PERIODO: XXI SECOLO
AREA: PIANETA TERRA
parole chiave: Climatologia
International report confirms 2016 was third consecutive year of record global warmth
A new State of the Climate report confirmed that 2016 surpassed 2015 as the warmest year in 137 years of recordkeeping. Major indicators of climate change continued to reflect trends consistent with a warming planet. Last year’s record heat resulted from the combined influence of long-term global warming and a strong El Niño early in the year. The report found that the major indicators of climate change continued to reflect trends consistent with a warming planet. Several markers such as land and ocean temperatures, sea level, and greenhouse gas concentrations in the atmosphere broke records set just one year prior. These key findings and others are available from the State of the Climate in 2016 report released online today by the American Meteorological Society (AMS). The 27th annual issuance of the report, led by NOAA National Centers for Environmental Information, is based on contributions from nearly 500 scientists from more than 60 countries around the world and reflects tens of thousands of measurements from multiple independent datasets (highlights, full report (link is external)). It provides a detailed update on global climate indicators, notable weather events, and other data collected by environmental monitoring stations and instruments located on land, water, ice, and in space.
The report’s climate indicators show patterns, changes, and trends of the global climate system. Examples of the indicators include various types of greenhouse gases; temperatures throughout the atmosphere, ocean, and land; cloud cover; sea level; ocean salinity; sea ice extent; and snow cover. Report highlights include these indications of a warming planet.
Greenhouse Gases Highest on Record
Major greenhouse gas concentrations, including carbon dioxide (CO2), methane, and nitrous oxide, rose to new record high values during 2016. The global annual average atmospheric CO2 concentration was 402.9 parts per million (ppm), which surpassed 400 ppm for the first time in the modern atmospheric measurement record and in ice core records dating back as far as 800,000 years.This was 3.5 ppm more than 2015, and it was the largest annual increase observed in the 58-year record.
Global Surface Temperature Highest on Record
Aided by the strong El Niño early in the year, the 2016 annual global surface temperature observed record warmth for a third consecutive year, with the 2016 annual global surface temperature surpassing the previous record of 2015.
Sea Surface Temperatures Highest on Record
Global Upper Ocean Heat Content Near-Record High
Global Sea Level Highest on Record
Extremes Were Observed in the Water Cycle and Precipitation
A general increase in the water cycle (the process of evaporating water into air and condensing it as rain or snow), combined with the strong El Niño, enhanced the variability of precipitation around the world. In addition to many parts of the globe experiencing major floods in 2016, for any given month at least 12 percent of global land was experiencing at least “severe” drought conditions, the longest such stretch in the record. Drought conditions were observed in northeastern Brazil for the fifth consecutive year, making this the longest drought on record in this region. The increased hydrologic cycle was also reflected, as it has been for more than a decade, by patterns of salinity (saltiness) across the globe’s ocean surface.
The report also documents key regional climate and climate-related events.
The Arctic Continued to Warm, Sea Ice Extent Remained Low
The average Arctic land surface temperature was 3.6°F (2.0°C) above the 1981–2010 average, breaking the previous record of 2007, 2011, and 2015 by 1.4°F (0.8°C), representing a 6.3°F (3.5°C) increase since records began in 1900. Average sea surface temperatures across the Arctic Ocean during August in ice-free regions ranged from near normal in some regions to around 13° to 14°F (7° to 8°C) above average in the Chukchi Sea and eastern Baffin Bay off the west coast of Greenland, and up to 20°F (11°C) above average in the Barents Sea.
Increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On March 24, the smallest annual maximum sea ice extent in the 37-year satellite record was observed, tying with 2015 at 5.61 million square miles, 7.2% below the 1981–2010 average. On September 10, the Arctic sea ice annual minimum extent tied with 2007 for the second lowest value on record, at 1.60 million square miles, 33 percent smaller than average. Arctic sea ice cover remains relatively young and thin, making it vulnerable to continued extensive melt.
Antarctic Sees Record Low Sea Ice Extent
During August and November, record low daily and monthly sea ice extents were observed, with the November average sea ice extent significantly smaller (more than 5 standard deviations) than the 1981–2010 average. These record low sea ice values in austral spring 2016 contrast sharply with the record high values observed during 2012–2014.
Global ice and snow cover decline
Preliminary data indicate that 2016 was the 37th consecutive year of overall alpine glacier retreat across the globe, with an average loss of 2.8 feet (852 mm) for the reporting glaciers. Across the Northern Hemisphere, late-spring snow cover extent continued its trend of decline, with new record low April and May snow cover extents for the North American Arctic. Below the surface, record high temperatures at the 20-meter (65-feet) depth were measured at all permafrost observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island.
Tropical cyclones were well above average overall
There were 93 named tropical cyclones across all ocean basins in 2016, well above the 1981–2010 average of 82 storms. Three basins—the North Atlantic and eastern and western North Pacific—experienced above-normal activity in 2016. The Australian basin recorded its least active season since the beginning of the satellite Era in 1970.
The State of the Climate in 2016 is the 27th edition in a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society. The journal makes the full report openly available online.
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