The Definitive Global Climate Change (aka Global Warming) Thread -- General Discussion and Questions

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thank

Wow!  Great answers.  Thanks!

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Where's the beef?

sofistek wrote:

Ah, I see, Stan; you're taking one data set that appears to support your case and assuming that is the whole picture. I guess I did the same, to some extent.

This news release concerns comparisons between different data sets. You might find it of interest. One notable quote is:

Quote:
All three records show peaks and valleys that vary in virtual sync with each other since 1880. All three show particularly rapid warming in the last few decades. And all three show the last decade is the warmest in the instrumental record.

Tony 

So what is your beef? All of those things that were mentioned above were shown in my last graph. All of the mentioned records show a flat temperature trend for the last ten to fifteen years. The UAH satellite record and BEST also agree. Since all of the GCMs are unequivocal about CO2 causing warming, it seems pretty clear to me that they are missing something important.

Stan

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The 5 main datasets

Stan and Tony,

Here is a depiction of the five main datasets for global temperatures in both raw form and with the major known perturbations (El Nino/La Nina (ENSO), solar cycle, volcanic eruptions) removed as per Foster and Rahmstorf (2011)

Also, here is the average of the 5 datasets with the perturbations removed.

Mark

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Adjusted Data

Thanks, Mark. This reminds me of the adjusted data shown in a RealClimate post, a while back. It was about rising sea levels, which showed an acceleration when looked at from almost every starting year on record, apart from a few years mid century. When adjustments for on land water storage (reservoirs and dams) were factored in, there was acceleration for all years on record (and a larger acceleration in latter years.

Adjustments aren't tricks; it's important to understand when data may be skewed by something that masks the underlying trend.

Tony

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Meanwhile, in the real world

Just in case anyone was blinded by the flashing lights of Mark's temperature plots, what they are showing is a rate of temperature increase of only 1.7 C per century; whether detrended or not.

CO2 is the dominant presumed driver of the average rate of temperature increase. Physics says that the temperature anomaly is logarithmically related to CO2 concentration.  So without having to worry about a time scale yet, I plotted the HadCru temperature anomalies against atmospheric CO2 concentration. The CO2 record was from NOAA prior to 1958. Mauna Loa observatory monthly records thereafter began at about 314 ppm.

As shown below, there is a fairly good linear trend of temperature anomaly vs log CO2. The black line shown below is the least squares best fit line for data from 1958 (315 ppm) to 2012 (correlation 0.83). The line slope corresponds to an expected temperature increase of 2.1 C per CO2 doubling. A line fit to the entire data record from 1850 yields 1.9C. The difference hardly matters as 95% confidence limits for these calculated temperatures are +- 0.08 C.

Some systematic variations are evident in the data. Temperatures rose from, 1850 -1880, fell to about 1910, rose to about 1945, fell slightly to 1970 and then rose more rapidly again after 1979. The rate of increase in each of the three warming periods was about the same 0.16 - 0.17 C per decade, but the long term average rate of rise has been lower due to the periods of decline. What seems to be the case is that there are sinusoidal oscillations with about a 60 year period superimposed on a rising trend. If these oscillations are real rather than artifacts of the process of constructing global average anomalies, they might well be associated with the decade scale variations of Pacific, Atlantic and Indian oceans temperatures.

So, if the atmospheric concentration of CO2 is going to double, when will it get there? The plot below shows the Mauna Loa data as a function of time. The black line is a least squares fit to the data from 1992 to 2012. The standard deviation is 2.2 ppm, which is less than the seasonal variability and the correlation is 0.98. It shows concentration increasing at a rate of 5.08% per decade and a doubling time of 147 years.

If we extend Mark's rate of temperature rise of 1.7 C per century to 1.5 century, that would yield an expected temperature rise of 2.5C. In view of the periods of slower rates of rise that will likely still occur in the next 1.5 century, the actual temperature rise would very likely be less.

The results obtained from this analysis yield an expected temperature increase of 2.1 C for a doubling of C02 concentration. That will take 150 years at current rates of production. This expected temperature increase is at the low end of the likely range, 2.5 - 4 C, of the IPCC, well below its likely case of 3C and far below its extreme case projections. In addition, the time scale for the change is much longer than projected by the IPCC. It is possible that the future rates of CO2 production might be either higher or lower than at present. That depends how peak oil might affect how much coal will be burned, but I would be surprised if the doubling time would be less than a century.

I leave it to others to prefer the IPCC model results if they wish, but these are model independent data shown here. They are telling us what the real world is doing. What's more, it is doing it with full participation of all feedback mechanisms, both known and unknown. They do not just magically turn on at the time the IPCC simulators start. This is a reality check.

Stan

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BAU

You're assuming that feedbacks continue to have exactly the same impact, going forward.

Forgive me if I still prefer the analyses of climate scientists. However, if the rise is "only" 2.1C, there are plenty of expected impacts for that kind of temperature rise that still look very ugly to a lot of people. Just because politicians think that 2C is the max to be aimed for doesn't mean that 2C is going to be a walk in the park.

Tony

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Strange physics.

Mark Cochrane wrote:

Hello Stan,

You show an excellent ability for back of the envelope calculations and authoritative statements without any cited sources to back them up.

According to the IPCC climate simulation models, they are supposed to hold heat in the lower troposphere in the low latitudes, but that has not been observed. Its conspicuous absence points to one of the corrections to feedbacks that will be necessary to give some credibility to their models.

Stan, if you have any credible source(s) for this statement please provide it/them. Otherwise retract your assertion or qualify it as solely an unsupported opinion that you seem to hold regardless of scientific observations to the contrary.

If you look on pages 115 and 116 here www.climatescience.gov/Library/sap/sap1-1/finalreport/sap1-1-final-chap5.pdf  you will find the figures below. One of the flaws of the climate models is that they attribute more heating to the tropical lower troposphere than has been observed in the radiosonde data.

Quote:

Your post seems compound misunderstanding of how greenhouse gas concentrations increase and decrease over time with a curious ignorance of Conservation of Energy Laws and Thermodynamics in general.. . . . .

. . . Now here is where the conservation of energy comes into play. All of that energy doesn't just disappear into the oceans, slowly radiating downwards as Stan implies. All of that energy storage is a buffer that will have to be paid out back into the atmosphere and eventually radiated back to space. That 'thermal diffusivity' works in both directions. This isn't a Law that can be evaded. We own this energy debt and even if we can manage to reduce CO2 levels, we will not reduce the temperature of the atmosphere because the oceans will then start exporting that stored energy if we get back to a negative net energy state for the planet. (Note, this isn't yet getting to Stan's question of when the planet's radiative stability point will be reached - but it's headed there!)

Thank heavens! This is quite enough error for a while. Once heat gets below the thermocline it won't be coming back. There is a little thing known as the second law of thermodynamics that forbids thermal conduction from transporting heat from a lower temperature to a higher one. I think that I will skip the rest of your lecture.

Stan

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The magic sink

Stan Robertson wrote:
Once heat gets below the thermocline it won't be coming back.

This strikes me as nonsense, as though there is some magical heat black hole, from which heat can never escape. Perhaps in a still column of water, several hundreds of metres deep, the heat might stay there for an awfully long time, but I suspect the world's oceans and seas don't really act like a still column of water.

Tony

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So the second law of thermodynamics is nonsense?

Tony,

The trouble with the alarmist viewpoint is that belief trumps physics. When it involves the second law of thermodynamics, I am afraid that I become very judgmental. This discussion began with Mark saying,  "Now here is where the conservation of energy comes into play. All of that energy doesn't just disappear into the oceans, slowly radiating downwards as Stan implies. All of that energy storage is a buffer that will have to be paid out back into the atmosphere and eventually radiated back to space. That 'thermal diffusivity' works in both directions. This isn't a Law that can be evaded."

So here I am, a physicist, being fed BS about heat transfer. For your information, thermal diffusivity refers to heat transfer by conduction and it NEVER goes from lower to higher temperature.

But I will cut you a little slack because you are saying that bulk motions of fluids may transport heat and they might, for example, take some water from a warmer lower latitude region to a colder higher latitude region or vice versa. Several generally accepted climate models give that process a time scale of about 500 years to produce an equilbrium temperature distribution for the oceans.  But that is not at all the same as saying that mean surface temperature will still be increasing for 500 years while ocean heat is returned. Radiative equilibrium at the surface occurs on a five to ten year time scale.

Stan

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Physics lesson (3)

Ok, going to try to get this finished off.....

Stan raised the excellent point of just how long we can expect warming to continue if we were to actually manage to stop carbon emissions (i.e. when the pigs are flying freely). Stan made an inference from some of the existing data to a postulated quick equilibrium in the near future. This is an overly rosy picture for several reasons.

Ok, lets start with the basics. We release upwards of 8 petagrams of carbon to the atmosphere each year. Luckily for us, only about 43% remains in the atmosphere. The remaining 57% gets roughly split down the middle by uptake by plants/soils and the oceans.

1. Carbon dynamics and greenhouse forcing - First, what is the lifetime of CO2 in the atmosphere? This is often misperceived as the time of that a released carbon molecule spends in the atmosphere before it enters the oceans for example. It sounds reasonable that once the molecule disappears, so does the effect but this disregards the dynamic interchange with the ocean. All of which means that most of the time when a CO2 molecule enters the oceans it simply balances out another one that exits the oceans. There is a net uptake by the oceans, as mentioned above, but you can't just count molecules going in if you don't also count molecules going out. This would be like counting only deposits but ignoring debits to your savings account.

2. What we care about is the length of time that a higher concentration of carbon will persist in the atmosphere. We are increasing the concentration of carbon dioxide in the atmosphere over time but we are doing this at an increasing rate as we burn greater quantities of fossil fuels (not just oil).

Basically, back in the 1960s we added roughly 1ppm per year to the atmosphere while nowadays we add about 2 ppm per year on average. This is a noteworthy achievement since it exceeds any rate that we know of in the geologic record. The most commonly used analogue for the current climate warming is the Palaeocene-Eocene Thermal Maximum (PETM) which happened 55.9 million years ago. This warming was caused by a massive carbon release just like ours. However, that event had peak rates of increase of only 0.3-1.7 ppm (Cui et al. 2011).

However, what we are more concerned about at the moment is the amount of time that the climate takes to recover from such a pulse. If we can rely on the PETM as a proxy for the time of recovery, the answer is somewhere around 150,000 years. If we were to have a sudden stop of emissions as Stan proposed then, a good proportion of the increased levels would be taken up by the oceans as they continue to overturn. After 2-20 centuries between 20-35% of the original carbon increases would remain. Another 3-7 thousand years of weathering calcium carbonate rocks would be needed to lock up the rest of the excess (Archer et al. 2009). However, this is probably optimistic since it ignores changes in the Earth system caused by the ongoing warming and ocean acidification. If the Earth responds similarly to what occurred in the PETM, then the oceans will thermally stratify as they heat. If they stop turning over then the surface ocean saturates and more CO2 stays in the atmosphere. This stratification is now beginning to be observed (Helm et al 2011). As a side effect the oxygen content of the deep ocean drops. The PETM was worse for organisms of the deep ocean that the asteroid that killed the dinosaurs.

However, this still doesn't answer Stan's question about the amount of time that temperature would continue to rise if emissions ceased. The problem is that systems are dynamic and nothing responds as linearly as Stan has assumed. Most models typically show a 60% response within the first 100 years (although 40% happens in the first 5 years). The remaining amount takes about 1,000 years to play out. Hansen et al (2011) believes that the models have been overpredicting heat transport into the deep oceans and favors a 75% heating effect within the first century instead of the commonly used 60%.

SO, to finally answer the question, considering the rate at which CO2 would decrease in the atmosphere and the lag period of the climate response, I would estimate a net positive forcing for at least 50 years in the unlikely event of a sudden emissions moratorium. However, Stan, there is a very large elephant in the room that you have overlooked, namely aerosols.

The current energy imbalance, when you average over a solar cycle is 0.75 W/m2, however aerosols are currently shielding us from 1.3-1.9 W/m2. If the emissions moratorium scenario were to play out we would get a lot hotter in a big hurry because most of the aerosols have lifetimes on the order of weeks. Therefore, within a few months of the zero emissions mandate the average global warming forcing term would be roughly three times what it is now (about 2.25 W/m2). Welcome to the Faustian bargain the human race has made.....

That sort of warming is likely to put the various positive feedbacks that amplify global warming into overdrive, meaning that CO2 levels would likely stay higher for longer. It might take longer to stabilize than 50 years and even if we do, the ramifications will still take hundreds to thousands of years to play out as the ice sheets melt, oceans rise and life takes it on the chin. We won't be getting back to the climate we have now anytime soon.

The first rule of climate science is energy conservation. You have to keep track of all of it because it never disappears. (well, at least in the real world it doesn't)

Mark 

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politics of AGW

Ok, I know this isn't science, but this is the CT dungeon, so WTH.

http://www.huffingtonpost.com/marvin-meadors/why-does-the-gop-ignore-i_b_1307806.html

Quote:
According to a fascinating article by Katherine Bagley prosaically titled "GOP Not Listening to its Own Climate Scientists on Climate Change," a group of prominent conservative scientists, many of them evangelicals, approached conservative politicians to educate them on climate change and predictably the pols have not "warmed," shall we say, to their efforts.

Although usually loath to announce their political leanings, these Republican-affiliated scientists thought conservatives may be receptive to scientists with conservative credentials. Who are these concerned scientists and how do they get conservative politicians to embrace climate change when many of them see the use of alternative energies as a step toward anarchy?

Doug

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The Jet Stream: Is it normal?

It seems to me that the jet stream is doing some pretty bizarre things.  I believe it supposed to be flunctating like a sine wave following a definiive pattern regardless of the seasons.  But does go further north during the summer months.  But it doesn't behave like a sine wave.  It does some weird gyrations and can even come back on itself.  Is this caused by changes in our climate? or is this normal behavior for the jet stream?

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No

Thanks for cutting me some slack, Stan. It's like Mark says, energy is conserved; it doesn't just disappear, as you implied.

Tony

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Some agreement here!

Mark,

I agree on most points here. If CO2 emissions were to cease now, temperature would continue to rise for a good while and perhaps for another 0.6-0.8C; depends on how much of the ocean heat capacity is contributing to a lag. But I had not considered the jolt that would be caused by cessation of aerosols. So if China cleaned up its coal burners, the first thing that would happen is an increased rate of warming for a while. Bummer.

Stan

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Second law of thermodynamics just needs to used correctly

Stan,

Glad to see we can agree on some things even while we agree to disagree on others. Your interpretation of the 2nd Law of Thermodynamics is correct but you haven't thought through how it applies in the climate. In a static world, think of a light bulb hanging over a bathtub your conception would work until a new equilibrium was reached but the real world and real ocean do not work this way. Energy comes back from the ocean into the atmosphere every day and it doesn't require any exceptions from the laws of thermodynamics.

Anyone who has lived or visited near a large body of water like an ocean in the autumn/early winter has experienced this. Those locations will be warmer than the inland areas because of the warmth coming from the relatively warm ocean waters once the air has gotten colder. On the other hand, springs will be cooler longer for the opposite reason, the now cool waters act as a temperature sink for atmospheric heat. If you've ever been on ship, expecially in the tropics at night, you will experience a similar phenomena. The temperature drops to just about the water temperature and stays there. In the winter in higher latititudes the surface waters will often become colder than the deeper waters they are on top of. At that point the second law of thermodynamics starts transfering the heat upward through the water, even without advection processes. Incidentally, the thermohaline circulation will even bring heat to/from the deep oceans but on longer time scales.

Now those are surface dynamics that are local to regional but the same principle holds when there are changes at a larger scale. For example, if we have a another Pinatubo like eruption, the planet will cool, but it will cool a lot less than it would be expected to now because some of that stored heat will be released from the oceans during the period of reduced solar radiation. That second law of thermodynamics at work again. Incidentally, this is likely at least part of the reason that we have not been cooling despite beiing at the trough of a deep and extended (2 years extra!) solar cycle.  Less solar radiation should yield cooling but increased thermal radiation from the oceans and greater retention of heat due to the greenhouse gases are now cancelling out or at least seriously blunting the effects of the solar cycle lows. This would help explain the obvious drops in energy uptake rates in the surface waters in recent years but this is also confounded by the large increase in atmpospheric aerosols from China and India, among others.

Furthermore, ocean currents moving from low latitudes to higher latitudes transfer much more energy than corresponding air movements. Alas, this will exacerbate sea ice melting rates even further. The tropics subsidize the temperate latitudes with energy. Lastly those warmer sea surface temperatures fuel stronger hurricanes. The jury is still out on whether they might create more hurricanes in a few regions.

Mark

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Mark, The second law of

Mark,

The second law of thermodynamics is the reason that some of that heat must come back every day. The daytime heat is absorbed by land and water. At night the warmer surface regions lose some of that heat to the cold of outer space and the deeper ocean. (At least on a whole hemispheric average, but some smaller locales might even be warmer at night.). The parts that go to outer space or below the tropical to mid-latitudes thermoclines won't be coming back any time soon. The reason for that is that there aren't many places in the ocean where water from below these thermoclines could be transported to replace colder surface waters. But between the surface and the lowest temperature zone of the thermocline, some of the heat that enters may be returned to the surface by currents, waves and thermohaline processes on some time scale. So I think that we are in agreement here.

Maybe this will clarify things a bit for Tony as well, however, he is mistaken if he thinks that I ever said that energy was not conserved. I just said that some of it wouldn't be coming back. It would still exist in the deep ocean or outer space. But I should have said, won't be coming back on a time scale of human concern.

If ocean surface temperature begins to change for any reason, temperatures at lower depths will respond with a time lag that is progressively longer at greater depths. If the surface temperature then begins to change in the opposite sense, temperatures at depth will again respond with a time lag of similar duration. We see this on a seasonal basis here in the mid-latitudes, where peak summer heat lags peak solar insolation and winter cold lags the minimal insolation.

About half of solar flux that reaches the surface is absorbed within the upper 25 meters of the ocean. This much of the mixing zone will respond to solar flux changes with a thermal lag of about six months. When volcanic eruptions such as Pinatubo transiently reduce solar flux, ocean surface temperatures spread the event out over time by about an additional half a year to a year of surface temperature reductions followed by recovery period that corresponds to the time scale at the depth of oceans affected by the transient event. The point is that the time scale for the recovery is set by the depth of ocean affected by the process, but essentially not longer than the response time at the lowest temperatures at the base of the thermocline. 

Stan

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The face of climate change in western North America

All,

The whole climate change debate can seem esoteric and surreal with seemingly no connection to your daily life but I thought I'd help make it real and current. If you want to know what climate change looks like, go to the Front Range in Colorado, USA.

Or British Columbia in Canada

In recent years, an area of forest the size of Washington State has been heavily impacted by a few insect infestation epidemics. Let me be clear, these sorts of outbreaks are not new but what is unprecedented is the scale, synchrony and duration of these outbreaks. There are forests that look like these from Alaska to New Mexico. To put things in perspective, the extent of this outbreak is already 10-times bigger than the second largest known outbreak and it is nowhere near over yet.

Ground zero for this massive ecological change has to be British Columbia where over 17.5 million hectares (44 million acres) have been affected. The mountain pine beetle has now managed to cross the continental divide and has adapted to eat jack pine, which means it can now spread across Canada. The mountain pine beetle is now at epidemic levels throughout the Rocky Mountains region and as far east as South Dakota and Nebraska (link). North America has been the hardest hit to date but there have been large areas of forest die off in Australia, Russia, France and other countries in recent years as well. For an easy read that lays out the issues, read "What's Killing the Great Forests of the American West".

This is climate change in action. Changes in climate, in particular, increases in drought and temperatures stress trees. Stressed trees are more susceptible to attack by these insects. Normally a healthy tree can fight them off but stressed trees are vulnerable. Then, when the bugs build to epidemic proportions even the healthy trees are overwhelmed. Winters are no longer getting cold enough to kill off the overwintering larva so each year the problem grows. In addition, the breeding season is getting longer so the beetles are starting to have multiple generations within a single year, exponentially increasing the problem. While out in one of my student's research areas, I personally saw mountain pine beetles in May in the Black Hills of South Dakota last year. They shouldn't be flying until at least late June and it was early May.

I wish I knew how to embed a video here but I don't. Therefore I encourage people to see the short (9 min) video here that will better explain these issues from research in Colorado.

I'd also like to here from anyone who knows of similar outbreaks anywhere in the world. Pictures if you have them!

Mark

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Impacts

Thanks for raising this impact of climate change. There are many examples of impacts and I've got to shake my head at this kind of story not being on people's TV screens or in the news media, regularly and frequently, instead of the trivial stuff that is there. Humans are the pine beetle of the world, really; wreaking huge damage on our only known habitat and too damned stupid to realise it or to seriously attempt any mitigation or adaptation. All we get is denial, denial, denial and talk about getting economic growth going again. Madness reigns.

Tony

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Mark pine beetles

My daughter told me about the infestations in the Rockies, but I had no idea they are as pervasive as they are.  Thanks for sharing.  When will alarm become appropriate?  We don't want to be accused of being alarmist, after all.

Meanwhile, in the east we have the Asian longhorn beetle and the emerald ash borer.  The latter has been found near where I live.  I'm just waiting for my ash trees to start dying.  Being the second greatest population density in my woods (next to sugar maple), they will leave significant holes in the canopy when they die.

I should mention that I'm unaware of a connection to climate change with the two eastern infestations.  Do you know if there is?

Doug

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Hearing the alarm bells.....

Hello Doug,

I was at Michigan State University when the Emerald ash Borer first came on the scene and saw the efforts to try to contain it in the greater Detroit metro area. It was already a lost cause at that point with about 6 billion ash trees slated for the ongoing feast. Here is the most recent US nationwide map of various insect infestations. I think it is due to be updated again later this year.

You can get access to the full resolution map products here.

The take home message was that as of 2006, 58 million acres were at risk of 25% or more mortality of standing trees within 15 years.

Here is the map of the epicenter in British Columbia

The Asian Long Horned Beetle and Emerald Ash Borer are self inflicted damages. They are invasive species that we imported from Asian countries in pallets together with the cheap products they held. They are not directly linked to climate change. If you pull up the full resolution map you will be able to read the full list of 'agents' behind the mortality. I believe that only one of the top 11 (gypsy moth) is an invasive. Climate stress is causing our endemic species to feast on the sudden bounty of susceptible trees.

I don't know about you but I keep hearing a persistent ringing....

Mark

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Depressing

Thanks for the links Mark, but I can't tell you how depressing it is.  I live in the NE at least partially because of the mixed forests.  My daughter is beginning a career in tree pathogens.  Going through the maps of the various tree epidemics (if that's the right word) I'm reminded of the stories of many species, and have something more to worry about for others.  Just a short list from my small property and my neighbors:

American Chestnut are largely gone from eastern forests where they once dominated, although I still run across an occasional small one that apparently has come up from the roots.

American Elm.  They grow to about 6"-1' dbh before another wave takes them all out at once.

Butternut-I have a small copse of them that have the blight but they continue to be pretty healthy and producing nuts.

I have two maple species, sugar and red, both of which appear to be threatened but still doing ok in my neighborhood.

Ash -  I have a lot of white ash that are still ok, but the EAB seems inevitable.

Beech - All mature beech in my neighborhood are dead.  Although, when I get loads of logs for firewood I get a lot of beech.  But, many of them appear sickly or starting to rot out from the inside.  My daughter tells me that the smooth bark beech are more susceptible than those that have rougher bark.

Aspen, willows, white oak and black cherry are pretty much the balance of trees on my property and they seem to be fine.

Doug

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Re-defending climate models
 

Mark

You make a VERY bold caim "Predicting the climate is vastly simpler."

Chris suggets this topic comes down to a matter of belief.

You believe modeling long term climate is simpler than modeling the weather 5 days out. Why?

Without scientific proof of this claim, it is just a belief.

To quote you......  "Stan, if you have any credible source(s) for this statement please provide it/them. Otherwise retract your assertion or qualify it as solely an unsupported opinion that you seem to hold regardless of scientific observations to the contrary."

Strike out Stan and insert your name....

Cheers Hamish

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Doug

L’Affair Heartland

“Without being a trained climate scientist, I can read the various blogs and try to parse the academic papers, but ultimately I have to rely a lot on the good faith and judgment of the scientists themselves. The Heartland affair has reassured my earlier conviction that the case for climate alarmism is far weaker than the alarmists have been telling us.”

As an economist who has done some research on climate change policies, I am often asked questions along the lines of, “Is the science right or is it really a hoax like Rush Limbaugh says?” My standard reply is to acknowledge first of all that I’m not trained in the field, but to say that from my outsider perspective, it seems that the people warning of imminent catastrophe are vastly overrating the likelihood of their dire forecasts.

The behavior of Joe Romm and other famous climate-change alarmists during the recent Heartland Institute affair beautifully illustrates my position.........(snip rest of it. Follow link if you want to read the rest. )

Loss of faith..........growing

Cheers hamish

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Heartland

Hamish,

From my perspective, there is nothing in the Heartland affair that suggest climate scientists are getting the science wrong, so I don't know why your "faith" is being lost.

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Not so bold...

Hello Hamish,

The claim that climate modeling is simpler than weather forecasting isn't some wild idea. At its simplest, it comes down to trying to predict tomorrow's temperature at a given location versus trying to determine the average temperature for a year of the entire planet. The weatherman has to try to assimilate all of the imperfect information from observations and satellites to model the coming day's weather. I don't know how well they do in your neck of the woods but they missed by about 20F here today. This isn't a knock on weathermen/women, it is just that they have a very tough job trying to deal with lots of variables and a chaotic system. Some places are easier than others. Here is a somewhat simple analysis of weather accuracy with time in England (link) that illustrates the difficulty (50-55% accuracy for the next day's weather). If you've got only one shot to get something right over say a 100 km2 area of a system that is very variable in nature this is very tough.

For global climate models however the analogy is the need to get the temperature right but you get to take the average of estimates for 30 years of 365 days each (give or take a few leap year days) at 5,000,000 locations. That is, you have about 55 billion attempts then you average them. The Law of Large Numbers (LLN) says that your difference from the mean temperature of the planet should be extremely small. The problem for the climate models is how they partition the solar energy between the atmosphere, land and oceans and the parameterization of various processes. If they have systematic errors then they will become progressively less accurate over time. As per the IPCC, the various models predict a 1.5-4.5 C increase in temperature for a doubling of CO2 with most agreeing on about a 3 C increase.

They don't just make these models and look forward to say what they expect to happen. One of the first tests for validation of a model is to use it to 'hindcast' previous climates.

 

Hindcasting is a way of testing or validating a climate model, by running it for a past time period and comparing results with observations.(source)

The point being that if you can't predict climate conditions that we know occurred (e.g. Little Ice Age, Medieval Warm Period) by comparisons with independent observations/proxies, then there isn't much confidence that it will be able to simulate future climates. If you have a physical model that manages to simulate past climates then you will have reason to think the model might be able to provide useful information about future changes. Hindcasts can be used to evaluate what the strengths and weaknesses are of the various models. For example, Kim and Lee (2003) used hindcasting to evaluate regional climate model performance:

A Multiyear Regional Climate Hindcast for the Western United States Using the
Mesoscale Atmospheric Simulation Model

In preparation for studying the effects of increased CO2 on the hydrologic cycle in the western United States,
an 8-yr hindcast was performed using a regional climate model (RCM) driven by the large-scale forcing from
the NCEP–NCAR reanalysis. The simulated precipitation characteristics agree well with observations, especially
in the winter. The simulated precipitation compares with rain gauge data at similar accuracy as the NCEP
reanalysis, but the RCM-generated precipitation is more accurate than the reanalysis data at the scales of individual
basins. Important characteristics of the hydrologic cycle of the region, such as seasonal snowfall, frequency of
heavy and extreme daily precipitation events, and interannual variations of precipitation associated with the
North American monsoon are also well represented in the hindcast. Compared to the Climate Research Unit,
University of East Anglia (CRU), analysis, the simulated low-level air temperatures show cold biases except in
summer. The temperature biases are difficult to quantify, however, due to suspected warm biases in the CRU
data. The RCM overestimates surface insolation and outgoing longwave radiation at the top of the atmosphere
(OLR-TOA). The errors in the simulated radiation are smaller over the land than the ocean. Both simulated and
observed OLR-TOA suggest strong influence of low-level temperatures on the seasonal variations of OLR-TOA
in the region. The results suggest that the RCM employed in this study possesses reasonable skill for studying
regional climate change signals in the western United States.

If you really are bold, then you make predictions of how global climate will react to unforeseen conditions like a volcanic eruption as a test for the validity of your model. This is what Jim Hansen did when Mount Pinatubo erupted (link) and his predictions held up well. Note, if you just try to make simplistic pattern matching models, your hindcasts will fail miserably and therefore your future accuracy is in great doubt. This is why the Loehle and Scafetta (2011) curve fitting model positing 60 and 20 year solar cycles has been poorly received by most climate scientists. It fails the hindcasting validation.

The green and blue lines are different climate reconstructions based on a variety of data sources. Obviously, Loehle and Scafetta don't see the Medieval Warm Period or anything else earlier.

If you don't like my explanation perhaps you'll prefer Bruce Wielicki's.

It is important to note that climate change is different from changes in weather.

Wielicki explained that weather is the day-to-day fluctuation of temperatures and other atmospheric conditions. Considerable fluctuation can occur within a single day. For example, Tuesday's high was 93 degrees, yet the low was 72 degrees. Not only do people expect that level of variation, they also understand that it is nearly impossible to predict the exact temperature for a specific time of day.

Climate, on the other hand, is the long-term average of weather. Wielicki explained that averaging temperatures for a longer period of time and for more places results in less temperature fluctuation, making climate easier to predict than weather. The variation in temperature is so small that tenths of a degree matter significantly when monitoring changes in climate.

You can read his whole article here (link).

I hope this helps you in your hour of doubt.

Cheers,

Mark

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Stan Robertson
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Mark, I think that your

Mark,

I think that your answer for Hamish was entirely too glib. If the climate models could take the conditions of GHG concentrations by year from, say 1850 to present, as inputs along with some reasonable estimates of soot and aerosol effects and then start from 1850 conditions and reproduce the temperature record to the present, I would have no complaint about them. But the simple fact is that they cannot do this. There have been some model fits to past history that account for cooling from 1880-1910 or 1950-1970 by throwing in aerosol concentrations and then removing them as necessary. I have done my share of simulations in the past and learned that if your model can't retrodict the known developmental details, no one will believe them. Worse yet, in the real world, you won't get paid for your work.

Most of the climate models give miserably bad results when compared to local conditions. One such test of hindcasts has been reported here

Quote:

A comparison of local and aggregated climate model outputs with observed data

Anagnostopoulos, G. G. , Koutsoyiannis, D. , Christofides, A. , Efstratiadis, A. and Mamassis, N. ‘A comparison of local and aggregated climate model outputs with observed data’, Hydrological Sciences Journal, 55:7, 1094 – 1110

Abstract
We compare the output of various climate models to temperature and precipitation observations at 55 points around the globe. We also spatially aggregate model output and observations over the contiguous USA using data from 70 stations, and we perform comparison at several temporal scales, including a climatic (30-year) scale. Besides confirming the findings of a previous assessment study that model projections at point scale are poor, results show that the spatially integrated projections are also poor. . . . . .

CONCLUSIONS AND DISCUSSION

It is claimed that GCMs provide credible quantitative estimates of future climate change, particularly at continental scales and above. Examining the local performance of the models at 55 points, we found that local projections do not correlate well with observed measurements. Furthermore, we found that the correlation at a large spatial scale, i.e. the contiguous USA, is worse than at the local scale.

However, we think that the most important question is not whether GCMs can produce credible estimates of future climate, but whether climate is at all predictable in deterministic terms.. . . . . .

With respect to Loehle and Scafetta, let me say up front that I am not a fan of their work. It is simple curve fitting at best, but the graph you showed that extrapolated them back in time for nearly 2000 years was a typical Skeptical Science cheap shot. Harmonic function fits to data often fail when extrapolated into regimes with periodicities different from those used in the fitting. Judging by the data shown in the insert portion of the graphic below, it seems entirely possible that harmonic fitting of temperature records for the last 1300 years might alleviate most of the cheap shot problem. I think that Loehle & Scafetta just threw in a linear rising trend to represent some long period behavior from 1850 forward. Going forward in time for periods not exceeding the longest periodicities in the fitted data can provide predictions for the future. For what it is worth, to my knowledge, this is the latest such prediction from Loehle and Scafetta.

It seems unlikely to me that Loehle & Scafetta's harmonic fit would have correctly captured the effects of rising CO2 levels, because their most pronounced effects have only occurred for the last few decades. If one just extends the trend of what has been going on in the real world, on average, for the last 100 years, that would give about a 1.4 C increase between 2000 and 2100. If temperatures really were to follow the Loehle & Scafetta projection for a couple of decades that would definitively reject the IPCC models, but would not necessarily confirm Loehle & Scafetta.

Stan

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gyrogearloose
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Posts: 480
Faith

Tony

I had long ago lost faith......

Sorry, I should have been clearer

It seems the loss of faith in the general population that is growing.

But  as to your point that you believe there is nothing in the Heartland affair  to suggest the are getting the science wrong, you have faith in those scientists, the problem is that when the public see the head of ethics task force of  AGU lying......they then ask 'what else are they lying about????'

To me the heartland affair is a sad indictment of the lack of integredy that gives the appearance of being pervasive in the front runners of the AGW believers camp.

What is your analysis on the ethics of the believer camp, (speciffically around the memo that Heartland claim is forged) in comparison to the climagate email release.

Cheer Hamish

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sofistek
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Posts: 641
Faith

Hamish,

I'm not sure how one scientist lying to get information in any way equates to climate scientists, in general, lying in peer reviewed science papers (which, as far as I'm aware, is not the case). Of course, those who were outright deniers of climate change or that it is primarily human caused, might well be expected to play up this one incident that doesn't even address the science. And they have. You have to remember that it is one incident and did not directly involve any of the science done.

I honestly don't look on it as a "believer camp". For a start, it includes almost all climate scientists who are looking at the evidence, not at someone's unbased declaration. Secondly, speaking for myself, I currently see the climate science consensus as strong enough to sway policy on climate change, though that isn't happening to any significant degree. The so-called climategate incident was shown to be a storm in a teacup by several inquiries into the affair. Those inquiries revealed some things that could have been done better but didn't show either that climate scientists were lying or that the science was misrepresented. It, therefore, was not comparable with the Heartland incident which didn't involve science but did involve lying (on both sides).

Tony

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gyrogearloose
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Posts: 480
Faith in models

Mark

What you say about models and hind casting for validation is standard.

As a Chemical and Process eigineer I have dabbled in modeling, but only in situations of fairly limited and reasonably well understood variables and parameters.

Nothing of what you said enlitened me on how long term predictions of an EXTREMELY complex system with poorley understood response mechanisims ( cloud feedback for one ) is "vastly simpler."

I presume this is current   ( http://www.masterresource.org/2012/03/lower-climate-sensitivity-estimates/ )

With reffernce to the first graph, equlibrium climate senitivity....

Big question, what is the number ?????????????????????????????

simple old GIGO will bite you in the ass if you put the wrong one in

http://clivebest.com/blog/?p=3303

This would seem to imply they did put the wrong one in...... ( reffering in particular to graph of "Comparison of 2007 IPCC predictions with measurements "

How will the public percieve the bite,......  a misquito or great white 

From the last link where Bruce says

"You can't believe a single scientist, but you can believe thousands of scientists," he said,

Consider the flip side, the fallacy of consensus science.

Thousands of scientists may agree on a subject , but it would only take one to prove them wrong.

So I can so far see no scientific evidence that supports your belief  "Predicting the climate is vastly simpler."

Cheer Hamish

PS It is completly fair to allow unpredictibable volcanic erruptions  into the model a they occure, as long as you have them pre modeled in, and you only need to enter the observed amount of discharge etc for the event.

But I do not recall that there has been a many eruption, but then I dont see much mainstream news,  no TV.....

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Doug
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Posts: 2754
gyro

Quote:
So I can so far see no scientific evidence that supports your belief  "Predicting the climate is vastly simpler."

See Mark's last post.

Quote:
Thousands of scientists may agree on a subject , but it would only take one to prove them wrong.

Let us know when you come up with that one.  In the meantime, what specifically do you think the wealth of evidence so far suggests?

Heartland?  As shills for the tobacco and now fossil fuel industries, when did they suddenly develop any credibility?  If I were a libertarian, I would be ashamed to have my ideology associated wtih them.

Doug

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