A Tale of Two Cities

I recently posted a chart of Los Angeles annual temperatures 1881-2011. Here it is again:

Los Angeles annual temperatures 1881-2011 GHCN via GISS

Looks like a fairly typical temperature chart - a warming trend into the 1930s, a dip in the 1940s, then a climb to a peak in the 1990s, followed by the un-typical dip to lower temperatures this century, the subject of that post. The data is GHCN (Global Historical Climatology Network) provided by the NOAA GISS website, and denoted as "unadjusted" which means no further adjustments by GISS. The GHCN data is most certainly adjusted however, as the following chart shows.

Los Angeles annual temperatures 1881-2011 GHCN vs Unadjusted (raw)

GHCN have lowered the raw data from 1881 to 1930 to produce a convincing upward trend. Note that the adjustment is progressively less, from a massive 1.9°C in 1881, smoothly to zero in 1930. There can be no justification for this "adjustment to fit an agenda", which is exactly what it is. Note the difference in the trend line slopes: from 0.08°C per century (raw), which is effectively zero trend, to 1.62°C per century. Instant global warming sans added heat. I've plotted data from the same sources for San Francisco:

San Francisco annual temperatures 1881-2011 GHCN vs Unadjusted (raw)

This is even more blatant jiggery-pokery, with a progressively increasing negative adjustment from zero for the present all the way back to 2.1°C in 1881. GHCN has turned a slightly negative (effectively zero) trend into a surprisingly (is it a surprise?) similar trend to that for Los Angeles of 1.62°C per century. The precise values are 0.016157 for LA and 0.016144 for San Francisco. Coincidence, perhaps, but I think not. I've seen some large GHCN adjustments, but the blatant fiddling here takes the prize.

As I said earlier, "instant global warming" without added heat. There are those who call sceptics "deniers". To those I say "explain or deny this if you can".

UPDATE 13th Feb 2011

I've just checked the GHCN data for both stations on the GISS site, and both have changed slightly since I downloaded the data on 7th Feb. I also had a dataset for SF from December last, and that's different too. Not just rewriting the past, but doing it regularly. I though only totalitarian regimes rewrote the past?

UPDATE 13th Feb 2011

Just a few minutes ago, I had displayed the GHCN temperature chart for Rochester, Minnesota, among others. With a dozen browser tabs open, I didn't realise that the chart was still displayed, so I reselected it from the GISS station selector, and displayed it again. Unbelievably, the data had changed by a few tenths of a degree (both for early and late years) within ten minutes! Some kind of official investigation is needed of this unjustifiable shenanigans.