
November 2015 was warmest November on record - cryptoz
http://www.ncdc.noaa.gov/sotc/summary-info/global/201511
======
tertius
So I'll take one of the statements to ask a question.

> This was the highest for November in the 1880–2015 record, surpassing the
> previous record set in 2013 by 0.27°F (0.15°C)

So the NOAA claims that this November was 0.15C higher than the previous
record high.

What does this mean in a larger climate context?

Probability theory tells me that a single number like this is meaningless, but
other than that I don't know how to interpret this except that it is
information that was published with no specific agenda other than reporting
it.

~~~
mrow84
I'm not sure that the single number is entirely meaningless, because you would
expect reversion to the mean in the absence of a trend, so if you computed the
likelihood function then I guess it would be weighted toward there being a
positive trend, if only slightly. I think :-/.

~~~
paulmd
The null hypothesis (no warming) would posit independent events with equal
probability (the chance of an above-average and below-average year are
equivalent).

So in that case you're basically asking the question "given that I've flipped
a fair coin and gotten heads 9 times in a row, what is the probability of
heads on the 10th flip?" It's deceptive because you want to say 0.5^10, but
the answer is actually 50% (because it's one throw of a fair coin). The 0.5^10
is the chance of _10 heads in a row_ occurring, but you can't disregard the
prior (you have already thrown 9 heads).

Reversion to the mean is a _trend_ , it says nothing about any individual
event in a series. In the event that it's not warming, the chance of a warm
year is just as likely as a cool year.

Now, _as a trend_ , the evidence is highly suggestive of global warming being
the case. When you have a sufficient sample of throws with a huge number of
heads, the chance of the coin being biased* increases.

* Note: you cannot actually bias a flipped coin. But you can bias a die, or a spun coin: [https://www.stat.berkeley.edu/~nolan/Papers/dice.pdf](https://www.stat.berkeley.edu/~nolan/Papers/dice.pdf)

~~~
mrow84
I think the difference in this case is that we are looking at a point that
exceeds the current series maximum. If we had a single value from a series
without a trend, we would expect it to fall below the maximum value observed
so far (perhaps after sampling at least 2 points - I will think about that
later), and so I reckon that the likelihood of a positive trend will be higher
than for a zero or negative trend because of that fact.

I may try and actually work it out to see if what I'm saying is correct, but
one thing I _can_ tell you that likelihood of me not doing so is greater ;-).

~~~
paulmd
Yes, looking at the sample minimum/maximum does change the probabilities.
You're looking for Extreme Value Theory.

[https://en.wikipedia.org/wiki/Extreme_value_theory](https://en.wikipedia.org/wiki/Extreme_value_theory)

I kept it simple (above or below average should be equal probability if your
average is really average) to try and avoid that. I have no idea what kind of
distributions weather follows, and as the other guy noted weather is not fully
independent either. But it works for a simple explanation. :)

It's been a long time since my stat courses and I don't remember this stuff
all that well. Maybe there is something that expresses it better. Either way
the fact that we're suddenly having a big run of Nth Warmest Year events is
pretty suggestive that something is going on. But you do have to look at it as
a trend, particular years aren't all that meaningful.

------
cryptoz
Here is also an article by the Capital Weather Gang:
[https://www.washingtonpost.com/news/capital-weather-
gang/wp/...](https://www.washingtonpost.com/news/capital-weather-
gang/wp/2015/12/17/november-autumn-and-year-to-date-were-all-hottest-on-
record-for-earth-noaa-says/)

------
guscost
There is a lot of agreement, even among the anti-CAGW people, that we have had
a gradual trend towards higher global temperatures for many decades, and
longer if you are OK not using the satellite record. Looks like that trend may
be continuing. It's definitely at least a warm end of the year for the eastern
US.

------
swampthinker
More anecdotal than anything, but this is the warmest December in Boston that
I've ever seen. It's 50 outside right now.

~~~
crygin
This is more likely El Nino-related (the extremely strong El Nino currently in
process is likely to make the East & South much warmer than usual), though of
course worldwide temperature increases will compound to make the temperature
higher than it might have been without climate change. My understanding is
that it's still fairly unclear how climate change might be affecting
equatorial oscillations like El Nino (as opposed to the Arctic/North Atlantic
oscillations where there are some pretty specific mechanisms of action
hypothesized).

~~~
3JPLW
It definitely is… but what's the extremely strong El Niño related to?

------
merpnderp
Not according to the RSS and UAH satellite tropospheric data sets.

The MSU and AMSU sensors have issues, but still have wider coverage and
superior accuracy to the ground station data the NOAA is using. Additionally,
RSS and UAH are two different teams, with different methodologies, and using
different sensors, with corroborating data.

[http://images.remss.com/msu/msu_time_series.html](http://images.remss.com/msu/msu_time_series.html)

[http://vortex.nsstc.uah.edu/data/msu/v6.0beta/tlt/tltglhmam_...](http://vortex.nsstc.uah.edu/data/msu/v6.0beta/tlt/tltglhmam_6.0beta4.txt)

[EDIT] I'm absolutely wrong. Both the RSS and UAH data confirm that November
is the hottest November in the sattelite record also.

Thanks jacobolus for pointing this out (and making sure I stop assuming the
NOAA is exaggerating on its hottest month claims.)

~~~
jacobolus
Here are some of the relevant rows from your second link (hottest values in
one of the “GLOBAL” columns). I’m not sure I completely understand what the
columns all mean though. Can you elaborate a bit?

    
    
       YEAR  MON  GLOBAL     NH      SH    TRPC  NO.DAYS   GLOBAL     NH      SH    TRPC  DAYS
       1990   11   0.255   0.268   0.242   0.121    0      -0.005  -0.037   0.026  -0.092    0
       1998   11   0.121   0.126   0.116   0.111    0       0.484   0.502   0.465   0.733    0
       2001   11   0.168   0.203   0.133   0.153    0       0.101   0.108   0.095   0.013    0
       2002   11   0.196   0.164   0.227   0.242    0       0.215   0.172   0.257   0.192    0
       2005   11   0.198   0.234   0.161   0.209    0       0.197   0.240   0.154   0.293    0
       2009   11   0.277   0.203   0.350   0.428    0       0.093   0.091   0.094   0.122    0
       2010   11   0.170   0.260   0.080  -0.202    0       0.343   0.405   0.281   0.430    0
       2014   11   0.229   0.251   0.207   0.239    0       0.178   0.203   0.153   0.127    0
       2015   11   0.330   0.433   0.228   0.525    0       0.248   0.343   0.153   0.314    0
    

Maybe you can also extract and quote the relevant data from your first link?
I’m not sure what I should be looking at.

~~~
merpnderp
Wow, I totally missed that. November was incredibly warm. This will bring up
the long term trends significantly.

Looks like you excerpted the UAH data which is year, month, global average,
Northern Hemisphere, Southern Hemisphere, Tropics, not sure what No.Days is
for, and then the 12 month running mean for each of the previous.

I'm just so used to the NOAA saying "Warmest month ever" and it being
contradicted by the MSU/AMSU data, it didn't even occur to me they were right.

Thank you so much for double checking me.

~~~
jacobolus
Here are the 27 hottest months on record, if anyone was curious about
comparing to e.g. the hottest october or december:

    
    
       YEAR  MON  GLOBAL     NH      SH    TRPC 
       2010    4   0.330   0.449   0.210   0.687
       2015    6   0.330   0.410   0.251   0.456
       2015   11   0.330   0.433   0.228   0.525
       2004    3   0.334   0.490   0.179   0.271
       2010    6   0.336   0.432   0.240   0.449
       2010    7   0.354   0.520   0.188   0.315
       2003   12   0.357   0.462   0.252   0.272
       2010    8   0.370   0.518   0.222   0.272
       1987   12   0.382   0.573   0.191   0.656
       2010    9   0.393   0.356   0.429   0.144
       1998   10   0.400   0.484   0.315   0.368
       2007    1   0.406   0.484   0.327   0.550
       2010    5   0.426   0.611   0.241   0.804
       2015   10   0.426   0.638   0.213   0.530
       2013    1   0.429   0.345   0.512   0.420
       1998    9   0.437   0.506   0.367   0.356
       2010    2   0.441   0.392   0.491   0.856
       1998    3   0.482   0.509   0.455   1.128
       2010    1   0.483   0.553   0.412   0.599
       1998    1   0.491   0.402   0.580   1.132
       1998    7   0.496   0.617   0.375   0.467
       2010    3   0.503   0.560   0.446   0.776
       1998    8   0.513   0.482   0.544   0.459
       1998    6   0.561   0.572   0.551   0.629
       1998    5   0.636   0.566   0.706   0.975
       1998    2   0.665   0.688   0.642   1.275
       1998    4   0.742   0.852   0.633   1.177
    

1998 was just incredibly hot throughout (but not in November).

------
ptaffs
[http://www.npr.org/2014/01/07/260408972/polar-vortex-
blames-...](http://www.npr.org/2014/01/07/260408972/polar-vortex-blames-for-
dangerously-cold-weather)

[http://www.npr.org/2015/12/15/459871063/climate-change-
plays...](http://www.npr.org/2015/12/15/459871063/climate-change-plays-fairly-
insignificant-role-in-current-warm-weather)

two NPR links here, the 2014 says how the cold in winter 2014 is the polar
vortex, and the warm in 2015 is a combination of tight polar vortex and el
nino, he* resisted saying it was related to climate change.

he is Mike Halpert, NOAA's deputy director of the Climate Prediction Center

