The past four years have been the warmest since meteorological records began in the late 19th century. Century. This is confirmed by the 2017 annual report of the US climate agency NOAA, which was published on wednesday and on which more than 500 researchers from 65 countries had worked.
The more than 300-page report summarizes the main global climate trends of 2017. Last year was therefore the third warmest year since measurements began. However, it was the warmest year not affected by the el nino climate phenomenon, said NOAA climate scientist deke arndt. El nino causes pacific to warm in certain years.
The report highlights some of the intensifying climate trends of an arming planet: concentrations of greenhouse gases such as CO2 and methane rose to new highs in 2017. The average sea level also rose to a new high last year, 7.7 centimeters above that of 1993, when high altitude measurement by satellite was introduced. Since 1993, sea levels have risen an average of about three centimeters per decade, the authors write.
The arctic is also showing signs of increasing global warming. The flatness of the sea ice measured there in september 2017 was a quarter smaller than the long-term average at that time. "Sea ice in the arctic has become new, dark and prone to breaking and melting in recent years," it says. "The shallow area covered by old, thicker ice continues to diminish."Ten of the lowest ice levels have been recorded in the september months of the past eleven years.
In the meantime, the oceans are becoming increasingly overexposed, especially on coral reefs. The bleaching from june 2014 to may 2017 was unusual partly because of the long time period, but also because it occurred outside the nino climate phenomenon.
Corals can be compared to rainforests on land, as they house an enormous number of creatures in a very small space. In addition, the fish and other animals that live there provide food for up to one billion people worldwide, according to NOAA. Moreover, they are the basis for the sand on some beaches and provide protection from storms and waves.
Coral reefs in the pacific are bleaching particularly badly – including around guam, american samoa and hawaii. Nearly 30 percent of the world’s coral reefs experienced life-threatening bleaching between 2014 and 2017. Severe bleaching is happening more and more frequently and is thus repeating itself in less time than the coral reefs need to recover from it.