Arctic ice melt could trigger uncontrollable climate change at global level

[LeafByNiggle]

…The best estimate of the true value of the measured quantity is given by the mean of the measurements, and the precision of the determination of the mean is given by the precision of the individual measurement, divided by the square root of the number of measurements.

So if there are thousands of measurements averaged over the course of one year (spacial and temporal averaging), we can easily add two more digits. All it take is 10,000 measurements to do that. The square root of 10,000 being 100.

 

[Theo520]

Lynn, that chart’s data points appear to be rounded in thousandths of a degree, not tenths. What’s shown on the y axis is merely a presentation decision. A graph with data points rounded to tenths would more accurately represent the precision (and uncertainty) of what we know. It currently implies greater precision than we have.

I have an idea. How about creating a chart that rounds all the temps to whole numbers. Here’s the chart in tenths. In your mind round them all off to the nearest whole numbers, then we will get a chart in which all the results before 1995 are 0C, and all the results after 2000 are 1C, with the intervening years (1995, 1996, 1997, 1998, 1999, 2000) fluctuating between 0C and 1C.

http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif

 

[LeafByNiggle]

Lynn, that chart’s data points appear to be rounded in thousandths of a degree, not tenths. What’s shown on the y axis is merely a presentation decision. A graph with data points rounded to tenths would more accurately represent the precision (and uncertainty) of what we know. It currently implies greater precision than we have.

Do you really think rounding to tenths of a degree would make this graph** not** show nearly as much warming as it does now?

Each annual mean in this graph is the result of averaging about 1500 station annual means.

Each station annual mean is the result of averaging, say, 365 daily readings - maybe more.

Therefore the annual mean is the grand average of 1500 x 365 = 547,500 individual readings. As explained by dvdjs and by one of my earlier authoritative references, the precision is improved by a factor of the square root of the number of values in the average. The square root of 547,500 is about 740. So even if the individual readings are precise only to the nearest whole degree, this huge number of values averaged is precise to 1/740 of a degree - pretty close to 0.001 degree. You can’t ignore these facts and just say “I only believe in tenth of a degree precision”.

 

[Theo520]

Do you really think rounding to tenths of a degree would make this graph** not** show nearly as much warming as it does now?

Each annual mean in this graph is the result of averaging about 1500 station annual means.

Each station annual mean is the result of averaging, say, 365 daily readings - maybe more.

Therefore the annual mean is the grand average of 1500 x 365 = 547,500 individual readings. As explained by dvdjs and by one of my earlier authoritative references, the precision is improved by a factor of the square root of the number of values in the average. The square root of 547,500 is about 740. So even if the individual readings are precise only to the nearest whole degree, this huge number of values averaged is precise to 1/740 of a degree - pretty close to 0.001 degree. You can’t ignore these facts and just say “I only believe in tenth of a degree precision”.

Pretending there is greater precision than the raw data provides is misrepresenting the data.

This site lays out the accuracy of our measurement stations, with the majority having an error range >2C

surfacestations.org/

(Please Note: This uploaded content is no longer available.)

 

[dvdjs]

Pretending there is greater precision than the raw data provides is misrepresenting the data.

I think that it has been clearly explained to you that your claim is wrong. This is a fundamental element of measurement theory: we make multiple measurements and average results in order to gain better precision that we could get from the fewer, “raw” measurements.

 

[LeafByNiggle]

Pretending there is greater precision than the raw data provides is misrepresenting the data.

This site lays out the accuracy of our measurement stations, with the majority having an error range >2C

surfacestations.org/

It seems climate change denier Anthony Watts and his charts have deceived you again. You see, the chart you referenced is about accuracy, not precision. For the purpose of calculating temperature trends, it is precision that is relevant - not accuracy. Let me explain:

Suppose you have a thermometer that reads to the nearest 0.1 degrees, but is off by 6 degrees. Therefore it would be classified by your chart as >5 degrees accuracy. Looks pretty bad, right? That’s what the deniers want you to think. Suppose over the course of one week, the readings from this thermometer were:

23.5
23.6
23.7
23.7
23.8
23.9
24.0

Since the thermometer is off by 6 degrees, the true temperatures were actually 29.5, 29.6, 29.7, 29.7, 29.8, 29.9, 30.0.

Nevertheless, it is clear that the temperature was rising over the course of that one week of measurements. We know that because the precision is 0.1 degrees, and the offset of 6 degrees is a constant that affects all the measurements. Furthermore, by later comparison with a more accurate thermometer, the faulty readings can be corrected so they can be combined with readings from other thermometers in a meaningful way.

To understand instrumentation, it is very important to understand the difference between accuracy and precision. But the confusion of these two concepts is just what Mr. Watts was counting on. So you would be better off avoiding his website and any website he has any control over.

 

[Theo520]

The discussion confuses fundamental concepts.

1. Suppose you are making direct measurements of some particular quantity. The best estimate of the true value of the measured quantity is given by the mean of the measurements, and the precision of the determination of the mean is given by the precision of the individual measurement, divided by the square root of the number of measurements. This result, by the way, follows directly from case 1. The precision can be, in principle, infinitely better than the precision of the individual measurements. If the uncertainties in the individual measurements being averaged are not all the same, the result is not as simple, but the principle that a large number of measurements can give rise to precision greater than the least precise individual measurement still holds.

Source please.
I think you are referencing uncertainty of the mean, not how the appropriate significant digits are determined.

 

[LeafByNiggle]

Source please.
I think you are referencing uncertainty of the mean, not how the appropriate significant digits are determined.

But the number of significant digits is determined by the uncertainty of the value. If you know the mean to within 0.001 degrees, why not present it with 3 digits past the decimal? As for the source, look at the the list of sources I provided in first post on this subject. One of them gives this formula. In any case, it is a textbook fact. We should not have to argue it here.

 

[vz71]

Here’s an example of the station thermometer broadly in use, for the temp record in the US. The precision is to whole degrees of temperature, not even tenths of a degree.

Minimum Maximum Temperature Systems (MMTS)

https://upload.wikimedia.org/wikipe...Thermometer.JPG/250px-Max_Min_Thermometer.JPG

If that is in use today, do you suppose they used more accurate tools in the 19th century?

 

[Theo520]

From an authoritative source, for perspective

metoffice.gov.uk/hadobs/hadcrut4/faq.html
Q: Was 2010 (or 1998 or 2005) the warmest year on record?
A: The short answer is, maybe. It is not possible to calculate the global average temperature anomaly with perfect accuracy because the underlying data contain measurement errors and because the measurements do not cover the whole globe. However, it is possible to quantify the accuracy with which we can measure the global temperature and that forms an important part of the creation of the HadCRUT4 data set. The accuracy with which we can measure the global average temperature of 2010 is around one tenth of a degree Celsius. The difference between the median estimates for 1998 and 2010 is around one hundredth of a degree, which is much less than the accuracy with which either value can be calculated. This means that we can’t know for certain - based on this information alone - which was warmer. However, the difference between 2010 and 1989 is around four tenths of a degree, so we can say with a good deal of confidence that 2010 was warmer than 1989, or indeed any year prior to 1996.

 

[dmelosi]

You brought up the Hitler card, so I’ll play it.

Hitler annihilated millions of people. Now we, esp the rich and profligate of the world, are annihilating billions and billions of people over the next 100s and 1000s of years.

The only question that remains is will we go to Hell for it. (Of course, we can repent in the last minute and confess.)

RE the abortion issue, I’ve found it much more easy to convince environmentalists that abortion is wrong by telling them that we are saving the earth for the children, so it makes no sense to abort them – than to convince climate change denialists that CC is real and is and will be harming & killing people, esp as it progressively worsens in the future from what we have emitted to date and will be emitting during our lifetime.

There is absolutely nothing to change their minds, even those among them that are against abortion, like “why be concerned about only those threatened with elective abortions and not care at all about others threatened with death from environmental hazards?”

One can be against abortion AND against killing of innocents thru other means. One can walk and chew gum at the same time.

I’m not sure why CC denialists are so difficult to convince.

Is it that THEY (other people) are committing abortion, while WE ourselves are the goody-goodies and could not possibly be doing anything wrong, ergo CC could not possibly be real and we could not possibly be harming and killing others.

Or politics – the party that seems to be against abortion (one wonders if they truly are) is the one that for the most part denies CC and has no problem with killing and harming people thru environmental harms. If one favors that party, then striving to rid oneself of cognitive dissonance makes it difficult to find any fault at all with the “death and destruction” part of their platform, or even see that it is there.

One could vote for the anti-abortionists, then write letters to them that they should also do right by the environment

I am just now reading through this thread as global warming caused by humans is so politicized.
A quick comment on this post as I read through.
I do find it curious that you use “anti abortionist” rather than pro life.

 

[vz71]

I am just now reading through this thread as global warming caused by humans is so politicized.
A quick comment on this post as I read through.
I do find it curious that you use “anti abortionist” rather than pro life.

I caught that too.

 

[lynnvinc]

I am just now reading through this thread as global warming caused by humans is so politicized.
A quick comment on this post as I read through.
I do find it curious that you use “anti abortionist” rather than pro life.

I consider “pro-life” to be a much broader term that includes anti-abortion, as well as anti-violence, anti-environmental harms (that kill, and some also causing miscarriages), etc.

I think you could include drunk-driving, reckless driving, etc. Anything we do that risks killing people.

It would be great to have some “pro-life” marches and protests that also bring in at least some of these other more major issues that kill people thru human causes.

 

[lynnvinc]

From an authoritative source, for perspective

metoffice.gov.uk/hadobs/hadcrut4/faq.html
Q: Was 2010 (or 1998 or 2005) the warmest year on record?
A: The short answer is, maybe. It is not possible to calculate the global average temperature anomaly with perfect accuracy because the underlying data contain measurement errors and because the measurements do not cover the whole globe. However, it is possible to quantify the accuracy with which we can measure the global temperature and that forms an important part of the creation of the HadCRUT4 data set. The accuracy with which we can measure the global average temperature of 2010 is around one tenth of a degree Celsius. The difference between the median estimates for 1998 and 2010 is around one hundredth of a degree, which is much less than the accuracy with which either value can be calculated. This means that we can’t know for certain - based on this information alone - which was warmer. However, the difference between 2010 and 1989 is around four tenths of a degree, so we can say with a good deal of confidence that 2010 was warmer than 1989, or indeed any year prior to 1996.

But wouldn’t you agree 1998 and the few years before and all the years after are significantly above the years before 1980, and certainly all the years before 1970?

That is the main point of CC science, the trend over the decades, not the year-to-year comparisons, since there are more than just GHGs impacting CC. I’ve said this over and over again. It just doesn’t sink in.

I realize it’s difficult to understand the idea of long-term trends, maybe because we live in an age of short attention spans.

 

[dvdjs]

Source please.
I think you are referencing uncertainty of the mean, not how the appropriate significant digits are determined.

The certainty/uncertainty is what makes digits significant/insignificant,
The links from others are sufficient sources, but let’s not get proof-texty.

 

[dmelosi]

I consider “pro-life” to be a much broader term that includes anti-abortion, as well as anti-violence, anti-environmental harms (that kill, and some also causing miscarriages), etc.

I think you could include drunk-driving, reckless driving, etc. Anything we do that risks killing people.

It would be great to have some “pro-life” marches and protests that also bring in at least some of these other more major issues that kill people thru human causes.

Pro-life, since Roe v Wade has been used for those against abortion. It sure seems that those trying to ease their conscience for supporting the party of death try to paint pro lifers in a negative way by labeling them with the “anti” label.

 

[lynnvinc]

I am just now reading through this thread as global warming caused by humans is so politicized…

Why did it become politicized and who made it politicized.

When I got into the issue in the late 80s, it was just a matter of scientists explaining, “Houston, we’ve got a problem.”

Since I had already learned about the greenhouse effect in my extra science readings in high school in the early 60s, I was able to understand the issue very well.

However, I don’t think it became “politicized”; it became “fallen human naturized.” It’s just not something people want to deal with or think about because it would disrupt their lives, esp since the worst would be happening in future decades, centuries, and millennia. They would have to become conscientious and take reusable bags when shopping, and a myriad of other measures, etc. Too bad there’s no silver bullet that can be applied by experts.

It’s just too much trouble, when people are honed in on making a living or raising one’s economic standing.

 

[vz71]

Pro-life, since Roe v Wade has been used for those against abortion. It sure seems that those trying to ease their conscience for supporting the party of death try to paint pro lifers in a negative way by labeling them with the “anti” label.

And try to broaden the meaning of pro-life to such a degree as to be meaningless.

Notice the definition given eliminates those that use fossil fuels and do not cater to the mmgw hysteria.

 

[Theo520]

The certainty/uncertainty is what makes digits significant/insignificant,
The links from others are sufficient sources, but let’s not get proof-texty.

"The certainty/uncertainty is what makes digits "???

A large sample size for your mean doesn’t change the number of significant digits in the calculated mean. I quoted support for this claim, and asked you to back up your questionable math.

I also provided confirmation from the UK Met that they only go down to tenth of a degree, not a thousandths.

 

[dvdjs]

Theo520:
Please re-read my post #330. I am happy to answer questions about it.
Also, if you can articulate them clearly, I am also happy to answer any questions that you may have about the meaning “significant digits”.