The bad, the mean, and the average.

Starting this post is a poll of readers view’s on a CO2 emissions target for Australia, announced recently by the Prime Minister. Please take a moment to respond, before moving on to the rest of the post.

Results

This was prompted by a bad article in The Australian newspaper called Climate change: 2008 is world’s 10th hottest year. I put aside the subtext of the article, such as abundant references to phenomena of La Nina, droughts, and Arctic Ice, where global warming is the usual explanation of convenience, and take exception to the statement that:

Australia is on track for its 15th warmest year on record, with a temperature 0.37°C above average, according to the World Meteorological Organisation.

The average, according to wikipedia, is the central tendency of a data set, a measure of the “middle” or “expected” value of the data set. That is, an average is the value to be expected with a sufficiently long run of observations. How long? In the case of climate, 10,000 years would only represent a sample of an exceptionally warm period called the holocene; 100,000 would capture the fluctuation of a single ice age cycle while a million years would be needed to represent a long term expected value, or average.

But with only 100 to 150 years of global temperatures on record, how could the temperature be 0.37°C above average? Based on the multi-ice age ice core data from Vostok Antarctica, the earth is usually much colder, perhaps an average of 8°C colder than the present.

The correct terminology would be to say the temperature is 0.37°C above the mean temperature over whatever period the baseline is calculated. The arithmetic mean (or simply the mean) of a list of numbers is the sum of all of the list divided by the number of items in the list.

Update: For fun, try clicking the link on The Australian exclusive poll “POLL: Is the target too high or too low?” right hand side. Follow the link in Pollnet to get to The Australian article.

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0 thoughts on “The bad, the mean, and the average.

  1. jae #1

    If Australia gets 5%, that will be better than Europe’s 4%, LOL.

    and what is more we’ll do it all without benefit nuclear power stations.

  2. jae #1

    If Australia gets 5%, that will be better than Europe’s 4%, LOL.

    and what is more we’ll do it all without benefit nuclear power stations.

  3. I’d be for publicity on the McKitrick scheme, where imposts are related to observed temperature changes in the tropical troposphere. They can be positive or negative. Ross McK proposed a method of caclulation using a reference point.

    Ross’s Home Page is http://www.uoguelph.ca/~rmckitri/ross.html

    For Southern Hemisphere, the BOM has 2008 average temperatures by months compared to historical. See http://www.bom.gov.au/cgi-bin/silo/reg/cli_chg/g_timeseries.cgi?variable=global_t&region=sh&season=01
    and enter each month in turn in the box provided.

    It is possible to say from these SH (these are NOT Australia, but Sth Hemi) data that the monthly temperature drops in many months of 2008 are among the 5 biggest monthly drops since 1980. Shown well in Jan, Feb Mar 2008. July, Aug, Sept 2008 are some contra-exceptions. But what does this mean? To me, very little. It’s like noise on a longer time signal. With the noise from the Antarctic being a big player for SH.

    It does not remind me on an irreversible, unrelenting conversion of incoming solar to increased terrestial heat without pause. Why, some places are actually getting colder over the century or half century.

  4. I’d be for publicity on the McKitrick scheme, where imposts are related to observed temperature changes in the tropical troposphere. They can be positive or negative. Ross McK proposed a method of caclulation using a reference point.

    Ross’s Home Page is http://www.uoguelph.ca/~rmckitri/ross.html

    For Southern Hemisphere, the BOM has 2008 average temperatures by months compared to historical. See http://www.bom.gov.au/cgi-bin/silo/reg/cli_chg/g_timeseries.cgi?variable=global_t&region=sh&season=01
    and enter each month in turn in the box provided.

    It is possible to say from these SH (these are NOT Australia, but Sth Hemi) data that the monthly temperature drops in many months of 2008 are among the 5 biggest monthly drops since 1980. Shown well in Jan, Feb Mar 2008. July, Aug, Sept 2008 are some contra-exceptions. But what does this mean? To me, very little. It’s like noise on a longer time signal. With the noise from the Antarctic being a big player for SH.

    It does not remind me on an irreversible, unrelenting conversion of incoming solar to increased terrestial heat without pause. Why, some places are actually getting colder over the century or half century.

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