Medieval Climate Not So Hot

University Of Arizona ^ | 10-20-2003 | U of Arizona

[blam]

Ping.

[T. P. Pole]

To reconstruct climate, scientists use natural archives, including tree rings, ice cores and laminated sediments. These natural records of temperature, precipitation and other environmental history have been carefully calibrated with instrumental observations, giving scientists quantitative information on past conditions at particular locations.

How about the archives that include the facts that people lived and grew crops in Iceland? Or is that too subjective?

[smith288]

[Always Right]

Medieval Warmth
in Alaska (3 Oct 03)

A new paper in Science (v.30, 26 Sept 03, p.1890) by Feng Sheng Hu et al, reveals that western Alaska enjoyed the full warmth of the Medieval Warm Period (850 AD to 1200 AD), based on cores from tundra lake sediments. There was also a previous warm period from 0 AD to 300 AD, the periods of warmth apparently following a cyclic pattern, consistent with changes in the Sun.

Ordinarily, climate events 1,000 years ago would not excite public interest, were it not for the IPCC's obsession with a spurious claim, based on the flimsiest of evidence, that no time in the past was as warm as it is today.

This is the infamous `Hockey Stick' theory, the latest incarnation of which was recently published in Geophysical Research Letters.

The key claim of the `Hockey Stick' theory was that the major known climatic events of the past millennium - the Medieval Warm Period and Little Ice Age - were merely local events in Europe and that the bulk of the northern hemisphere - and even the world as a whole - enjoyed an even and stable climate until the human warming of the 20th century. That's the theory - and none of it is true.
(contd...)

Now we have recent evidence that it spread far beyond Europe, all the way into the northern Pacific via western Alaska, thus rendering the `Hockey Stick' as a junk theory which is now only propped up by political correctness and public vilification of its critics.

Numerous papers and studies are now being published which demonstrate what a nonsense the IPCC's `Hockey Stick' really is, and its almost fanatical adoption by the greenhouse industry reflects badly on their scientific competence.

Source: John Daly

[Always Right]

Scientists have well-calibrated, detailed data from such proxy records covering the past 1,500 years of temperature for only a few locations around the globe, the researchers noted.

Well-calibrated??? How do you calibrate tree ring data which tells you more about the length of the growing season than the tempreture?

However, recent modeling studies show that increased solar irradiance does not warm Earth's surface at all locations, the research team wrote.

The is just great scientific work. Use your computer models to prove your theory. Of course your models assume your theory is correct. Computers just tell you what you told them to tell you, which isn't proof of anything.

[NotQuiteCricket]

(six-tenths of a degree Fahrenheit)
Is there a reason for this to not be three-fifths? What happened to always reducing fractions?

[Ole Okie]

(six-tenths of a degree Fahrenheit)
Is there a reason for this to not be three-fifths?

---

Well, six is greater than three. And ten is much larger than five.

See, global warming is PROVED!

Oh, global warming searches high and low for facts such as this.

And most of their models are built on crap. GIGO.

[Wonder Warthog]

"Well-calibrated??? How do you calibrate tree ring data which tells you more about the length of the growing season than the tempreture?"

Uh, the calibration is inherent in the ring patterns themselves. Individual rings may be wider or narrower due to variations in climate, but there is always "one set of rings per year". Measurement of the stable isotope ratios of oxygen (I believe oxygen 16 vs. oxygen 18 are the ones used) within any given ring tell you the average temperature over that ring/year.

Do a web search on "dendrochronology" to learn more.

[Lion Den Dan]

calibration is inherent in the ring patterns themselves. Individual rings may be wider or narrower due to variations in climate, but there is always "one set of rings per year"

Gee, what does it tell us when a single ring or series of rings is wider on one side of the tree than on the other?

[DustyMoment]

The problem with all of this is that prior to accurate temperature records being kept (starting in the late 19th Century) we don't really know what the climate was like other than in the most general terms. Theories abound.

Global warming is condemned as a bad thing that threatens all life on the planet and, yet, the Renaissance is attributed to a period of global warming that allowed people to get out of dark, damp houses filled with exhaust gases from fires and lamps and get into the sunshine. The Renaissance sparked one of the greatest periods (to date) of growth, exploration and artistic expression. So, is global warming necessarily an evil thing?

The fact is that we simply have too little knowledge of earth's climate and the influences on it. Until we have a much larger data sample size (at least another century and possibly more) of climatological data, we are unable to accurately explain climatological anomalies with anything other than speculation and hysterical hyperbole.

[Mackey]

Is there a reason for this to not be three-fifths?

Because it's a decimal: 0.6.

[lizma]

How do you calibrate tree ring data which tells you more about the length of the growing season than the tempreture?

Exactly. Tree rings are very dependent on rainfall. Also most climatologist believe volcanic eruptions lead to global cooling.

The problem is that politics (and maybe grant money(?)) has been such a major motivator in this argument that it is impossible to distinguish fact from propaganda.

[avg_freeper]

I imagine that being a climate researcher is very difficult when you're required to spend so much time running around the lab with fingers in your ears yelling "La La La I CAN'T HEAR YOU".

[Always Right]

It was my understanding that dendrochronology is used for dating the rings, not for calculating temperature. The size of the rings is used to obtain climate information, which doesn't really give you a temperature so much as tells you how the overall growing season was which is based on amount of rainfall and numerous other variables.

[Wonder Warthog]

"Gee, what does it tell us when a single ring or series of rings is wider on one side of the tree than on the other?"

Basically that the tree was lopsided. But that doesn't change anything about the validity of the isotope ratio temperature data. In your postulated case, one would take measurements in the wide and narrow areas and compare them.

[null and void]

Gee, what does it tell us when a single ring or series of rings is wider on one side of the tree than on the other?

It tells you the tree was leaning. The ratios of width ring-to-ring are still the same on each side. Wider rings are the same percentage wider than narrower rings.

[Wonder Warthog]

"It was my understanding that dendrochronology is used for dating the rings, not for calculating temperature. The size of the rings is used to obtain climate information, which doesn't really give you a temperature so much as tells you how the overall growing season was which is based on amount of rainfall and numerous other variables."

Which is why you need the isotope ratio, as that is independent of rainfall. The tree ring pattern gives you the dates, the isotope ratios in the rings give you the temperatures for the year of a specific date.

I suspect they also cross check these against the same isotope ratios in seashells deposited in silt layers (again, the silt layer gives you the year, and the isotope ratio again gives temperature).

You have to remember that these measurements always involve many, many data points--they are not trying to get one temperature from a single tree ring.

[farmfriend]

Rights, farms, environment ping.

Let me know if you wish to be added or removed from this list.
I don't get offended if you want to be removed.

[blam]

FYI, The tree ring chronology is now over 10,000 years long. This guy, Mike Baillie, has done some amazing work with this data.