CLIMATE TRENDS Brian Gunter, Narooma, NSW, Australia http://members.westnet.com.au/brigun/antarctica-temps.html |
"Trends are not always trendy"
TEMPERATURE
TRENDS
IN ANTARCTICA |
Has the Antarctic continent become significantly warmer in recent years?
Are there any reliable, long-term temperature records available for this region?
Do historical temperature records give us any indication of probable future temperature trends?
Are the snow and ice deposits in Antarctica likely to melt and result in significant worldwide rises in sea level?
Some of these questions are answered below. Please send me your comments.
Long-term air temperature records at 13 stations (all polar research bases) in Antarctica have been extracted from the website of KNMI (Royal Dutch Meteorological Institute). This is all raw data (GHCN), without any adjustments ever having been made (as far as I am aware). Only stations with records over a period of at least 50 years, with largely complete and post-2005 records were selected. Eleven of the stations are located in coastal areas of the continent and of these three are located on the more northerly Antarctic Peninsula (south of South America). Two stations are located at higher, inland locations including one station at the South Pole. The KNMI database has records up to March or April 2015.
I have not been able to make any quality checks on the data. It is possible that there have been some changes in station locations and instrumentation over the periods of record, but sudden steps in the data and comparisons with other adjoining stations would be expected to identify any inconsistencies.
Graphical
plots are presented below of annual mean temperatures at each of the 13 stations. [ Annual mean temperatures are the average of the mean daily
temperatures over each year (the mean daily temperatures are the average of the
observed daily maximum and minimum temperatures). ]
In addition, the mean monthly temperatures for the warmest and coldest months (based on long-term averages) at each station are plotted. The coldest months (on average) are always July or August while the warmest month (on average) is January (except for the two inland stations that are slightly warmer in December).
A polynomial trend line was fitted through each of the sets of data.
MY CONCLUSIONS:
1. Apart from at the three stations located on the Antarctic Peninsula, none of the records at the other ten stations show any consistent trend to either increase or decrease significantly over the past 50-70 years. This conclusion applies to both the mean annual and individual monthly temperatures.
2. The three stations located on the Antarctic Peninsula all have increasing temperatures over the past 60-70 years, although there are differences in magnitude. These three stations are definitely inconsistent with the other ten stations and it is possible that they are affected by changing wind patterns, ocean currents and volcanic activity that don't affect the more southerly stations.
3. The effectively zero temperature trends for the main regions of the Antarctic continent are interesting and possibly significant. In most regions of the world there have been a well-defined, but not alarming, increase (of less than 1ºC/century) in mean annual temperature over the past 100-150 years but, for the main land mass of Antarctica, such a trend cannot be identified in the records of the past 50-70 years.
So, apart perhaps on the Antarctic Peninsula, the white continent can be expected to stay white for a long time in the future!
UPDATE (18 May 2015): A more detailed analysis of the temperature trends at Mawson may be seen at: http://members.westnet.com.au/brigun/mawson-temps.html
STATION
NAME |
COUNTRY OPERATING STATION |
LAT/LONG |
MEAN
ANNUAL TEMPERATURE |
PERIOD
OF DATA |
COMPLETE
YEARS |
Halley | UK | -76/-27 | -18.7 | 1956-2015 | 48 |
Novolazarevsk | Russia | -78/12 | -10.5 | 1961-2015 | 30 |
Syowa | Japan | -69/40 | -10.5 | 1957-2015 | 44 |
Mawson | Australia | -68/63 | -11.2 | 1954-2015 | 55 |
Davis | Australia | -69/78 | -10.2 | 1957-2015 | 47 |
Mirnyj | Russia | -67/93 | -11.3 | 1956-2015 | 42 |
Casey | Australia | -66/111 | -10.2 | 1957-2015 | 47 |
Dumont d'Urville | France | -67/140 | -10.9 | 1950-2015 | 45 |
Vostok | Russia | -78/107 | -55.4 | 1958-2015 | 32 |
Amundsen-Scott | USA | -90/00 | -49.4 | 1957-2015 | 42 |
Rothera | UK | -68/-68 | -4.9 | 1946-2015 | 44 |
Faraday/Vernadsky* | UK/Ukraine* | -65/-64 | -3.8 | 1944-2015 | 53 |
Esperanza | Argentina | -64/-57 | -5.3 | 1945-2015 | 48 |
* Operation of the Faraday station was transferred from UK to Ukraine in 1996 and it was renamed as Vernadsky station.
UPDATE (8 June 2015):
Detailed plots of mean annual and monthly temperature trends at each of the 13 stations may be seen at the following links:Amundsen-Scott Vostok Halley Novolazarevsk
Syowa Mawson Davis Mirnyj Casey
Dumont d'Urville Faraday/Vernadsky Rothera Esperanza
ANNUAL, SUMMER
& WINTER MEAN TEMPERATURE TRENDS IN ANTARCTICA [ These are
trend plots of the annual and the normally warmest and coldest months of each
year. More detailed plots are available for individual months - see
links above ]
Amundsen-Scott
(USA), Antarctica
42 complete years of data, 1954-2015
Vostok
(Russia), Antarctica
32 complete years of data, 1958-2015
Halley
(UK), Antarctica
48 complete years of data,
1956-2015 Novolazarevsk
(Russia), Antarctica 30 complete years, 1961-2015 Syowa
(Japan), Antarctica
44 complete years of data, 1957-2015
Mawson
(Australia), Antarctica 55
complete years of data, 1952-2015
Davis
(Australia), Antarctica
47
complete years of data, 1957-2015 Mirnyj
(Russia), Antarctica
42 complete years of data, 1956-2015
Casey (Australia),
Antarctica 47 complete years of data, 1957-2015
Dumont
d'Urville (France), Antarctica
45 complete years of data, 1950-2015
Rothera
(UK),
Antarctica
44 complete years of data, 1946-2015
Faraday/Vernadsky
(UK/Ukraine), Antarctica
53 complete years of data, 1944-2015
Esperanza
(Argentina), Antarctica
48 complete years of data, 1945-2015
The
Author:
This
article was written by Brian Gunter of Narooma, NSW.
In his previous life Brian was an engineering hydrologist involved over
many years in the analysis of rainfall and river flow data for the planning of
water resources projects in Australia, Asia and Africa.
In recent years he has been one of the Marine Rescue NS
Brian Gunter
30 September 2013
Updated 7 October 2013 (Detailed analysis for Mawson station)
Updated 25 May 2015 (Updated to 2015 and more detailed graphical presentation)
Updated 8 June 2015 (Links provided to individual monthly trend plots)
|
|