My hunt for global warming in uninhabited areas of the Southern Hemisphere continues with Antarctica. Given the proclamations of the climate alarm community and global media I was expecting to find a continent in melt down. Nothing could be further from the truth. 14 stations distributed around the edge and in the centre of the continent show a warming trend of +0.35˚C since 1954. If the regression is started in 1969, the trend is completely flat. There is scant evidence of warming on the main Antarctic continent for 42 years.
This observation does not include 3 stations from the Antarctic Peninsula that clearly belong to a separate climatic regime and are therefore treated separately. These three stations show warming of +3˚C since 1944. Given that the continent to the South and Patagonia to the North show barely any signs of warming at all, the dramatic rise in temperature on the Antarctic Peninsula can hardly be attributed to CO2 forcing of temperature change or to ozone depletion. Rather, there appears to have been a change in climatic regime that is shared with the South Orkney Islands (Base Orcadas) and South Georgia (Grytviken). Warmer temperatures may be attributed to greater marine and less continental influence in the atmospheric circulation pattern.
In this post I use the GHCN V2, slightly adjusted records. I calculate T anomalies two separate ways 1) relative to the station mean and 2) relative to a 1963 to 1992 fixed base period for each station. There is no material difference between the two approaches.
Average temperature anomalies for 14 stations from the main Antarctic continent. There is clear sign of gradual warming confirmed by regression and rising tops and bottoms.
Geography and Temperatures
Stations were selected by clicking around on the NASA GISS V2 map, looking for stations with long and continuous records. I ended up with 14 stations from the main continent, 3 stations on the Antarctic Peninsula that reaches up towards South America and 2 stations from Islands to the NW of the Peninsula (Figure 1, 2).
Figure 1 Antarctic stations arranged in order of latitude with the exception of Rothera Point that is plotted out of order. Most records begin 1956/58. On the peninsula they begin 1944/46 and on the islands we have two long records that begin in 1903/05.
Figure 2 Map of Antarctica from this source. Most of the stations can be found on the map. Following the Antarctic Circle that passes through the northern tip of the peninsula it can bee seen that the coastline for much of the continent to the E lies on the Antarctic Circle. Halley, Scott and McMurdo lie further south than the other coastal stations and are at a similar latitude to Vostok.
Figure 3 Owing to the research station basis for Antarctic bases, this is one of the most continuous set of temperature records on the planet. The only limitation is that it begins in earnest in 1956 and there is only 55 years of data (better on the peninsula and islands). My main charts begin in 1954 when continuos records began.
Figure 4 Some well ordered temperature spaghetti for continental Antarctica. There are a large number of key observations to be made. There are three groups of data. One centred on -10˚C, one on -17˚C (McMurdo, Scott and Halley) and one very cold group comprising Amundsen-Scott and Vostok. Vostok lies further N than the S pole but is colder than Amundsen-Scott in part because of its higher altitude: 3488m, compared with the S Pole at 2835m. McMurdo, Scott and Halley lie at similar latitude to Vostok but are at sea level. The vast difference in temperature cannot be attributed to altitude alone. Assuming a lapse rate of 1.9˚C / 1000ft we would expect Vostok to be 22˚C colder than these coastal stations owing to its greater height. Clearly the coastal setting is warmer and the coastal stations climate is influenced by the ocean. All the trends appear orderly and flat because of the immense Y-axis scale on this chart which raises an interesting question. Should temperature trends, for example +0.35˚C warming be referenced against diurnal and geographic dT in a region, >>45˚C in this case. One final observation. There is a small positive bump in the temperature record in 1980 seen in Vostok and the majority of other stations.
Figure 5 Converting the temperatures in Figure 4 to anomalies creates this picture of dT spaghetti. In this chart the station mean is used to calculate the anomaly. In other words, dT for a station = annual mean temperature minus mean temperature for the station over the time series for that station. In this chart I can see a high degree of congruity between stations, in other words they are all going up and down together, with some exceptions. And there is no clear trend. No trend of rising tops and bottoms, it looks flat.
Figure 6 Averaging the dT stack shown in Figure 5 we get this picture. Here I have added normalisation to a fixed period of 1963 to 1992 where the station anomaly is referenced to the mean temperature for that station in that fixed time period. It can be seen quite clearly for this group of stations that the dT gradient is identical for both normalisation procedures.
It’s not obvious from Figure 5, but there is in fact a small positive gradient running through this data of approximately +0.35˚C from 1954 to 2011. The gradient suggested by the regression is confirmed by tops and bottoms rising at similar gradient.
Figure 7 From the way I have over the years learned to view trends, I could see from Figure 6 that arbitrarily selecting a different start date would produce a different outcome. Doing so allows me to claim that there is no evidence of warming in the Antarctic continent since 1969, that is for the last 42 years.
The Antarctic Peninsula projects northwards into the ocean and is almost surrounded by water. Its temperature records are distinctly different to the continent and are therefore treated separately. The Peninsula shows clear signs of recent warming. To the NW lies Base Orcadas on the S Orkney Islands. This provides an important record stretching back to 1903. And about 900 kms to the NW, lies S Georgia and the station at Grytviken. This is also a long record stretching back to 1905 and shows recent warming. The Falkland Islands’ records stop in 1988, and so we don’t if they belong to this group or not.
Figure 8 Temperature spaghetti for Rothera Point, Faraday and Base Esperanza (Figure 1). These three stations show a fairly high degree of congruity and the trend of rising tops and bottoms is quite clear. One striking feature is the sharp drop in temperatures in 1980, in marked contrast to the continent that showed warming at this time. The significance of this is discussed below.
Figure 9 Adding Base Orcadas and Grytviken we can see that Base Orcadas blends in with the peninsula records. Grytviken, 6.5˚ further North, is clearly a lot warmer and has much less year on year variance. The latter is likely caused by distance from the continent and temperature buffering effect of the surrounding ocean. But Grytviken also shows distinct warming from the 1950s to the present day, despite a long break in the record.
Figure 10 Looking at dT anomalies from the Peninsula we can see that the two normalisation methods give identical results. The data suggest warming of +3˚C since 1944 when records began. If CO2 forced warming or ozone depletion are the cause, then in the Antarctic peninsula it began in 1944 at a time when much of the northern hemisphere began to cool and at a time when the atmospheric CO2 was of the order 310 ppm, barely elevated from pre-industrial levels.
Figure 11 Adding the tw0 islands to the dT stack, two things happen. Since the pre-1944 records for the islands are flat, stretching the record back to 1903 has the effect of substantially reducing the warming rate. And second, in the pre-1944 part of the record the two normalisation procedures diverge, but not materially so. Given the distribution of the small number of records (Figure 9) this is a real test. The fixed 1963 to 1992 base is being projected back up to 60 years. Using the full record as a base, all the data are used. Both methods are flawed and reality likely lies in between. And since the difference between the methods is not material, none of this really matters.
The station average base method suggests warming of +1.8˚C since 1903. The fixed 1963 to 1992 base suggests warming of 2˚C since 1903. But what does this mean, if anything?
Figure 12 Simply running linear regressions through data like this actually makes little sense. It is an unavoidable first approach but there is more to this data than simple linear trends. This is a theme I will return to repeatedly in future postings.
This data shows three crucial things. 1) There is very high amplitude oscillation between short “warm” periods and short “cold” periods; 2) there is a marked trend of rising tops that is continuous since 1903; 3) the bottoms trend needs to be split into two parts, declining until 1959 and then rising thereafter. It is this latter feature that imparts the main structure to the gross data. Warming tops and cooling bottoms giving rise to a flat trend until about 1959, and then rising tops and bottoms giving rise to a warming trend. Understanding the reasons for this pattern will unlock the understanding of the reasons for warming on the Antarctic Peninsula.
One feature of the Antarctic data that I believe is significant is the large amplitude oscillations in temperature that can take place from one year to the next. For example on the Peninsula plus islands dT in 1956 was +1.5˚C in 1959 -2.6˚C. A swing of 4.1˚C in average temperature in just 3 years. The Peninsula receives wind from two principle areas 1) off the continent which will always be very cold air (katabatic winds blow continually from the centre to the coast) and 2) off the ocean that will always be much warmer air. And so I think it is reasonable to presume that the warm years had on average a larger share of oceanic circulation and the colder years a larger share of continental circulation.
The 1980 temperature anomaly lends support to this idea. The cold temperatures on the peninsula that year linked to a greater amount of wind blowing from the South. To compensate for this, the continent will have had to “suck in” more air from the surrounding ocean giving rise to its positive temperature anomaly. This may happen via a large convection cell that sucks air up from the ocean and blows it down over the pole ( a strengthening of the polar cell).
Can a simple climatic circulation model such as this explain the substantial warming trend on The Peninsula? I believe it can. The argument would go that with the passage of decades The Peninsula has come under progressively greater influence of marine climate. While still oscillating between continental and marine influence from one year to the next. The area lies in the path of the circumpolar marine current and circumpolar atmospheric vortex. It is an incredibly hostile and unstable environment to be in. This theory is easy to check through comparison with wind direction and speed records that I’m sure will exist but I can’t find any. Corroboration must wait until another day.
Does the rise in temperature 0f 0.35˚C since 1954 and 0.00˚C since 1969 for the continent data set give rise for any concern? Of course it does not. If you look at the summer monthly averages (Dec and Jan) for the warm group of stations it can bee seen that some months do average just above zero meaning that day time temperatures will regularly be above zero for brief spells each summer. But I’m sure if you go a short way in land temperatures will never rise above zero and +0.35˚C will make absolutely no difference at all. To some extent it will depend where this tiny amount of warming lies in the seasonal data and we can check that by looking at seasonl trends (Figure 13).
Figure 13 dT for the 14 continental stations show a warming of about +0.15˚C for the summer quarter DJF. Note that the data begins in 1955 and not 1954 (no 1954 DJF data for Mawson).
It is only during the summer months of DJF that melting is possible and there has been effectively no warming in these months since 1955. Starting the regression in 1956 and the gradient disappears all together. Most of the +0.35˚C rise must reside in the autumn, winter and spring months when temperatures will rarely rise above 0˚C anywhere and will therefore have no impact on Arctic ice at all. Doing this exercise prompted me to look at seasonal temperature change on The Peninsula that will be the subject of a separate post.
With news packed with stories about melting Antarctic ice, global warming causing Antarctic Sea ice to expand and so on, readers have every right to be confused and disorientated by what the data actually shows. I am beginning to become increasingly alarmed and concerned by the conduct of the climate science and climate alarm community.
Temperature anomalies for 14 Antarctic stations, distributed around the coast and in the interior of the continent, excluding the peninsula, show a warming of +0.35˚C since 1954. If the regression is begun in 1969, the trend is totally flat. There has been virtually no warming in Antarctica for 57 years. The summer months (DJF) show virtually no warming. The activities of Man, CO2 increase and ozone depletion have had no significant impact on the temperature records of the Antarctic continent.
The Antarctic Peninsula, in contrast, shows distinct warming of +3˚C since 1944. The temperature records for the Peninsula are congruous with islands to the NW (New Orkney and South Georgia) and bear witness to a larger area of warming that is dominated by the marine environment. While the climate alarm community have sought to explain this warming by anthropogenic causes, in particular via ozone depletion, the simplest explanation is that natural climate variability has seen this area receive increasing amounts of ocean-atmosphere circulation with time.