A classic Hansen – 1999

Famous climate scientist James Hansen informed us in 1999 about the state of the world climate. On the US he had something to say that is very strange indeed, by standards of today:

“The U.S. temperature increased by about 0.8°C between the 1880s and the 1930s, but it then fell by about 0.7°C between 1930 and the 1970s and regained only about 0.3°C of this between the 1970s and the 1990s.

The year 1998 was the warmest year of recent decades in the United States, but in general, U.S. temperatures have not recovered even to the level that existed in the 1930s. This contrasts with global temperatures, which have climbed far above the levels of the first half of this century.”

This is backed up with a graph (fig. 6) of the GISS US temperatures as published in 1999:

hansen1999

What he says is is clearly true. The 1930ies were the hottest decade on record. This is also backed up by the list of highest temperatures ever recorded in the US. Almost half of all those records were recorded in the 1930ies and have not been surpassed since then. This is exactly what you would expect in the hottest decade on record.

All this is so straight forward that it doesn’t seem to make a blog post. So here is the twist. The GISS US temperatures as published in 2013, described as an “update” of the figure in Hansen 1999. It is impossible not to conclude from this description that a few points were added for the years 2000 to 2012 and nothing else happened to the graph:

hansen2013

This seems almost like the first graph, except that suddenly, the temperatures of the year 2000 are EXACTLY on the level of the 1930ies. Of course this flies in the face of Hansens own words in 1999: “U.S. temperatures have not recovered even to the level that existed in the 1930s.”

The graph isn’t just longer. It is DIFFERENT. In fact, temperatures of the year 1999 are almost 0.5°C higher than in the previous diagram and temperatures of the year 1936 are suddenly  0.2°C lower. By scaling the first graph and putting it on top of the second in blue color, in the same diagram, it becomes obvious what happened. Past temperatures were shifted down, recent temperatures were shifted up. Since all those temperatures were derived from historic records of weather stations, this is very strange indeed.

hansen1999+2013

Now you may say that this merely represents some kind of correction of a mistake made in the past. But it leaves us with a puzzle. If 2012 was the hottest year on record, by a margin of 0.8°C, how is it possible that only one US state (South Carolina) set a new temperature record?

Whereas in the year 1936 – the hottest year on record according to the graph published in 1999 – new record highs were set in 13 US states that have yet to be surpassed. Another 5 unsurpassed records survive to this day since the year 1930. And finally 3 more were set in 1934.

This observation is implausible. If the year 2012 was 0.8°C warmer than the year 1936, we should have seen many new records. Not just one. That is the reason why I see the graph of 1999 as much more consistent with actual observations than the one of 2013.

This begs the question, what other records have been changed in such ways? Climate science has become the strangest science of them all. It is the only science in which historic facts change to fit the present hypothesis.

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