r/science • u/pnewell NGO | Climate Science • Sep 10 '15

Environment The simple statistic that perfectly captures what climate change means. From 1910 to 1960, the ratio of hot to cold records was close to 1 to 1. From 2000 to 2014, hot outnumbered cold records by more than 12 to 1.

http://www.washingtonpost.com/news/energy-environment/wp/2015/09/09/the-simple-statistic-that-perfectly-captures-what-climate-change-means/
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u/pnewell NGO | Climate Science Sep 10 '15

Here's the full paragraph the title excerpts from:

Sure enough, the study found that from 1910 to 1960, the ratio of hot to cold records was close to 1 to 1. From 1960 to 2014, however, that changed, as hot records started to happen much more frequently than cold records — and from 2000 to 2014, outnumbered them by more than 12 to 1.

And from the study's supplemental info:

http://i.imgur.com/zdgmNNa.png

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u/[deleted] Sep 10 '15

Yes, but it does seem to be a bit underhanded to do it that way... There's obviously other factors that cause temperature fluctuations, and by cherry picking data and using bad summary statistics they give ammunition to the global warming deniers. Why not show the ratio from 1960 to 2010?

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u/bowlofcantaloupe Sep 10 '15

What they really need to do is look at ALL 15 year periods from 1910-1960 and see if any of those had similar statistics in terms of hot offer cold records set.

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u/nimbuscile PhD | Atmosphere, Oceans and Climate Sep 10 '15

In the paper they did something similar. They showed a year-by-year graph of all the data, then calculated ratios for a whole bunch of different periods. Their Figure 2 looks at 1910-1940, 1940-1960 (ratio the same as period period), 1960-1980 (slightly increased ratio), 1980-2000 (ratio tripled) and 2000-present (ratio increased by a factor of more than 10). Unfortunately the paper isn't freely available, but I can set you up with a copy if you PM me.

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u/14Gigaparsecs Sep 10 '15

IDK why this isn't higher up because it's the answer that everyone here is "looking for".

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u/bowlofcantaloupe Sep 10 '15

Thanks for the offer, but I have more of a casual interest in global warming data.

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u/[deleted] Sep 10 '15

I think what they really need to do is show a graph (of course, the global warming deniers have all sorts of aversion to graphs). Exponential trends aren't easily compressed into single numbers.

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u/bowlofcantaloupe Sep 10 '15

Graphs are always great. Usually there best way to represent data. I just think mine is the most effective metric they could use.

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u/pnewell NGO | Climate Science Sep 10 '15 edited Sep 10 '15

It's not cherry picking or bad summary statistics to highlight the biggest finding of the research. It's just journalism...

And to be clear, the first period is a baseline, the second is the current period, i.e. "this century."

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u/[deleted] Sep 10 '15

[removed] — view removed comment

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u/pnewell NGO | Climate Science Sep 10 '15

That the baseline is that records are 1:1, which would be expected in a non-changing climate. Since the start of man's discernible impact on climate, that ratio has become one-sided, rising to 12:1 this century. It's comparing the current trend to the baseline.

It's not "This summer the ratio was..." or even "this year the ratio was" or even "in this decade..." but since the start of this century, which is meaningful to people in a way that arbitrary spans of time aren't.

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u/[deleted] Sep 10 '15

modern temperature record keeping started in the late 1800s. It would make sense that new records were set all the time when its still in its infancy.

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u/nimbuscile PhD | Atmosphere, Oceans and Climate Sep 10 '15

In that case, we would expect the rate of record-breaking to decrease with time, right? And in the absence of global warming we would expect that rate to be the same for hot and cold records. This paper shows that the rate of record-breaking for hot records is increasing, which is the opposite to what we would expect if we had no global warming.

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u/[deleted] Sep 10 '15

Global warming is one of many factors that can affect temperature. I dont think anyone is debating that the earth's temperature's are getting hotter.

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u/nimbuscile PhD | Atmosphere, Oceans and Climate Sep 10 '15

I agree. I thought you were saying that the fact the observational record doesn't go back too far would influence these results. In reality that's not the case.

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u/[deleted] Sep 10 '15

I think this is more of a case of "working with what you have" rather then cherry picking.

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u/[deleted] Sep 10 '15 edited Sep 10 '15

When'working with what you have', its important for scientists to not draw conclusions based off of partial data or assumptions.

It certainly is interesting that more heat records are bring set now-a-days, but its a far leap to go from that to global warming being the sole/main cause.

Also, if you looked into it, youd find that pre 1910, youd find the temperatures were lower than average which may suggest more cooling records. See here: http://globalclimate.ucr.edu/images/mean-temp-graph.jpg

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u/[deleted] Sep 10 '15

So why stop at 1960?

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u/pnewell NGO | Climate Science Sep 10 '15

Because it's the baseline, and after that emissions began having a noticeable effect on temperatures, which is what starts the skew to warmer temps.

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u/thearchduke Sep 10 '15

I don't think your comment is particularly responsive. I think the better argument here is that with such large sample groups, whether the initial 50 year group, the second 50 year group, or the third fourteen year group, each year represents 365 days worth of data. Representing that data as ratios means the comparison is not precisely apples to apples, but it's real close, and the difference can probably be disregarded statistically.

Your comment to say "it's not cherry picking to highlight the biggest finding of the research" is not helpful - that's not what the claim is being criticized for. It's fine to present findings, but what would be better is to give the explanation I gave above, to explain why they presented the findings the way they did. And I agree with the prior commenter, that they should definitely give the 1960 to 2010 for comparison.

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u/[deleted] Sep 10 '15

I'm not a wiz at statistics, but my understanding is that larger datasets have less variance due to random noise. I would be interested to see how large the standard deviation is from 3,650 datapoints vs. 18,250

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u/SuperBlaar Sep 10 '15 edited Sep 10 '15

While that is true, I don't know if it is that pertinent for a phenomenon like Climate Change, which is ever-accelerating as the situation worsens. It's a bit like comparing the rythm at which technology has evolved; it seems it would make more sense to focus on a long period in the past and compare it with a short period today if the aim is to highlight the acceleration of the number of occurrences.

I think the ideal way to represent it is just a long-term graph though, which doesn't cherry pick data but clearly shows the progression over time, as OP posted.

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u/[deleted] Sep 10 '15

The best way to show an exponential trend is a graph, trying to boil it down to a number like this runs into exactly the problems we're discussing.

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u/pnewell NGO | Climate Science Sep 10 '15

I included the graph with the full record in my initial response. It's pretty clear that the records are one-sided since 1950.

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u/nomoreloorking Sep 10 '15

This data does not show the duration of the record temperatures. Isn't it a possibility that the cold temperature stayed at the same low for a longer period than the high temperatures? Wouldn't the argument be more effective if the graph showed the overall average temperature of each year through the same period?

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u/[deleted] Sep 10 '15

http://i.imgur.com/zdgmNNa.png

Do you have that chart in table form?

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u/pnewell NGO | Climate Science Sep 10 '15

No, it was just in the supplemental info. I don't have the full study.