Dave, thanks for the link to the paper, which I have just read....and then wondered if you sent me the right link or went beyond the abstract.
Adams et al. constantly refer periods well in excess of a few decades (typically, several thousand years ) and only speculate about changes over periods equivalent to a human lifetime. They candidly admit many, many times the data simply does not have the resolution, is too localized
or both.
But I rather liked this quote:
"If sudden, dramatic climate changes could occur ..... then they could perhaps occur in the future during our present interglacial, especially if we perturb the system by adding greenhouse gases"
Their conclusion (I cut through the waffle):
...sudden shutdowns or intensification (of the gulf stream)..... by the (climate) disturbance caused by rising greenhouse gas levels....is like '...an ill-tempered beast, and we are poking it with sticks"
You have not produced one iota of evidence that current CO2 levels are not man made (its OK, no-one else has) and in light of the above...you've simply made a stronger case we (humans) are in for a rough ride.
Peter,
Sorry I owe you a reply, I should have got to it sooner.
I don't want to get into a quoting war over a decade old paper, so I'll restrict myself to only the following (unedited) exert:
"From present understanding of the record of the last 150,000 years, at least a few large climate changes certainly occurred on the timescale of individual human lifetimes, the most well-studied and well-established of these being the ending of the Younger Dryas, and various Holocene climate shifts. Many other substantial shifts in climate took at most a few centuries, and they too may have occurred over a few decades. The high time resolution in the climate record, however, is either not available, or records have not yet been studied in enough detail."
I think that summaries the conundrum. On this topic the IPCC said on pg. 465
"If warming continues unabated, the resulting climate change within this century would be extremely unusual in geological terms."
I take that to mean that, if it stops warming now, nothing unusual has happened. And further on:
"Hence, although large climate changes have occurred in the past, there is no evidence that these took place at a faster rate than present warming."
But neither is there evidence that they occurred at a slower rate. Perhaps the onus is on the proponents of AGW to show that the present rate of change is unusual/unprecedented.
Regarding duration of the present warming, I think Fig 6.10 (pg 467) of the IPCC (attached) demonstrates that the present warming commenced around 1600, with a brief (2-3 decade) cooling in the early 1800s. In contrast, prior to 1600 temperatures had fallen since about 1400.
In any case the purpose of my original post was to argue against your suggestion that natural climate change only occurs over millions of years (eg. change has been over *geological* times.....and given geological time scales are in the *millions* that natural change occurs only over millions of years). Since you are now talking of change over thousands of years I'll take that as a win (I'll stop short of suggesting that your understanding has increased by three orders of magnitude ).
I wonder why you introduced the rise in CO2 concentrations? Since it wasn't the topic, I can only assume you wanted to get on to more familiar territory. The reason I didn't mention CO2 is that the facts are not in doubt. Neither is the reason why rising CO2 conc. should warm the planet. I just don't want to fall into the trap that Les described in another thread and think that I have to see everything in black and white and speak in sound-bites. Real science is much more than that. One needs to be able to see the weaknesses in one's own position and see the strengths in the counter-arguments.
For what it's worth, I think that AGW is the most likely scenario. In any case all the measures proposed to stop AGW should be done anyway for other very good reasons. I'm just not willing to paper over shortcomings in our understanding. This forum deserves better.
........Perhaps the onus is on the proponents of AGW to show that the present rate of change is unusual/unprecedented............
The most compelling evidence for AGW ironically is not what is happening in the troposphere but in the lower stratosphere.
The lower stratosphere is ordinarily warmed through heat radiative transfer from the troposphere.
What is actually happening however is that the lower stratosphere is cooling. The mechanism is not as simple as the greenhouse effect blocking heat transfer, it involves some complicated thermodynamics but the greenhouse effect is the catalyst for cooling.
If global warming was initiated by an increase in solar flux the temperature of the lower stratosphere would be increasing.
Venus is a particularly interesting example. The surface temperature is 460C mainly due to the greenhouse effect and hotter than Mercury but the temperature of the lower stratosphere is considerably cooler than the Earths.
Regards
Steven
Last edited by sjastro; 24-06-2009 at 10:02 AM.
Reason: spelling
"From present understanding of the record of the last 150,000 years, at least a few large climate changes certainly occurred on the timescale of individual human lifetimes, the most well-studied and well-established of these being the ending of the Younger Dryas, and various Holocene climate shifts.
Dave, I discounted the above as Adams et. al. in the same breath point to a lack of record and resolution in the data.
It is not clear to me what they meant by climate change in the above, as the literature elsewhere shows the younger Dryas and Holocene shifts were likely not global in nature and were localized events, but again there is still that lack of global record and data resolution.
However I do take your point that natural climate change in the past is likely to have occured over several thousand years rather than million and stand corrected.
As for my understanding increasing at three orders of magnitude, is this a bad joke or cheap shot?
That said, if the current change continues unabated, then it will have happened at least one, perhaps 2 orders of magnitude faster than
the most rapid of "natural" events.....which is no doubt to what the IPCC refer and have serious concerns over.
"From present understanding of the record of the last 150,000 years, at least a few large climate changes certainly occurred on the timescale of individual human lifetimes, the most well-studied and well-established of these being the ending of the Younger Dryas, and various Holocene climate shifts.
Dave, I discounted the above as Adams et. al. in the same breath point to a lack of record and resolution in the data.
It is not clear to me what they meant by climate change in the above, as the literature elsewhere shows the younger Dryas and Holocene shifts were likely not global in nature and were localized events, but again there is still that lack of global record and data resolution.
However I do take your point that climate change is likely to have occured over several thousand years rather than million and stand corrected.
As for my understanding increasing a three orders of magnitude, is this a bad joke or cheap shot?
That said, if the current change continues unabated, then it will have happened at least one, perhaps 2 orders of magnitude faster than
the most rapid of "natural" events.....which is no doubt to what the IPCC refer and have serious concerns over.
According to this Fielding said ".... it is a fact that the evidence does not support the notion that greenhouse gas emissions are causing dangerous global warming". I wonder what it feels like to be so sure of anything ... especially in a debate like this.
Oh, and what happened to the precautionary principle.
The most compelling evidence for AGW ironically is not what is happening in the troposphere but in the lower stratosphere.
Steven
How does this constitute "compelling" evidence?
There is simply no evidence that CO2 is anything but a minor climate forcer. In fact, the proposition that a minor trace gas in the atmosphere can influence climate is absurd, if you care to think about it.
That atmospheric CO2 is rising is not in doubt - but historically it has been far higher without any emissions from industrial society. This should tell us that other factors govern the atmospheric concentration of CO2, and that absolutely no-one understands the carbon cycle. In fact, the balance between known sources of emissions and absorptions are way out.
If you bother to look at the evidence, rather than quote the narrative, you will find that average global temperatures are falling whilst atmospheric CO2 is rising - there is clearly much more important factors influencing "climate".
The global circulation models on which AGW is based, and assume CO2 forcing, have failed to predict the temperature decreases over the last 10 years, they have failed to predict the lack of increase in temperatures in the Antarctica (according to the models, the poles should be heating) and the stratospheric hot spot is missing from the data.
AGW is a falsified hypothesis, and does not justify a massive transfer of wealth from the household sector of the economy to carbon traders, governments and investors in marginal technologies like wind and solar power generation.
"Global warming might be good for us: Warmer climate and an increase in CO2 could be good for farming and agriculture".
Same argument can be made for acid rain....
How can the same argument be made for "acid" rain? (I think you mean mildly acidic).
As Ian Pilmer points out in his book "Heaven and Earth", agriculture is far more productive in a warmer climate such as the medieval warm period. Plants respond rather well to warm climates. Do you dispute this?
Even if the nonsense of AGW is even modestly correct, the change in climate to a warmer wetter world is only beneficial to humans.
I was all open to GW ideas originally until the mention of carbon trading and the billions that could be made of this by certain businesses including the investment banks doing the trades. Also that all a big emitter had to do was buy credits to keep polluting and pass the charges onto us. Not only would we be taxed by the government but also slugged by the big polluters passing the costs onto us. If the governments were serious they would just force the big businesses to reduce emissions. But of course countries like China and India wont have to. And as if they will take notice of what we do when their people are living in poverty and are just happy to work.
I'm not saying that GW isn't happening but come on, big polluters just having to buy credits to pollute is no answer. Someones making a bucket load of money somewhere and it isn't me or you.
How can the general public understand everything about it when there is such a dark cloud hanging over the whole thing. No wonder there are skeptics.
One question I do have which I cant find an accurate answer for. What percentage of the co2 created each year in the world is man made compared to naturally occuring?
One question I do have which I cant find an accurate answer for. What percentage of the co2 created each year in the world is man made compared to naturally occuring?
Easy enough to find: "Most carbon dioxide — about 97 percent — comes from natural sources. That's roughly 300 billion metric tons per year of CO2 gas from breathing animals, decaying plants, forest fires, volcanic eruptions and other naturally occurring phenomena.
Human activities, like driving cars, burning coal, farming, industrial production and other practices, account for 3 percent, or about 8 billion metric tons of carbon dioxide production per year."
Of course, what is not disclosed is that these are just estimates based on models, but they are probably broadly accurate.
When computer models can predict the weather accurately for the next month (or even 10 days) then perhaps the nonsense of man made global warming from computer modelling for the next 10, 20 50 years might carry some weight. Is the climate changing, yes, of course it has been for billions of years as noted by Trevor G.
Thankfully a growing voice of scientists and others are challenging this nonsense that has almost turned into its own religion replacing Y2K (and keeping many in good employment). Until recently anyone who presented evidence or views contradicting man made global warming was cast into a pit, read David Bellamy's Price of Dissent on GW. Tis a sad day when the foundations of science (ie peer review) get thrown out the window. Trevory G you are spot on, we have 4 billion years of history compared with a few years of computer modelling. This whole issue is sadly showing that there is science and questionable science.
PeterM.
There is a difference between predicting long term trends and short term variations. I cannot tell you what the weather will be like tomorrow, but I'm willing to bet Christmas day will be a lot hotter than tomorrow.
As for the 2YK. People keep saying nothing happened. That's because we took the steps required to avoid it. It's a bit like getting new break pads on your car and then saying "These work fine, so why did the guy tell me I had to replace them?"
There is a difference between predicting long term trends and short term variations. I cannot tell you what the weather will be like tomorrow, but I'm willing to bet Christmas day will be a lot hotter than tomorrow.
So that is your argument? That summer is warmer than winter?
Are you suggesting that this validates climate models?
Climate, or any other modelling, is fraught with problems. The real world is far too complex to quantify, and there are always exogenous factors. I really don't believe that anyone can predict the future.
So that is your argument? That summer is warmer than winter?
Are you suggesting that this validates climate models?
Climate, or any other modelling, is fraught with problems. The real world is far too complex to quantify, and there are always exogenous factors. I really don't believe that anyone can predict the future.
I know I have to go to work tomorrow and run a seminar........ or I wont get paid next week !!!!
So that is your argument? That summer is warmer than winter?
Are you suggesting that this validates climate models?
Climate, or any other modelling, is fraught with problems. The real world is far too complex to quantify, and there are always exogenous factors. I really don't believe that anyone can predict the future.
I was just using this as one of many possible examples to point out that trends are often easier to predict than short term variations from the trend. The fact that summer is warmer than winter follows from the scientific fact that the earth's axis is tilted with respect to the ecliptic.
And no, it doesn't validate global warming, but nor does your argument that we cannot predict next week's weather invalidate GW
And no, it doesn't validate global warming, but nor does your argument that we cannot predict next week's weather invalidate GW
It is not my argument that the failure to predict next weeks weather invalidates GW, but I would suggest that it doesn't give any credibility to climate models. Weather forecasting models have modest success, climate models have no predictive value. Weather forecasters at the BOM are, in my experience, the most skeptical of climate models.
As for GW (or global warming), I have no doubt that there are measurements of increases in average global temperatures a few tenths of a degree, most of which were in the last centuary.
Even though the concept of an average global temperature is a bit like averaging the telephone book, these increases seem to be real, as both land based and satellite based measure show up the 0.4 degree C or thereabouts increases. To call this a "trend" is nonsense.
What caused these increases, which now appear to have stopped, I really don't know. I suspect some form of heat island effect, as most of the increases are in the northern populated hemisphere.
I very much doubt that it is due to CO2, as there is not even a correlation between CO2 and temperatures, much less a causual effect.
If you want to talk trends, there aren't any, except maybe a cooling trend. The globe isn't warming, the oceans are cooling, antarctica ice is at its greatest extent since measurements began 30 years ago, arctic ice is at the long term average, and anyone who claims to predict future climate is a charlatan.
None of this justifies a massive transfer of wealth via a carbon tax/CPRS/ETS from the household sector of the economy to governments, carbon traders and uneconomic wind, geothermal and solar power that is a waste of resources to "solve" a non-problem.
).
or I wont get paid next week !!!!
