KlimaNotizen – supplementing information about climate change
Alaska – the land of bears, wolves and plenty of untouched nature makes the traveler’s heart beat faster. But this enthusiasm is being tempered.
„Pineapple from Alaska? - The Arctic melts and the industrial countries keep watching” was the title of a dramatic press release published by the Global Conservation Organization WWF (11) after the publication of the “Arctic Climate Impact Assessments” report (ACIA). This report claims that human induced greenhouses emissions are the cause of the global temperature rise.
However, a closer look at the facts is amazing: the temperature in Alaska has been almost constant for 27 years. This and other information can neither be found in the WWF publications nor in the ACIA report.
So this is the topic of this newsletter.
Alaska and the temperature leap
Temperatures in the recent past
Temperatures in the past 2000 years
Pacific Decadal Oscillation (PDO)
Points of view:
ACIA: 1. Temperatures in the recent past, 2. Temperatures in the past 2000 years, Conclusion
In 1976, a temperature rise of 1.7 °C within one year was observed. The Pacific Decadal Oscillation (PDO) is considered to be the reason for this.
Since 1977, the mean annual temperature in Alaska has been almost constant.
Alaska has a population of 650,000 inhabitants with 50,000 being Inuits, Aleuts and Indians (the highest percentage in the US). The capital Juneau, Anchorage and Fairbanks are the most important cities. …
Due to the large woodland timber and paper industry is the most important income source in Alaska. A lot of gold, copper, silver, lead, tin and iron mines can be found in the mountains, and salmon and codfish are the most important export goods of Alaska’s fishing industry. Also, Alaska has coal deposits … (1)
Large oil deposits were discovered in 1968.
Permafrost occurs everywhere in Alaska except for the South and South-East. The ground is permanently frozen up to 300 m below the surface. Only in summer the upper layer melts for a short period. Nevertheless, thanks to its high mountains and coasts at three oceans, Alaska is not an icebox, but can be divided in three to five climatic zones:
Temperatures of the recent past
Reliable measurement data for Alaska have only been available since 1949. The Alaska Climate Research Center (2) analyzed the temperature development and worked out the curve below.
Mean annual temperatures in Alaska
This temperature curve holds some surprises:
Since 1977, the mean annual temperature in Alaska has been almost constant. One single temperature leap in 1976 caused a temperature increase of 1.7 °C in only one year.
The authors state that such a non-linear trend can hardly be linked to the linear increase in CO2 concentration in the atmosphere.
It is rather believed that the temperature leap was caused by a phase shift in the Pacific Decadal Oscillation (PDO) in 1976. Then, the PDO shifted from a negative to a positive phase, and, according to the authors, this lead to higher temperatures in Alaska.
2.2 Temperatures are given in Fahrenheit (4)
Warming and cooling in Alaska from 1977 to 2003.
The average increase is +0.3°F=+0.17°C
Temperatures of the past 2000 years
Feng Sheng Hu et al. analyzed sea sediments in Lake Farewell to determine the temperatures of the past 2000 years. The reason why they decided to conduct this study is that the lack of reliable climate information covering longer time periods makes it difficult to understand nature and the reasons for the current warming. The results of their study are shown in the diagram below.
The curve shows three comparable warm periods for the years 0 to 300, 850 to 1200 and for the 20th century.
According to the temperature curve in the diagram, the current global warming trend is not unusual and, when seen in the context of the past 2000 years, not even unexpected.
Pacific Decadal Oscillation (PDO)
Alaska’s South coast borders on the Pacific and is thus under a strong climatic influence of the largest ocean on earth.
The PDO is an abrupt change in the water temperature of the Pacific. Every 20 to 30 years a cold to warm change and vice versa is observed over a wide area. This happened in 1925 (warm), 1947 (cold) and 1977 (warm). However, research in this field is still young and ongoing. Only in 1996 Steven Hare from the University of Washington first introduced the term Pacific Decadal Oscillation (PDO). In co-operation with a team of other researchers he had discovered this phenomenon and traced it back until 1900. (6)
Moreover, a warming in Alaska and cooling in Greenland and vice versa can be observed every 60 years. (7) Computerized modelling of PDO is not yet possible. (9) There is still a great need for research.
Since 1977, the average temperature in Alaska has practically not increased.
Alaska’s climate is mainly determined by maritime and atmospheric flows that are not yet sufficiently understood. Obviously, current temperature trends are not only well in the natural range of variability from the past 2000 years, but also fully coherent with this range. At the moment, the impact of human-induced greenhouse gases on the climatic changes can hardly be estimated.
Translation: Silke Kamprich
Last modifications: 09 december 2009
4. Umrechnung Fahrenheit<->Celsius
F = (C * 9/5) + 32
C = (F - 32) * 5/9
5. Feng Sheng Hu, Emi Ito, Thomas A. Brown, B. Brandon Curry¶, and Daniel R. Engstromi
Pronounced climatic variations in Alaska during the last two millennia
6. Nasa: SCIENCE - El Niño/La Niña & PDO
Pacific Decadal Oscillation (PDO)
7. Nature v. 02.12.2003: Alaska's climate: Too hot to handle
“...It is also hard to tell how much of Alaska's climate change is due to global warming and how much to natural climate cycles. The Pacific Decadal Oscillation - an El Niño-like fluctuation of temperatures between the north and tropical Pacific that takes place over 20-30 years - flipped Alaska into a warming phase in the 1970s. The North Atlantic Oscillation has also contributed to warmer winters in Alaska since the late 1960s. But at the same time it has been associated with a 2-3 °C cooling just across the continent in Greenland. There seems to be a 60-year see-saw in temperatures between the east and west of this part of the Arctic: when one side heats up, the other cools down. In a few years, this could flip again and reverse Alaska's recent warming trend. No one yet knows....”
8. Arktische Konferenz - Arctic Climate Impact Assessment (ACIA)
Impacts of a Warming Arctic: Arctic Climate Impact Assessment
ACIA, Impacts of a Warming Arctic: Arctic Climate Impact Assessment. Cambridge University Press, 2004, http://www.acia.uaf.edu
"What's striking is that the PDO pattern is similar in both the North and South Pacific and covers a huge area from the Aleutian Islands to the South Pacific," said Chao. "No computer models developed so far have been able to reproduce this symmetric pattern across the equator. This symmetry is a key to understanding what creates the PDO."
10. The ACIA report and the presentation of temperatures in Alaska:
Selected temperature rises are presented (8, p. 12). A geographical or temporal overview of the temperature development is missing.
Also, it is tried to indirectly prove a warming in Alaska: permafrost thawing, changes in the vegetation and glaciers, snow-covers at selected locations, etc.
One diagram shows the ice break-up dates of the famous Nenana ice winning bet (8, p. 75). The temperature leap in 1976 can hardly be recognized in this diagram, because the ice break-up date not only depends on temperature but also on other factors (wind, rain, water level, waste heat, i.e. from Fairbanks, etc.)
11. WWF v. 07.11.2004: Bald Ananas aus Alaska? Die Arktis schmilzt und die Industriestaaten schauen zu
If the facts change, I'll change my opinion.
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