Peter Bissolli, Mesut Demicran, J. M. Gutiérrez, Mike Kendon, John Kennedy, Monika Lakatos, Gerard McCarthy, Colin Morice, M. R. Pons, Rütger Rollenbeck, Serhat Sensoy, Katja Trachte, Gerard van der Schrier
- In 2016, the dominant greenhouse gases released into Earth’s
atmosphere—carbon dioxide, methane, and nitrous oxide—
continued to increase and reach new record highs. The 3.5 ±
0.1 ppm rise in global annual mean carbon dioxide from 2015
to 2016 was the largest annual increase observed in the 58-
year measurement record. The annual global average carbon
dioxide concentration at Earth’s surface surpassed 400 ppm
(402.9 ± 0.1 ppm) for the first time in the modern atmospheric
measurement record and in ice core records dating back as
far as 800000 years.
One of the strongest El Niño events since at least 1950 dissipated in spring, and a weak La Niña evolved later in the year.
Owing at least in part to the combination of El Niño conditions
early in the year and a long-term upward trend, Earth’s surface
observed record warmth for a third consecutive year, albeit
by a much slimmer margin than by which that record was set
in 2015. Above Earth’s surface, the annual lower troposphere
temperature was record high according to allIn 2016, the dominant greenhouse gases released into Earth’s
atmosphere—carbon dioxide, methane, and nitrous oxide—
continued to increase and reach new record highs. The 3.5 ±
0.1 ppm rise in global annual mean carbon dioxide from 2015
to 2016 was the largest annual increase observed in the 58-
year measurement record. The annual global average carbon
dioxide concentration at Earth’s surface surpassed 400 ppm
(402.9 ± 0.1 ppm) for the first time in the modern atmospheric
measurement record and in ice core records dating back as
far as 800000 years.
One of the strongest El Niño events since at least 1950 dissipated in spring, and a weak La Niña evolved later in the year.
Owing at least in part to the combination of El Niño conditions
early in the year and a long-term upward trend, Earth’s surface
observed record warmth for a third consecutive year, albeit
by a much slimmer margin than by which that record was set
in 2015. Above Earth’s surface, the annual lower troposphere
temperature was record high according to all datasets analyzed,
while the lower stratospheric temperature was record low
according to most of the in situ and satellite datasets.
Several countries, including Mexico and India, reported
record high annual temperatures while many others observed
near-record highs. A week-long heat wave at the end of April
over the northern and eastern Indian peninsula, with temperatures surpassing 44°C, contributed to a water crisis for 330
million people and to 300 fatalities.
In the Arctic the 2016 land surface temperature was 2.0°C
above the 1981–2010 average, breaking the previous record of
2007, 2011, and 2015 by 0.8°C, representing a 3.5°C increase
since the record began in 1900. The increasing temperatures
have led to decreasing Arctic sea ice extent and thickness. On
24 March, the sea ice extent at the end of the growth season
saw its lowest maximum in the 37-year satellite record, tying
with 2015 at 7.2% below the 1981–2010 average. The September 2016 Arctic sea ice minimum extent tied with 2007 for the
second lowest value on record, 33% lower than the 1981–2010
average. Arctic sea ice cover remains relatively young and thin,
making it vulnerable to continued extensive melt. The mass of
the Greenland Ice Sheet, which has the capacity to contribute
~7 m to sea level rise, reached a record low value. The onset
of its surface melt was the second earliest, after 2012, in the
37-year satellite record.
Sea surface temperature was record high at the global scale,
surpassing the previous record of 2015 by about 0.01°C. The
global sea surface temperature trend for the 21st centuryto-date of +0.162°C decade−1 is much higher than the longer
term 1950–2016 trend of +0.100°C decade−1. Global annual
mean sea level also reached a new record high, marking the
sixth consecutive year of increase. Global annual ocean heat
content saw a slight drop compared to the record high in 2015.
Alpine glacier retreat continued around the globe, and
preliminary data indicate that 2016 is the 37th consecutive
year of negative annual mass balance. Across the Northern
Hemisphere, snow cover for each month from February to
June was among its four least extensive in the 47-year satellite
record. Continuing a pattern below the surface, record high
temperatures at 20-m depth were measured at all permafrost
observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island.
In the Antarctic, record low monthly surface pressures were
broken at many stations, with the southern annular mode setting record high index values in March and June. Monthly high
surface pressure records for August and November were set
at several stations. During this period, record low daily and
monthly sea ice extents were observed, with the November
mean sea ice extent more than 5 standard deviations below the
1981–2010 average. These record low sea ice values contrast
sharply with the record high values observed during 2012–14.
Over the region, springtime Antarctic stratospheric ozone
depletion was less severe relative to the 1991–2006 average,
but ozone levels were still low compared to pre-1990 levels.
Closer to the equator, 93 named tropical storms were observed during 2016, above the 1981–2010 average of 82, but
fewer than the 101 storms recorded in 2015. 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. Overall, four tropical cyclones reached
the Saffir–Simpson category 5 intensity level.
The strong El Niño at the beginning of the year that transitioned to a weak La Niña contributed to enhanced precipitation
variability around the world. Wet conditions were observed
throughout the year across southern South America, causing
repeated heavy flooding in Argentina, Paraguay, and Uruguay.
Wetter-than-usual conditions were also observed for eastern
Europe and central Asia, alleviating the drought conditions of
2014 and 2015 in southern Russia. In the United States, California had its first wetter-than-average year since 2012, after
being plagued by drought for several years. Even so, the area
covered by drought in 2016 at the global scale was among the
largest in the post-1950 record. For each month, at least 12% of
land surfaces experienced severe drought conditions or worse,
the longest such stretch in the record. In northeastern Brazil,
drought conditions were observed for the fifth consecutive
year, making this the longest drought on record in the region.
Dry conditions were also observed in western Bolivia and Peru;
it was Bolivia’s worst drought in the past 25 years. In May, with
abnormally warm and dry conditions already prevailing over
western Canada for about a year, the human-induced Fort
McMurray wildfire burned nearly 590000 hectares and became
the costliest disaster in Canadian history, with $3 billion (U.S.
dollars) in insured losses.…
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