Is The Antarctic Actually Cooling?

[seer]

It seems so, but you guys would know better..

Abstract

The Antarctic Peninsula (AP) is often described as a region with one of the largest warming trends on Earth since the 1950s, based on the temperature trend of 0.54 °C/decade during 1951–2011 recorded at Faraday/Vernadsky station. Accordingly, most works describing the evolution of the natural systems in the AP region cite this extreme trend as the underlying cause of their observed changes. However, a recent analysis (Turner et al., 2016) has shown that the regionally stacked temperature record for the last three decades has shifted from a warming trend of 0.32 °C/decade during 1979–1997 to a cooling trend of − 0.47 °C/decade during 1999–2014. While that study focuses on the period 1979–2014, averaging the data over the entire AP region, we here update and re-assess the spatially-distributed temperature trends and inter-decadal variability from 1950 to 2015, using data from ten stations distributed across the AP region. We show that Faraday/Vernadsky warming trend is an extreme case, circa twice those of the long-term records from other parts of the northern AP. Our results also indicate that the cooling initiated in 1998/1999 has been most significant in the N and NE of the AP and the South Shetland Islands (> 0.5 °C between the two last decades), modest in the Orkney Islands, and absent in the SW of the AP. This recent cooling has already impacted the cryosphere in the northern AP, including slow-down of glacier recession, a shift to surface mass gains of the peripheral glacier and a thinning of the active layer of permafrost in northern AP islands.

http://www.sciencedirect.com/science...48969716327152

[Leonhard]

Sounds interesting, I wish it wasn't behind a paywall though. I'll check around the scientific blogosphere to see if anyone has commented on it.

[Leonhard]

Found a non-paywall link. http://idlcc.fc.ul.pt/pdf/Oliva%20et...017_STOTEN.pdf

[seer]

Found a non-paywall link. http://idlcc.fc.ul.pt/pdf/Oliva%20et...017_STOTEN.pdf

So if I understand that link correctly (and I'm not saying that I do) the Antarctic is cooling and more ice is being formed.

[Leonhard]

Okay, read some parts of how it handled the data, though not all their talk about the behavior of weather.

There are a few things that should be noted. The report isn't about the entire antarctic continent, but the majority of the measurements in the article are actually from Nothern Peninsula.



Most of the measurements are clustered around the northern tip, and some of the others further inland show opposite signs meaning they're getting warmer. This means that when you have to calculate a proper amount temperature change, you have to take into account spatial bias. You can accidentally oversample an area and neglect others. You can see how tightly clustered some of those weather stations are in Fig. 1. And if you look at Table. 3. you'll see that there are a couple of the weather stations Esperanzas being one of them in the northern part, which is increasing in mean annual temperature. Rothera and San Martin also increased in temperature, and both cover huge areas of land.

So it seems from this we could conclude that we know with some confidence that the tip of the Northern Peninsula is getting colder, but that an area as large as that a little bit to the south is getting warmer. Averaging those two out isn't trivial, as there's also a big area of the Northern Peninsula that remains undocumented.

The confidence intervals of those decreases in temperature aren't that strong though. It's not below a 5% p-value, which means that the results might just be spurious.

In general, while the Antarctic is expected to get warmer, it isn't expected to rise at the same rate as the equatorial. It is expected to remain mostly unforced (forced is the term for the influence of the greenhouse effect on temperature), and the temperature increase will come from winds carrying the heat from countries further north.

I think the reporting on this article got a bit overboard. But I'm used to that happening to science articles. Journalists can't be trusted to report on science accurately anymore.

Wish we had more weather stations on the Antarctic, but it's not exactly a hospitable place.

[Leonhard]

So if I understand that link correctly (and I'm not saying that I do) the Antarctic is cooling and more ice is being formed.

On the tip of the Antarctic Peninsula? It seems so!

As for the rest of the continent, this article does nothing to dispell the reports of ice melt.

[seer]

On the tip of the Antarctic Peninsula? It seems so!

As for the rest of the continent, this article does nothing to dispell the reports of ice melt.

But they also said that the past warming reports were overrated and that the predictions were also overrated. And they did say "significant parts of the AP" not just the northern tip.

Future research will unveil if the recent cooling trend observed in
significant parts of the AP is part of the natural climatic variability in
the region, or shows a turning point in the long-term warming trend observed
during the second half of the 20th century

[Leonhard]

But they also said that the past warming reports were overrated and that the predictions were also overrated. And they did say "significant parts of the AP" not just the northern tip.

Well there's what they say, and there's what they got. You can see the location of the weather stations here. And as you can see most of them are on the tip of the Antarctic Peninsula. Looking into their analysis of the past warming reports will have to wait. The boss from my former employment called me with an IT emergency situation.

[seer]

Well there's what they say, and there's what they got. You can see the location of the weather stations here. And as you can see most of them are on the tip of the Antarctic Peninsula. Looking into their analysis of the past warming reports will have to wait. The boss from my former employment called me with an IT emergency situation.

OK, but in their conclusion they do suggest that this could be "a turning point in the long-term warming trend" in the area. And this would be significant since as they said, this Peninsula is "often described as a region with one of the largest warming trends on Earth since the 1950s..."

[TheLurch]

I went to NASA's climate map making tool to see what's going on with this period (roughly 1998 to present). One thing that's clear: we still don't have good Antarctic data (note the chunky, pixellated nature of the data that's there, plus the grey area where data is absent). Within the limits of what we do have:
Some parts of Antarctica have been cooler in recent decades compared to the baseline.
The Antarctic peninsula isn't one of them.
Antarctica as a whole appears to be getting warmer.

amaps.jpg

NASA defaults to a baseline of 1950 to 1980, so i reran the map making using 1975 to 1998 as the baseline, and then 1998 to present. This should show if there was a warming period followed by a cooling period in recent years. It doesn't - the Antarctic peninsula still shows as warming.

My best guess as to an explanation: as Leonhard has been saying, this paper's using lots of stations that are located near each other. It's possible that there's a very small region that's showing a cooling trend that isn't present on the peninsula as a whole.

[seer]

I went to NASA's climate map making tool to see what's going on with this period (roughly 1998 to present). One thing that's clear: we still don't have good Antarctic data (note the chunky, pixellated nature of the data that's there, plus the grey area where data is absent). Within the limits of what we do have:
Some parts of Antarctica have been cooler in recent decades compared to the baseline.
The Antarctic peninsula isn't one of them.
Antarctica as a whole appears to be getting warmer.

[ATTACH=CONFIG]22113[/ATTACH]

NASA defaults to a baseline of 1950 to 1980, so i reran the map making using 1975 to 1998 as the baseline, and then 1998 to present. This should show if there was a warming period followed by a cooling period in recent years. It doesn't - the Antarctic peninsula still shows as warming.

My best guess as to an explanation: as Leonhard has been saying, this paper's using lots of stations that are located near each other. It's possible that there's a very small region that's showing a cooling trend that isn't present on the peninsula as a whole.

Don't the authors also claim the the past warming has been over blown? I mean they do ask if this isn't "a turning point in the long-term warming trend." And they are speaking of the Antarctic peninsula, not just a portion of it from what I understand.

However, most of these studies, typically using periods spanning between
the late 1950s and the early 2000s, often do not include climatic
data referred to the last decade. Moreover, the trends are usually inferred
for the whole period of the instrumental series, but generally
do not analyse the interdecadal or short-term variability. Certain reports
recently presented preliminary indications that the warming over the
AP region has slowed down markedly since the beginning of the century
(Blunden & Arndt, 2012; Turner et al., 2015). Carrasco (2013) detected a
decrease in the warming rate in stations from the western side of the AP
between 2001 and 2010 with even a slight cooling trend in King George
Island (South Shetland Islands, SSI). More recently, Turner et al. (2016)
have presented a thorough analysis of the regional stacked temperature
record of the AP for the period 1979–2014, with the choice of 1979 as
start of the time series because it marks the start of the availability of reliable
atmospheric reanalyses datasets that incorporate satellite data, as
well as fields of sea-ice concentration. Their analysis has shown a diverging
trend from warming (by 0.32 ± 0.20 °C/decade) during 1979–
1997 to cooling (by −0.47 ± 0.25 °C/decade) during 1999–2014, with
the cooling trend being largest in summer.

[TheLurch]

Don't the authors also claim the the past warming has been over blown?

Where do you get that?

I mean they do ask if this isn't "a turning point in the long-term warming trend." And they are speaking of the Antarctic peninsula, not just a portion of it from what I understand.

Well, Leonhard showed that this wasn't the case, since the stations they had data from are almost all at the northern tip or from offshore islands. So, no, it doesn't appear that their data covers the entire peninsula.

In any case, are you trying to suggest either that: a) NASA doesn't have the data it says it does, or b) I graphed it wrong?

[seer]

Where do you get that?

Over the last decade the AP region has largely been described as one
of the fastest warming regions on Earth, with comparable amplitude to
the Arctic region. The IPCC (2007) suggested an increase of MAAT
between 2 and 3 °C for 2080–2099 with respect to the average 1980–
1999, although this range was later reduced by the latest IPCC assessment
(IPCC, 2013) to circa 1.8 °C for the entire continent. It should be
stressed that these recent temperature increments are significantly
lower than the corresponding temperature increase projected in the
Arctic by the end of the 21st century estimated at 4.9 °C (IPCC, 2007,
2013)

Well, Leonhard showed that this wasn't the case, since the stations they had data from are almost all at the northern tip or from offshore islands. So, no, it doesn't appear that their data covers the entire peninsula.

In any case, are you trying to suggest either that: a) NASA doesn't have the data it says it does, or b) I graphed it wrong?

Future research will unveil if the recent cooling trend observed in
significant parts of the AP is part of the natural climatic variability in
the region, or shows a turning point in the long-term warming trend observed
during the second half of the 20th century.

I don't think they would even suggest that if this was limited to a few stations.

[TheLurch]

I don't think they would even suggest that if this was limited to a few stations.

Then how do you explain the image that Leonhard took from the paper?

[shunyadragon]

Don't the authors also claim the the past warming has been over blown? I mean they do ask if this isn't "a turning point in the long-term warming trend." And they are speaking of the Antarctic peninsula, not just a portion of it from what I understand.

Simply no. This is old turf addressed in previous threads. Antarctica is not warming as much as the rest of the world (See referenced maps), because its climate is isolated by circular currents and upper air jet streams, but it is warming.