The Definitive Global Climate Change (aka Global Warming) Thread — General Discussion and Questions
I think. It's an irritating thing to contemplate. Whatever the truth is it's sort of complicated to say the least. So, maybe people tend to either: disaster, or what-me-worry? POVs, and then spend time defending it. I would fall in the latter admittedly, but as I see it, existence is always in peril, and complicated by lots of variables and nothing really matters, (to quote Queen again), so just enjoy the ride.
Last year I got chilblains, on my toes,
This winter I get mosquitoes.
(It's supposed to be winter on the top half of the world.)
(Why do they label it an upside down map? No it's not.)
Your hemisphere is not the southern, any more than ours is northern, but that's how it was labeled by science. Maybe not science but our understanding of the planet guided by discovery which science is based on. So, mosquitoes. Well, life is grand. Hope you are enjoying it mosquitoes and all.
I read through your source, but couldn't find the answer to two questions. Could you please be so kind and elaborate:
1) Is it an apples to apples comparison, i.e. comparing real troposphere temperatures to what is being modeled?
2) Does that include all the climate models that track this or only those that have been overestimating warming.
The answer to Q1 is that there are no completely honest comparisons as far as I know. The tropospheric temperature measurements are real data from radiosondes and two satellites reported as RSS and UAH measurements. I hate citing a wikipedia source for anything, but this article does provide a decent explanation of what they measure and how they are used to provide lower troposphere temperatures. I give them a fairly good level of credibiltiy because they agree within error limits with other temperature records such as HadCruT4, they avoid urban heat island effects and they are not subject to dubious revisions.
It is sometimes hard to compare the various temperature records that are presented as "anomalies", which are deviations from the mean over some arbitrary period of time. But the place where the dishonesty occurs is in the model calculations. The climate records from some period of past history are used to "train" the models; i.e., adjust their parameters so that the model outputs agree with observations at some time. The common practice is to train up to the current present time, and then let the models generate projections for the future. This has the effect of continually resetting the starting points of the projections and eliminating the accumulation of errors of predictions. The current models always look to be in agreement with current conditions. What Dr. Spencer did in producing the graph that I posted was to end the model training period in 1979. I believe that he ran every model that has participated in the CMIP5 project. While James Hansen's 1988 model was not among them to my knowledge, it projects a result that tracks the mean of the 73 models. This says that the climate models haven't changed much over the years. I am not aware of any of them that under predict the observed temperatures, but the discrepancies show more clearly for projections that started in earlier times.
I can appreciate your frustrations in trying to assess the risk of seriously deleterious climate change, but that is something that only you can do for yourself. My opinon, for what it might be worth is that the only reason for expecting a large future mean temperature increase is that that is what the climate models predict. We have had half a CO2 doubling and only 0.8C and that is about what I expect for the next half. I believe that the climate models overpredict the future temperature increase because they include positive feedbacks of a magnitude that have never been shown to actually exist. If you want to see a really shocking display of the inadequacies of the climate models, have a look here. Clouds and precipitation are two of the most fundamental things that climate models must get right in order to be credible.
Trying to catch up on some of the posts!
With regard to your question, global climate models (GCMs) are 'variables' based at this point without any adjustment factors or momentum indicators for the physical aspects. Modeling of potential future climates are scenarios based because no one is either trying to predict the next asteroid or how every person on the planet will procreate or recreate.
There are a massive number of variables that are calculated for multitudinous 'voxels' (3D-pixels) of air and ocean for each time step. This is why it takes lots of time on supercomputers to get results. They didn't just whip these things up from scratch. Various aspects have been tested over space and time with sensitivity analyses to determine just how precise each of the variables need to be defined. For sensitive variables lots of research has been conducted to better quantify what they are and how they change over time and space.
How do you test such a thing? They generally 'spin it up' from some time in the distant past and then see if it models the global climate reasonably for the historical period when we have observations, and note the model's strengths and weaknesses. If it is deemed reasonably accurate then it is forced with possible future values of solar irradiance, greenhouse gas emissions and other factors as desired.
No one pretends that they can predict what humanity will do but they have set some basic scenarios that range from business as usual where we keep burning more fossil fuels faster to total green energy transformation in order to bound the possible climate changes in the future. None of them are expected to be 'right'. They are just guide posts to let us know which path we are most closely following. People from McPherson to our local 'skeptics' simply do not know how to use models. In the forthcoming IPCC document they have dropped the emissions scenarios and simply gone to 'representative concentration pathways' that assume some rate of growth in greenhouse gas forcing, side stepping any socio-economic modeling since it really doesn't matter for the estimations of future climate change.
To add further confusion, the many GCMs all show different results for the same inputs because they are all parameterized differently and are considered equally plausible. The models are all different but every single one of them indicates that we are warming the planet quickly, though they disagree on just how much and where it is going to change fastest. To get a best estimate of what climate results from any given amount of greenhouse gas forcing they create ensemble models which are effectively the average of all of the GCMs together. I am not a big fan of blind ensembling but there are now efforts underway to figure out which models are the most accurate for different regions, or for a given phenomena so that improved ensembles that more accuarately depict known physical phenomena can be derived.
As the quote goes "All models are wrong, some are useful". Those who like to cast doubt upon the utility of existing GCMs generally use the uncertainty involved in the modeling to imply that this means that there is nothing to worry about, however, there is just as much probability that they are underestimating as overestimating the likely climate changes.
Just a quick note on your question about a possible rapid Antarctic ice melt. Climate extremists who postulate some sudden flash melt of the Antarctic never seem to do any energy calculations to back up their doomsaying.
There is a lot of ice in Antarctica (26.5 million km2), which, if melted completely would raise sea levels by about 70m. What would it take to melt that much ice? Some rough back of the envelope calculation shows that if we truly had godlike powers and wanted to do this we could tilt the Earth and point Antarctica at the sun. Then if we made giant reflector dishes to funnel all of the solar energy that currently gets absorbed by the Earth down to the ice it would only take 2.3 years to melt Antarctica's ice (of course the rest of the planet would freeze…). Not too realistic.
Conversely, if we could take all of the excess energy that we are currently accumulating on Earth due to anthropogenic greenhouse effects and used it to melt ice it would take a bit longer. Say we had the mad idea to chop up the Antarctic ice as a geoengineering experiment to keep the planet cool. Ignoring the energy that would be required to actually turn the Earth into a monster slushy, we could offset 'global warming'. If we counteracted all of the current global energy imbalance, effectively stopping average global warming in its tracks, using the Antarctic ice stash would stop all warming for about 950 years at the current energy imbalance. Now we will certainly increase things far beyond this but it would still take hundreds of years to use up the ice while holding the current climate in place.
Now there is no way we are going to turn the continent into a giant crushed ice machine, and the high latitudes of the Antarctic don't even get sunlight for several months of the year, so it is going to take a very long time to melt all that ice. The West Antarctic ice sheet is potentially vulnerable to rapid decay because much of it is grounded below sea level but the more masive Eastern ice sheet is high and dry and will take centuries, if not millennia to melt even under the worst case scenarios entertained by the IPCC.
Greenland is more vulnerable because it is smaller, closer to the equator and potentially impacted by warm water currents. Antarctica sits over the southern pole and so much of the continent is isolated from warm ocean currents even if they somehow reach the continental shore.
Things are bad enough without creating fanciful imminent catastrophes.
I'm all for geoengineering.
How about this plan? I see that the temperature at the south pole is lower than the deposition temperature of CO2. -78C
So how about a set of book lungs at the South pole made of blackened aluminum sheeting vertically mounted? The wind flows over the aluminum sheeting which is cold enough to freeze the CO2 into dry ice. There wil be latent heat of freezing that could be harvested. All sorts of tricks could be tried to shake the dry ice off the sheets. Black non stick surfaces spring to mind as well as wind flutter.
So what do we do with the dry ice that falls off? Nothing. We lift the sheets above the dry ice. The higher the mountain of dry ice the colder the temperature, but the thinner the air.
If all the dry ice does not sublimate in the summer sun, then gradually a glacier of Dry Ice would form.
There might even be a market for it.
On second thoughts, forget the aluminum. Make the sheets from carbon (Graphene).
Even better: Form the graphine sheets into balloons filled with hydrogen or ammonia. Then it is a trifling to keep the sheets suspended above the growing mountains of CO2. (Forget the Ammonia- It has a freezing temperature of -77.73, as luck would have it. Hydrogen it is.)
The whole project could be a money spinner.
(Cue the patent Trolls)
Nice idea! Alas, with a deposition temperature of 78.5C, there is no month that even averages those levels at the pole. There have been a few record lows that could have allowed for a little deposition for special occassions. Maybe over at Vostok they could do better.
For the record, actual glacier ice (looks bluish) pops and fizzes in drinks quite nicely!
|Climate data for the South Pole|
|Record high °C (°F)||−14
|Average high °C (°F)||−25.9
|Average low °C (°F)||−29.4
|Record low °C (°F)||−41
|Mean monthly sunshine hours||558||480||217||0||0||0||0||0||60||434||600||589||2,938|
. Yes but I do see two months in your chart that woud be passively productive.
It is a great pity to have to make it more complicated by first compressing the lifting gas, hydrogen, and then use it's expansion to cool the sheets down the small amount needed.The hydrogen could be continously circulated through a compressor and radiator and bach to the book lungs to lift and cool them.
But it might still be worth while. I shall make up a mathematical model.
Anyway the south pole has the advantage that it has the smallest delta T, the smallest energy requirement to freeze the CO2 on the planet.
I'll be interested to see what you turn up. Energetically that would be the place to do it. How much CO2 could potentially be harvested in those months? What would the energy costs be to solidify it and then maintain it in that form for the rest of the year when ambient temperatures are considerably higher? Even stacking it on the ice to form the CO2 mountain would lead to sublimation due to conduction of heat from below as the Earth's natural heat bleeds up through the ice. The ice itself is warmer than the necessary temperature for keeping the CO2 frozen. Could we ever capture the CO2 with less emissions than needed to do accomplish the feat? There might be a scale of production that reduced surface loss rates enough to be somewhat sustainable through the year, basically make 2 units and save 1 unit by the end of the year. However, at best case, even if the energy trade off can be worked out, we would be creating a growing but very unstable CO2 reserve that would quickly return to the atmosphere if we ever stopped refrigerating the South Pole. One little economic glitch that stops the South Pole resupply and all that work would literally evaporate.