
No year before 1973 was as hot as 1973. - hedonist
https://twitter.com/KenCaldeira/status/357328429785440256/photo/1
======
nkarpov
While this is interesting, it really strikes me that there isn't that much
data available. Would this pattern hold if you saw another 100 years into the
past? Will it hold an additional 100 years in the future?

Cute, but... doesn't seem very significant?

~~~
Zuider
>Would this pattern hold if you saw another 100 years into the past?

Yes. In the 1700s The Earth was just beginning to emerge from 'the little ice
age'. There is some controversy over whether the medieval warm period may have
been as hot, or hotter than present.

Caldeira has apparently used the GISTEMP LOTI Global mean series, but this
seems to have been smoothed to remove any peaks. I tried plotting this
particular series at.

[http://woodfortrees.org/plot/](http://woodfortrees.org/plot/)

The pattern he describes in his tweet is not so clear with higher resolution
data. In particular, there is a pronounced spike in the late 1930s, and
another in the mid 1950s:

[http://woodfortrees.org/plot/gistemp-
dts/from:1880/to:2013](http://woodfortrees.org/plot/gistemp-
dts/from:1880/to:2013)

Furthermore, this does not seem to be replicable using other available
temperature series. For instance HADCRUT4 global mean series from 1880 to 2013
seems to have a peak in the late 1940's that is not present in Caldeira's
graph.

[http://woodfortrees.org/plot/hadcrut4gl/from:1880/to:2013](http://woodfortrees.org/plot/hadcrut4gl/from:1880/to:2013)

It is even less visible in the earlier HADCRUT3 variance adj. global mean:

[http://woodfortrees.org/plot/hadcrut3vgl/from:1880/to:2013](http://woodfortrees.org/plot/hadcrut3vgl/from:1880/to:2013)

Or the CRUTEM4 variance-adj land global mean

[http://woodfortrees.org/plot/crutem4vgl/from:1880/to:2013](http://woodfortrees.org/plot/crutem4vgl/from:1880/to:2013)

Similar for BEST global land mean (preliminary)

[http://woodfortrees.org/plot/best/from:1880/to:2013](http://woodfortrees.org/plot/best/from:1880/to:2013)

In short, unless I am missing something, his claim is based on the one outlier
among temperature series which can be made to support it (if you squint your
eyes real hard, I suppose).

~~~
nkarpov
Wasn't expecting such an awesome response - thank you!

------
iaw
That is a true statement on a 150 year timescale (or possibly even a
millennial timescale) but on a geologic timescale it is very false. Also, it
is misleading to attribute this deviation solely to the activities of man when
solar output has been on the rise for nearly two centuries
([http://en.wikipedia.org/wiki/File:Solar_Activity_Proxies.png](http://en.wikipedia.org/wiki/File:Solar_Activity_Proxies.png))

