Talk:Little Ice Age
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Global vs local paragraph
This article includes discussion of global warming which is off the topic. Would it be better if the second paragraph were moved to the global warming page? Robert McFaul 00:28, 28 Feb 2004 (UTC)
(William M. Connolley 11:22, 2004 Feb 28 (UTC)) Do you mean:
- It was initially assumed that the LIA was a global phenomenon. It is now less clear that this is true [1]; for example the reconstruction of temperature in the northern hemisphere over the last 1000 years [2] does not show a pronounced period of cooling. See Medieval Warm Period for more on this. The IPCC describes the LIA as a modest cooling of the Northern Hemisphere during this period of less than 1°C.
If you do, I don't understand your comment. This is pure LIA.
- I was referring to making the article follow the form - In European history ... the LIA ... etc. For discussion of global rather than regional climate changes, see Global Warming.
This alternative I am suggesting is to describe the LIA as a European History event and refer global climate change interested readers to the Global Warming page. Robert McFaul 02:57, 2 Mar 2004 (UTC)
- (William M. Connolley 09:36, 2004 Mar 2 (UTC)) I advise against it. For one thing, there is the politics: for some people it is important for the LIA to be global, and if you go and describe it as pure European you will annoy them a lot. For another, whether it was global or not is one of the LIA's interesting questions and belongs (I think) with the LIA page.
OK, I will accept your advice. Robert McFaul 22:02, 3 Mar 2004 (UTC)
Phrasing of dates
(SEWilco 04:01, 21 May 2004 (UTC)) I used the other phrasing, with 14th century, to make Wiki Preferences date handling easier. If "century" is outside the brackets, Wiki coders will have to work harder to detect and properly display that. I recognize the century is unlikely to change unless Wiki includes display using other calendars.
Classification of links
(SEWilco 04:12, 21 May 2004 (UTC)) I thought it was appropriate to group references based on POV (the labels were from the hosting site's "About" descriptions). Similar to how pages about organizations have those grouped based upon their focus. Or perhaps the hosting organization should simply be present as a label, being linked to their About page, just as a study from a University site might have a link to that organization.
- (William M. Connolley 08:41, 2004 May 21 (UTC)) I disagree. Labelling the IPCCs discussion of LIA/MWP under "risk of human cl ch" makes little sense. OTOH as far as I'm concerned the greening-the-earth-soc folk are POV-pushers, so if you want to label them as Skepticism concerning catastrophe I won't object again.
- (SEWilco 15:40, 21 May 2004 (UTC)) Both phrases are POV from the definition of the organizations. I'll let readers interpret the organizations themselves.
(SEWilco 04:29, 21 May 2004 (UTC)) Apparently someone read two of the linked studies, and added summaries or notes. Other readers are invited to do that. The current links are a few which seemed particularly relevant, particularly another which shows little LIA signature.
- (William M. Connolley 08:41, 2004 May 21 (UTC)) I added the notes. The problem is there are countless LIA studies around, you can only make a random selection of a few to link to.
Glob/reg ref
(WMC) For SEW: Google Groups search for "little ice age" "climatic change" connolley (http://groups.google.com/groups?q=%22little+ice+age%22+%22climatic+change%22+connolley&hl=en&lr=&ie=UTF-8&selm=3qen1v%24eu5%40kwuz.nerc-keyworth.ac.uk&rnum=2)
- (SEWilco 15:40, 21 May 2004 (UTC)) You forgot the preceding paragraph, which indicates interest in the MWP. There seems to be agreement that the LWP was a global decline in temperatures associated with the Maunder Minimum and punctuated by volcanic activity. The MWP is more controversial, but in whether the higher temperatures were globally synchronous or regionally scattered (and corresponding colder regions).
- "We come back to our original question: was there a "Medieval Warm Period",
and if so, where and when? Some of the evidence compiled here and in the 12 articles of this special volume suggests that the time interval known as the MWP from the ninth to perhaps the mid fifteenth century AD may have been associated with warmer conditions than those prevailing over most of the next 5 centuries (including the 20 C), at least during some seasons of the year in some regions."
(William M. Connolley 17:31, 2004 May 21 (UTC)) I really don't understand why you persist in this. "The generalised behaviour of the global climate of the last millenium as a Medieval Warm Period followed by a Little Ice Age, each of one or more centuries long and global in extent, *is no longer suppported by the available evidence*." Thats from a paper published in 1994. So please stop the rubbish about IPCC changing its mind in 2001. You need to read more scientific papers and fewer right wing websites.
Orbital cycles
I've removed the stuff about the Milankovitch cycles as a reason for the Little Ice Age. The explanation an anon editor had added was:
- The Earth's axis of rotation slowly changes through time, much as a quickly spinning child's top will slowly precess. The direction the axis is pointing relative to the sun defines the Earth's seasons (See Milankovitch_cycles). The rate of axial precession changes the dates of the seasons by one day per 58 years. The Earth's orbit around the sun is somewhat elliptical, meaning that at some points during the year the Earth is closer to the sun than at other times. In about the year 1250 AD, each European summer was coming when the Earth's north pole was tilted toward the sun when the Earth was farthest from the sun, causing cooler than average summer temperatures in the northern hemisphere.
This is hopelessly confused. 1 day per 58 years seems about right, but summer on the Northern hemisphere is always when the North Pole is tilted towards the sun. It's just that this happens every some 21000 years when the Earth is at its aphelion, which results in about a 6% decrease in insolation compared to when it happens at the perihelion. And anyway, take about 750 years and divide by 58: you'd get a difference of some 12 days. The Milankovitch cycle is just too long to explain such relatively short phenomena as the Little Ice Age.
Lupo 13:48, 20 Jul 2004 (UTC)
end of lia / recovery
(William M. Connolley 11:03, 29 Aug 2004 (UTC)) If the lia ended in 1850, how can we still be recovering from it?
- Maybe we're still warming back up to MWP or HTM temperatures? (SEWilco 06:20, 18 May 2005 (UTC))
- (William M. Connolley 16:28, 18 May 2005 (UTC)) Since we're already clearly above MWP temperatures, that would seem rather unlikely.
- I'm sure you have your sources. (SEWilco 18:28, 18 May 2005 (UTC))
LIA artwork
There was a flurry of cold-scene paintings during the LIA. Anyone have more precise timings? So far all I've found was mention of there being a transition between two painting styles during that period. (SEWilco 06:19, 18 May 2005 (UTC))