The ‘Introductory Paper’ is fair in acknowledging that there are many open question, but has little prove to offer if it claims that the past 100 years are significant for “the changeover of a climate system dominated by natural forcing to a climate system dominated by anthropogenic influences”. The paper presents the matter as fact which is elsewhere formulated as question: “Was the 1910–1945 trend a result of “natural variability” and the 1950–2003 trend an “anthropogenic” warming?” (p.9). The paper says also that the introduction gives an overview of the book in the context of recent research, highlighting some of the key findings and concepts (p.2), but rarely does. Instead a mingle-mangle of other findings are presented with little, if any, critical review.
INTRODUCTION p.2: During the past 100 years the Arctic experienced two pronounced warming periods. Between 1915 and 1945, annual mean temperatures increased by about 1.8°C. This period was followed by a cooling and a more recent warming, which started around 1970 and is still ongoing.
• Any assessment of the recent climate should acknowledge that a global warming trend had started at the end of the Little Ice Age around 1850, because the mentioned two pronounced warming periods could be part of one warming-up since 1850, interrupted by a three decade cooling phase. By global warfare? See here PDF
• The sudden increase of temperatures started in winter 1918/19 (see: upper graphic) and not 1915.
• The warming was initially not global, but had an impact in the USA until about 1933 (see graphic: Global Temp.)
• The warming did not lasted until 1945 but ended with three extreme Northern Europe winters immediate after World War II commenced. See HERE
INTRODUCTION p.8/9: The 1910–1945 (warming) trend was most pronounced over the Atlantic and North America, while Europe experienced a winter cooling. In contrast, the 1950–2003 period exhibited a strong winter warming of the northern hemispheric land masses. What may have caused this difference in climatic response?
• The third shown graphic for the time period Nov.1936 to Oct.1938 indicates the trend was quite different as claimed by Brönnimann.
• The period between 1940 and 1970 was strongly influenced by a global cooling.
• And: is there a difference in climatic response? Yes & No!
o YES: The early warming had been caused by the West Spitsbergen Current, while the second warming was actually marking the end of the interrupted warming trend from 1940 to 1970s presumably partly due to the naval warfare during WWII. o NO: Because the discussed changes had been generated and controlled by the oceans and seas.
The Booklet here presented discusses the two climatic shifts during the last century in detail.
 Brönnimann; S.; Luterbacher, J.; Ewen, T.; Diaz, H.F.; Stolarski, R.S.; Neu, U. (Eds.) ; 2008; “A Focus on the Climate During the Past 100 Years”; pages 364
 Ditto; the Introductory Paper is titled as the book; “A Focus on the Climate During the Past 100 Years”; p.1-28.
 For example: (p.3): Our understanding of the climate mechanisms operating in the Arctic on different timescales is still limited; (p.8): What may have caused this difference in climatic response?
 See: Introduction, p.2 and Conclusion, p.20
 According James Hansen the overall Earth’s average temperature rose by about 0.4°C for the period from 1880 to 1978, interrupted by a global cooling from 1940-1970; see: David Herring, November 5, 2007, „Earth’s Temperature Tracker“ , NASA at : http://earthobservatory.nasa.gov/Study/GISSTemperature/printall.php