Horst-Joachim Lüdecke (who is involved with EIKE, the German sceptic group) emails about two new papers he has on surface temperatures. He tells me that these contradict BEST.
The first is in the International Journal of Modern Physics and is entitled "How Natural is the Recent Centennial Warming? An Analysis of 2249 Surface Temperature Records".
Abstract. We evaluate to what extent the temperature rise in the past 100 years was a trend or a natural fluctuation and analyze 2249 worldwide monthly temperature records from GISS (NASA) with the 100-year period covering 1906-2005 and the two 50-year periods from 1906 to 1955 and 1956 to 2005. No global records are applied. The data document a strong urban heat island eff ect (UHI) and a warming with increasing station elevation. For the period 1906-2005, we evaluate a global warming of 0.58°C as the mean for all records. This decreases to 0.41°C if restricted to stations with a population of less than 1000 and below 800 meter above sea level. About a quarter of all the records for the 100-year period show a fall in temperatures. Our hypothesis for the analysis is - as generally in the papers concerned with long-term persistence of temperature records - that the observed temperature records are a combination of long-term correlated records with an additional trend, which is caused for instance by anthropogenic CO2, the UHI or other forcings. We apply the detrended fluctuation analysis (DFA) and evaluate Hurst exponents between 0.6 and 0.65 for the majority of stations, which is in excellent agreement with the literature and use a method only recently published, which is based on DFA, synthetic records and Monte Carlo simulation. As a result, the probabilities that the observed temperature series are natural have values roughly between 40% and 90%, depending on the stations characteristics and the periods considered. 'Natural' means that we do not have within a defi ned con fidence interval a defi nitely positive anthropogenic contribution and, therefore, only a marginal anthropogenic contribution can not be excluded.
There is also an Arxiv paper called "Long-Term Instrumental and Reconstructed Temperature Records Contradict Anthropogenic Global Warming".
Abstract. Monthly instrumental temperature records from 5 stations in the northern hemisphere are analyzed, each of which is local and well over 200 years in length, as well as two reconstructed long-range yearly records - from a stalagmite and from tree rings that are about 2000 years long. In the instrumental records, the steepest 100-year temperature fall happened in the 19th century and the steepest rise in the 20th century, both events being of about the same magnitude. Evaluation by the detrended fluctuation analysis (DFA) yields Hurst exponents that are in good agreement with the literature. DFA, Monte Carlo simulations, and synthetic records reveal that both 100-year events have too small probabilities to be natural fluctuations and, therefore, were caused by external trends. In contrast to this, the reconstructed records show stronger 100-year rises and falls as quite common during the last 2000 years. Consequently, their DFA evaluation reveals far greater Hurst exponents. These results contradict the hypothesis of an unusual (anthropogenic) global warming during the 20th century. The cause of the diff erent Hurst exponents for the instrumental and the reconstructed temperature records is not known. As a hypothesis, the sun's magnetic fi eld, which is correlated with sunspot numbers, is put forward as an explanation. The long-term low-frequency fluctuations in sunspot numbers are not detectable by the DFA in the monthly instrumental records, resulting in the common low Hurst exponents. The same does not hold true for the 2000-year-long reconstructed records, which explains both their higher Hurst exponents and the higher probabilities of strong 100-year temperature fluctuations. A long-term synthetic record that embodies the reconstructed sunspot number fluctuations includes the di erent Hurst exponents of both the instrumental and the reconstructed records and, therefore, corroborates the conjecture.