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Comment by mikeash | Hacker News Reader

Daily records at a point are completely irrelevant to this discussion. The fact that points set multiple daily records per year has no bearing whatsoever on the significance, or lack thereof, of a monthly, global record.

You're right of course, that a single record high is not compelling. Even when it's a global, monthly record high. My point in my original reply is that pointing this out is irrelevant and annoying.

Was your point merely that this data point, by itself, is not compelling? If so, my original comment, which you complained about missing the point, was exactly about that. Was it something else? If so, I'm having a seriously tough time figuring out what your point is supposed to be.

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The fact that points set multiple daily records per year has no bearing whatsoever on the significance, or lack thereof, of a monthly, global record.

Exactly the same principle applies.

Look at the title of this submission. Stop and before you knee-jerk a response, contemplate that this isn't "it's hot, yo, and getting hotter". It is specifically that July was the hottest month "ever recorded", which someone quite rightfully noted was since 1880.

> before you knee-jerk a response

> zealots such as yourself

Stuff like this breaks the HN guidelines, and there is much of it in your comments. Please post civilly and substantively, or not at all, even when others are wrong. In fact, especially when others are wrong.

The exact same principle applies, yes. But the quantities are way different.

Variation at a point is high. Variation for a period of a single day is high. Samples are taken frequently. Thus new records will be set regularly.

Variation for the entire globe is low. Variation for a period of an entire month is low. There are twelve samples per year. Thus new records would not be expected to be set frequently.

Again, what exactly is your point?

Thinking about this more, samples are actually taken at the same rate: yearly. The difference is how many different things you're tracking in each year.

For regional records, you're tracking 365 events per year. Each one is compared with that day on prior years.

For global records, you're tracking one event per year (since July will always be the warmest month).

Thus, if you'd expect to set a new record every 50 years, then you'd see on average one global record every 50 years, but you'd see about seven daily regional records every year.

Also consider that you should be seeing both record highs and record lows. Record lows continue at a good pace for regional daily records, but there hasn't been a global record low for well over a century.

Records don't occur linearly for a stationary variable. That is you don't expect "an average record every 50 years". The longer you observe the signal the more more extreme the expected outlier.

Sure, that's just a simplification to illustrate the principle. Whatever the expected recurrance for records is, you'll get a lot more of them when you're testing 365 (really 730, since you have both highs and lows) separate values each year than when you're just testing one (realy two).

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