Originally posted by Rren
Appreciate that, short bus. I know it ain't easy for ya.
yes, short-bus. People generally say window-licker over here. So, yeah, cheers.
i'm sorta temporally-challenged (i.e. lots of stuff to do), but I'm also a big fan of procrastination.
I believe the way he worded that he meant to say, 'even now with all of the data we have, we can't, via peer-reviewed science, rule out a
natural cause for most of our recent warmth. Not every possible variable but, the most significant cause. Does that change your answer at
all?
But when he says 'rule out', what is he really trying to say? 100% certainity? Of course, we can't provide that. What we can do is make assessments
of various factors. And when we do, the evidence suggests that human factors are very important.
Whether human factors can account for 49%, or 51% post-industrial isn't really that important. Even at 30% it's enough to worry about. We started at
280ppm, now at 380ish, at doubling we estimate 2-4.5'C for CO2 induced effects (ghg + feedbacks) alone - this comes from models and observations. And
that's without accounting for other factors (i.e. natural variability, cooling aerosols, etc).
So, we take each influence as we find them. Solar- not likely major influence for at least the last 30 years. Cosmic rays - not likely a major
influence. ENSO/PDO - no real evidence for long-term influences. So is that
all natural effects? Probably not. But do we wait in hope to find
other influences? Or act on the information we have?
Information based on very basic physics, which has been producing verified predictions.
That report is a bit much for me, but I guess I asked for it, so I'm
giving it a go. Slowly.
But this is what you're talking about here, right:
Changes in radiative forcings between 1750 and 2005 as estimated by the IPCC.
They are the estimated forcings at the current time. And we are seeing the fingerprints of human impacts. As you can see, clouds have a big range of
uncertainity. We can base our decisions on that I suppose, and ignore what we are more certain of.
So wouldn't that qualify as a peer-reviewed study showing man/GHB's as the main cause for most of our current warming?
No? I was surprised by his statement because I assumed that there were numerous papers out there pointing towards man as the major
cause/force. I thought that was the whole point. What am I missing?
I think it goes down to the 'rule out' thing, and also the notion we should have a single paper to rule out natural effects, all of them in one go.
Research is disparate, but the IPCC attempts to bring the stuff together.
Anyway, for example, Pielke Sr. thinks that solar effects and human land-use effects are under-estimated. He believes that CO2 effects might only be
around 30% of current forcings. if correct, is that enough to ignore?
Others, like Hansen and many others, think we underestimating. The IPCC is pretty conservative actually, heh.
Isn't the PDO already in evidence? What do you mean by "long-term" trend and why wouldn't the PDO be considered evidence wrt climate
forcing (would that be the proper term here?)...Are you saying that it's insignificant, or most likely is, or we just don't understand it well
enough, or we understand it fine and it's already factored in,... none of the above. Sorry for all the questions, mel. I'm tryin'.
It exists, if that's what you mean.
But, as i said, it just moves energy around. It's not a forcing.
Amazing the recent change from 'it's solar!', 'it's cozmik rays!', to 'it's PDO!'.
I'll have to take your/their word on "statistically significant" and how they got there. Could you maybe break that down into layman's terms?
Especially the last part I quoted and the "three times larger than expected from anthropogenic... " part. That may be unreasonable to do on a
discussion board, mel. That's cool. I'll keep chugging in my free time but, it's hard to know where to start and what to focus on.
OK, they assessed the changes observed from radiative effects in a single area. wm-2 is a measure of energy. They found a total of 5.2wm-2 increase in
forcing, of which 1wm-2 was directly attributable to clouds.
Of the 4.2wm-2 remaining. They could show that 1.8wm-2 was readily attributed to human-sourced GHGs. The remainder was due to water vapour effects,
which are a feedback from temperature increases, and can be affected by regional influences. Thus, the 1.8wm-2 is for human GHG effects, the rest
regional and feedback.
Similarly, the estimated predictions contain these sort of feedbacks. Thus, about 1'C of the 3'C best estimate (2-4.5) is due to CO2, the remainder
is from feedbacks like water vapour and albedo changes (less ice to reflect)etc.
Only based on the part you provided, wouldn't this also be, "solid published evidence" of an unnatural cause for climate change? The
language in these papers is hard for someone like me to parse. Seems solid but, then "consistent with concerns" seems odd language.
Because science doesn't deal in absolutes. The evidence is consistent with current theory, rather than proven. It's what I spend some of my time
pointing out to undergrads - data supports/confirms/consistent with rather than proves hypotheses/theories.
Tentative rather than absolute. On this, the ideologues play their games - you know, you can't explain x to my satisfaction, so the whole theory is
wrong.
I understood him to be saying that it's just a coincidence and we have no reliable way of knowing if the warming is anything out of the
ordinary. No? Is there an issue here that you're aware of wrt Alaskan measurements or do you not have any clue what he was talking about in the
article?
to me, he's essentially saying that we didn't have good data from alaska until the satellite age, therefore we probably can't depend on anything at
all, and must obviously forget all the other evidence, and I guess we can keep emitting. Cool.
You must see why this is just obscuration? We also don't have good data from my house ever, therefore I guess we must question the validity of the
science.
quote]No idea, mel. I'm asking you... but, I figure he's going for a 'it's just a normal cyclic thing.' Again, is there nothing interesting or
of note wrt the Northwest Passage? You already know the article and information contained there-in is garbage... I'm still trying to figure out
what's what. (Still stuck on your first cite [IPCC])
It's just obscuration. It doesn't matter that the NW passage was open in the past. Not a jot. it's a regional issue. Makes a change from 'they
grew grapes in england during the middle-ages' lark they normally play.
How much of a difference are we talking? Doesn't seem all that much, or did I read that graph wrong?
Looks to be a few tenths of a degree (maybe .4ish) for short periods in the highest proxy study. Average all proxies, maybe 0.8ish. But, R., we are
only 100ppm into where we could be heading. we could easily hit levels of 1000ppm before we've used up all fossil fuels. Then we might be talking a
potential 6'C above pre-industrial.
Reading that page - from 2002 - it seems that the tests to resolve the contradictions by better modeling cloud cover were to be in the works.
Do you know if that's still the case, or have the findings been released already? If so, whom did they support?
You mean for the Iris effect? There's minimal evidence for it, and more against.
The recent IPCC report contains more information for where we are for clouds, and it does point out we have a bit more knowledge than the last report.
Clouds are an issue. They can both reflect and absorb. So, they might have a net positive effect, or a net negative effect. As I said, the
uncertainties are somewhat accounted for.
There's a good video of a presentation by a cloud researcher I watched a few weeks back, I'll see if I can hunt it down.
But clouds are unlikely to save the day. They'd have to have a massive negative forcing, and they don't appear to have helped during the PETM.
Suppose we can live in hope.
Enjoy your easter sunday, R.
[edit on 23-3-2008 by melatonin]
