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Thursday, April 23, 2015

Signatures

I have enjoyed reading some older explanations of "signatures" of global warming as related to Greenhouse Gas increases.  "Signatures" of anthropogenic caused warming or in other words warming that could only be caused by CO2 equivalent gases would be nice.  That would give the world a real test of Climate Change, as in human related climate change, so we could move on.

Stratospheric Cooling with Tropospheric Warming (SCTW) should be a signature of well mixed greenhouse gases.  The well mixed CO2 equivalent gases would basically blanket the lower troposphere reducing the flow of energy through the stratosphere.  Realclimate had a hilarious post on this subject some time ago.  There is also the Tropical Tropsphere Hot Spot (TTHS) which is a "signature" of GHG warming but it is not a "unique" signature.  If warming is caused by GHGs then there would be a TTHS, but if the warming is caused by something else then there would still be a TTHS.  If there is no TTHS then that would be evidence of no warming, at least in the tropics.

The fact of the matter is neither of these are "unique" signatures.  If there is any warming, since there are already GHGs in the atmosphere, the troposphere would warm and the stratosphere cool.  However, you can have variations in stratospheric ozone and water vapor that can change the temperature of the stratosphere that would change the troposphere temperature.  You can also have changes in ocean surface temperature which would cause changes in troposphere temperatures and moisture with water being another of those greenhouse gases.  If the atmosphere were perfectly stable, then you could easily figure out what caused what, but thanks to dynamics it is not so easy.

You can get a better idea by assuming CO2 equivalent gases have a 1C per 3.7 Wm-2 impact on lower troposphere temperatures and then tease out an estimate for lower stratospheric cooling related to that change.  Since any warming would also have an impact, you would need to estimate the equivalent change in energy flux due to "other" warming.  The two are very similar making attribution difficult.

The tropical oceans for example, while still impacted by AGW, have more latent and convection heat flux change and much less radiant heat flux change.  The TTHS is supposed to be "driven" by the latent flux increase, provided of course the convective flux changes at some predictable rate so it doesn't eliminate the TTHS.  Richard Lindzen hypothesized an Iris Effect where increased SST would reduce tropical cirrus cloud impact offsetting a great deal of the tropical warming.  That basically would erase most of the TTHS.  I am not particularly sure that Dr. Lindzen's Iris analogy is all that great, but changes in deep convection related to increased SST would change cloud cover distribution, stratospheric water vapor, stratospheric ozone and vary the Brewer-Dobson circulation.  Notice that the tropical SST is about 0.5 C warmer than "average" and about the same as in the early 1940s.

My focus has been of the Brewer-Dobson circulation changes which impact the planets real heat sinks, the poles, by changing pole ward advection of stratospheric water vapor and ozone which changes the intensity of Sudden Stratospheric Warming Events and "Arctic Winter Warming".

That is a big mouthful of not very often discussed climate mechanisms.  A simple way to think of this is that variation is inefficient and stable is efficient as far as engines performance goes.   We have polar winter vortexes that if stable tend to reduce heat loss and  when unstable allow more heat loss.  In the news the "POLAR VORTEX" is the new villain in the winters are colder that usual explanation toolbox. What they are referring to is a break down in the vortex related to large changes in the high northern jet stream.  A stable jet stream/polar vortex would related to a milder winter, a milder winter allows the surface to retain more energy which is really what global warming is about, retaining more energy.  If there isn't an increase in energy retention then no TTHP or SCTW.

Well if you talk to any true believer in AGW/CLIMATE CHANGE, you know that the oceans are gaining energy which is energy retention, therefore we should have the signature TTHS and SCTW.  Well, that isn't a given.  Right now the Southern Hemisphere is doing the heat uptake thing and the Northern Hemisphere is doing the heat rejection thing.  A few years I estimated the heat rejected by a large SSW event to be of the same order of magnitude as the energy imbalance.  There are now papers that tend to confirm that my estimate was pretty good.

There are several interesting things about the hemispheric imbalance.   The current stage of the solar precessional cycle is a biggie.  There is more solar energy available in the southern hemisphere summer along with a larger percentage of ocean surface area.  With out any consideration of change in GHG concentration, there should be more ocean heat uptake in the southern hemisphere.  In order for there to be an "equilibrium" the northern hemisphere heat rejection would have to increase OR yep that is a big or, more energy must be stored in the form of glacial ice.  The part after the big or would mean Earth is primed for a shift into some degree of glacial period.  Fortunately or not depending on your point of view, glacial mass requires land area and there aren't many people/nations willing to donate to the glacial cause.  With the current state of technology it is much easier to melt snow than it is to grow glacial mass.

This low probability of glacial mass growth leads to the second interesting point.  Since land area required for glacial growth isn't really symmetrical any significant growth would produce an orbital wobble.  A wobble is variability which implies inefficiency for our heat engine which could trigger a more rapid rate of heat rejection should someone donate enough land for the global glacier international park.

This potential wobble influence leads to the third interesting point, where is there any "equilibrium" involved in this climate problem?  We have shifting psuedo-steady states with pretty unpredictable time frames.  However, if you talk with the true believers again there is no evidence of past variability or any reason to consider hemispheric imbalances.  Besides that would complicate a perfectly "obvious" theory with several "signatures" that will likely pop up any decade now, provided of course we have an extremely stable atmosphere that allows us to use "equilibrium" assumptions validly.

Kind of reminds me of those Boy's Life cartoons.  Instead of circular logic it is more like a circle jerk.





Monday, April 20, 2015

Carbon Balance

There will continue to be a debate over the carbon balance because it is complex.  This carbon cycle graphic from NASA Earth Observatory is about average.  Human emissions via fossil fuels are about 9 gigatons per year and about half remains in the atmosphere with land and ocean sinks removing a little over half.  The annual transfer between the land/ocean and atmosphere is roughly 200 gigatons or about 22 times greater than the annual human emissions.  Man kind does more than burn fossil fuels we also impact the land and ocean carbon sinks.

Since the oceans provide a great deal of food for humans and their livestock, some portion of that carbon is more rapidly cycled than if it were not disturbed.  Same with land where food sources are more rapidly cycled due to a few billion people and their livestock.  If it were not for mankind, some portion of that carbon would still be cycled, but what is "normal" isn't all that easy to determine.

Obviously, burning the very long term sequestered carbon in fossil fuels is part of the change in the carbon cycle, but land and ocean abuse also play a significant role.  Since a very small change in land and ocean carbon sinks can completely offset fossil fuel emissions, it should also be obvious that changes in agricultural, ocean harvesting and general construction have a large impact.

Estimates of land use impacts, specifically soil carbon, are wild ass guesses.  For example, "pre-industrial" is vague and soil carbon estimates are limited to at most the top meter of soil.  Replacing deep rooted native plants with shallow rooted crops could have twice the impact of current estimates.  In the southeastern US, former cotton and tobacco fields have been replaced with tree farms and orchards.  Today the yield per acre is a factor of ten or more greater than it was at the turn of the 20th century, so more of these crops can be grown on less acreage freeing considerable land for "conservation" of soil uses.  Most likely because of that transition, the US is now a net carbon sink, meaning that US land area is taking up more carbon than it is releasing.

Globally, land carbon balance is negative, meaning it is a source rather than sink and is contributing about a third to the atmospheric carbon increase.  If that land area were managed to produce an equal carbon sink, then roughly two thirds of the atmospheric carbon uptake would be reduced.  "Science" tends to select when it wants to use gross values and net values in a haphazard manner greatly complicating understanding of the situation.  From what I have been able to determine so far, land use has roughly twice the estimated impact, but that really depends on what "pre-industrial" condition is selected.

Potential damage of increased fossil fuel use appears to be over estimated by a factor of two which depends on what "normal" is selected again invoking "pre-industrial" definitions.  If you pick 1700 to 1918 as "pre-industrial"  you have potentially more warming than if you select 1000 to 1200 as "pre-industrial".    The is a growing "war", if you will, in paleo-science with some factions claiming a "pre-industrial" nirvana that never changes, the hockey stick crowd and the new guard of ocean paleo-climatologists indicating considerable variability in past climate.

So despite the claims of "consensus" there are large areas where the climate science is far from being resolved.  Politically, the advantage in this uncertainty goes to the precautionary principal crowd.  It is really to their advantage to keep large uncertainties all the while playing the Merchant of Doubt uncertain card, belittling the realists with rational questions.  Actually solving some parts of the climate problem reduces the precautionary urgency, so don't expect many simple cost effective mitigation attempts to be very well publicized.

Conservation agriculture for example has a positive impact of soil carbon and water retention but requires evil Monsato products like "Roundup" brand weed killer.  Like any product, Roundup can be over used and since it isn't "natural" it doesn't have much "green" support.  Pesticides which also make life bearable can be over used and aren't on the "green" happy face list along with antibiotics, genetically modified crops, radiation and a surprising large amount of scientifically developed "solutions" to feeding the world and making the world more bearable.  Use of these scary science developments can reduce land abuse increasing the acreage that can be set aside for "conservation" which is really a much longer time scale version of crop rotation.

To add insult to injury, the Green Police have started alienating themselves from the third world counties they profess to care for.  Coal is one of the least expensive energy sources for many nations that are not allowed to dabble in nuclear and the new Asian Bank initiative is providing funding for projects the Green Police cannot stomach.  Every one of these developing nations will run into the same environmental problems faced by the developed nations and will turn to the same "solutions" used in the developed world with the appropriate 10 to 30 year lag time.  Instead of trying to force "solutions" on the third world the developed world is better off actually solving problems by losing the not in my backyard mentality knowing that those solutions will be copied, likely without appropriate attribution of intellectual property, by the poorer nations of the world.

All this basically means is that global "de-carbonation" is an incredible myth for at least the next 30 years so focus on the "low hanging fruit", land use improvement, is about the only viable option until some of the energy of the future technologies arrive and are then predictably pirated by the third world.

We live in a hand me down world folks.  Leading by example is more than a cliche, it is business as usual.  If we use it, properly, they will too.  You cannot force "solutions" on a cost conscious world.


Saturday, April 11, 2015

Are Human Influences on Climate Really Small?

Are human influences on climate really small is the title of a post by Steven Koonin on Climate Etc.  The magnitude of the radiant gas forcing, CO2 and equivalent "greenhouse" gases, can be relative to your perspective.  That really isn't the way it should be.  Increasing one force on a stable system should be fairly easy to figure out.

For a "global" impact though you can pick a number of frames of reference.  Surface air temperature aka lower troposphere temperature, as I have mentioned is the worst possible choice of frames.  From the "surface" you have radiant, latent and convection energy flows that has different impacts on the "surface" temperature.  You can use an "effective" surfaces energy and temperature, for example 395 Wm-2 radiant, 90 Wm-2 latent plus 25 Wm-2 convective would produce an effective surface energy of 510 Wm-2 which would be roughly and effective temperature of 308 K degrees.  With a Top of the Atmosphere energy value of 240 Wm-2 which would have an effective temperature of 255 K degrees.  So the combined "greenhouse" effect from the "surface" would be 510-240=270 Wm-2 per 308-255=53 K degrees.  That produces a 5.1Wm-2/K forcing ratio.  There is of course some uncertainty involve so the "standard" of 5.35 Wm-2/K is close enough.

So if you are going to determine "small" for a doubling of CO2 which happens to use the "standard" dT=5.35ln(CO2f/CO2i), you should stick with an apples to apples comparison.  If you neglect latent and convective heat flux you would get 395-240=155 Wm-2 per 289-255=34 K degrees producing a 4.56 Wm-2/K ratio.

With a doubling of CO2 expected to add 3.7 Wm-2 of "forcing", everything else remaining equal, you would have a 3.7/270 yields 1.3% to 3.7/155 yields 2.4% impact on "surface" energy/temperature provided temperature and energy have a linear relationship.  They don't have a linear relationship of course, but for small changes you have small error with that assumption.

A simpler "guestimate" is to use the estimated forcing versus the estimated "force" or Down Welling Longwave Radiation (DWLR) estimated at about 340 Wm-2.  That gives you a touch over 1% impact, all things remaining equal, and the DWLR value should include all feedbacks for your small change and hopefully small estimation error.  I prefer that simplification since DWLR energy is roughly equal to the average ocean energy at an average temperature of ~4C degrees.  That produces an all things remaining equal estimate of  almost one C degrees per CO2 equivalent doubling or 3.7 Wm-2 of anthropogentic forcing.

So if you pick the worse thermodynamic frame of reference and assume away the reasons that it is the worst frame of reference you get a bigger impact than if you pick a simpler frame of reference.  Imagine that?

Following Koonin's post the "let's" play thermodynamics games begin.  The simple minded warmists pick the "global" surface temperature sans complications, the coldists pick their cherry, but if you consider dT~5.35ln(CO2f/CO2i) you should pick effective surface temperature and energy which includes latent and convective heat loss estimates.

The you could blow that off and use the "subsurface" temperatures which have less latent and convective flux to worry about.  I have been saying this for some time, but I noticed some others are moving into a similar train of thought.

Issac Held has a post on "Addicted to Global Mean Surface Temperature" and Roy Spencer an anti-skydragon post or soil temperatures.  Neither quite gets to the real simplicity of "sub-surface" energy which is the actual best possible reference for a change in atmospheric forcing.  It will be interesting though to see just how complex and convoluted the extreme factions of the debate will go to preserve their personal ideology.