Data Abuse

Global warming is really happening. It’s because of us. And it’s dangerous.

But some people can’t accept that, so they deny the truth of it. Perhaps the most popular website which does so consistently is “What’s Up With That” (WUWT), a cornucopia of articles trying to show “evidence” that the climate scientists — the ones who are warning us — have got it all wrong.

To make their claims, they often use climate data. Most climate data make it extremely difficult to deny the reality of the problem, so a recurrent theme is to imply — or say outright — that the data we use are wrong because they’ve been adjusted. It’s implied — or said outright — that the adjustments are arbitrary, that their only purpose is to give the impression of a global warming trend, and they can’t be relied upon.

For example, a recent post had this to say about temperature data:

It may seem unreasonable to refer to the official data as “adjusted”. However, the basis for the official data is what is known as the Global Historical Climatology Network, or GHCN, and it has been arbitrarily adjusted. For example, it is possible to compare the raw data for Cape Town, 1880-2011, to the adjustments made to the data in developing GHCN series Ver. 3:

The Goddard Institute for Space Studies is responsible for the GHCN. The Institute was approached for the metadata underlying the adjustments. They provided a single line of data, giving the station’s geographical co-ordinates and height above mean sea-level, and a short string of meaningless data including the word “COOL”. The basis for the adjustments is therefore unknown, but the fact that about 40 successive years of data were “adjusted” by exactly 1.10 degrees C strongly suggests fingers rather than algorithms were involved.

There has been so much tampering with the “official” records of global warming that they have no credibility at all. That is not to say that the Earth has not warmed over the last couple of centuries. Glaciers have retreated, snow-lines risen. There has been warming, but we do not know by how much

Setting aside who’s responsible for the GHCN, let’s look more closely at the “adjustment” of data for Capetown, South Africa. Here are annual averages of unadjusted data:

Does anything look odd to you? It looks to me like a sudden shift — one which contradicts how long-term temperature behaves — occurred between 1960 and 1961.

We can see more by looking at monthly data. We’ll be swamped by the seasonal cycle, unless we remove it, so we’ll take each month’s value and subtract the average for that same month to generate anomaly values. We get this:

Not its’ even more clear that a sudden shift occurred, one which is not physical. It probably represents a non-climate influence, like moving the station to a different location.

That’s why the data were adjusted. Because if you want to study climate, it’s necessary.

After adjustment, the monthly anomalies look like this:

With the discontinuity corrected for, we have a valid picture of how the climate has changed at this location (at least as far as temperature is concerned). The adjustment isn’t “arbitrary,” the basis for the adjustment is known, and it didn’t involve using “fingers,” it used an algorithm.

Even when the folks at WUWT don’t raise a fuss about data being adjusted, they still manage to abuse it. Willis Eschenbach has a post at WUWT which looks at sea ice, using the data from HadISST (the Hadley Centre/Met Office Ice and Sea Surface Temperature data set). He isolates the data after 1974, because that gives him this:

That enables him to claim that global sea ice area doesn’t show any overall trend, rising or falling, since 1974.

Problem is, that claim is contradicted by direct observational satellite data (from Cryosphere Today)

It looks like the data Eschenbach is using shows a sudden shift about 2009, one which needs to be corrected for but hasn’t been in the HadISST data set. If you go looking, you’ll find that the Met Office itself reports thus:

08/MARCH/2011. The switch of satellite source data at the start of 2009 introduced a discontinuity in the fields of sea ice in both the Arctic and Antarctic.

When one post at WUWT doesn’t like the use of data that have been corrected for a non-physical shift, that’s a problem — so it’s time for them to imply that the adjustment is “arbitrary” and based on “fingers” and “have no credibility at all.” But when another post likes what data show because they contradict common sense due to the lack of an adjustment that’s needed — no problem at all.

---

This blog is made possible by readers like you. If you find it helpful, join others by donating at Peaseblossom’s Closet.