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If that was the case, the number of record lows and record highs would be roughly equal, assuming no shift in distribution. However, according to this paper (ht

by jfim 5y ago

If that was the case, the number of record lows and record highs would be roughly equal, assuming no shift in distribution. However, according to this paper (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009GL040736 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...), it's not the case, with record highs outnumbering record lows. > Since January 1, 2009 (also compiled to the end of September, 2009), there had been 11,711 record highs and 7,449 record lows, with a ratio of just less than two to one. We can also check whether that ratio is consistent with a random process that has an even probability of giving record lows and record highs: > binom.test(c(7449,11711), p=0.5) Exact binomial test data: c(7449, 11711) number of successes = 7449, number of trials = 19160, p-value < 2.2e-16 alternative hypothesis: true probability of success is not equal to 0.5 As such, the data indicates that there is a shift in distribution.

blix 5y ago
> 11,711 record highs and 7,449 record lows, with a ratio of just less than two to one. If 1.57 is "just less than 2", I am just less than 8 ft tall. I am a staunch believer in the dangers of climate change, but it's easy to see why people are skeptical of arguments like this. The evidence is compelling enough that it doesn't need to be massaged into more.
- jfim 5y ago
  It makes more sense in the context of the paper. The previous sentence ends with > [...] since January 1, 2000, there had been 291,237 record high maximum daily temperatures set, and 142,420 record low minimum daily temperatures, or a ratio of roughly two to one. It seems like "just" shouldn't be in that sentence though.
G3rn0ti 5y ago
Thanks, this is a well written and accessible article! To other commenters: Of course, there wouldn’t be a straight line but rather the curve would flatten out the longer the random sampling would take place. This is due to the fact that it gets increasingly unlikely that a random „temperature“ would be higher than any drawn before. As the paper explains the ratio between the number of maxima and the number of minima decays in a 1/n law if there is no underlying temperature trend and approach 1:1. What is observed is that the ratio between maximum and minimum temperatures indeed approached this limit until the 1970s but since then increased to almost 2:1 — at least for the US. Simulations suggest the number to increase up to 100:1 by the end of the 21st century. However, this would not so much be due to ever increasing extreme high temperatures but due to a decreasing number of extreme temperature lows.
cout 5y ago
Wouldn't this logic only apply if the distribution is symmetric? We know it can't be symmetric, because there is a lower bound to how cold it can get, but no upper bound to how hot it can get; the question then whether the asymmetry is significant or whether a symmetric model is close enough. (To clarify: I'm specifically asking about your use of a binomial distribution, not about the linked paper).
- jfim 5y ago
  I'd have to think more about it, but assuming a mild skewness in the distribution, it shouldn't matter too much. This is not unlike the Mann–Whitney U test where the sign of the difference matters, not the magnitude of the difference. As for the bounds on the distribution, while it's true that there is an absolute minimum temperature, in practice I don't think a temperature anywhere near it has been reached by natural means on the surface of the Earth.
  - deleted 5y ago
    [deleted]

by jfim 5y ago

blix 5y ago

> 11,711 record highs and 7,449 record lows, with a ratio of just less than two to one. If 1.57 is "just less than 2", I am just less than 8 ft tall. I am a staunch believer in the dangers of climate change, but it's easy to see why people are skeptical of arguments like this. The evidence is compelling enough that it doesn't need to be massaged into more.

jfim 5y ago
It makes more sense in the context of the paper. The previous sentence ends with > [...] since January 1, 2000, there had been 291,237 record high maximum daily temperatures set, and 142,420 record low minimum daily temperatures, or a ratio of roughly two to one. It seems like "just" shouldn't be in that sentence though.

G3rn0ti 5y ago

Thanks, this is a well written and accessible article! To other commenters: Of course, there wouldn’t be a straight line but rather the curve would flatten out the longer the random sampling would take place. This is due to the fact that it gets increasingly unlikely that a random „temperature“ would be higher than any drawn before. As the paper explains the ratio between the number of maxima and the number of minima decays in a 1/n law if there is no underlying temperature trend and approach 1:1. What is observed is that the ratio between maximum and minimum temperatures indeed approached this limit until the 1970s but since then increased to almost 2:1 — at least for the US. Simulations suggest the number to increase up to 100:1 by the end of the 21st century. However, this would not so much be due to ever increasing extreme high temperatures but due to a decreasing number of extreme temperature lows.

cout 5y ago

Wouldn't this logic only apply if the distribution is symmetric? We know it can't be symmetric, because there is a lower bound to how cold it can get, but no upper bound to how hot it can get; the question then whether the asymmetry is significant or whether a symmetric model is close enough. (To clarify: I'm specifically asking about your use of a binomial distribution, not about the linked paper).

jfim 5y ago
I'd have to think more about it, but assuming a mild skewness in the distribution, it shouldn't matter too much. This is not unlike the Mann–Whitney U test where the sign of the difference matters, not the magnitude of the difference. As for the bounds on the distribution, while it's true that there is an absolute minimum temperature, in practice I don't think a temperature anywhere near it has been reached by natural means on the surface of the Earth.
- deleted 5y ago
  [deleted]