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jshell wrote: I've actually been pretty straight about sitting on the fence on this matter.
No you haven't. As I said before, you have exaggerated the meaning and significance of this stuff, pretending that small things debunk the whole field, equating right-wing denier blogs with real scientists, and applying a false understanding of the science. That is denier stuff.
jshell wrote: [Does the atmosphere contain CO2?]
1. Of course it does.
Hurrah, we agree.
jshell wrote: [does it influence global temperatures?]
2. That's unproven
You're simply wrong there. It's provable in a laboratory equipped for children. It is an uncontroversial established fact of atmospheric physics, far pre-dating any widespread ideas about climate change.
To say otherwise requires a new and radical theory on global temperatures that doesn't exist yet. If you can come up with one and prove it you have a great career in science ahead of you.
jshell wrote: [Will that influence be enhanced by the addition of more carbon dioxide?]
They are having problems proving that CO2 is causing warming as they haven't seen the warming they expected despite increasing CO2.
You're wrong again. Climate is complex with many factors affecting it, which is why we measure global average temperatures. The 'cooling' and 'decline' that deniers like to talk about are relative to the recent highest temperatures on record, where carbon emissions were augmented by El Nino events.
As the Met Office explained:
"The evidence is clear – the long-term trend is that global temperatures are rising, and humans are largely responsible for this rise. Global warming does not mean that each year will be warmer than the last. Natural phenomena will mean that some years will be much warmer and others cooler.
"You only need to look at 1998 to see a record-breaking warm year caused by a very strong El Nino. In the last couple of years, the underlying warming is partially masked caused by a strong La Nina. Despite this, 11 of the last 13 years were the warmest ever recorded."
jshell wrote: There's also other periods of history where there's been warming without CO2 spikes
That wouldn't disprove CO2 as a greenhouse gas at all! It's like saying leaving chip pans unattended causes house fires, but some house fires have been caused by other things, therefore there's no clear evidence that unattended chip pans are a risk.
As it is, ice core records for the last 800,000 years show strong correlation between the levels of atmospheric carbon dioxide and methane, and the temperature.
jshell wrote: CO2 is not directly linked to rising temps
Really, your Nobel Prize for Physics awaits you.
Carbon dioxide is a greenhouse gas. The effect of adding more to the atmosphere, well, the clue's in the word 'greenhouse'.
jshell wrote: [Have human activities led to a net emission of carbon dioxide? ]
4. Yes, but the figure quoted is 4% of total global emissions and that appears negligible to me. So, in order for man to decrease global carbon emissions by 1%, we'd have to cut back by a whopping 50% of man's total
You misunderstand how it works. The CO2 emitted from natural sources has been balanced by the amount absorbed (largely by plants and oceans). Thus, the amount in the atmosphere remained stable since the end of the ice age 10,000 years ago (between 260 and 280 parts per million).
Since the beginning of industrial times 200 years ago we have burned a lot of fossil fuels (emitting CO2) and cut down a lot of forests (preventing emissions being absorbed). Now CO2 is at 387 parts per million - an increase of nearly 40% - and the rate of emission is rising fast.
It's like overspending your income by 5 percent a month, and keeping upping it even as your overdraft level decreases. Now imagine your rate of overspend is increasing all the time. What would your bank account look like in 20 years?
jshell wrote: gains which could be wiped out overnight by one volcano 'cough'.
Once again, you really show a poor understanding of the physics, of probability, and even of elementary arithmetic. Humans *are* adding vast amounts of CO2 to the atmosphere, and doing it constantly. Volcanoes *might* erupt en masse, but presently they account for a fraction of 1 perecent of the amount of CO2 that humans release.
The eruption of Mount Tambora in 1815 - the largest for 1600 years - contributed to a massive global climate event. For a year.
Certainly, the eruptions at the end of the Permian period, where temperatures increased by 6 degrees in a short space of time, just as we're on course to do now, was caused by volcanoes. It resulted in the extinction of over 90% of species. That, though, was over 250 million years ago. The likelihood of that sort of thing coming up is not great. I don't think you'll find vulcanologists who'd refer to events of that magnitude as a cough.
To return to our analogy, it's like saying your house could be burned down by meteor strike so you might as well leave chip pans turned up on all the hobs.
jshell wrote: that the whole thing is bullshit, based on bullshit and calculated using bullshit.
You know that overstatement I mentioned? This appears to be scientists disputing one another's methods, on one thing, one time. This is far from saying that the whole thing is bullshit.
In 2004 there was a study done of papers in the world's pre-eminent scientific peer-reviewed publication Science. They looked for papers containing the words 'global climate change'. Of the 928 papers, not one disagreed with the consensus position. I stress, these are peer-reviewed. If there were a scientist out there with evidence to the contrary, acclaim and fortune are there for the taking.
The study said:
"This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies. Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect."
If you can show me where these Hadley Centre emails actually doubt anthropogenic climate change, or even the broad severity of it, I'll be impressed.
If you can show me a single peer-reviewed paper doing the same, I'll be equally impressed. Deniers sound so grand when their names have 'professor' in front, until you find out that they're economists, geologists or astrophysicists.
You and I have no expertise in the subject, we are reliant on those who do. Sourcing your information from economists, or from blogs misreading emails and extrapolating to a whole scientific field is not going to guide you to a wise position.
So, we not only have climatologists and meteorologists - who, as I said, are in as much agreement as doctors are about tobacco and cancer - but we have scientific bodies like the Royal Society in Britain, and equivalents around the world.
Not one of them has questioned climate change, and in their dozens, despite their natural scientific reserve, they issue strongly worded statements in line with the consensus position, contrary to that held by the likes of Melanie Philips or those who believe in made-up physics the way you do.
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