Is HELCOM ignoring a crucial aspect ? -Why is the Baltic Sea warming stronger than the global trend?

-Why is the Baltic Sea warming stronger than the global trend?-

Air temperature in the Baltic Basin has increased by 0.7°C per 100 years since the late 19th century – a stronger trend than the global trend, is widely claimed[1]. A HELCOM  Report subsequently concluded that “based on available regional modelling studies, a warming of the mean annual temperature in the order of 3ºC to 5ºC is projected for the total basin during this century[2]. Despite this alarming facts and claims a major aspect, which could significantly enhance the warming trend is not even mentioned, respectively discussed.

1ocean 1climateHelcom recognizes that the Baltic Sea is one of the most intensely trafficed marine areas in the world. Both the numbers and the sizes of ships have grown in recent years, especially oil tankers, and this trend is expected to continue.[3]  There are about 1,800 – 2,000 ships in the Baltic marine area at any given moment[4]. This armada is turning the Baltic Sea upper sea level of a thickness up to 7 meters and more ‘up-side-down’ within two weeks or less. And that shall have no effect on the regional air temperatures over the four seasons?

1ocean 1climateThe impact of shipping in the Baltic region is simple: The upper 3m of water has the same heat capacity as the whole of the atmosphere. Hence the heat required to raise the temperature of the atmosphere by 1ºC can be obtained from cooling the upper 3m of water by the same amount[5]. One can only wonder why this fundamental aspect in the Baltic Sea climatology is completely ignored.

For example: a recent paper concluded: Centennial time scale results indicate that the seventeenth and nineteenth centuries were the coldest centuries, while the 1690s were the coldest decade and 1695 the coldest year in the last 500 years. The results also indicate that the twentieth century was the warmest century with the least MIB (annual maximum ice extent) of the last 500 years. On a decadal time scale, the 1990s, 1930s and 1730s were the warmest decades and comparable in terms of both water temperature and MIB.[6]

As the 1930s decade belongs to the warmest, and while factual this decade ended abrupt in winter 1939/40, an answer should be given: why?. Only four months into World War II, and due to huge naval activities and warfare, the climate was back in the Little Ice Age, giving Northern Europe the coldest winter for more than 100 years, as thoroughly explained at this site. 
1ocean 1climate
Why exist today so little willingness to listen to an eye witness, like M. Rodewald[7], who wondered back in 1947: >>a “secular heat wave” made itself felt over most of the Earth. We noticed this especially in the increasing mildness of the winters which, while beginning in the previous century, became more and more striking between 1900 and 1939. So it is all the more surprising that there was a series of three severe winters in succession in 1939/40, 1940/41 and 1941/42, appearing to indicate a sudden reversal of the previous development rather than a slow deceleration, contrary to the sustainment tendency of circulation and temperature deviation.>>
When HELCOM Secretary Juha-Markku Leppänen[8] considers that: “The HELCOM strategy in relation to climate change should aim to limit or mitigate adverse impacts as well as to enhance the resilience of the Baltic marine environment by improving its capacity to cope with the stress of climate change,” he should require that Helcom adviser pay attention to the temperature impact of movement of ships. The Large-Scale Experiment with Climate during war winter 1939/40 should not longer be ignored.

A Large-Scale Experiment with Climate
 – The Extreme Winter of 1939/40 and Climate Research –


[1] Omstedt, A. & Storch, H.; 2006,  „Assessment of Climate Change for the Baltic Sea Basin“, BACC Conference for EUROceans.doc. With reference to: The BACC Author Team, 2008, Assessment of Climate Change for the Baltic Sea Basin, Berlin 2008.  

[2] HELCOM Thematic Assessment in 2007, Climate Change in the Baltic Sea Area, Proceedings No. 111, p. 6 .

[3] Summary of HELCOM Baltic Sea Action Plan, adopted by HELCOM Ministerial Meeting, 15 November 2007, Krakow, Poland    

[4]  Press release 03 August 2006, at

[5] B.R.Stanton, 1991, “Ocean Circulation and Ocean-Atmosphere Exchanges”, Climate Change, Vol. 18: p.175-194

[6] Hansson, Daniel and A. Omstedt;  2007, „Modelling the Baltic Sea ocean climate on centennial time scale: temperature and sea ice“, Climate Dynamics, p. 763-778

[7] M. Rodewald, 1948, „Das Zustandekommen der strengen europäischen Winter“, in: Annalen der Meteorologie, Heft 4/5, S. 97.

[8] Helcom Press release March 2007: “Baltic Sea region air temperature likely to achieve 3ºC to 5ºC increase this century”