What's a regional anomaly?

Question

Evidence for the MWP comes from around the world, and no contravening explanation has ever been offered - just why were tree lines higher in both the Alps and the Sierra Nevadas? What's a regional anomaly? Are the Alps and the Sierra Nevadas part of one weather region? I didn't know that.


http://www.climateaudit.org/?cat=8

Ard-Druid - isn't the global climate the sum of all the micro-climates?

The physical evidence from the period indicates that all of the micro-climates but one were warmer.

Dig, no no, the evidence for the MWP is multifarious and global. Higher tree lines, trade routes though mountain passes now glaciated, wild and domestic plant and animal species growing closer to the poles than they do today, etc....

Trevor tree lines were 300 feet higher in both the Sierras and the Alps.

Yes, at the present temps, if sustained, tree lines will grow again - - but that's my point - - at least these temps existed for a few centuries.

I'm not saying that disproves man-made GW - I'm just saying it's silly to argue that it didn't happen. You want to talk about concensus, it was the uniform position of 100% of climatologists that the MWP happened - until 1998. Not "a few mentions based on scant evidence" - the evidence is voluminous.

And what of all those people who 1000 years ago WROTE their observations that these things were happening and who attributed them to the climate?

Were they part of the vast right wing conspiracy, 1000 years before their time?

OK so other than flat out lies or errors (Trevor's note about tree lines not being higher than now even though they were 300 feet higher during the MWP), nobody has an answer.

Look, I think that if you're going to say that something that since it happened has been universally accepted as having happened all of a sudden didn't in fact happen, you're obligated to explain away the evidence that it did happen - and that hasn't begun to have happened.

It's simply not possible to argue that yes they all happened but that doesn't mean it was warmer. We're talking about trade routes now ice bound, hand-tool farming in areas now covered with permafrost. And we're talking about almost the entire civilized world, with almost no evidence that it was colder somewhere else.

How did these things most of which could not happen today happen then if not for a similar and stronger warming?

Answer 1

There are a lot of variances in the world wide propaganda network. What ever the cause you can always blame it on global warming and the lemmings will believe you.

Answer 2

Tree lines have been higher in places other than the Alps and Sierra Nevada's but not that much higher than they currently are. During the interglacials they would have been much higher, trees grew in the Arctic and Antarctic regions during these periods.

During prolonged periods of above average temperatures, such as those witnessed in the MWP, glaciers retreat and the snowline recedes exposing the ground beneath. This ground is sterile, it has little or no nutrients and is incapable of supporting plants or trees, for all intents and purposes it's the same as subsoil.

The natural processes by which soil is nourished are not established (aeration, decomposition of other plant matter, bacteria, faeces etc) so it takes a long time for the soil to become enriched with nutrients and able to support flora.

Over many hundreds of years the treeline would creep slowly up the mountainside. If there was a period of cooling and the glaciers advanced or there was permanent snow cover the treeline would recede back down the mountain.

The current warming trend hasn't been established long enough for the treeline to have naturally advanced far up the mountainsides. Where commercial foresrty is planted we're now able to plant at higher altitudes than we were in the past.

I have a property in a forest in Scotland and 40 years ago when the first crop was planted the treeline was established at about 500 metres, the trees are currently being harvested and the new planting has been extended closer to the 600 metre contour.

If the planet didn't warm any more than it already has done and you were to return in a few hundred years you'd find that the treeline had advanced further than it currently is.

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Re your additional comments:

Maybe my opening sentence was ambiguous, what I meant to say was that I agree with you in that the tree lines have been higher in the past and it's not only the Alps and the Sierra Nevada where they have been higher.

The lapse rate with altitude is 1 degree C per 150 metres (1 degree F per 300 feet). A historical tree line established 300 feet higher than the current tree line would indicate temperatures were 1 degree F higher in the past and this is the rise that we see in relation to the MWP. This is what we would expect to see.

We also expect to see the present day tree line advancing, and it is. Becuase there's a lag behind rising temperatures the tree line will continue to advance even if temperatures rose no further. In the last 200 years temperatures have risen by 1.1C, we would expect that during a period of a few hundred years commencing around 1800 the tree line will advance by about 160 metres (500 feet). This being the case it will be about 65 metres (200 feet) higher than the maximum reached during the MWP. 65 metres equates to a temperature difference of 0.4C (0.7F). The math, although rough, is shown to be accurate when we look at the maximum temp reached during the MWP and the present day temp, namely that it's now 0.4C warmer than the MWP peak.

I've never disputed that there was a MWP, what I do dispute is people saying it was warmer during the MWP than it is now.

The MWP was a period of about 600 years of generally above average temps. It happened but the speed at which it came and went was far slower than the rate of change we're experiencing now and it was never as warm as it is now.

I studied climatology back in the 1980's, we learned about the MWP, the graphs and charts back then are basically the same as they are now although I do have a book (Climatology and Physical Geography, probably from the 1960's) that shows a slightly higher peak during the MWP but only 0.1C higher than the revised charts used today.

Answer 3

I understand that MWP evidence is primarily in the form of pollen counts and such in the geologic record, predicated on the assumption that warmer weather encourages plant growth and flowering. Hence, you end up with data counts based on the exact locations where you obtained your core samples. I don't see a problem with tree lines being higher in two different mountain ranges. You could expect that to happen in a warm phase, and it would be more pronounced in a narrow mountain range than in a broad mountainous region where there was sufficient mass to retain colder temperatures for a longer time. A regional anomaly would be an area where data doesn't correspond with data from the larger surrounding region. Once the reason for the anomaly is identified, it can be added to the model and the model will then more closely depict the actual data. Reasons that might cause regional anomalies might include a geothermic feature such as a hot spring or a semi-active volcano which increases temperatures in a part of an otherwise cold region, a springfed heavy tree canopy which shades the ground below from solar activity and thus keeps a cool area in an otherwise hot desert region, abrupt altitude differences in an area, isolated differences in mineral content in soil which might cause uneven solar absorption, or a village of arsonists that really, really like to build bonfires that cause a constant smoke haze which interrupts chlorophyll production in the adjacent valleys. Anything out of the norm, really, can cause an anomaly.

Answer 4

I see no one actually answered your question. A regional anomoly in defenition is an unusual, or peculiar happening within a specific region....

The Alps, and the Sierra Nevadas are NOT within the same weather region.

the tree lines in these areas are most probably higher than normal, because of thier remoteness, the local fauna in these areas dont see as many ill effects of civilization.

Answer 5

Micro-Climates.

Answer 6

freaky weather for that region

Answer 7

I think it depends