According to data published in January 2017 by the US National Oceanic and Atmospheric Administration, NOAA, the global mean temperature over land and ocean surfaces ex-ceeded the 20th century mean of 13.9°C by 0.94°C, surpassing the previous record set in 2015 (0.90°C) by 0.04°C. The linear trend over the period 1880 to 2016 reveals an in-crease of 0.93°C. This is one of several methods used to determine the increase in temperature produced by climate change since the pre-
The 2015 record was influenced by the strong El Niño phase in the tropical Pacific, which still had an impact on the global mean temperature in the first half of 2016. In addition, large sections of all of the ocean basins featuring above-average surface temperatures significantly contributed to the global temperature development. These areas included not only the Pacific off the west coast of the Americas, but also the western North Atlantic and large parts of the Western Pacific and the Indian Ocean. Of the land masses, regions in the high latitudes were of particular significance and have already experienced disproportionate warming over the last few decades. Regions in North America, Africa, South and Southeast Asia, and the eastern half of Australia also contributed to the increase in temperature.
The El Niño conditions and their lasting impact in the first half of the year also triggered drought phases, for example in northern South America and parts of Central America, as well as in the neighbouring Caribbean. Southern Africa, Ethiopia, eastern Australia, Indonesia, the Philippines and parts of India also experienced exceptionally dry conditions. Conversely, the northern half of Argentina, southern Brazil, Southeast China and southern parts of the USA saw greater precipitation than usual due to this phenomenon. In some areas, there was an abrupt change from dry to unusually wet conditions, coinciding with a shift to neutral and then to weak La Niña conditions in the second half of the year. These regions included the eastern half of Australia and Tasmania, as well as large parts of Indonesia, in particular Java and Sumatra. In South India, on the other hand, there was a shift to unusually dry conditions from September on, once again in line with the typical effects of the El Niño/Southern Oscillation (ENSO) phenomenon. Admittedly, the influence of the sometimes extremely varied partial periods is not evident in the annual average on the precipitation chart.
As in the previous year, the maximum extent of Arctic sea ice in March 2016 marks the lowest value since satellite recordings began 37 years ago. The minimum recorded in September 2016 was the second-smallest area, along with an identical value measured in 2007. In seven months of the year, the extent of the ice was smaller than ever previously ob-served. From October on, warm North Atlantic air masses moved into parts of the Arctic, whereupon sea surface temperatures rose significantly. As a result, the extent of sea ice actually shrank in the middle of November, and was still significantly reduced in December. At the same time, sea ice in the Antarctic receded at an increasing rate from September. The main reason for this was probably abnormal wind fields in the Southern Ocean. As a result of these developments, the global sea ice extent (Arctic and Antarctic sea ice combined) fell to a record low, mainly in the second half of the year, and especially in the months of September, October, November and December. The precise climatological connections are still the subject of research.
In the same way as for 2015, the review of 2016 produced the important finding that the influence of El Niño over the first half of the year was clearly reflected in the temperature signal. In general, the fluctuations generated in the climate system always overlap the signal of climate change in every area. Research has shown that internal fluctuations in this overlap can produce decades-long phases with a less pronounced increase in tem-perature. After this, there may be “spring-back” effects, with phases characterised by a sharper increase in temperature. It is therefore more difficult to clearly identify climate change in individual years, or from the perspective of just a few years. Instead, we need to observe the long-term change since the 19th century. Once such a long-term perspective is taken, despite all the fluctuations in the increase behaviour, there have been no indications up to now of any long-term weakening in the increase in temperature. In fact, the most recent record years tend to indicate the opposite.