Man Based Global Warming....

As for this "Milankovic cycle", is it also possible we are tipping to a new angle as the plates shift?

Not denying we might be (still gets colder than hell up here) warming, but that there are many things affecting this change not just man.

It's like we have returned a bit to how the weather was when I was really young, 40 yrs ago. No snow until after thanksgiving, then you get dumped on, freeze your tail off most of the winter, then get dumped on again in the early spring and then hotter than hell and a good rain or periods of after the 4th.

 

This has been discussed previously. If you have a point why don't you simply express it.

 

In my opinion, the greatest source of uncertainty with respect to AGW is the General Circulation Models (GCMs – i.e., climate models) used for climate projections themselves. According to the IPCC, GCMs are essentially numerical weather prediction (NWP) models and I suspect somewhat simplified versions at that (presumably, it would take too long to run very sophisticated NWP models out years/decades).

I use NWP models (e.g., GFS, WRF, ECMWF, GEM, SREF, GEFS) on a daily basis (I’m an atmospheric scientist) and based on my experience, NWPs are virtually clueless after about a week (i.e., have no skill), never mind projecting decades in the future, even on the climate temporal scale and global spatial scale. I generally work in the mesoscale, but errors in the mesoscale will eventually affect the global scale. The atmosphere (troposphere) is simply too complex to model out to extended periods of time.

The biggest uncertainty with these models is their depiction of cloud cover. In my experience this is something that occurs from initialization. How anyone can actually expect these models to have any idea of what cloud cover will look like in a warmed climate is beyond me. IPCC does address this to some degree, suggesting the negative feedback from increased cloud cover could potentially offset the warming induced by anthropogenic greenhouse gases.

That being said, I’m also not prepared to call AGW “a crock†either. CO2 and other greenhouse gases do absorb IR – that’s not controversial. I think we simply don’t know what the effect will be, and we’re essentially conducting a vast experiment with our atmosphere. Thus, I think it’s prudent to limit emissions to the greatest degree practicable.

 

Do you work for the TVA?

So what you're saying is, now would be a Great time to execute some serious changes while people are actually thinking about change vs dragging them screaming into change.

The old guys are about gone and us older ones are still some what youngsters. Being born into the rocket, tech or what ever age you want to call it.

Still, some just hate change though.

 

No - but I do work for a federal agency (standard disclaimer - the opinions expressed here are mine and do not necessarily reflect those of the U.S. Government ).

Yup - I think it would be prudent to pursue technologies that decrease greenhouse gas emissions.

 

+1

Do you believe in clean coal? The university up here is working on it.

 

Clean coal can be beneficial from a reduction-in-imported-oil perspective (e.g., CTL). However, it doesn't address greenhouse gas emission reductions.

 

My guess is that that he works at ORNL (Oak Ridge National Laboratory) just north of Knoxville, TN.


I like clean coal and in particular coal gasification because it increases efficiency and reduces pollutants that we know are harmful; SOx, NOx, CO, mercury, particulates. For example NOx levels of 15 ppm down from 250 - 600 ppm now. (Current emissions depend on how old the plant is)

We know without a doubt these pollutants are harmful so we should be pushing forward efforts to eliminate them.

I also don't see a short-term way forward for the electrification of personal transportation without coal powered base loads. We know that there are large efficiency and pollution benefits to switching from gasoline powered cars to EV's even if they are powered buy our current coal-fired plants.

 

The GCMs do include precip. Solar activity is included in the models' "physic packages".

With respect to precip, climate/weather models incorporate "parameterization schemes" (Precipitation & Cloud Parameterization - PCP) which are techniques for estimating precip based on certain modeled atmospheric conditions (e.g., lift, instability, CAPE). So precip is actually a "byproduct" of atmospheric processes based on the behavior of previously-encountered conditions. Precip has to be parameterized because many precip processes are sub grid scale (e.g., typical summer air mass thuderstorms - the convective cells are much smaller than the horizontal resolution of the models). Clearly parameterization does not work well with convective processes.

This is another of many reasons why I don't believe atmospheric conditions can realistically be modeled decades in the future even on the global scale. Atmospheric models represent POSSIBLE future conditions but it's really still just speculation in my opinion.

 

I mentioned I wasn't going to comment on this thread any longer since it seemed we were just going around in circles, but since we now have somebody with apparent subject matter expertise - and since you mention GCMs - I am wondering if you have any comments on climatologist Roy Spencer's criticism of the models.

Specifically, he believes current GCMs are incorrectly characterizing feedback. My understanding is that he believes net feedbacks are negative (due to mishandling of clouds), not positive as per their treatment in the models. Spencer says:

"Instead of the currently popular practice of building immensely complex and expensive climate models and then making only simple comparisons to satellite data, I have done just the opposite: Examine the satellite data in great detail, and then build the simplest model that can explain the observed behavior of the climate system.

The resulting picture that emerges is of an IN-sensitive climate system, dominated by negative feedback. And it appears that the reason why most climate models are instead VERY sensitive is due to the illusion of a sensitive climate system that can arise when one is not careful about the physical interpretation of how clouds operate in terms of cause and effect (forcing and feedback)."

If Spencer is correct, then current models would overstate effects of CO2. In his words: I consider the IPCC climate model forecasts of strong global warming in the coming decades to be completely unreliable for basing policy decisions on.

 

It's such a brutally cold winter

 

not here. It's been shockingly mild. We'll be in the high 50's - 60's over the weekend. Fortunately, the mountains are getting good snow. It's been warm, dry, and windy on the front range. Hell, we had a wild fire a week ago! That's a first in my 8 years in CO.

 

And that proves the climate isn't changing?

 

Yes, CO2 production from fossil carbon, which increases the concentration of CO2 in the air.

"Make everything as simple as possible, but not simpler." -Einstein

 

That can happen, but it's very slow (millions of years). It does not account for the last 200 years' warming.

 

The basic mechanism is as simple as putting a lid on a pot on the stove: it's very difficult to predict exactly where the convection cells will be and where the drops of condensation will form, but the pot *will* get hotter and boil faster.

Adding CO2 to the atmosphere traps more heat, so it is like putting a lid on the pot. It's very hard to predict the *detailed* consequences (how will the weather systems change? where will they be?) but it is a physical certainty that the Earth (overall, on average) will get hotter.

 

Tim - that pretty much reflects my feeling about CGMs - they're unreliable in forecasting the degree of warming, if any, because I do not believe they can project cloud cover (especially in a warmed environment) with any certainty whatsoever. NWPs are abysmal in forecasting cloud cover in the hours time frame, never mind years or decades.

However, I'm not saying this dramatic warming couldn't happen. I think we just don't know one way or the other.

 

To illustrate my skepticism with atmospheric models and how they become less reliable with time, consider the graphic in this link...

Animation using Javascript Animation Player

...This is a "spaghetti plot" of 500 mb height contours projected out over 360 hours (15 days) of the SAME model (GFS) with 21 slightly different initial conditions (but still within the margin of error) and/or physic packages.

The 500 mb height contours generally reflect the configuration of the jet stream. Notice they all start out in relatively good agreement before diverging to wildly differing solutions by day 15 (January 30). Anyone care to guess what the configuration of the jet stream will be on January 30 over the Eastern Pacific/Western CONUS based on the 00z January 15 run?

 

Thanks for the response. In fairness to the AGW promoters (and out of a desire to learn more) - let me ask another question...

I have heard it stated that the comparison of near term weather models to long term climate models is an unfair one. Certainly, I don't place a lot of faith in the long term models for several reasons (they don't handle water vapor well; I'm not sure we have a very good reading on some of the model inputs/feedbacks - for instance - how much particulate /aerosols are currently in the atmosphere and whether that has a warming or cooling effect; whether the models can adequately account for the effects of natural cycles, many of which we don't understand and perhaps have not even identified; etc).

That said (and this is spoken from a great deal of ignorance) I have heard it argued that while a weather model starts with a current state and evolves it, if you will, over a span of time, a climate model places a future set of conditions over our current situation to reach a conclusion. That is, the models don't actually run 100 years worth of iterations to reach a future condition. They start with the current state, impose new future conditions, and model the expected result.

Can you comment?