5 ms·

November 2015 was warmest November on record

50 points by cryptoz 11y ago

cryptoz 11y ago
Here is also an article by the Capital Weather Gang: 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/ https://www.washingtonpost.com/news/capital-weather-gang/wp/...
tertius 11y ago
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.
- imglorp 11y ago
  It seems the number of records set per year in either direction is a useful signal to climatologists. More records than prior years indicates a trend.
- eCa 11y ago
  > Probability theory tells me that a single number like this is meaningless That is true. But when considering that the ten warmest years since 1880 all have occurred since 1998[1] it is no longer a single number. I'm guessing after 2015 that the eleven warmest years will have occurred after 1998. [1] http://climate.nasa.gov/blog/2224 http://climate.nasa.gov/blog/2224
- mrow84 11y ago
  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 11y ago
    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
    - nonbel 11y ago
      >"The null hypothesis would posit independent events with equal probability (the chance of an above-average and below-average year are equivalent)." Why should that be the null hypothesis? Is that a theory someone subscribes to? That would be a theory of no trends and no auto-correlation in temperature. I doubt you will find someone espousing such a theory, so why should we make something no one believes a null hypothesis? If you can find someone claiming that, I am interested in the reasoning.
    - mrow84 11y ago
      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 ;-).
- DougWebb 11y ago
  Two things strike me about that quote. First, the range starts in 1880, which is just about the end of the Little Ice Age.[1] So yeah, pretty much every year since then is likely to be warmer than the last one. For a fairer comparison, you'd have to go back to 1100 or so to the Medieval Warm Period. We're still warmer today than back then, but not by as much. The second thing that struck me was the same thing that struck you: a single number is meaningless. If the fluctuations were completely random, you'd still always have a 'highest' one, but it wouldn't mean anything. And since we're trending upwards anyway (still coming out of that cool period, which only ended 100 or so years ago) you'd expect new highs to occur fairly often and fairly recently. I don't think this particular record says much; at most it fits with the fairly obvious warming trend we're in. If it was the coldest November since 1880, that'd be news because it would be a really odd occurrence. [1] https://en.wikipedia.org/wiki/Little_Ice_Age https://en.wikipedia.org/wiki/Little_Ice_Age
swampthinker 11y ago
More anecdotal than anything, but this is the warmest December in Boston that I've ever seen. It's 50 outside right now.
- tertius 11y ago
  I've not been in Houston long (6 years) but this December also has been much warmer than I've experienced. Anecdata ftw!
- james33 11y ago
  We've been in the 60's and 70's for all of December so far here in OKC. I've lived here my whole life and it usually doesn't get above 40-50 this time of year.
  - merpnderp 11y ago
    We've hit 70's in January often enough over the years.
- berberous 11y ago
  Yup, NYC here, been here 20+ years, warmest December I can remember. It was 60 degrees last weekend!
- sbov 11y ago
  Anecdotally, where I live, this December is cooler than last year's. But I've only lived here 1.5 years.
- crygin 11y ago
  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).
deleted 11y ago
[deleted]
guscost 11y ago
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.
merpnderp 11y ago
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_6.0beta4.txt http://vortex.nsstc.uah.edu/data/msu/v6.0beta/tlt/tltglhmam_... [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 11y ago
  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 11y ago
    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.
ptaffs 11y ago
http://www.npr.org/2014/01/07/260408972/polar-vortex-blames-for-dangerously-cold-weather http://www.npr.org/2014/01/07/260408972/polar-vortex-blames-... http://www.npr.org/2015/12/15/459871063/climate-change-plays-fairly-insignificant-role-in-current-warm-weather http://www.npr.org/2015/12/15/459871063/climate-change-plays... 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

50 points by cryptoz 11y ago

Here is also an article by the Capital Weather Gang: 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/ https://www.washingtonpost.com/news/capital-weather-gang/wp/...

tertius 11y ago

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.

imglorp 11y ago
It seems the number of records set per year in either direction is a useful signal to climatologists. More records than prior years indicates a trend.
eCa 11y ago
> Probability theory tells me that a single number like this is meaningless That is true. But when considering that the ten warmest years since 1880 all have occurred since 1998[1] it is no longer a single number. I'm guessing after 2015 that the eleven warmest years will have occurred after 1998. [1] http://climate.nasa.gov/blog/2224 http://climate.nasa.gov/blog/2224
mrow84 11y ago
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 11y ago
  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
  - nonbel 11y ago
    >"The null hypothesis would posit independent events with equal probability (the chance of an above-average and below-average year are equivalent)." Why should that be the null hypothesis? Is that a theory someone subscribes to? That would be a theory of no trends and no auto-correlation in temperature. I doubt you will find someone espousing such a theory, so why should we make something no one believes a null hypothesis? If you can find someone claiming that, I am interested in the reasoning.
  - mrow84 11y ago
    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 ;-).
DougWebb 11y ago
Two things strike me about that quote. First, the range starts in 1880, which is just about the end of the Little Ice Age.[1] So yeah, pretty much every year since then is likely to be warmer than the last one. For a fairer comparison, you'd have to go back to 1100 or so to the Medieval Warm Period. We're still warmer today than back then, but not by as much. The second thing that struck me was the same thing that struck you: a single number is meaningless. If the fluctuations were completely random, you'd still always have a 'highest' one, but it wouldn't mean anything. And since we're trending upwards anyway (still coming out of that cool period, which only ended 100 or so years ago) you'd expect new highs to occur fairly often and fairly recently. I don't think this particular record says much; at most it fits with the fairly obvious warming trend we're in. If it was the coldest November since 1880, that'd be news because it would be a really odd occurrence. [1] https://en.wikipedia.org/wiki/Little_Ice_Age https://en.wikipedia.org/wiki/Little_Ice_Age

swampthinker 11y ago

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

tertius 11y ago
I've not been in Houston long (6 years) but this December also has been much warmer than I've experienced. Anecdata ftw!
james33 11y ago
We've been in the 60's and 70's for all of December so far here in OKC. I've lived here my whole life and it usually doesn't get above 40-50 this time of year.
- merpnderp 11y ago
  We've hit 70's in January often enough over the years.
berberous 11y ago
Yup, NYC here, been here 20+ years, warmest December I can remember. It was 60 degrees last weekend!
sbov 11y ago
Anecdotally, where I live, this December is cooler than last year's. But I've only lived here 1.5 years.
crygin 11y ago
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).

deleted 11y ago

[deleted]

guscost 11y ago

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.

merpnderp 11y ago

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_6.0beta4.txt http://vortex.nsstc.uah.edu/data/msu/v6.0beta/tlt/tltglhmam_... [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 11y ago
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 11y ago
  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.

ptaffs 11y ago

http://www.npr.org/2014/01/07/260408972/polar-vortex-blames-for-dangerously-cold-weather http://www.npr.org/2014/01/07/260408972/polar-vortex-blames-... http://www.npr.org/2015/12/15/459871063/climate-change-plays-fairly-insignificant-role-in-current-warm-weather http://www.npr.org/2015/12/15/459871063/climate-change-plays... 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