Forget Gores film that shows glaciers receding from 1980.

http://aycu39.webshots.com/image/42758/2004893524491921913_rs.jpg
http://aycu19.webshots.com/image/44618/2004881440297032940_rs.jpg
http://aycu24.webshots.com/image/44263/2004885309439382820_rs.jpg

This relates to the link above:

On her second visit to Glacier National Park in 1894, Mary Vaux (pronounced “vox”) was aghast at how the Illecillewaet Glacier had retreated since her previous visit seven years earlier. The lowest edge of the Great Glacier, as it was also known then, was clearly withdrawing upslope. We now know that most of the world’s glaciers were in retreat then as they are now. CO2 was I believe about 220ppm at that time.

Obviously Gore was unaware of the fact that glaciers were on the retreat before 1850.

Gore mentions lake Chad, suggesting global warming is the cause of the lakes loss of water, when in fact the main cause of the loss is that water from the rivers that flow into the lake are being diverted in increasing amounts for irrigation purposes. It is estimated that about one-third of the stream flow today is diverted from the Chari River before its flow reaches Lake Chad.

Diversion of stream flow had been at a relatively low level, until the late 1970s when Lake Chad basin countries began to sharply intensify their food and fiber (e.g., cash crop) production efforts. According to UNEP GRID, “between 1953 and 1979, irrigation had only a modest impact on the Lake Chad ecosystem. Between 1983 and 1994, however, irrigation water use increased four-fold. About 50% of the decrease in the lake’s size since the 1960s is attributed to human water use, with the remainder attributed to shifting climate patterns.

There is a long list of omissions, half truths and mistakes in this film, it is beyond me why the US and the UK governments have insisted the film should form part of the school curriculum.

The slight warming is natural.

I’m not aware of a significant increase in the trend in sea level rise either.

Have you looked for papers which discuss errors in a more quantitative way or are you just assuming that they don’t exist? I can tell you they do exist and they are not hard to find.

Again it’s worth remarking that the paper we’re talking about only covers the US. There is plenty of empirical evidence of dramatic global warming – the US has hardly warmed at all in comparison to other parts of the world. You and others seem to be getting very hung up on minor aspects of the temperature record of 2% of the planet, when simple facts like rising sea levels and 95% of non-polar glaciers receding tell us that temperatures are rising rapidly. You can’t seem to see the wood for the trees.

Looking again at page 20, I see that the time of day adjustment, apparently due to the fact that many of the stations have, in concert, conspired to change the time at which they record temperature, in such a way that decreases observed temperature, contributes a 0.17 degC warming delta to the raw rural data.

Further then the “Max/Min & SHAP Data” adjustment contributes a whopping 0.22 degC warming trend delta. But wait, I read the rest of the paper. And I didn’t see anything about a “Max/Min & SHAP data” adjustment. Perhaps this is the Station History Adjustment – SHA? – guess I don’t know the lingo. Assuming it is, I find it amazing that the strongest component of the warming trend is based on an adjustment for stations histories for which the paper admits there is very sparse data. For many stations, we just don’t know where they were located. We don’t know when the moved, or where they moved from. But never fear, we can adjust, and on the basis of this adjustment rests the largest component of the rural data warming trend.

The “Data fill & urban adjustment” then contribute the final 0.05 degC delta. I am not sure why “filling” in data would contribute to a trend in any statistically significant way, or why the rural stations require urban adjustment, but whatever, it’s a tiny adjustment, and probably not significant.

And all of this is presented with absolute certainty, error bars are utterly lacking. I was trained as physicist. I’ve read my share of scientific papers. One thing always present in most serious scientific papers is a quantitative estimate of error. Error bars however are conspicuously lacking in this analysis. Is the time of day adjustment exactly +0.17 degC? Really? Wow, that’s pretty amazing.

Is the station history adjustment, based on admittedly poor data, exactly +0.22 degC? Exactly? Again – wow.

Perhaps you can point me to another analysis that includes an estimate of error.

Adrian – if by ‘linguistic nonsense’ you mean describing science carefully and accurately, no, you’re not done. Your result didn’t relate to your null hypothesis (which wasn’t worded carefully or accurately), and your ‘breakdown’ was supposition unsupported by the data. Sorry and all, but science does involve a bit more rigour than that.

joshv – you can use just the rural data by all means but you can’t use the raw data. You do first need to correct for various effects, as described in the Hansen paper we’re talking about. The urban adjustment is only one of them. The process really is described in plenty of detail. Understanding scientific papers is not simple but the detail is all there if you persevere. And like I say, you can ignore every single word Hansen has ever written and you can still find extremely clear evidence of global warming and humanity’s influence on it.

Now, we might be misinterpreting Hansen’s calculations – but since he’s keeping them secret…

You’re correct, though, I didn’t make a temporal distinction – but, and you might gather this as important, this is wholly because the experiment in question didn’t cover the temporal direction. The question is wholly whether or not the UHI has a significant effect on individual readings.

If it does, it is then either extrapolation and definition, or further experimentation, which renders the temporal case meaningful. This is “The Breakdown” – this was me extrapolating these results on a temporal scale using armchair logic, basic knowledge of thermodynamics, and the definition of the UHI effect. There’s a reason I made that a distinct statement from “The Results.”

Am I done with your linguistic nonsense yet?

Good then we are in agreement, the raw rural data doesn’t show a warming trend.

According to page 20, the adjusted rural data however somehow takes on a roughly 0.4 degC anomaly via the adjustment process, which closely matches the adjusted urban anomaly, which then allows Hansen to produce the following page of trend graphs showing no overall difference in the trends between rural and urban station data.

This quite clearly demonstrates that warming in rural areas is purely an artifact of the adjustment process.

Looking at the raw data, knowing that UHI is real, and that urban areas have been expanding, if I wanted to calculate the average US temperature over the last century I’d simply throw away the urban data points and never consider them in my analysis. Sure you’d have lower coverage, but certainly no worse than other areas on the planet.

But instead they attempt to correct for UHI by using nearby rural stations – fair enough. I would expect this process to lower the anomaly in urban areas, given the absence of anomaly in the rural raw data. But instead, on page 20, we see the adjustment process raising the anomaly. I would also expect such an adjustment to leave the rural data untouched, as after all, it’s serving as the gold standard for the nearby rural stations, but no, somehow the adjustment process raises the rural anomaly as well. This is fascinating mathematics.

I do not comprehend this adjustment process. You take one set of data with a trend, another set of data without a trend, and somehow combine them to create two sets of data with almost identical trends that are larger than the original.

You will have to forgive this layman for failing to understand why we shouldn’t just use the raw rural data.

As for the rest of the world, I’d like to sort out the US first as we’ve got some of the best data on the planet.

As for melting glaciers, etc. I will readily admit that the US, rural or urban, using raw or uncorrected data, is significantly warmer than it was 30 years ago. Thus I think it is reasonable to believe that the rest of the world has also significantly warmed, this may or may not be the cause of some of the effects you list.