OK, here's a go at the Junk Science site ... hopefully Mom will sleep long enough for me to finish.
Just going through his summary points at the end of the article:
The temperature effect of atmospheric carbon dioxide is logarithmic, not exponential.
It is logarithmic in the absence of human interference. That's because as temperatures warm and temperate and tropical zones expand, earth's biomass and sequestration potential increases. But when humans undertake to both increase carbon emissions and deforest, we don't know whether the relationship will continue to be logarithmic. All indications are that it will not.
The potential planetary warming from a doubling of atmospheric carbon dioxide from pre-Industrial Revolution levels of ~280ppmv to 560ppmv (possible some time later this century - perhaps) is generally estimated at less than 1 °C.
As I mentioned in my earlier post, our only criterion for judging whether this is a big change or a little change is its impact on human potential. We may have already doomed ourselves to extinction with this little itty-bitty change. We don't know yet.
The guesses of significantly larger warming are dependent on "feedback" (supplementary) mechanisms programmed into climate models. The existence of these "feedback" mechanisms is uncertain and the cumulative sign of which is unknown (they may add to warming from increased atmospheric carbon dioxide or, equally likely, might suppress it).
Science Lesson #1: Don't confuse the model with the phenomenon.
All models contain uncertainty and no model contains all the factors found in reality. The name of the game is to identify those factors that have statistically significant influence and then look at outcomes when the state of those factors is varied. Climate models do yield contradictory results, depending on how you set the parameters. It is the preponderance of models yielding the same result that leads us to believe that a particular outcome is more probable than any other.
The total warming since measurements have been attempted is thought to be about 0.6 degrees Centigrade. At least half of the estimated temperature increment occurred before 1950, prior to significant change in atmospheric carbon dioxide levels.
Pre-1950 is not prior to significant change in atmospheric carbon dioxide levels. What has happened is that carbon dioxide levels have increased exponentially, so if you eyeball the curve, things look much, much better the earlier you look. But it is quite possible that the change in CO2 was already 'significant' much earlier than 1950 ... one theory suggests that it was already becoming 'significant' 8000 years ago ... if by significant we mean likely to impact long-range human potential.
As far as the "half" is concerned, the news is exactly the opposite of what the author here implies. Measures started to be taken around 1880. So the first half of our measured temperature increase was spread over 70 years and the second half of our measured temperature increase was spread over 50 years. Temp change is increasing at an increasing rate, in other words, just like CO2 measures.
Assuming the unlikely case that all the natural drivers of planetary temperature change ceased to operate at the time of measured atmospheric change then a 30% increment in atmospheric carbon dioxide caused about one-third of one degree temperature increment since and thus provides empirical support for less than one degree increment due to a doubling of atmospheric carbon dioxide.
But this resolution in quantifying the causal relationship is exactly what we have been unable to achieve at a statistically significant level of confidence. Industry 'experts' would be the first to pooh-pooh a statement like this, because we really don't know what these correlational coefficients are. All we can say at this point is that we have a culprit on which to pin causality, and the secular trends are moving in the same direction.
There is no linear relationship between atmospheric carbon dioxide change and global mean temperature or global mean temperature trend -- global mean temperature has both risen and fallen during the period atmospheric carbon dioxide has been rising.
He confuses annual data with the secular trend. Annual data fluctuates. The secular trend suggests a strong relationship between atmospheric CO2 and global mean temperature
The natural world has tolerated greater than one-degree fluctuations in mean temperature during the relatively recent past and thus current changes are within the range of natural variation. (See, for example, ice core and sea surface temperature reconstructions.)
Yes, but humans have not tolerated change at this pace ever in their history! It is human potential we are concerned about. What the heck do I care how cold or hot a darned rock will be if you plant it in a glacier or throw it in a volcano? We had thousands of years to adjust to the last ice age, and we really don't know what adaptations were thrust upon us during that time. Civilization as we know it emerged under certain circumstances, and if we drastically change those circumstances we can't predict how well or how quickly our civilization will adapt.
It's not about air, it's about us.
Despite attempts to label atmospheric carbon dioxide a "pollutant" it is, in fact, an essential trace gas, the increasing abundance of which is a bonus for the bulk of the biosphere.
The most corrosive element in our atmosphere is oxygen. It is one of those miracles of nature that organisms evolved which could burn oxygen as fuel instead of being incinerated by it.
Therefore what?
Whether or not CO2 is a trace element and used as fuel by plants is irrelevant to the question at hand. The question of interest to us as humans who do not use CO2 as fuel is: how much CO2 can we add to the atmosphere before it causes changes that are unfavorable to human potential?
There is no reason to believe that slightly lower temperatures are somehow preferable to slightly higher temperatures - there is no known "optimal" nor any known means of knowingly and predictably adjusting some sort of planetary thermostat.
No, but there is range, outside of which ecosystems will begin to adapt in ways that may be very unfavorable to humans.
A cockroach can survive ground zero of a nuclear blast and walk away laughing, but it is too late for us to evolve into cockroaches because we are already humans.
Fluctuations in atmospheric carbon dioxide are of little relevance in the short to medium term (although should levels fall too low it could prove problematic in the longer-term).
Again, he conflated annual fluctuations with the secular trend.
And he peppers his summary with statements to the effect that 'these are not the droids you're looking for':
Other anthropogenic effects are vastly more important, at least on local and regional scales ... Fixation on atmospheric carbon dioxide is a distraction from these more important anthropogenic effects ... Activists and zealots constantly shrilling over atmospheric carbon dioxide are misdirecting attention and effort from real and potentially addressable local, regional and planetary problems.
Yes, we should all devote ourselves to solving homelessness and leave those poor oil companies alone.
The fact is, all environomental problems are intertwined because the planet is one big organism.
Lord M., you said a couple other things in your post that I wanted to comment on:
I’m starting to suspect that humans have caused more climate change through deforestation than pollution.
I too consider deforestation a more immediate threat. But the short-term impact of deforestation is on microclimates, not global climate. At the rate we are deforesting, this also impacts planetary sequestration potential, and I am inclined to say that the impact is significant, but without looking at the actual numbers, my guess is that even if there had been no deforestation over the past 100 years there would still be a net increase in ambient emissions because of pollution. Both sides of the carbon cycle have to be addressed for us to make headway.
Finally, what I really need is a clear indication that the earth is now warming significantly faster than usual.
You know, I had to look up myself how they measure temperature historically ... I know they get atmospheric carbon from ice core samples. Apparently temperature measures are geologic - from sediment and sea core samples and from the distribution and depth of various types of rocks and fossils. These are models, of course ... just as the evolutionary tree is a model, because we don't have perfect data sets going back hundreds of thousands of years. But there is an established methodology for extrapolating into the past, much of it creditable to Darwin. I have yet to see a model whose secular trend contradicted the thumbnail sketch that my colleagues gave to me twenty years ago:
Over the past 400,000 years, we have seen fluctuation between glacial and interglacial periods ... these are short cycles, actually, in geologic time. Each cycle, from peak to peak, lasts about 100,000 years. The difference in mean global temperature between the coldest part of the cycle and the hottest is about 3 degrees centigrade. So an increase of 1 degree centigrade represents approximately 17,000 years along a secular trend. That is the temperature increase we've seen since in the past 250 years since the beginning of the Industrial Revolution.
Jn
We're the only species that can imagine 400 years into the future. Then we stop. We imagine, all right, but then we go right back to using a new baggie every day for our kids' school lunches, and buying an SUV that gets 12 mpg . . . .
