Temperature Record of the Last 1000 Years

[wevets]

I see the thread has moved quite a bit since my last post - I apologize if this disrupts the flow, but I’ll address where I left off and after the holidays read the rest of the thread to catch up.

@brazil84

I wouldn’t quite agree with that,

(in response to my comment about moving averages being lagging indicators and longer moving averages becoming less sensitive to trends)

A simple moving average is calculated like this:

<!--------y[sub]t[/sub] + y[sub]t-1[/sub] + y[sub]t – 2[/sub]… y[sub]t-n[/sub]
//---------->
<!--SMA = __________________________________________________
//--------->
<!-----------------n
//------------------->

Where n is the number of time periods.

An exponential moving average is calculated using this term:

<!----------2
//------->
<!---α = ______
//------->
<!-------n + 1
//------->

Where n is the number of time periods. When n grows larger, α grows smaller, and the moving average more closely follows the past than the present.

In either case, as n increases, the moving average tends to more sluggishly respond to trends, regardless of the direction of the trend. We can imagine three trend directions:

[ul]
[li]Increasing trend – a larger n will tend to make the moving average lower and it will lag behind the trend more than with a smaller n.[/li][li]Decreasing trend – a larger n will tend to make the moving average higher because there are more past terms (y[sub]t-n[/sub] for example) that are large relative to present values.[/li][li]Steady or flat trend – a larger n will tend to reflect values from before y became flat – higher if y[sub]t-n[/sub] and its fellows are large, lower if y[sub]t-n[/sub] and its fellows are small.[/li][/ul]

In none of these cases does the moving average more rapidly follow a trend when n is higher or become more sensitive to trends when n is higher.

A 40-year moving average may be appropriate when you’re talking about 1000 years of proxy temperatures, but it is inappropriate with 100 or 150 years of instrumental temperature data.

@wikipedia

The question of how far back to go for an initial value depends, in the worst case, on the data. If there are huge p price values in old data then they’ll have an effect on the total even if their weighting is very small. If one assumes prices don’t vary too wildly then just the weighting can be considered.

If we disagree on the mathematics above, I don’t see much hope of us being on the same page.

Let’s define an “elbow” as a point where there is a large change in the slope of the graph. All things being equal, a graph with a 40 year smooth will have equal or fewer elbows than a graph with a 5 year smooth. Right?

Generally the longer moving average will always be smoother - but remember that the moving average is a trend analysis tool it does not replace the data. Like every trend analysis tool, it can be misleading if used improperly - such as a 40 year smooth on a 100 or 150 year temperature record.

Let’s carry this analogy a little further: Suppose that you leave the TV on from 5:00 to 5:40 with the brightness on maximum and don’t see anything. At around 5:45, give or take, you turn the brightness down and you start seeing whales every few minutes. Would it be reasonable to infer that Fox started broadcasting whales at 5:45?

You’re misconstruing the analogy - instrumental temperature records have a far higher resolution than any of the proxies, in temperature precision, global reach, and temporal accuracy. They show fundamentally more accurate data, and can be examined at a different scale than the proxy record can.

The thread isn’t about looking for a signal in recent temperatures. It’s about comparing recent temperatures to older ones.

Unless you can see a trend in the recent temperatures (the last 1000 years does include the last 150 years) there’s little point in comparing a non-existent current trend to any trend further in the past.

Well, I’m off to Mexico for two weeks - I wish you all a Happy Holiday and hope you and your loved ones are well. See you in the new year!

[brazil84]

@wevets

Generally the longer moving average will always be smoother -

This is the key point that I’ve been making. The fact that you look at the instrumental record alone and see an “elbow” (actually multiple elbows) doesn’t necessarily mean anything and doesn’t undercut my basic point about splicing.

You’re misconstruing the analogy - instrumental temperature records have a far higher resolution than any of the proxies, in temperature precision, global reach, and temporal accuracy. They show fundamentally more accurate data, and can be examined at a different scale than the proxy record can.

That’s almost certainly true. And it shows why the hockey stick is wrong. If the proxies are not fully capturing the temperature trends of today, it follows that they do not fully capture the temperature trends of 1000 years ago.

Unless you can see a trend in the recent temperatures (the last 1000 years does include the last 150 years) there’s little point in comparing a non-existent current trend to any trend further in the past.

And if you CAN see a trend in recent temperatures, you need to ask yourself if there is any way of measuring similar trends in past temperatures. Conversely, if you find a trend in past temperatures, you need to ask what happens if you apply the same technique to recent temperatures.

Well, I’m off to Mexico for two weeks

Have a safe trip.

[aptronym]

@brazil84

Actually, the first study you cite is only from 1600 to 1990.

Do you contest that the first study I cited shows what I said it said, since you’re posting no criticism of it?

@brazil84

But let’s take a closer look at the second study you cite, which covers 831 to 1992. (The point I’m about to make also applies to the first study.)

Let’s address the first study first.

@Science 29 April 2005: Vol. 308. no. 5722

The derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions. Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin. This warming was notably coherent over the globe. The warming signals from glaciers at low and high elevations appear to be very similar.

This is in direct contradiction to any claim that the records diverge. This warming is in line with, and perhaps a little greater than, what we observe with the instrumental records.

@brazil84

By doing a google image search, I was able to find what I believe is a graph showing the temperature reconstruction you have cited. (It’s apparently the blue line.):

http://www.wooster.edu/geology/tr/esper1.jpg

This is an accurate reproduction of the graph. The full text can be found from the first author’s home page: http://www.wsl.ch/staff/jan.esper/publications/Science_2002.pdf

@brazil84

What’s important to note, for purposes of your argument, is that there is no dramatic change in the slope of the graph in the 20th century. This undercuts your argument that the rate of temperature change in recent times is unprecedented.

But you’ve also argued that the temperatures diverge in the 20th century - you cannot claim both that the proxy record is wrong because it diverges, and then claim that the divergent part proves the proxy record.

But let’s settle the factual issues first - what are the slopes in the picture you’ve shown? Saving as a JPG, and clipping out the relevant parts, I find the the time period from 1850 to 2000 is 114 pixels wide and 61 pixels tall (slope = 0.54). The slope from 1000 to 1150 is 117x57 (slope = -0.50), from 1150-1300 is 114x36 (slope = -0.30), from 1300-1450 is 117x6 (slope = +0.05), 1450-1600 is 116x17 (slope = -0.15), from 1600-1750 is 112x39 (slope = +0.35), and 1750-1900 is 114x16 (slope = +0.14). So the simple claim that there’s no dramatic change in the slope is simply false altogether.

@brazil84

To get the result you have claimed, one needs to compare the proxy record from before 1900 with the instrumental record from after 1900.

False, as shown above.

@brazil84

Not only that, but it seems clear that the study you have cited did not pick up the rate of temperature change in recent history as indicated by the instrumental records.

The height of a 1[sup]o[/sup]C anomaly from the picture you linked is 85 pixels tall, which would suggest that the warming from 1850-2000 is 61/85*1 = +0.72[sup]o[/sup]C.

The same analysis on File:Instrumental Temperature Record.png - Wikipedia gives a height of 309 pixels for 1853-2000 with an scale of 260 pixels per 0.6 degrees, or an instrumental temperature record of 260/309*0.6 = +0.71[sup]o[/sup]C. I suppose you could criticize the fact that the proxy data doesn’t go all the way until 2000, but that would again only indicate that the proxy temperature changes are greater than, rather than equal to, the instrumental temperature record.

@brazil84

Bottom line: You are comparing apples and oranges.

No. The bottom line is that you have made a vast number of unsubstantiated claims. The records don’t diverge at all.

[aptronym]

@intention

OK, I see what some parts of the problem are. First, you can’t extrapolate from twenty years to a century, or from a short period to a long.

For a variety of reasons, brazil84 has rejected each of the other data sets. At first, I wanted to compare the instrumental temperature record with proxies - he claimed proxies were worthless. He then challenged the instrumental temperature record and claimed the urban heat islands were the cause. The only thing remaining is satellite data, which only goes from 1980-2000.

@intention

Second, I know of no instrumental data that show a 0.8°C/century trend from 1900-1999 (or 1901-2000, your figure from 1900-2000 is more than a century). Both the HadCRUT3 and the GISSTEMP datasets show only about 3/4 of that.

Do you have any raw data, so I don’t have to cut-and-paste and count the pixels as I have done above?

@intention

Third, comparing numbers without error estimates is meaningless. The 95% confidence interval on the 1900-1999 annual HadCRUT3 trend is 0.6±0.2°C. Note that this does not include the error estimate of the data itself, which is ±0.2°C (95%CI) for the most recent years, more for the earlier years

The 95% confidence interval on the 1980-2000 annual RSS satellite troposphere trend is 1.6 ± 1.5°C. Thus, statistically there is no difference between the two trends. Indeed, the satellite data is only barely statistically different from zero.

That there is no difference between the two trends is a point in my favor. I am using the satellite data to show that the instrumental temperature record is reliable, and the instrumental temperature data to show that the proxy data is reliable.

@intention

Second, the satellite data is only barely significantly different from zero.

For the purposes of my argument, I’ll gladly accept “barely significant”. Brazil84 claims there’s no evidence the Earth has warmed at all; a small, but non-zero increase is sufficient to disprove that.

@intention

the idea that glacier length (your first proxy) is related to temperature is highly uncertain. The same is true of tree ring data. Neither of these can be shown to be temperature proxies of any accuracy.

I am unqualified to support or contest that statement - certainly people who publish in Science think there’s a relation, and their reviewers did. Is there an equivalent amount of peer-reviewed literature on the other side?

@intention

In addition, 91% of the glaciers measured are north of 35°N … hardly ideal for a “global” reconstruction, since that is only ~20% of the earth’s surface.

The abstract of the paper I quoted above claims there is good agreement between “global” data sets. Would you care to explain the discrepancy? (e.g. Are there glaciers on Kilimanjaro that he might be using that other people contest?)

@intention

Finally, the Esper paper you cite has too many problems for me to even begin to chronicle. See here for half a dozen threads covering some of these problems.

I request peer-reviewed articles to counter peer-reviewed articles. I don’t cite RealClimate.org as an authority in favor of my arguments; I’d appreciate it if others wouldn’t cite equivalent organizations in favor of theirs.

On a very broad scale, I agree that temperature proxies don’t “prove” anything. But then again, I created a whole other thread for proving global warming without citing any temperature proxies at all. You are welcome to participate. (brazil84’s Global Warming Thread).

I’m fine with people questioning the temperature proxy record. However, you cannot both attack the temperature proxy record and claim anything about a Medival Warming Period or Little Ice Age. If you want to say the proxies are shit, that’s fine - in subsequent discussion, just don’t ask why the Earth was warmer in the MWP. Either you accept the proxies as a whole or reject them as a whole.

[intention]

aptronym, thanks for your post. You say:

@aptronym

Either you accept the proxies as a whole or reject them as a whole.

I fear that this quote perfectly exemplifies and encompasses the problem with your worldview. Proxies are like anything else, good, bad, and indifferent. Each one has its own unique problems and strengths, both as a class (e.g. tree rings) and individually (e.g. Thompson’s widely cited but unarchived data). Beer intake is a good proxy for level of intoxication, while age is a poor proxy for intelligence.

In addition, it is quite possible to get bad results from any proxy, valid or not, by making any one of a number of statistical errors and mis-steps (e.g. Mann’s Hockeystick).

Thus, it is obviously necessary to look at, not only each individual proxy, but at each individual proxy-based study, and to judge it on its own merite.

You, however, have a black-and-white view (accept them all or reject them all) which has no relationship to science.

w.

PS - I had said

@intention

Second, I know of no instrumental data that show a 0.8°C/century trend from 1900-1999 (or 1901-2000, your figure from 1900-2000 is more than a century). Both the HadCRUT3 and the GISSTEMP datasets show only about 3/4 of that.

To which you replied

@aptronym

Do you have any raw data, so I don’t have to cut-and-paste and count the pixels as I have done above?

Umm … the HadCRUT3 and GISS temperature datasets are raw data … are you sure you’re familiar with the field of science we’re discussing?

[brazil84]

But let’s settle the factual issues first - what are the slopes in the picture you’ve shown? Saving as a JPG, and clipping out the relevant parts, I find the the time period from 1850 to 2000 is 114 pixels wide and 61 pixels tall (slope = 0.54). The slope from 1000 to 1150 is 117x57 (slope = -0.50), from 1150-1300 is 114x36 (slope = -0.30), from 1300-1450 is 117x6 (slope = +0.05), 1450-1600 is 116x17 (slope = -0.15), from 1600-1750 is 112x39 (slope = +0.35), and 1750-1900 is 114x16 (slope = +0.14). So the simple claim that there’s no dramatic change in the slope is simply false altogether.

Nice cherry-picking. But I can cherry-pick too:

Slope from beginning of graph to Year 1000: 0.54
Slope from year 1000 to year 1050: -1.04
Slope from year 1950 to end of graph: 0.12

In any event, try to imagine the first derivative of that graph.

My point stands.

The records don’t diverge at all.

Esper’s graph shows a temperature change of +0.05C between 1950 and 1992 (the end of the graph).

Are you confident that the instrumental record shows a similar change?

Do you contest that the first study I cited shows what I said it said

Of course I do - it doesn’t even cover the time period you claim it does.

But you’ve also argued that the temperatures diverge in the 20th century - you cannot claim both that the proxy record is wrong because it diverges, and then claim that the divergent part proves the proxy record.

Straw man. I’m not trying to “prove” the proxy record. My point is that if one accepts YOUR proxy record, it doesn’t show what you claim to be the case – a dramatic increase in rates of change of temperatures.

The only way to show your claim is to accept the proxy up until 1900 or so, and then reject it in favor of the instrumental record.

i.e. to compare apples and oranges.

[aptronym]

@intention

Each one [proxy] has its own unique problems and strengths, both as a class (e.g. tree rings) and individually (e.g. Thompson’s widely cited but unarchived data) … Thus, it is obviously necessary to look at, not only each individual proxy, but at each individual proxy-based study, and to judge it on its own merite.

I do not have the expertise to look at each individual proxy.

(1) Do you?
(1a) If you do, which datasets are acceptable and which are unacceptable?
(1b) Are there any datasets that you consider acceptable that show both the existence of a MWP and LIA and temperature divergence in the 20th century? Which one(s)?

(2) Both authors and reviewers at Science magazine accept these proxies.

@intention

the HadCRUT3 and GISS temperature datasets are raw data … are you sure you’re familiar with the field of science we’re discussing?

I was asking for the raw data in a chart, rather than graph, format. That would allow a quick calculation of warming and cooling rates without having to use the Count The Pixels method of temperature estimation.

Are you sure you understood the question before answering?

@brazil84

I can cherry-pick:

I don’t contest that you can cherry-pick. I kept each of the time frames constant in 150 year chunks, and I evaluated each of the 150 year chunks throughout the graph. You did neither.

@brazil84

Esper’s graph shows a temperature change of +0.05C between 1950 and 1992 (the end of the graph).

You did not argue that the temperatures only diverged in the “last” 42 years - you claimed they diverged for the instrumental temperature record, which is 150 years. I took 150 year chunks throughout the graph and showed that the increases neither diverge nor are they large compared to recent warming.

You have taken smaller chunks for random ranges and compared them with mis-sized chunks.

@brazil84

Of course I do - it doesn’t even cover the time period you claim it does.

Verifiably false.

[GEOGRAPHIC REGION: Global
PERIOD OF RECORD: 1600-1990 AD

DESCRIPTION:
Global temperature reconstruction based on glacier length records from
169 locations.](ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/oerlemans2005/oerlemans2005.txt)

@brazil84

My point is that if one accepts YOUR proxy record, it doesn’t show what you claim to be the case – a dramatic increase in rates of change of temperatures.

A point which is factually false.

Here is the glacier record, with every single 150-year difference calculated (so that there’s no discussion of cherry picking).

Begin End Temperature Change
1600 1750 0.044
1601 1751 0.042
1602 1752 0.04
1603 1753 0.039
1604 1754 0.039
1605 1755 0.038
1606 1756 0.037
1607 1757 0.036
1608 1758 0.035
1609 1759 0.031
1610 1760 0.028
1611 1761 0.024
1612 1762 0.021
1613 1763 0.016
1614 1764 0.013
1615 1765 0.007
1616 1766 0.003
1617 1767 -0.001
1618 1768 -0.002
1619 1769 -0.004
1620 1770 -0.008
1621 1771 -0.01
1622 1772 -0.013
1623 1773 -0.015
1624 1774 -0.014
1625 1775 -0.014
1626 1776 -0.013
1627 1777 -0.012
1628 1778 -0.01
1629 1779 -0.009
1630 1780 -0.007
1631 1781 -0.005
1632 1782 -0.004
1633 1783 -0.004
1634 1784 -0.003
1635 1785 -0.003
1636 1786 -0.004
1637 1787 -0.006
1638 1788 -0.008
1639 1789 -0.011
1640 1790 -0.013
1641 1791 -0.017
1642 1792 -0.023
1643 1793 -0.028
1644 1794 -0.034
1645 1795 -0.039
1646 1796 -0.045
1647 1797 -0.048
1648 1798 -0.053
1649 1799 -0.056
1650 1800 -0.06
1651 1801 -0.063
1652 1802 -0.067
1653 1803 -0.07
1654 1804 -0.072
1655 1805 -0.072
1656 1806 -0.073
1657 1807 -0.075
1658 1808 -0.076
1659 1809 -0.076
1660 1810 -0.076
1661 1811 -0.075
1662 1812 -0.075
1663 1813 -0.076
1664 1814 -0.08
1665 1815 -0.081
1666 1816 -0.082
1667 1817 -0.083
1668 1818 -0.083
1669 1819 -0.085
1670 1820 -0.085
1671 1821 -0.084
1672 1822 -0.083
1673 1823 -0.082
1674 1824 -0.079
1675 1825 -0.079
1676 1826 -0.078
1677 1827 -0.077
1678 1828 -0.078
1679 1829 -0.08
1680 1830 -0.083
1681 1831 -0.085
1682 1832 -0.086
1683 1833 -0.087
1684 1834 -0.086
1685 1835 -0.083
1686 1836 -0.081
1687 1837 -0.078
1688 1838 -0.075
1689 1839 -0.073
1690 1840 -0.071
1691 1841 -0.069
1692 1842 -0.068
1693 1843 -0.069
1694 1844 -0.071
1695 1845 -0.072
1696 1846 -0.074
1697 1847 -0.074
1698 1848 -0.074
1699 1849 -0.078
1700 1850 -0.081
1701 1851 -0.083
1702 1852 -0.083
1703 1853 -0.083
1704 1854 -0.083
1705 1855 -0.085
1706 1856 -0.087
1707 1857 -0.084
1708 1858 -0.081
1709 1859 -0.075
1710 1860 -0.065
1711 1861 -0.055
1712 1862 -0.047
1713 1863 -0.038
1714 1864 -0.032
1715 1865 -0.029
1716 1866 -0.024
1717 1867 -0.019
1718 1868 -0.016
1719 1869 -0.012
1720 1870 -0.009
1721 1871 -0.004
1722 1872 -0.001
1723 1873 0.005
1724 1874 0.013
1725 1875 0.021
1726 1876 0.027
1727 1877 0.033
1728 1878 0.037
1729 1879 0.04
1730 1880 0.043
1731 1881 0.047
1732 1882 0.051
1733 1883 0.053
1734 1884 0.054
1735 1885 0.056
1736 1886 0.057
1737 1887 0.057
1738 1888 0.051
1739 1889 0.045
1740 1890 0.046
1741 1891 0.044
1742 1892 0.039
1743 1893 0.029
1744 1894 0.019
1745 1895 0.011
1746 1896 0.006
1747 1897 0.001
1748 1898 -0.003
1749 1899 -0.007
1750 1900 -0.009
1751 1901 -0.011
1752 1902 -0.011
1753 1903 -0.012
1754 1904 -0.01
1755 1905 -0.007
1756 1906 -0.003
1757 1907 0.002
1758 1908 0.009
1759 1909 0.017
1760 1910 0.026
1761 1911 0.038
1762 1912 0.049
1763 1913 0.063
1764 1914 0.076
1765 1915 0.093
1766 1916 0.111
1767 1917 0.13
1768 1918 0.151
1769 1919 0.174
1770 1920 0.198
1771 1921 0.222
1772 1922 0.246
1773 1923 0.269
1774 1924 0.289
1775 1925 0.307
1776 1926 0.325
1777 1927 0.343
1778 1928 0.359
1779 1929 0.376
1780 1930 0.393
1781 1931 0.41
1782 1932 0.43
1783 1933 0.449
1784 1934 0.47
1785 1935 0.502
1786 1936 0.533
1787 1937 0.553
1788 1938 0.566
1789 1939 0.574
1790 1940 0.577
1791 1941 0.577
1792 1942 0.577
1793 1943 0.574
1794 1944 0.57
1795 1945 0.566
1796 1946 0.561
1797 1947 0.555
1798 1948 0.55
1799 1949 0.543
1800 1950 0.538
1801 1951 0.531
1802 1952 0.525
1803 1953 0.519
1804 1954 0.516
1805 1955 0.512
1806 1956 0.51
1807 1957 0.509
1808 1958 0.506
1809 1959 0.504
1810 1960 0.5
1811 1961 0.496
1812 1962 0.492
1813 1963 0.487
1814 1964 0.484
1815 1965 0.478
1816 1966 0.473
1817 1967 0.469
1818 1968 0.466
1819 1969 0.466
1820 1970 0.466
1821 1971 0.466
1822 1972 0.467
1823 1973 0.471
1824 1974 0.475
1825 1975 0.481
1826 1976 0.487
1827 1977 0.492
1828 1978 0.5
1829 1979 0.51
1830 1980 0.522
1831 1981 0.535
1832 1982 0.548
1833 1983 0.563
1834 1984 0.577
1835 1985 0.594
1836 1986 0.612
1837 1987 0.634
1838 1988 0.66
1839 1989 0.688
1840 1990 0.725

Not a single 150-year period before 1766-1916 shows a greater than 0.1[sup]o[/sup]C warming.

Not a single 150-year period after 1767-1917 shows a less than 0.1[sup]o[/sup]C warming.

The total increase for 1840-1990 is +0.725[sup]o[/sup]C.

[brazil84]

@aptronym

I don’t contest that you can cherry-pick. I kept each of the time frames constant in 150 year chunks, and I evaluated each of the 150 year chunks throughout the graph.

Lol. My claim was about the slope of the graph. Where in your calculus textbook does it state that slopes must be evaluated in “150 year chunks”?

You did not argue that the temperatures only diverged in the “last” 42 years - you claimed they diverged for the instrumental temperature record, which is 150 years.

Sheesh . . . do you think you are accomplishing anything by setting up strawmen?

Here’s what I said:

Not only that, but it seems clear that the study you have cited did not pick up the rate of temperature change in recent history as indicated by the instrumental records.

Verifiably false.

[url=ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/oerlemans2005/oerlemans2005.txt]GEOGRAPHIC REGION: Global
PERIOD OF RECORD: 1600-1990 AD

Lol. Here’s what you said:

@aptronym

Meanwhile, temperature reconstructions from the glaciers (Science 29 April 2005:
Vol. 308. no. 5722, pp. 675 - 677) suggests a historical cooling/warming of +/- 0.2oC/century from 0-2000 CE

bolding added.

Looks like you are the one whose post is verifiably false.

[intention]

aptronym, I took a look at the glacier reconstruction you cited (Science 29 April 2005: Vol. 308. no. 5722, pp. 675 - 677), and was less than overwhelmed …

They claim to be able to tell the global temperature in the year 1600 with an error of a quarter of a degree.

Now, in the year 1600, they have exactly three glacier length data points, two of which are only about 100 km apart, and all of which are in Northern Europe.

The current error for instrumental data (HadCRUT3) with hundreds of stations worldwide is estimated by the HadCRUT folks at about an eighth of a degree.

Now tell me, aptronym … if we can only tell modern global temperature to an eighth of a degree or so, do you really believe that the length of three European glaciers four hundred years ago can tell us the global temperature at that time to a quarter of a degree? Just three glaciers?

Because if so … I’ve got a bridge for sale that you might be interested in …

Plus, if what they say is true, we could get rid of all of our modern temperature stations, and replace them with a couple dozen glaciers, it would be much cheaper.

Or, if just three European glaciers can tell the global mean temperature to a quarter of a degree, we could just replace them with three temperature stations (which have to be more accurate than glaciers) and we’d know the world temperature to better than a quarter of a degree.

So while you, and the author, and the reviewers might believe that study … I don’t. It doesn’t even pass the smell test. Three European glaciers four hundred years ago can tell the global temperature to a quarter degree? Riiight …

This is a perfect example of why peer review can’t be trusted to do anything than remove the most obvious of errors.

w.

[aptronym]

@brazil84

Lol. My claim was about the slope of the graph. Where in your calculus textbook does it state that slopes must be evaluated in “150 year chunks”?

You stated that the proxy record diverges from the instrumental record. The instrumental record is 150 years long.

@brazil84

Not only that, but it seems clear that the study you have cited did not pick up the rate of temperature change in recent history as indicated by the instrumental records.

False for almost any time frame you choose to play with.

Time Frame: Proxy[sup]1[/sup] Instrumental[sup]2[/sup]
1861-1990: +0.761[sup]o[/sup]C +0.815[sup]o[/sup]C
1871-1990: +0.704[sup]o[/sup]C +0.513[sup]o[/sup]C
1881-1990: +0.644[sup]o[/sup]C +0.477[sup]o[/sup]C
1891-1990: +0.623[sup]o[/sup]C +0.580[sup]o[/sup]C
1901-1990: +0.663[sup]o[/sup]C +0.505[sup]o[/sup]C
1911-1990: +0.614[sup]o[/sup]C +0.814[sup]o[/sup]C
1921-1990: +0.447[sup]o[/sup]C +0.535[sup]o[/sup]C
1931-1990: +0.270[sup]o[/sup]C +0.389[sup]o[/sup]C
1941-1990: +0.108[sup]o[/sup]C +0.182[sup]o[/sup]C
1951-1990: +0.176[sup]o[/sup]C +0.420[sup]o[/sup]C
1961-1990: +0.230[sup]o[/sup]C +0.292[sup]o[/sup]C
1971-1990: +0.263[sup]o[/sup]C +0.426[sup]o[/sup]C
1981-1990: +0.194[sup]o[/sup]C +0.118[sup]o[/sup]C

[sup]1[/sup] As referenced above.
[sup]2[/sup] http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/annual

@brazil84

Here’s what you said:

@aptronym

Meanwhile, temperature reconstructions from the glaciers (Science 29 April 2005:
Vol. 308. no. 5722, pp. 675 - 677) suggests a historical cooling/warming of +/- 0.2[sup]o[/sup]C/century from 0-2000 CE

bolding added.

Probably a typo. Here’s another proxy data set if you really want the 1-1600 time frame.

Moberg, A.; Sonechkin, D.M.; Holmgren, K.; Datsenko, N.M.; Karlen, W.
Nature 2005, 433, 7026, 613-617.

Time Frame: Proxy[sup]1[/sup] Instrumental[sup]2[/sup]
1850-1979: +0.3488[sup]o[/sup]C +0.458[sup]o[/sup]C
1860-1979: +0.1547[sup]o[/sup]C +0.434[sup]o[/sup]C
1870-1979: +0.0977[sup]o[/sup]C +0.313[sup]o[/sup]C
1880-1979: +0.3465[sup]o[/sup]C +0.266[sup]o[/sup]C
1890-1979: +0.2302[sup]o[/sup]C +0.434[sup]o[/sup]C
1900-1979: +0.3645[sup]o[/sup]C +0.198[sup]o[/sup]C
1910-1979: +0.0754[sup]o[/sup]C +0.615[sup]o[/sup]C
1920-1979: -0.0675[sup]o[/sup]C +0.379[sup]o[/sup]C
1930-1979: +0.1553[sup]o[/sup]C +0.229[sup]o[/sup]C
1940-1979: -0.3062[sup]o[/sup]C +0.043[sup]o[/sup]C
1950-1979: +0.2922[sup]o[/sup]C +0.395[sup]o[/sup]C
1960-1979: +0.3922[sup]o[/sup]C +0.193[sup]o[/sup]C
1970-1979: +0.1112[sup]o[/sup]C +0.128[sup]o[/sup]C

[sup]1[/sup] ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/moberg2005/nhtemp-moberg2005.txt
[sup]2[/sup] HadCRUT3, as referenced above

@brazil84

Looks like you are the one whose post is verifiably false.

:rolleyes:

[aptronym]

@intention

I took a look at the glacier reconstruction you cited (Science 29 April 2005: Vol. 308. no. 5722, pp. 675 - 677), and was less than overwhelmed …

You are free to be underwhelmed or overwhelmed, but unless you have some particular expertise in climatology, it’s really irrelevant.

(1) Do you?
(1a) If you do, which datasets are acceptable and which are unacceptable?
(1b) Are there any datasets that you consider acceptable that show both the existence of a MWP and LIA and temperature divergence in the 20th century? Which one(s)?

(2) Both authors and reviewers at Science magazine have accepted this as an acceptable proxy.

@intention

if we can only tell modern global temperature to an eighth of a degree or so, do you really believe that the length of three European glaciers four hundred years ago can tell us the global temperature at that time to a quarter of a degree? Just three glaciers?

This is an applaudable evasion of the issues at hand. The issue of whether the proxy data is representative of global temperatures is an issue that is completely separate from what we have discussed so far.

The question is whether the proxy data matches the instrumental data in the overlapping time frame.

(1) If YES, then the issue is settled - brazil84 claims to reject all proxies based on divergence, and if there is no divergence, he has to accept them.

(2) If MAYBE, then the issue is again settled - brazil84 is making a positive claim that peer-reviewed, published scientific data should be ignored. If there is any ambiguity, again, I appeal to the fact that authors and reviewers in Science have accepted such proxies. In the absence of any authoritative reason why they should be ignored, they should be accepted.

(3) If NO, then I have one final question for both you and brazil84 - if the proxies irreconcilably diverge (i.e. even if you show a divergence I would argue that it may not be irreconcilable), then how would you ever know there was a Medival Warming Period or Little Ice Age? Without a proxy record, no temperature statements can be made prior to 1850 at all. Our understanding of a MWP and LIA come from proxy records - if you reject proxy records, you cannot then claim that there was even a MWP.

@intention

do you really believe that the length of three European glaciers four hundred years ago can tell us the global temperature at that time to a quarter of a degree?

(quoting again so I can answer your question proper)

I believe that multiple glaciers, plus multiple tree-ring chronologies, all paint a consistent picture across most of the globe. That the data is not global per se is a caveat when looking at a single study, not a reason for rejection of all data.

The single study itself does not prove global temperatures - multiple, independent studies (glaciers, tree rings, sediments, etc.) which all show similar trends proves global temperature shifts.

@intention

So while you, and the author, and the reviewers might believe that study … I don’t.

In other words, you are taking a position which is directly contrary to peer-reviewed science. I want you to be absolutely clear, because this is a fundamental shift from your past argument - you’re going from “science supports my position” to “science is wrong.”

[brazil84]

@aptronym

You stated that the proxy record diverges from the instrumental record. The instrumental record is 150 years long.

So you no longer dispute my claim about the slope of the graph?

Simple yes or no question. (Not that I expect an answer.)

False for almost any time frame you choose to play with.

Let’s take 1950 to 1990, which encompasses the bulk of the “back half of the century.” According to your own calculation, the proxy picks up well under half of the warming as allegedly detected by instruments.

Looks like my claim is correct.

Probably a typo.

Lol. A demonstrably false typo.

[brazil84]

@aptronym

(1) If YES, then the issue is settled - brazil84 claims to reject all proxies based on divergence, and if there is no divergence, he has to accept them.

It depends what you mean by “reject” and “accept.” But anyway, I mean exactly what I say - nothing more, and nothing less.

(3) If NO, then I have one final question for both you and brazil84 - if the proxies irreconcilably diverge (i.e. even if you show a divergence I would argue that it may not be irreconcilable), then how would you ever know there was a Medival Warming Period or Little Ice Age? Without a proxy record, no temperature statements can be made prior to 1850 at all. Our understanding of a MWP and LIA come from proxy records - if you reject proxy records, you cannot then claim that there was even a MWP.

Assuming for the sake of argument that the proxies irreconcilably diverge (and I don’t know this to be the case), one can still be pretty confident that there was a medieval warm period based on the proxy record. You just don’t know the temperatures with a lot of precision.

For example, during the medieval warm period, there was apparently agriculture in parts of Greenland that are now subject to permafrost. If you combine this with similar types of evidence, you can infer that things were probably warmer then than now.

[aptronym]

@brazil84

So you no longer dispute my claim about the slope of the graph?

Simple yes or no question. (Not that I expect an answer.)

No, I completely dispute your claim.

@brazil84

Let’s take 1950 to 1990 … According to your own calculation, the proxy picks up well under half of the warming as allegedly detected by instruments.

Looks like my claim is correct.

No, it looks like you’ve arbitrarily picked a random date which happens to coincide with your prejudice.

1981-1990 shows a warming greater than the instrumental record. How come you don’t cite that as your example?

Your claim was that the proxies diverge from current data. Picking a certain set of numbers and a short time frame only plays with the short-term variation on temperature.

For example, I could move back a year and make the proxies look worse …
Time Frame: Treering Instrument
1950-1990: +0.168[sup]o[/sup]C +0.587[sup]o[/sup]C

… or forward one and make them look better.
Time Frame: Treering Instrument
1952-1990: +0.184[sup]o[/sup]C +0.336[sup]o[/sup]C

I could point to the period from 1858-1990, where both warmings are exactly +0.777[sup]o[/sup]C. Hey, look, a perfect match; am I right? No, that proves my point no more than the 1951-1990 data proves yours.

This is why I advocate taking as long a time as possible - average as many 11-year solar cycles; smooth out as many anomalies due to volcanic eruptions; etc. Any way you cut the data, you see a modest warming from the 1850’s to the 1940’s; a small cooling from the 1940’s to the 1960’s, and then another modest increase from the 1970’s to the 1980’s in both data sets. The longer of a time period you look at, the more reliable the results are. Data based on short time periods are simply artifacts of noise.

My analysis does not depend on the exact date picked. Yours does.

@brazil84

which encompasses the bulk of the “back half of the century.”

The “back half of the century” quote is yours, not mine.

Allow me to remind you of the quote that you contest.

@brazil84

@aptronym

The existence of a Medieval Warm Period (which is included in the texts of the 3AR and 4AR but confusingly missing from the Summaries) really has limited influence on this conclusion - absolute temperature doesn’t matter since humans are adaptable; rate of temperature change is the key. Historically, temperatures have moved about 0.3[sup]o[/sup]C per century in recent history, current warming is 1[sup]o[/sup]C per century.

For reasons explained in my “temperature record” thread, I dispute this.

@brazil84

Assuming for the sake of argument that the proxies irreconcilably diverge (and I don’t know this to be the case), one can still be pretty confident that there was a medieval warm period based on the proxy record. You just don’t know the temperatures with a lot of precision.

You completely understand - when you filter out the year-to-year variation in temperatures, you can get a decent picture of the centennial-length climatological shifts.

Now simply apply the same statement to the entire proxy record. It’s not contested that the absolute temperatures are pretty nebulous - so nebulous, in fact, that scientific publications use “Temperature Anomaly” instead of “Kelvin”. Ice cores sometimes just report [sup]18[/sup]O/[sup]16[/sup]O ratios rather than the corresponding temperature. Few attempts to measure absolute temperature make it into the publishable realm.

That is why the only analyzable characteristic is temperature difference. While the absolute temperatures are debatable, the difference remains constant. You are free to pick a time frame between 100 and 150 years, and I will analyze the data to show that the long-term averages support my assertion.

@brazil84

For example, during the medieval warm period, there was apparently agriculture in parts of Greenland that are now subject to permafrost. If you combine this with similar types of evidence, you can infer that things were probably warmer then than now.

By that measure, you can be sure that global warming is happening because the ice cap keeps shrinking. Poor polar bears stranded in the Arctic Ocean! Icebergs the size of Rhode Island breaking off of Antarctica!

Pul-eeze.

I don’t cite this crap in favor of global warming nor do I accept the same crap against it.

[aptronym]

@brazil84

If you combine this with similar types of evidence, you can infer that things were probably warmer then than now.

I forgot to single this out and it’ll probably take me more than 5 minutes so I’ll just put it in a new post.

That things were warmer then than now is completely irrelevant to the topic of discussion. I never claimed that we are at the warmest point ever; I claimed that the temperature now is increasing faster than it did before.

I don’t contest that humans can adapt to any absolute temperature - even +/- 10[sup]o[/sup]C. Even our cavemen ancestors were able to do it at the end of the last Ice Age - but that change happened over several hundred or thousands of years.

Thus, it’s the rate at which temperature changes which is the most relevant. That we can successfully plant crops in Nunavut if warming turns it into a breadbasket is not in doubt - whether we could do it in a decade without massive famines is. That Siberia and Canada would become the new world superpowers is no problem by itself - but if it were to happen in the space of a decade, we’d have some serious political problems.

The problems of global warming stem from the rate of temperature change, not the absolute temperature.

[brazil84]

@aptronym

No, I completely dispute your claim.

Too bad the only facts you’ve cited to dispute the claim were cherry-picked. As I suggested before, there’s no rule that says the slope of a graph must be evaluated in 150 year chunks.

All you’ve done on this point is obfuscate.

No, it looks like you’ve arbitrarily picked a random date which happens to coincide with your prejudice.

False. Anyway, since I’m the one questioning the proxy, it’s my privilege to pick out a time period. 1950 to 1992 (the end of the study) is a reasonable choice.

The proxy record you chose diverges, even though the study authors no doubt calibrated the proxy as best they could to the instrumental record.

The bottom line is very simple. Just look at the graph with your own eyes: There’s no hockey stick.

It’s as simple as that.

By that measure, you can be sure that global warming is happening because the ice cap keeps shrinking.

Not sure, but one can infer that things are likely warmer now than they were in the 1970s when the artic had a lot more ice.

That things were warmer then than now is completely irrelevant to the topic of discussion. I never claimed that we are at the warmest point ever; I claimed that the temperature now is increasing faster than it did before.

Lol. Obfuscating again, are you? Do you remember that a couple posts ago you asked me and intention how one could know that there was a medieval warm period? I guess that’s “irrelevant” now. Lol.

[wevets]

Happy New Year, everyone!

Mexico was great – I hope everyone had at least as good a Hannukah/Christmas/Kwanzaa/Winter Solstice/Deforestation and Consumerism Festival time as I did.

@brazil84

The fact that you look at the instrumental record alone and see an “elbow” (actually multiple elbows) doesn’t necessarily mean anything and doesn’t undercut my basic point about splicing.

Here’s why I don’t see it that way. There are two requirements for a “hockey stick” like figure to exist:

1. A long, relatively flat “handle.”
2. A shorter, steeper, “blade” at the end.

An “elbow,” as I mentioned in my first post in this thread, is a poorly defined feature that is a result – not a cause of - the two features listed above. “Elbows” cannot be used to define a hockey stick and are the least easily determined part of it, simply because they are subjective – one person’s “elbow” is not another person’s “elbow.” Which inflection point do you choose as your elbow? 1902? 1920? Ask different people and you’ll get different answers. However, you can identify a “hockey stick” like shape even if you don’t know which inflection point is the “correct elbow” – if such a thing as the “correct elbow” could even be said to exist.

What do I see when I look at the instrumental temperature record? A relatively steep “blade.”

What do I see when I look at the paleoclimate proxies? A curve that goes up and down, but generally less steep than the “blade” in the instrumental temperature record, making a “handle,” if you will (actually, I’m pretty sure you won’t .)

My point being that criticisms of a “hockey stick” shape based on the “elbow” are considerably less convincing than, say, an extremely warm Medieval Warm Period would be.

It’s very helpful that from about 1856-1890 you can see in the instrumental temperature record a relatively less steep portion which I would consider (and I’m guessing you would not consider) part of the “handle” of a “hockey stick.”

@brazil84

And if you CAN see a trend in recent temperatures, you need to ask yourself if there is any way of measuring similar trends in past temperatures. Conversely, if you find a trend in past temperatures, you need to ask what happens if you apply the same technique to recent temperatures.

And you think paleoclimatologists do not ask these questions?

Have you read any of the portions of their work where they describe the calibration, validation, and reconstruction portions of creating a paleoclimatic reconstruction? Or do you believe the answers they have come up with in these portions are incorrect?

[brazil84]

[QUOTE=wevets]
Happy New Year, everyone!
[/quote]

Thanks, you too.

Here’s why I don’t see it that way. There are two requirements for a “hockey stick” like figure to exist:

1. A long, relatively flat “handle.”
2. A shorter, steeper, “blade” at the end.

I defined it a little more precisely, but your definition sounds ok.

An “elbow,” as I mentioned in my first post in this thread, is a poorly defined feature that is a result – not a cause of - the two features listed above.

I would say that the “elbow” is the area where the stick meets the handle.

What do I see when I look at the instrumental temperature record? A relatively steep “blade.”

What do I see when I look at the paleoclimate proxies? A curve that goes up and down, but generally less steep than the “blade” in the instrumental temperature record, making a “handle,” if you will (actually, I’m pretty sure you won’t .)

It depends which proxies you look at, but even based on what you said, it follows that no splicing = no hockey stick.

And you think paleoclimatologists do not ask these questions?

I would hope that they do!

Have you read any of the portions of their work where they describe the calibration, validation, and reconstruction portions of creating a paleoclimatic reconstruction? Or do you believe the answers they have come up with in these portions are incorrect?

What answers? What paleoclimatoligists? Which works?

[FoieGrasIsEvil]

The Earth has gotten colder and warmer in the past millenia, centuries, decades, etc.
The Earth obviously has cyclical changes to it that are beyond our control and influence.
It’s probablt practical to assume that the more people and industry we have, the more pollution we have, which is harmful to the Earth and it’s land and waterways.
If we can reduce our output of emissions that affect these issues, then it’s good, right?
Do we need a politician or a government to tell us this? Can’t we figure out a way to slow this down on our own?
Indepedence on oil would be a GREAT start, both for the Earth AND for the foreign policies of Western nations.

The infrastructure of say the USA is designed for wheeled vehicles. Can we not manufacture wheeled vehicles to travel along the paved roads without being powered by internal combustion engines?

I know, I know, special interests. Defeated yet again we are.

[intention]

[QUOTE=aptronym]
Quote:
[QUOTE=intention]
I took a look at the glacier reconstruction you cited (Science 29 April 2005: Vol. 308. no. 5722, pp. 675 - 677), and was less than overwhelmed …
[/QUOTE]

You are free to be underwhelmed or overwhelmed, but unless you have some particular expertise in climatology, it’s really irrelevant.

(1) Do you?
(1a) If you do, which datasets are acceptable and which are unacceptable?
(1b) Are there any datasets that you consider acceptable that show both the existence of a MWP and LIA and temperature divergence in the 20th century? Which one(s)?
[/quote]
(1) Yes.
(2) I am not clear what you are asking here. Often, the problem lies not with the datasets, but with the interpretation placed on them. In this case, the dataset seems reasonable enough … but claiming we can tell the temperature 400 years ago to a quarter of a degree with this dataset is nonsense.
(3) Dunno … if a proxy shows divergence in the 20th century, I tend not to pay attention.

[QUOTE=aptronym]
(2) Both authors and reviewers at Science magazine have accepted this as an acceptable proxy.
[/quote]
Yes, that is true of everything that Science magazine publishes, it has been accepted by authors and reviewers. I truly, truly hope that you don’t think this means anything about the truth or falsity of a given paper.

[QUOTE=aptronym]

[QUOTE=intention]
if we can only tell modern global temperature to an eighth of a degree or so, do you really believe that the length of three European glaciers four hundred years ago can tell us the global temperature at that time to a quarter of a degree? Just three glaciers?
[/QUOTE]
This is an applaudable evasion of the issues at hand. The issue of whether the proxy data is representative of global temperatures is an issue that is completely separate from what we have discussed so far.

The question is whether the proxy data matches the instrumental data in the overlapping time frame.
[/quote]
Perhaps that was your question, but I was not attempting to answer that question. My question was whether the glacier study was believable. I found it not to be so. You have evaded the question of whether we should believe the claims made by the author of the glacier study.

[QUOTE=aptronym]
(1) If YES, then the issue is settled - brazil84 claims to reject all proxies based on divergence, and if there is no divergence, he has to accept them.

(2) If MAYBE, then the issue is again settled - brazil84 is making a positive claim that peer-reviewed, published scientific data should be ignored. If there is any ambiguity, again, I appeal to the fact that authors and reviewers in Science have accepted such proxies. In the absence of any authoritative reason why they should be ignored, they should be accepted.

(3) If NO, then I have one final question for both you and brazil84 - if the proxies irreconcilably diverge (i.e. even if you show a divergence I would argue that it may not be irreconcilable), then how would you ever know there was a Medival Warming Period or Little Ice Age? Without a proxy record, no temperature statements can be made prior to 1850 at all. Our understanding of a MWP and LIA come from proxy records - if you reject proxy records, you cannot then claim that there was even a MWP.
[/quote]
There are a variety of proxies which do not have the “divergence problem”. However, that doesn’t mean that they are necessarily valid, or that the conclusions drawn by a particular author from a given proxy are correct.

[QUOTE=aptronym]

[QUOTE=intention]
do you really believe that the length of three European glaciers four hundred years ago can tell us the global temperature at that time to a quarter of a degree?
[/QUOTE]
(quoting again so I can answer your question proper)

I believe that multiple glaciers, plus multiple tree-ring chronologies, all paint a consistent picture across most of the globe. That the data is not global per se is a caveat when looking at a single study, not a reason for rejection of all data.

The single study itself does not prove global temperatures - multiple, independent studies (glaciers, tree rings, sediments, etc.) which all show similar trends proves global temperature shifts.
[/quote]
You have not “answered my question proper”. You have not answered it at all. So let me ask it again. Do you really believe that the length of three European glaciers four hundred years ago can tell us the global temperature at that time to a quarter of a degree? It’s a simple question, a yes or no will do quite nicely, and anything else is obfuscation.

If YES, then we can throw out our thermometers, if three glaciers show global temperature to a quarter of a degree, then thirty of them would replace all of the world’s temperature stations at a fraction of the cost.

If NO, then why would we believe anything that the study’s author’s say?

And while you say that “The single study itself does not prove global temperatures”, the authors clearly claim that their single glacier study shows accurate global temperatures. Are you saying you don’t believe them?

[QUOTE=aptronym]

[QUOTE=intention]
So while you, and the author, and the reviewers might believe that study … I don’t.
[/QUOTE]
In other words, you are taking a position which is directly contrary to peer-reviewed science. I want you to be absolutely clear, because this is a fundamental shift from your past argument - you’re going from “science supports my position” to “science is wrong.”
[/QUOTE]
Ah, I see the problem. You think that if a paper is published in a peer reviewed journal, that makes it “science”, and thus if I disagree with a peer reviewed paper, I am saying “science is wrong”.

There are two problems with your claim. The first is the ludicrous idea that peer review establishes scientific truth. It does nothing of the sort. In some fields of science, well over half of the peer reviewed papers are eventually shown to be wrong. Mann’s original “hockeystick” paper contained egregious errors … but it was peer reviewed.

Here is how science progresses. Someone writes a paper, and someone else tries to find fault with it. If they can find fault with it, the paper is rejected. If no one can find anything wrong with the paper, it is provisionally accepted as scientific truth. The problem is thinking that peer review establishes the truth. It does not. The value of a scientific paper is how well it stands up to examination, not by peer reviewers, but by other scientists.

ALL PEER REVIEW DOES IS FIND OBVIOUS ERRORS. It does not guarantee that the claims of the author are correct. It does not make that paper “science”, as you seem to think.

The second problem with your claim is the idea that ordinary mortals such as yourself must accept all peer reviewed papers without question. Dude, you have a brain. Use it! Think about the claims the authors are making. Are they reasonable? Do they make sense? Scientists are not gods, and many of their claims are demonstrably false to even an untrained eye.

This glacier paper is a perfect example. As I pointed out, they make the remarkable claim that we can determine global temperatures to within ± 0.25°C, four hundred years ago, from the length of three northern European glaciers …

Now perhaps you just nod your head and say “author said it, reviewers passed it, it must be gospel scientific truth” … but in my world that claim doesn’t even pass the smell test.

You were given your fine mind for a purpose.

Use it or lose it …

w.