Inevitabley, they will locate anything that has to do with industry in the poor part of town. BTW Pete CO2 did not & cannot produce this 4 degree incline. CO2 behaves logarithimically.
I like your videos, but honestly, this is the first point I fail to follow when you say curvature is not considered in geostrophic wind. When the lines of constant pressure are curved, geostrophic wind flows along those lines, and that's what the equations for u and v tell us. When you introduced the geostrophic wind, you didn't limit yourself to linear flow (see pressure map over USA). Why is there suddenly a problem with this? Is it wrong in the end because the curvature is neglected? But the geostrophic equations were derived from the full set of equations, I can't see the point where we mistakenly ignored curvature. In my opinion the equations you derive at the end (momentum equations along and across flow direction) at 44:21 do not contain any "new physics", the are just written down in another coordinate system. So I cannot follow why those equations should be more correct as the originally derived ones. EDIT: ok, now I see: acceleration was neglected totally and what remained was just the balance of Coriolis and pressure gradient. However even in static flow we have acceleration, in curves which is nothing else than centrifugal force. It is always good to think twice ;-)
Geostrophic winds are derived from a balance between pressure gradient and Coriolis force, which are the dominant terms in the force balance for large-scale midlatitudinal systems. So geostrophic winds can be used to explain most of the real wind speed even when the trajectory is curved. The next largest term is the advective term, which includes centrifugal force. This term will be active when air parcels are following a curved trajectory, but for large scale midlatitudinal systems will only represent around 10% of the real wind speed. At smaller scales (which were not considered in chapter 2) the centrifugal force can be as important as the PGF and Coriolis force.
@@introductiontoatmosphericd284 Thanks a lot for your clarification. It became finally clear for me as stated in my last sentence - until the next question arises. I always have to sleep over each lecture in order to get it into my brain. Great channel - in fact one of the best I found ever on RU-vid.😀
@@introductiontoatmosphericd284 At 44:23 you derive equations: The particular equation for acceleration along flow direction is DV/Dt = -∂Φ/∂s For parcels flowing along geopotential height contours ∂Φ/∂s=0, so I wonder, how they can ever be accelerated along flow direction when acceleration along this direction is zero. It looks like V=const. along the line of the parcel, but when geopotential height contours get closer to each other, its speed must increase, because speed is proportional to the perpendicular pressure gradient. At the moment I cannot resolve this discrepancy...😒
@@wace470 I went through the same kind of questioning a while ago. In fact, it's important to bear in mind that these equations are diagnostic approximations and not meant to be thought through too deeply. For an moving air parcel to change speed, it must necessarily encounter a component of the pressure gradient in the direction of motion. So this acceleration necessarily implies a movement that intersects isohypses. We need to go back to more complete equations to understand this in the context of curved paths.
@@DertiDerty Hello and thanks - in the meantime it became clear. We covered this topic in our lecture. Yes, geostrophic wind is only a diagnostic quantity. The real wind cannot be purely geostrophic, because it would mean, that Dv/dt=0. Most interesting is the book "Mid-Latitude Atmospheric Dynamics" by Jonathan Martin, where he writes about " The geostrophic paradox and its resolution": Without an ageostrophic component the geostrophic wind would destroy itself. This leads to the Q-Vector form of the Omega-Equation which predicts a secondary vertical circulation, accompanying the pseudo-geostrophic flow..
What a series of videos! One of the best science lectures I've found on the internet so far. Reading that from books would take so much time. I enjoy watching a lesson every day and learning more and more. These videos allow me to better understand introductory books. Thank you!!!
You would need to take the Fourier transform of the time series to identify oscillations. Generally one takes the temperature data and mirrors it so as to maintain periodicity. Sharp peaks should emerge in the Fourier series associated with the seasonal cycle.
@14:45 : I think it's an error that air in the super-saturated regime is not observed in nature? We frequenty observe air to be super-saturated. Homogeneous condensation occurs only at about -40 deg Celsius and not at 0 deg C.
amazing lecture. I have a geophysics/geodynamics course at university , we had some sessions about paleoclimate. This lecture says so much in just 35 minutes, very good
