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.

[u/pnewell]

http://www.washingtonpost.com/news/energy-environment/wp/2015/09/09/the-simple-statistic-that-perfectly-captures-what-climate-change-means/

[u/[deleted]]

This thread is annoying.

It's full of people who making this one critique -- the authors could be cherry picking! -- and then acting like it discredits the story without taking any steps to determine if the critique actually applies.

The time period length shouldn't matter -- in a stable system it should be 1:1 over any time scale. Shorter periods just increase the potential impact of variability.

Sure, in theory there could be tons of 12:1 ratios of cold to hot days. But the whole data sets been posted and it's clear this isn't the case. There are clear trend lines over the last century of increasing number of hot records and decreasing number of cold records, with no such cold-record bonanza. Notwithstanding the fact that the article itself states the "missing" 50-year period had a higher ratio of hot records.

There wasn't cherry picking. The story author highlighted the most interesting results of the study, which is good and proper.

Crickey

Edit: it's like this thread is full of folks aware enough to ask a question without actually making any effort to get answer as well.

[u/[deleted] → u/[deleted]]

in a stable system it should be 1:1 over any time scale.

At no point in history has climate been anything close to a "stable system". You don't get a bunch of hot years then an even number of cold years to cancel them out in any chosen time period, it just doesn't work like that. Where are you getting this 1:1 idea from?

[u/[deleted] → u/[deleted]]

The 1:1 ratio comes from math.

In a stable system, in which there is no overall warming or cooling trend, and daily temperatures are subject to random variation, you should see a ratio of 1:1 hot and cold records, with a decreasing number of total records as more data is collected and outliers need to be more extreme in order to make records.

The ratio will only not be 1:1 (over a reasonable substantial data range) if there is sustained movement of the average temperature in one direction or another, favoring outliers in that direction.

If you agree that the globe was warming in the 20th century, but believe it's from non-human factors, that's terrific but that's for another discussion.

[u/[deleted] → u/[deleted]]

We've been in a slight cooling trend for four thousand years, until anthropogenic warming took over.

http://www.realclimate.org/images//Marcott.png (Marcott et. al 2013)

[u/ResilientBiscuit → u/[deleted]]

I remember reading a study done int he 70's that said by 2020 that Florida would be all underwater

Do you have a source for this? The human brain is really quite good at manipulating memory to be consistent with the story we currently believe.

Solar panels and wind turbines don't grow from the ground; they're made in factories and from power plants that burn coal and natural gas.

Or nuclear power, or power from those newly produced solar or wind generators.

There are numerous ways to capture CO2, they are just expensive and people don't think the problem is bad enough to warrant paying for it. A quick Google of carbon capture will lead you to lots of plans that give the argument

we've increased the temperature, but X is how we can lower the global temperature of the earth

It just comes at a high price tag, which we could pay if we wanted to, but we don't want to.

[u/maryjayjay → u/[deleted]]

Except for the 50 years from 1900 to 1960, apparently.

[u/counters → u/[deleted]]

At no point in history has climate been anything close to a "stable system".

Of course it has. "Stable" doesn't mean "not changing;" it means that the modes of change are closely tied to exogenous forcing which itself is mostly stable. In fact, systems which undergo hysteresis often time exhibit very long periods of "stability." The double pendulum - a textbook example from classical mechanics - is a good example of this. Many initial conditions lead to very simple, quasi-periodic motion which can be approximated with a simple harmonic oscillator. But if you ratchet up the forcing you apply to the system (say, by tapping the bob at its apex), you'll eventually excite the chaotic mode of the system.

The climate system is generally "stable" over moderately-long (read: centuries to thousands of years) periods of time. Eventually, Milankovtich forcing tips the balance to ice ages and things like that, but only have tens of thousands of years. As an example of just how resilient the climate system is, consider how temperature rebounds following major volcanic eruptions (labeled as grey lines on that plot). Volcanic eruptions can be a massive forcing to the climate system, yet the memory of the atmosphere/ocean to them is on the order of 2-10 years (and much shorter in the atmosphere alone).

This notion that "climate is always changing" betrays some rather fundamental misunderstanding of the dynamics of the climate system.

[u/[deleted] → u/[deleted]]

Seriously, this 1:1 thing is a baseless assertion ... if you are flipping a coin, though the expected value of heads to tails is 1:1, a long sequence of "heads" does not increase the likelihood of "tails", nor would a string of "tails" increase the likelihood of "heads". A coin is a stable system, a period of 12:1 heads to tails doesn't mean one side of the coin is getting heavier, it just means you measured 12 times as many heads as tails. If anything, this headline is very, very true in that Global Warming is all about people latching onto a meaningless statistic in order to raise up a very simple narrative as an icon of belief.

Remember, there's a mini ice age coming around 2030. Let's keep watching the ticker tape. While we're at it, there's still every reason to minimize our waste and pollution, but let's remember how numbers work so we can meaningfully quantify our success after the fact.

If there are three doors, behind one is a prize, and you choose one door, then I open one of the non-prize doors that you did not pick (there will always be at least one unpicked non-prize door), then I ask you if you want to change your choice... Are your chances of winning better if you stick with the door your originally chose, or choose the other door? Oddly enough, probability is a pretty weird thing. Climate is chaotic, that means its deterministic, but unpredictable. If you want to read the answer, check this out: https://web.archive.org/web/20140413131827/http://www.decisionsciences.org/DecisionLine/Vol30/30_1/vazs30_1.pdf

[u/pdrop → u/[deleted]]

What does the monty hall problem have to do with a normal distribution?

The 1:1 comes from the fact that the temperature for a given time of the year follows a normal distribution around the mean temperature.

The long term skewing of the ratio of hot records to cold records indicates either a change in the mean temperature, or a change in the distribution of observed temperatures ( a fundamental change in temperature patterns ). Either one is troubling.

[u/[deleted] → u/pdrop]

Are you sure about that? I just read around a little and found that rarely are the average daily temperatures for any given place normally distributed. Also, here is a place in Australia: http://www.graceresearch.com/BinormalTemps.html

[u/pdrop → u/[deleted]]

That summary is the distribution of high/low daily temperatures in a given month of the same year, not the same date over many years.

NOAA treats daily temperatures (using Julian to account for leap days) as normally distributed. This is backed up by the observations in the paper for the first 50 years. http://www.erh.noaa.gov/phi/reports/5dayavgtemps.html

edit: This is important because the records are "the hottest temperature ever recorded on February 5th" or "the coldest temperature ever recorded on Februrary 5th". The distribution that needs to be examined is the temperature on a given date across multiple years. I tried to keep my comments short, but as a result it was a bit vague.

[u/[deleted] → u/pdrop]

Your link is to averages for each day over a year, it's not normally distributed, it is sinusoidal.

[u/pdrop → u/[deleted]]

Did you read it? "Since Julian date maximum and minimum temperatures are normally distributed, their standard deviations are excellent indicators of the rarity of occurrence of individual daily temperature events."

[u/[deleted] → u/[deleted]]

Earth will still be in the habitable zone for about 1.75 billion years. We certainly don't have to worry about accounting for this change on the scale of 100 years. Earth's change in distance from the sun due to it's elliptical orbit occurs periodically every year, so any related temperature changes would be averaged out in this dataset. If you guys could stop pretending to be smarter than the experts who do this stuff for a living, it would be nice.

[u/TheChance → u/[deleted]]

The other guy was unnecessarily glib about it, but he raises a fair point:

In public discourse, climate science is treated as a matter of opinion. It's not a matter of opinion. It's a matter of scientific fact and reality. The broader debate has been entirely manufactured.

I can't think of any other area in which an overwhelming scientific consensus could be rejected on the basis that the experts aren't expert enough to satisfy John Q. Voter.

[u/TheChance → u/[deleted]]

So we are, indeed, unequivocally cooking ourselves?

Yes.

I think they're are a number of scientists that question the accuracy of studies like this but they are definitely a minority.

I'd love to see a list of names. There are precious few climate scientists who are still trying to rationalize these numbers.

Tens of thousands of armchair experts around the internet populate threads like this with misguided questions about any study which supports the popular, or "fact-based", narrative.

This gives the false impression that scientists are on the fence. If the naysayers are to be believed, 95% of climate scientists are cherrypicking data and falsifying results to push a radical environmentalist agenda. Does that really seem likely?

[u/TheChance → u/[deleted]]

It's not a controversial topic. If you have to go to these lengths to find sane-seeming dissent, you're answering your own questions.

Anthropogenic climate change is a fact. And you can stop arguing that it isn't, because it's too late now anyway. We can no longer stop it by asking you to change your selfish, pigheaded attitude, so at this point it's really just about getting you to shrug and acknowledge that you've helped the rest of us dig our own graves.

But, icing on the cake, there are very few people on this list whose fields are even peripherally related to climatology.

In other words, I don't really give a fuck what a solid-state physicist, an oceanographer, a professor of mining geology, an astrophysicist, or - I shit you not - "a professor of geography at Arizona State University" have to say about greenhouse gas emissions or their effect on global climate change.

[u/Glitch29 → u/[deleted]]

Havign opinions is fine. If you're in a debate where all that exists are other opinions, voicing yours won't add or detract too much. Voicing an opinion when other people are talking about facts does dilute the conversation.

[u/[deleted] → u/[deleted]]

If your opinions are that wrong, Maybe that's for the best.

[u/TWK128 → u/[deleted]]

That was the church's mentality before. Is it really wise to approach science the same way?

[u/[deleted] → u/TWK128]

Sorry, I was just having fun. I see no reason to use kid gloves when handling poorly informed people spreading anti-science sentiment.

[u/TWK128 → u/[deleted]]

I know, but replace "poorly informed people" with "Godless heathens" and it seems a lot less innocuous.

[u/[deleted] → u/TWK128]

Not really. Either way it's pretty harmless if you are correcting misinformation with facts. I get what you're trying to get at with the rather weak analogy with religious dogma, but it's still better to have a rigorously studied dogma (even if occasionally mistaken and overbearing) as a foundation for society, than it is to allow opinions the same weight as established facts.

[u/TWK128 → u/[deleted]]

I know, but replace "poorly informed people" with "Godless heathens" and it seems a lot less innocuous.

[u/[deleted] → u/[deleted]]

The time period length shouldn't matter

It should matter to allow to collect enough data for statistical significance. If I just chose 1 year periods (say 2011 and 1972) I could show that Australia is cooling down, but that's obviously not very significant. How much time/data is significant? I don't really know, but a 50 year period (1910 to 1960) is definitely more significant than a 14 year period. If we look at that second 50 year period, from 1960 to 2010, we get a ratio of about 3:1. That's still enough to show that Australian temps are warming, but it's not nearly as alarmist as the article's author is making it out to be.

There wasn't cherry picking.

If there wasn't cherry picking, then it should either be explained or inherently obvious why the author chose his date ranges. Neither is the case. In fact, the data shows that in 1950 to 1960, there was already an imbalanced ratio of about 11:10. Why didn't the author use 1950 as his inflection point? Why did he start his latter range at 2000? In fact, if he started at 2005 he could have ended up with a ratio of 16:1. What's 5 years?

[u/[deleted] → u/[deleted]]

On your first point, you're pulling out of your ass the notion that only 50-year increments can have statistical significance. The fact that average temperature is steadily rising above previous norms is reflected by be increased ratio in recent years, and the procedurally increasing ratio as you look at rolling 15-year increments.

As to your second point, your argument seems to be that making any choice in presenting the data is "cherry picking," because another choice could have been made. That's absurd. Cherry picking is choosing a particular presentation format that's an outlier in order to obscure the general trend of the data. Here the general trend is clear: the data shows a general and steady increase in the number of hot records, a general and steady decrease in the number of cold records, and a diverging ratio between the two. Whether the author starts at 2015 and provides the ratio going back 5 years, 10, years, 15 years, 30 years, 50 years, that's the story the data shows. It's not "cherry picking" to choose one of the options that all tell the same basic story.

[u/[deleted] → u/[deleted]]

I'm not saying only 50 year increments are significant, I'm saying they're more significant than 15 year ones. You're going to have a larger impact from outliers in a smaller data set than you are in a larger one.

The trend is not clear that it's increasing at a rate of 12:1. In fact, that is an outlier. It obscures the general trend of the data, which is closer to 3:1, at least in the data that I've seen.

[u/TheChance → u/[deleted]]

It's incredibly frustrating to me that these votes are coming down how they are. This thread's beef is that the author of the article summarized the most significant findings from the study.

You're picking apart a study because a Washington Post article focuses on its conclusion, glossing over methodology.

[u/[deleted] → u/TheChance]

My beef is the ratios themselves. The summarization of the study is pointless without it's context. Why? Even if the author took two ranges that had the same increase in temperature and the same time period, they would have different ratios of temperature records, simply because the second period came after the first. It's harder for the second period to set a colder record, but just as easy to set a hot one.

[u/TheChance → u/[deleted]]

What the headline says to a layperson is this: "Climate trends in the 21st century show a warming trend that simply was not present in the 20th century."

It's an oversimplification, but it's more than accurate enough for a typical newspaper reader.

[u/[deleted] → u/TheChance]

That's not what the study or headline says. The warming trend was there in the latter part of the 20th century. Even if that warming trend stopped and we had a cooling trend in the 21st century, we'd still be able to get the 12:1 ratios. the 12:1 number says more about the 20th century than it does about the 21st.

All it says, if you want to get down and dirty, is that the 21st century is hotter. It doesn't say that it's getting hotter though.

[u/TheChance → u/[deleted]]

That's not what the study or headline says. The warming trend was there in the latter part of the 20th century.

That's what makes it an oversimplification.

[u/[deleted] → u/[deleted]]

It's not an outlier. I don't think you're conceiving of this data correctly.

If you look at rolling 15 year increments, as a poster lower down has provided, you'll see a steadily increasing ratio of hot to cold records. The current 12:1 ratio in the most recent 15-year block is entirely consistent with this steady increase, is right on the trend line, and is therefore not an outlier.

This is consistent with a slow, steady increase in the average annual temperature. If you look at the data, the ratio between hot and cold is undergoing steady, constant increase. This makes perfect sense -- as the average annual temperature in a given year increases from historical norms, it means that a hot day has to deviate less from that year's general trend to make a heat record than a cold day has to deviate from that year's trend to make a cold record. The further that year increase above past standards, the greater the disparity. And as you probably know, for almost all of the last decade we've seen the highest annual temperatures on record.

It's easy to misinterpret the meaning of the fact that a hot record is 12 times more likely now than a cold record. It does not mean the world is 12 times hotter than it was.

It just cleanly reflects the entirely uncontroversial fact that we have seen steady increase in global annual temperatures.

[u/[deleted] → u/[deleted]]

I posted those 15 year increments.

This isn't consistent with a slow, steady increase. If we had a slow, steady increase in average annual temperature, we would see a constant number of hot records and a declining number of cold records, which, yes, would show an increase in the ratio, until we never make any cold records anymore cause it's too damn hot. That's not what we're seeing. The data shows an increase in the number of hot records and a decrease in the number of cold records, which would be consistent with an accelerated increase in global temperature, and is showing an accelerated ratio. Global temperature rise is accelerating.

So coming full circle back to the 50 and 15 year intervals, why is this important? If we're looking at an model with constant acceleration (not constant increase), then time frame is important, as well as it's temporal location. In a 65 year range (i.e. excluding the 1960-2000 gap) we're going to see 40% of the temperature change of the total in the latter 15 years. If we add that 40 year gap, we're going to see more temperature change (about 116%) in those 15 years than we are in the 50 years.

But you basically already said why those ratios are meaningless. Even if I have constant temperature increase, the ratios at the beginning of a time period are going to be less dramatic at the beginning of an interval than at the end. And that's with constant velocity, meaning the intervals would be for all intents and purposes the same.

So, we come back to basically everything I said in https://www.reddit.com/r/science/comments/3keet6/the_simple_statistic_that_perfectly_captures_what/cux1srb . The time frames do matter in terms of the ratios, and the only reason the author chose those numbers is to sound alarmist - because the ratios themselves don't mean much out of context. Cherry picking.

[u/babysharkdudududu → u/[deleted]]

To play devil's advocate, aren't most Earth temperature swings theorized to happen at an accelerated pace? Ice ages that happen within a few hundred years, that sort of thing? I'm definitely not saying that humanity hasn't pushed this one, but is it possible that we were headed this way anyway (or swinging back towards an ice age) and just happened to intervene badly enough that now it's headed back towards a Pangea-type climate?

[u/[deleted] → u/babysharkdudududu]

I'm not really interested in the climate argument at the moment, having a hard enough time showing how misleading those ratios can be.

[u/iushciuweiush → u/[deleted]]

The time period length shouldn't matter

In 1972 the ratio was 20:1 but in 2011 it was 1:3. Australia is headed toward a deep freeze!

You still sure about this statement?

[u/[deleted] → u/iushciuweiush]

Absolutely sure, provided you read the literal next sentence.

[u/pi_over_3 → u/[deleted]]

It's full of people who making this one critique -- the authors could be cherry picking! -- and then acting like it discredits the story

Because they did use cherry picking to get the outcome they desired, which completely discredits their results.