Artic temperatures highest in 2000 years

[Mokele]

A recently released study in Science shows that the Arctic is the warmest it's been in 2000+ years. Please note that the data only goes back that far, not that temperatures were just as warm back then.

 

Link to the actual article, PM me if you want the full article.

[dr.syntax]

and only recently has there been a sharp upward trend in Arctic temperatures. The evidence of a dangerously rapid warming trend seems all too obvious to me. Some simple but effective things we can all do is use white shingles on roofs, buy white cars,where ever practicle use white surfaces to reflect more light. ...ds

[bascule]

There's been a strangely disproportionate and historically unprecedented disparity in warming between the arctic and antarctic. There has been substantial warming near the northern pole, and negligible warming (and arguably cooling) near the southern pole.

 

Just recently (as of a year ago or so) the "northwest passage" opened up for the first time since the Medieval Warm Period.

[Green Xenon]

There has been substantial warming near the northern pole, and negligible warming (and arguably cooling) near the southern pole.

 

Why? Is it because there is more industry in the northern hemisphere?

[Mokele]

More to do with the amount of land vs water in the northern vs southern hemispheres.

[bascule]

Why? Is it because there is more industry in the northern hemisphere?

 

There are a number of proposed causes. As Mokele noted a greater portion of the surface is covered by oceans, and thus there is greater ocean heat uptake. There are various other more complex and nuanced explanations, such as patterns of winds providing natural barriers against the circulation of warm air, however I don't really understand how these work so I really shouldn't be discussing them.

[Psycho]

There are a number of proposed causes. As Mokele noted a greater portion of the surface is covered by oceans, and thus there is greater ocean heat uptake. There are various other more complex and nuanced explanations, such as patterns of winds providing natural barriers against the circulation of warm air, however I don't really understand how these work so I really shouldn't be discussing them.

There is no land there so the wind just goes round and round the world and isn't slowed or warmed on the land like in the northern hemisphere.

[SH3RL0CK]

Why? Is it because there is more industry in the northern hemisphere?

 

I have heard theories about this along the lines of the additional soot generated by industry falls on the snow and ice. Thus causing them to absorb more heat from the sun (as opposed to reflecting it back into space) which makes them melt. This doesn't happen (as much) in Antartica due to less industry in that part of the world.

 

But this is only one theory and I wouldn't use this theory to claim global warming via added CO2 isn't happening...

[rigadin]

Everybody write and talk about global warming, Global warming this, global warming that and it is a problem just it dosn't seem like many people are doing something to stop it.....

[bascule]

I have heard theories about this along the lines of the additional soot generated by industry falls on the snow and ice. Thus causing them to absorb more heat from the sun (as opposed to reflecting it back into space) which makes them melt. This doesn't happen (as much) in Antartica due to less industry in that part of the world.

 

But this is only one theory and I wouldn't use this theory to claim global warming via added CO2 isn't happening...

 

Anthropogenic pollutants generally alter the Earth's albedo by increasing reflectivity, not decreasing it. Anthropogenic aerosols typically reflect solar radiation back into space. These aerosols are also circulated throughout the atmosphere and won't remain localized to their point-of-origin.

 

Humans do increase surface absorption though... by building cities. Cities are generally made of things which absorb more solar radiation than the original surfaces they are built on. Asphalt is black and has an extremely low reflectivity, especially compared to natural terrain.

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Merged post follows:

Consecutive posts merged

In other arctic warming news, the Pacific brant (a type of goose) is choosing to linger in the arctic rather than migrating. Yet another effect of a changing climate.

Edited September 17, 2009 by bascule
Consecutive posts merged.

[JohnB]

I guess it depends on what weighting you give to which proxies, doesn't it?

On the left are 19 of the 23 proxies from Kaufman 2009, on the right the 4 that give him his hockey stick.

 

Damn but Briffas tree rings are popular.

 

Just to add from Mia Tiljanders thesis. (Which is used as one of the proxy records.)

Since the early 18th century, the sedimentation has clearly been affected by increased human impact and therefore not useful for paleoclimate research.

 

Which is why she uses terms like "mild" in the paper. Due to the contamination of the series since the early 1800s it is thought impossible to accurately calibrate against the historical record. The varves can certainly show which times were relatively warmer or cooler, but absolute temperature values can't be ascribed to the series. Although Kaufman (like a number before him) seems to believe that by inverting the values in the Tiljander series, absolute temperature values can be found.

Edited September 24, 2009 by JohnB

[bascule]

I guess it depends on what weighting you give to which proxies, doesn't it?

On the left are 19 of the 23 proxies from Kaufman 2009, on the right the 4 that give him his hockey stick.

 

I'm confused by these graphs. Any reputable reconstruction will include all of them. Is the plot on the left leaving 4 of them out, and the plot on the left the 4 which were left out of the other plot? If so, what is this attempting to prove? For what it's worth, both plots exhibit the same "hockey-stick" trend, one just more sharply so than the other, which I guess is what happens when you cherry pick the top four and show "oh gosh, the top 4 are more than the following 19 combined!"

 

Would you agree that we are seeing arctic warming at a historically unprecedented rate?

[JohnB]

bascule, the part missing is the complete reconstruction. However it is here.

 

Looking at graph C, you'll notice that the MWP is barely a bump in the road and modern temps are far higher than those in the MWP.

 

Looking at the left hand graph above demonstrates a distinct MWP at or above modern temps, while the right hand graph shows no MWP and distinctly elevated modern temps.

 

To again quote Mia Tiljander;

4. The Medieval Warm Period in AD 980-1250 is the most distinctive climate period in the whole sediment sequence identified by changes in sediment colour, X-ray density, varve thickness, LOI, as well as the isotopic composition of hydrogen in kerogen.

(Emphasis mine.)

 

Maybe I'm a twit, but to me any reconstruction should be robust WRT the removal of some of the proxy series. As in, the shape of the graph should change, but not dramatically with the romoval of any 4 proxies.

 

It is easily seen by comparing the three graphs that the results of Kaufman are reliant on the 4 proxies in the right hand graph. Without those 4, (if the study was of only the remaining 19 proxies), there is not much to talk about, is there?

 

To my mind, the removal of 4 proxies, any 4, should not have a dramatic effect on the final result. In the case of Kaufman, removal of those 4 changes the graph entirely. This says to me that the Graph C in the Kaufman paper is unusually reliant on those 4 proxies.

 

19 proxies show the MWP as being around the same as the modern period. 4 show the modern period as nearly 3 degrees higher than the MWP. (The author of one of those 4 says that her series should not be used.)

 

If you have 19 proxies showing one thing and 3 showing a dramatic divergence, wouldn't it be reasonable to say that those three are outliers and perhaps shouldn't be used?

 

I don't have a problem with Kaufmans results, I have a problem with how he got them. The methodology is heavily weighted by a small subset of the proxies which is, I believe, a flawed approach.

 

Have I explained myself clearly? I hope so.

 

Would you care to comment on the use of the Tiljander series even though the author says it should not be used for paleoclimate research?

 

I will give Kaufman credit in that he notes in the datafile concerning the Tiljander series.

§ Record was truncated because the original authors indicated that the lake was impacted by human activities

However, if you truncate the series at 1800 AD, how do you calibrate the series against temps?

 

General note: The Tiljander series is one of the long ones and goes back some 7,000 years.

[bascule]

bascule, the part missing is the complete reconstruction. However it is here.

 

Looking at graph C, you'll notice that the MWP is barely a bump in the road and modern temps are far higher than those in the MWP.

 

Looking at the left hand graph above demonstrates a distinct MWP at or above modern temps, while the right hand graph shows no MWP and distinctly elevated modern temps.

 

Well, based on "looking at the graph" alone, I see the same trend exhibited in both graphs, just more pronounced in one than the other.

 

Also, "looking at the graph" isn't exactly the most methodological approach. Can you paste the relevant analysis of the data (not your own) that these graphs are supposed to supplement? From a peer reviewed paper, I assume?

 

Also, you never answered my previous question, but perhaps I should ask a different one: do you believe the data do not support the position that Arctic temperatures are the highest they've been in 2000 years?

[coreview2]

One of the big problems I have with anyone's chart that "loses" the Medieval Warming and much of the magnitude of the Little Ice Age is that there is so much recorded history of these events in all manners of human documentation.

 

Something is fundamentally wrong when an extremely well documented set of historical events in such a wide array of recorded sources gets lost in a fog of numbers. Perhaps we need someone to specialize in paleoclimatology and human recorded history so we don't get lost in the trees.

 

 

 

 

bascule, the part missing is the complete reconstruction. However it is here.

 

Looking at graph C, you'll notice that the MWP is barely a bump in the road and modern temps are far higher than those in the MWP.

 

Looking at the left hand graph above demonstrates a distinct MWP at or above modern temps, while the right hand graph shows no MWP and distinctly elevated modern temps.

 

To again quote Mia Tiljander;

 

(Emphasis mine.)

 

Maybe I'm a twit, but to me any reconstruction should be robust WRT the removal of some of the proxy series. As in, the shape of the graph should change, but not dramatically with the romoval of any 4 proxies.

 

It is easily seen by comparing the three graphs that the results of Kaufman are reliant on the 4 proxies in the right hand graph. Without those 4, (if the study was of only the remaining 19 proxies), there is not much to talk about, is there?

 

To my mind, the removal of 4 proxies, any 4, should not have a dramatic effect on the final result. In the case of Kaufman, removal of those 4 changes the graph entirely. This says to me that the Graph C in the Kaufman paper is unusually reliant on those 4 proxies.

 

19 proxies show the MWP as being around the same as the modern period. 4 show the modern period as nearly 3 degrees higher than the MWP. (The author of one of those 4 says that her series should not be used.)

 

If you have 19 proxies showing one thing and 3 showing a dramatic divergence, wouldn't it be reasonable to say that those three are outliers and perhaps shouldn't be used?

 

I don't have a problem with Kaufmans results, I have a problem with how he got them. The methodology is heavily weighted by a small subset of the proxies which is, I believe, a flawed approach.

 

Have I explained myself clearly? I hope so.

 

Would you care to comment on the use of the Tiljander series even though the author says it should not be used for paleoclimate research?

 

I will give Kaufman credit in that he notes in the datafile concerning the Tiljander series.

 

However, if you truncate the series at 1800 AD, how do you calibrate the series against temps?

 

General note: The Tiljander series is one of the long ones and goes back some 7,000 years.