“science is *never* settled”: this is a false dichotomy. Yes, there are challenges to Relativity, even today, but even the believers in the challenges don’t see relativity changing except at the margins. Climate science is similar. We are unlikely to find that what we have known for 30-110 years is suddenly all wrong. We may find subtle adjustments to it, even important subtle adjustments, but it is not a house of cards that will fall the moment someone challenges one small piece of it.

The news item you cite is a perfect example of the above. While the effect may be real, it is unlikely that the magnitude of the effect on climate cited is as large as stated (even if that is what the calculations show) because it would not match observations. There could well be something going on there, but if the effect is as stated, it most likely means that there are other effects not yet understood. Otherwise the paleo record short-term climate sensitivity would not match the climate models so well. There are indeed lots of positive feedbacks not included in the climate models. Some may be more significant than realized. I also saw no smear.

“Now as an excercise, apply that mindset and approach to those who oppose nuclear power. Same technique.”: Note that Joe just posted a call for 700 GW of new nuclear (which is a repeat of what is in his book Hell and High Water). That seems like a pretty good example of telling you “specifically what their targets and actions would be.”

“and even build a sea wall”: I think this misses the point. Mitigating AGW is going to be cheaper than adapting (e.g. building sea walls). Also, there are plenty of places too poor to build sea walls. The mass displacement of poor people affected by drought or rising sea levels is a real issue, and it is also a security threat to rich countries like the US.

As far loss of credibility to over-stating risks, I agree. I believe that accuracy is important. However, there is a pernicious tendency to believe that we must have certainty before acting. We should act upon the risk itself. Right now the current situation could be compared to playing Russian Roulette while arguing about how many chambers are loaded. The proper question is why we are playing such a risky game.

That’s as silly as labelling terrorism an environmental threat because of all the bad air from the falling towers.

AGW first is a risk to regional climates and eco-systems simply because they are more sensitive to such things. Man can always bundle up or put on the A/C and even build a sea wall. no big deal. The threat to man is actually further down the line compared to the threat to other life. I suspect that higher CO2 will fertilize as much as harm crop production so the claims that famine will happen is a stretch. And now the latest study on the hurricane – global-warming link was a bit inconclusive.
Our national security is not threatened by climate change.

See my previous point – There is a risk to credibility in over-stating risks.

Now as an excercise, apply that mindset and approach to those who oppose nuclear power. Same technique.

Another error – every extreme weather event was cast as caused by global warming. Nice journalistic hype, but … the flipside is that temperatures have cooled and are now colder than 10 years ago.
So if a hot 2005 ‘proves’ global warming, does a cold 2007 ‘disprove’ global warming?

Hype gets disproven, and that leads to cynicism.

“Yes, certainly the West Antarctic Ice Sheet might collapse over a decade or two — and that is 15 to 20 feet.”

It *might* happen. And yet Antarctic temperatures are stable and total ice mass is stable/increasing. Its not really at risk. But when it doesnt happen (it most certainly is a highly unlikely event), will that ‘disprove’ the so-called alarmists? There is a risk to credibility in over-stating risks.

Because anyone not 100% wedded to the ‘orthodox’ view and the extreme “act now” contingent is a ’skeptic’. Those who want action now are doing themselves a disservice by attacking and dismissing the skeptics’, many of whom are scientists and/or actually understand and believe quite well the global warming concept, just dont agree in all the shibboleths the sky-is-falling crowd spreads.

Al Gore has been particularly destructive in his false claims that the ’science is settled’. First, he is not a scientist so shouldnt presume. Second, the science is *never* settled, on anything. And in this arena the models that are used to claim “this will happen” are far from proven, indeed cannot be proven unless we wait another few decades. In particular, good climate scientists acknowledge that there are unknowns in water vapor feedback and in cloud cover. Well, what about this:
http://www.uah.edu/News/newsread.php?newsID=875
This is climate science. Yet these climate scientists get a conclusion that disagrees with orthodoxy and are given a label to smear them.
Far more productive to say this is a part of the science and discuss the facts, then to engage in ideological tribalism.

Call it ’skepticism’ instead of what it is, more science, and – presto – you have pressed good climate scientists who doubt that climate sensitivity is as great as Hansen estimates as the ‘enemy’. Pity.

This is nonsense.

Given the limits to fossil fuel resources, we couldnt even get close to 800ppm anytime soon if we tried with all our might. CO2 increases are not accelerating and are not greater than 2ppm/yr.
800ppm requires us to emit about 20-30 times what we emitted in the 20th century in the 21st. This despite the fact that all economies are getting more efficient in use of energy and despite the fact that population is due to top out and *decline* after 2050.

As Co2 increases, the sink capacities improve, balancing higher emissions with more robust fixing of CO2, so we are more likely to be at 580ppm in a ‘do nothing’ scenario as any number higher.

But ‘do nothing’ really means – we will eventually move off of oil either due to AGW inspired post-fossil-fuel planning, or the ‘non-planning’ of higher oil prices driving scarcity-based alternatives. In short, by 2050 we will be driving plug-in hybrids fueled as much by nuclear energy and wind as by oil …

We need more realistic scenarios in between 800ppm “we are all gonna die!” and 450ppm “end all industrial activity now!” Neither will happen.

I bet on 2ppm/yr rise now until 2050, or about 480ppm in 2050. Then it levels off a bit as we work ourselves beyond the fossil fuel age, hitting 520ppm by 2100.

This level from a climate sensitivity perspective is equal to the rise from 280 to 380ppm thus far, and so will hit us about as hard as what we got already – ie about 0.6C rise in temps and no more than a foot of sea level rise.

Different personality types take their own learning path. We should let PaulK take his & not impute malmotive.

Nonethess, a drastic loss of ecosystem services would put human society in a state with which it is not familiar. As we see how well society comes together, discusses things, then redirections, we should have deep concern over our ability to change course. I sure do. Esp. with the lack of leadership on this planet today.

But as to the planet itself, it will survive this mass extinction event too. I, personally, feel that in the grand scheme of things another two or three mass extinction events (after the one Homo sapiens caused) will occur too. ‘Eh’, says the multiverse.

Best,

D

http://www.britannica.com/ eb/ article-65644/ ice-in-lakes-and-rivers#534086.hook

as an approximation for melting ice sheets (by running time backwards), the time derivative shows that the melt starts slowly and proceeds ever faster until the ice is gone. [This analysis assumes ice of only moderate thickness, so is not completely correct for thick ice sheets].