RSS MSU satellite data (graph, more graphs) for the lower troposphere show that November 2007 was the coldest month since January 2000. Other major teams that measure the global mean temperature have not yet published their November data.
The temperature anomaly was -0.014 °C. It means that the whole month was actually cooler than the the average recorded November. It was the first month in this century that was cooler than average.
The previous record low temperature anomaly in this century occurred in July 2004 when the anomaly was +0.053 °C. In other words, the record low for this century was improved by 0.07 °C. The continuing La Nina is the main reason behind the recent cold months; La Nina is expected to disappear in Spring 2008. January 2000, a month that was even cooler than November 2007, witnessed a La Nina, too. November 2007 was also a whopping 0.915 °C colder than April 1998.
Another reason could be an inactive Sun. We are expecting the solar cycle 24 to begin soon but it takes a longer time than expected and there are still almost no sun spots. Via a crucial mechanism, it means that we should be getting more galactic cosmic rays that should create more clouds.
The year 2007 is now very likely to become RSS MSU’s 9th warmest year on record which really means one of the coldest years of our times. It will end up colder than all other years in the 21st century so far as well as 1998 (by 0.4 °C) and 1995. We explained that 2006 was very cold but 2007 will be shown as 0.1 °C colder.
This extraordinarily cold conclusion of RSS MSU occurs partly (but certainly not completely) because RSS MSU omits the polar regions north of 82.5°N and south of 70.0°S latitude. The former region that occupies less than 0.5% of the surface of Earth was recently getting substantially warmer.
Other teams (HadCRUT3, UAH MSU) except for GISS will also report 2007 to be between the 6th and 9th warmest year. Dr James Hansen’s GISS deviates substantially – it may even announce that 2007 was the warmest year – and their method to measure temperature based on stations is probably dominated by urban heat islands and the results are most likely complete rubbish.
Because GISS was able to accumulate a 0.5 °C error (in the difference between 1998 and 2007 temperatures) during one decade and because the older measurements of temperature resembled those of GISS, it is conceivable that the whole 20th century warming by 0.6 °C is due to similar errors. Ross McKitrick and Patrick Michaels have just argued that the warming since 1980 is due to a similar contamination of data. That’s still better than the sea level data that were completely falsified according to Nils-Axel Morner, an ex-head of Earth Sciences in Stockholm.