
Earth Temperature Timeline - r721
http://xkcd.com/1732/
======
mc42
As is common, Mr. Munroe put things into context. I sincerely hope this image
is shared _thoroughly_. This "all in perspective" thing might help a _lot_
more than out of context quotes, and to kill the FuD.

However, I might be overly optimistic in light of the human condition.

------
leephillips
This does a great job of putting things in perspective.

------
wertghbkn
This picture is simply wrong.

First: Why is the temperature compared to the 1961-1990 average and not to the
range of the timeline (20000 BCE - 2016)?

Second: The measurements/estimates were not made in the intervals marked with
dots, they were not equally spaced and not exact as the chart suggests.

Third: It also doesn't take variance into account in the past estimates, yet
it does so in the recent measurements (1900-).

Fourth: There is no explanation for the drop of average temperature between
years 1000 and 1500, although the change was the same as between 1500 and 2000
and it clearly points out that this is (supposedly) due to human actions.

Fifth: It's funny how at 17500 BCE there's a note stating "Temperatures have
been creeping upward" (no explanation why), 10500 BCE "warming resumes" (no
explanation why), 7500 BCE "This warm stable period is called 'the holocene
stable optimum'" (no explanation why) ... But when it comes to modern times we
have explanation for everything (= we, the almighty narcissistic creatures).

And I could go on and on.

~~~
bwindels
1) because there's a steep change since then 2) He addresses this, there could
have been faster fluctuation that canceled each other out in measurements
longer ago, although unlikely.

~~~
wertghbkn
1) I think you misunderstood me. I think deviations should be compared to the
average of the whole data-set (22016 years) not only a tiny (29 years) subset
of it.

2) Exactly, but the point is that the recent data also contains normal
fluctuations. It's simply wrong to change the representation of data mid-
chart. How would you feel looking at a stock price chart where historical data
is displayed as an annual average and it then suddenly continues as an hourly
graph? Sure you would think some crazy stuff is going on with the stock price.

~~~
bqgray
Re: 2) This is a semi-valid point. We don't have accurate yearly global temp
data from 2,000BC or 20,000BC, so as the data gets older, it is necessarily a
smoother and smoother average. Ancient yearly temperature variability is
simple not something that we have a detailed view to.

Still, we do have decent variability data for the past 500 years, and the rate
of change that we are seeing for the past 50 is _truly extraordinary_ compared
to the past 500 years.

Based on the data that we do have, the likelihood that the hockey-stick
temperature trend is "normal" variability can now be calculated pretty
precisely... confidence levels are now in the 99%-99.9% range.
([http://phys.org/news/2014-04-statistical-analysis-natural-
wa...](http://phys.org/news/2014-04-statistical-analysis-natural-warming-
hypothesis-percent.html))

In short, we can say with better than 99% certainty that...

 _Yes, this is happening. The globe is now growing hotter at a truly
extraordinary rate_

------
anotheryou
My only problem with it is that i have no idea how coarse the dotted lines
data is

