@memester,
memester;113378 wrote:confirm literacy to whose satisfaction ? Your satisfaction does not particularly interest me.
Well, the inability to answer a yes/no question would probably not meet
anyone's satisfaction, but I was giving you the benefit of the doubt.
memester;113378 wrote:Seemingly you cannot properly state a question for me, so that I could possibly then look for an answer, for you.
I asked you the following question:
Is there evidence that the rate of global mean temperature change has accelerated during the last 100 years?
This is a properly stated question. I asked you "Is there evidence of X?" That is grammatically correct. It's a yes/no question about the existence of evidence. If you can't recognize it as such, then no wonder your literacy comes into question.
memester;113378 wrote:I've already stated what I have to say on the matter - you can find fault with that.
I can't find fault with it because you haven't actually communicated anything. There's nothing to criticize -- simply because there's nothing at all.
Arjuna;113369 wrote:I wonder if I could ask something about this. If mean temperatures have been higher in the 20th century, what does that tell us? Is temperature data for the last 100 years, or the last 1000 years sufficient to say something statistically significant about our situation?
Well, first, take note that you are misusing the phrase "statistically significant" here. Statistical significance has to do with comparison between groups and determination of how likely it would be that the observed difference is due to chance. In order to speak of statistical significance, then, you need to define your comparators.
So if you take two groups, one is ambient temperature readings in a given location during the 1890s and the other is the same but during the 1990s, you can of course calculate statistical significance.
But statistical significance is not the issue. The issue is about what story the data tell. So put together the data -- at least over the last 120-150 years of temperature readings, there is a marked and accelerating rise in temperatures, with a notable plateau during the 1940s-1960s. There has been a recession of glaciers all over the world, there has been a rise in sea levels, and there have been corresponding ecological changes.
So there is a story being told here that is corroborated by independent observations -- the world is getting warmer and it is getting warmer faster.
That doesn't tell us anything about what is responsible for it. But then when you look at earlier periods and find that there is no comparable situation, you need to ask what is unique. So the question naturally arises as to whether the simultaneous explosion in human populations and their activities has something to do with it, and from this you identify mechanisms that could plausibly be responsible.
So it's a good story, it ties together a lot of observations, it makes sense, and it will ALWAYS be an imperfect story whatever the truth happens to be.
But then the policy issue comes up. It's Pascal's wager. What if they're right that humans are responsible, that behavioral change can reverse the trend -- what does it mean if we do nothing? What if they're wrong -- what if behavioral change can't do anything because it has to do with solar flares or whatever.
Do we dare to be wrong? Isn't there enough
other justification to modify behavior (last I checked pollution isn't good for human health either, irrespective of the climate).
QUOTE=Arjuna;113369]It's not that we know how the greenhouse effect will change human life. We don't know that. It's more that if it turns out to be a disaster, we don't want to look back and see that we were afraid it would, and we did nothing.[/QUOTE]Yes, I agree. The question is whether our data are sufficient, given how quickly it would need to be acted upon (and how difficult it is to implement).