In 2005, Real Climate told us that the period from the 1950s to the 1970s had artificially cool temperatures – due to man made aerosols.
14 January 2005
The cooling trend from the 40?s to the 70?s now looks more like a slight interruption of an upward trend (e.g. here). It turns out that the northern hemisphere cooling was larger than the southern (consistent with the nowadays accepted interpreation that the cooling was largely caused by sulphate aerosols); at first, only NH records were available.
At the same time, they use 1951-1980 as their baseline for normal temperature.
Feb. 8, 2005
Earth Gets a Warm Feeling All Over
James Hansen of NASA GISS analyzed the data and said that the 2004 average temperature at Earth’s surface around the world was 0.48 degrees Celsius or 0.86 Fahrenheit above the average temperature from 1951 to 1980.
The years of 1951 to 1980 are used as a “baseline” or average for surface temperatures of Earth’s land and ocean surfaces.
NASA GISS: Research News: Earth Gets a Warm Feeling All Over
Three weeks apart in 2005, Gavin@GISS told us that 1951-1980 was artificially cool, and Hansen@GISS told us that the same period was normal. Besides all the corruption of the temperature data set, they are similarly pulling a fast one with the baseline.
The same junk posing as science, just as always : if the data does not fit, change the data. And if this is not enough, change the baseline. Neither brain, nor science inside those skulls.
Steve are you telling me that GISS is ignoring their aerosols because I thought that was the one thing they paid attention to.
So, if one were to adjust the temperature data up to compensate for Hansen’s dead-certain aerosol cooling in the 1940’s thru 1970’s, then warming since the 1950 appears to have decelerated compared with the warming from 1910 to 1950.
Of course, a decelerating warming trend is consistent with CO2 induced climate change…
Of course, the period 1951-1980 is a convenient baseline to show warming, because there was signficant cooling during that period. The temperature went down, then went back up. What does that prove other than the possibility of a cycle?