I have asked the met office for an explanation

When you look at the side by side comparison of GISS and HADCRU, it seems odd that you trust one dataset but ‘will have no truck’ with the other.

It also seems odd that you need roughly 60 years of warming, with accelerated warming at the tail end of that period, before you think it appropriate to take any mitigating steps at all, yet 10 years are enough for you to decide that we are in a stasis. I’m not sure I would call you a ‘luke warm skeptic’.

It also seems odd that you go out of your way to state that 2010 was a thousandth of a degree away from being beaten into 4th. From what I can tell, the error on a single year measurement is .05, or 50 times the difference you are quoting. Is that really significant to you?

It has been fun…

Chris

Re 2010 v. 1998, see http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt where 2010 was a thousandth of a degree away from being beaten into 4th.

For me to be comfortable with the World Government taking action now, I would need to see that in 30 years time the anomaly would have risen from the 2000′s decade +0.44C to +1.04C in the 2030′s. In my humble opinion we don’t have enough evidence yet that that is at all likely.

I’m close to calling time on this discussion – it’s been fun though.

Rich.

Couple other things, if you don’t mind… Please share your source that 2010 didn’t beat 1998. And, please share what you would need to see in 30 years that you aren’t seeing now that would make you comfortable having the World Government take action.

You seem to want to be using science, with good long periods like 30 years, which is for right or wrong an accepted length for establishing norms. If it’s just an academic exercise, then that’s fine, but unfortunately the World Government doesn’t want to wait that long before making political decisions. So we need better models of future temperature, and if the current models prove to be inaccurate then they need to be revised.

By the way, I never said that I disagreed with Hansen spouting after 15 years of global warming, so I reserve my right to spout after 10 years of “stasis”

You say that I need to take account of error bounds, but then of course I do – that’s what the 0.1degC standard deviation is about, which affects the Bayes factors. A value which is just 1 s.d. down on expected attracts a Bayes factor of exp(-1/2) = 0.61, which isn’t a big deal – until there are 6 in a row which turns into a 20:1 shot.

Rich.

All true. However, you didn’t address my comment. You’re trying to use statistics to address a PR move. What is the model you are testing there? Did he really quote the models accurately when he made that comment? Are you really testing a model or a silly PR comment? Either way is fine, but be up front about it.

>> I don’t follow. Aren’t all global temperature statements to do with AGW? Or is that only when the temperature is going up?

No and no. If I say “The global average temperature was really high this year”, it has nothing at all to do with AGW. Nothing. If I say, “there is a long term trend of increasing temperatures at a rate of X”, that is very much related to AGW. Seems a waste of time trying to test individual years as proof or disproof of AGW…

>>Isn’t that statement anti-science? We’re trying to use mathematics to assess the state and rate of global warming. There is, we are told, a scientific consensus in favour that it is a scary amount. Is the consensus actually correct?

No, it isn’t anti-science. I would say that it is anti-science to apply a test to an almost meaningless prediction from the MET and assume that it has some scientific meaning. If the MET wants to engage in PR, let them. If you want to engage in counter-PR, go ahead. But don’t call it science.

>> I can’t tell you how low an opinion I hold of GISS. I will have no truck with it. Just search on this admirable site for “GISS” and you will see numerous serious problems with that series.

I’m not actually ‘new’ to this site, and I have seen many of the discussions of GISS. It is difficult to argue with your statement that you will have no truck with them, so I guess we will leave that lie. So, whose data set that you trust have you used to show that 2010 is cooler than 1998?

>> Well, I think it’s important not to start at 1998, with a big El Nino, or at 1999/2000 with a big La Nina. As for using only 10 years, I would remind you of this. In 1988, when speaking to Congress rather than on a blog, James Hansen had at most 15 years of global warming to go on to make his disturbing predictions of doom. He felt it was important on the basis of that short length of data to make public pronouncements.

Interesting statement, but it didn’t answer my question. You seem to think that Hanson was wrong for only using 15 years worth of data. So your response to that is to use 10?

>> I feel it is important, cumulatively year by year, to test the “consensus” predictions.

I don’t argue with this. However, given that single year data points are subject to so much variability, I think it is important to note ‘error bounds’ when making statements based on 1 year of data. If you are testing a model prediction for 2011 and the model fails, what is the likelihood that the model is still accurate?

Thanks, Chris

Rich.

I’ve put some of your comments in italics below, with replies.

You make a couple comments about testing certain models and their predictions. But it doesn’t look like you are testing models. It looks like you are testing a few ridiculous extreme cases. What aspect of the model actually drove that silly prediction? Is that something that came from the PR department at the MET? Is it from a published scientific paper from the MET?

I don’t think the Met Office would agree that the “5 of next 10 years > 1998″ was a silly prediction, at least when they made it. Possibly, with 2010 failing, they may be rethinking it, or possibly they think that after this La Nina there will still be a good chance.

What did Schmidt really mean when he said that? Which model was he quoting? What were the error bounds?

Schmidt is one of the main people in the Team of “consensus scientists”, and it shows that they still think that the globe should warm by 0.2K this decade. They have recently realized that they need to become cleverer with error bounds, hence are now suddenly making statements (because 2010 wasn’t top) that 1998, 2005, and 2010 are statistically indistinguishable.

It looks like you are choosing a few extreme statements that really don’t have much to do with AGW.

I don’t follow. Aren’t all global temperature statements to do with AGW? Or is that only when the temperature is going up?

Maybe the MET has a model that says 5 years in the next decade will have temps higher than 98… So what? If it is only 4 years instead of 5, does that mean that the model is wrong?

The purpose of using statistics is to increase, or decrease, one’s confidence about certain statements. I am pretty sure that if 4 out of 10 years are higher than 1998, by a modest margin, then the Bayes factors will come out in favour of a linear +0.02 per year rise this decade. But if it’s 1 instead of 4, then that would be doubtful.

What could you possibly hope to prove by testing a prediction like that? Its a PR stunt on both sides and really doesn’t do much to increase understanding or knowledge by anyone.

Isn’t that statement anti-science? We’re trying to use mathematics to assess the state and rate of global warming. There is, we are told, a scientific consensus in favour that it is a scary amount. Is the consensus actually correct?

Oh, and according to GISS, 2010 did beat 98, despite 98 being a strong el nino and 2010 being a strong la nina (at least, according to John Lancaster below): http://data.giss.nasa.gov/gistemp/graphs/.

And if you are just going to look at the shapes of graphs to determine stasis or not, why wouldn’t you look at this one: http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.lrg.gif

I can’t tell you how low an opinion I hold of GISS. I will have no truck with it. Just search on this admirable site for “GISS” and you will see numerous serious problems with that series.

Personally, I’m not convinced either way, but it sounds like you are and you are going out of your way to present certain evidence to support that conclusion.

What do you mean by “either way”? Personally, I am convinced that CO2 causes some global warming, but I just don’t think it is by a large amount.

Thats fine, but please don’t be offended if I ask something like why do you choose 2000-2010 as your period to examine when looking for stasis. That seems like a completely arbitrary period. What is it about that 10 year period, bounded by big round numbers based on a calendar convention, that makes you think they show temperature stasis? That is, what are the criteria that you used, before knowing the result, that prompted you to look at those years?

Well, I think it’s important not to start at 1998, with a big El Nino, or at 1999/2000 with a big La Nina. As for using only 10 years, I would remind you of this. In 1988, when speaking to Congress rather than on a blog, James Hansen had at most 15 years of global warming to go on to make his disturbing predictions of doom. He felt it was important on the basis of that short length of data to make public pronouncements. I feel it is important, cumulatively year by year, to test the “consensus” predictions.

Rich.