Europe and the Middle East
(2017)
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 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.
Europe and the Middle East
(2018)
In 2017, the dominant greenhouse gases released into Earth’s
atmosphere—carbon dioxide, methane, and nitrous oxide—
reached new record highs. The annual global average carbon
dioxide concentration at Earth’s surface for 2017 was 405.0
± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in
the modern atmospheric measurement record and in ice core
records dating back as far as 800 000 years. The global growth
rate of CO2 has nearly quadrupled since the early 1960s.
With ENSO-neutral conditions present in the central and
eastern equatorial Pacific Ocean during most of the year and
weak La Niña conditions notable at the start and end, the global
temperature across land and ocean surfaces ranked as the second or third highest, depending on the dataset, since records
began in the mid-to-late 1800s. Notably, it was the warmest
non-El Niño year in the instrumental record. Above Earth’s
surface, the annual lower tropospheric temperature was also
either second or third highest according to all datasets analyzed. The lower stratospheric temperature was about 0.2°C
higher than the record cold temperature of 2016 according to
most of the in situ and satellite datasets.
Several countries, including Argentina, Uruguay, Spain, and
Bulgaria, reported record high annual temperatures. Mexico
broke its annual record for the fourth consecutive year. On 27
January, the temperature reached 43.4°C at Puerto Madryn,
Argentina—the highest temperature recorded so far south
(43°S) anywhere in the world. On 28 May in Turbat, western
Pakistan, the high of 53.5°C tied Pakistan’s all-time highest
temperature and became the world-record highest temperature for May.
In the Arctic, the 2017 land surface temperature was 1.6°C
above the 1981–2010 average, the second highest since the
record began in 1900, behind only 2016. The five highest annual
Arctic temperatures have all occurred since 2007. Exceptionally
high temperatures were observed in the permafrost across
the Arctic, with record values reported in much of Alaska and
northwestern Canada. In August, high sea surface temperature
(SST) records were broken for the Chukchi Sea, with some
regions as warm as +11°C, or 3° to 4°C warmer than the longterm mean (1982–present). According to paleoclimate studies,
today’s abnormally warm Arctic air and SSTs have not been
observed in the last 2000 years. The increasing temperatures
have led to decreasing Arctic sea ice extent and thickness. On
7 March, sea ice extent at the end of the growth season saw
its lowest maximum in the 37-year satellite record, covering
8% less area than the 1981–2010 average. The Arctic sea ice
minimum on 13 September was the eighth lowest on record
and covered 25% less area than the long-term mean.
Preliminary data indicate that glaciers across the world lost
mass for the 38th consecutive year on record; the declines
are remarkably consistent from region to region. Cumulatively
since 1980, this loss is equivalent to slicing 22 meters off the
top of the average glacier.
Antarctic sea ice extent remained below average for all of
2017, with record lows during the first four months. Over
the continent, the austral summer seasonal melt extent and
melt index were the second highest since 2005, mostly due to
strong positive anomalies of air temperature over most of the
West Antarctic coast. In contrast, the East Antarctic Plateau
saw record low mean temperatures in March. The year was
also distinguished by the second smallest Antarctic ozone hole
observed since 1988.
Across the global oceans, the overall long-term SST warming
trend remained strong. Although SST cooled slightly from 2016
to 2017, the last three years produced the three highest annual
values observed; these high anomalies have been associated
with widespread coral bleaching. The most recent global coral
bleaching lasted three full years, June 2014 to May 2017, and
was the longest, most widespread, and almost certainly most
destructive such event on record. Global integrals of 0–700-
m and 0–2000-m ocean heat content reached record highs in
2017, and global mean sea level during the year became the
highest annual average in the 25-year satellite altimetry record,
rising to 77 mm above the 1993 average.
In the tropics, 2017 saw 85 named tropical storms, slightly
above the 1981–2010 average of 82. The North Atlantic basin
was the only basin that featured an above-normal season, its
seventh most active in the 164-year record. Three hurricanes
in the basin were especially notable. Harvey produced record
rainfall totals in areas of Texas and Louisiana, including a storm
total of 1538.7 mm near Beaumont, Texas, which far exceeds
the previous known U.S. tropical cyclone record of 1320.8 mm.
Irma was the strongest tropical cyclone globally in 2017 and the
strongest Atlantic hurricane outside of the Gulf of Mexico and
Caribbean on record with maximum winds of 295 km h−1. Maria
caused catastrophic destruction across the Caribbean Islands,
including devastating wind damage and flooding across Puerto
Rico. Elsewhere, the western North Pacific, South Indian, and
Australian basins were all particularly quiet.
Precipitation over global land areas in 2017 was clearly above
the long-term average. Among noteworthy regional precipitation records in 2017, Russia reported its second wettest year
on record (after 2013) and Norway experienced its sixth wettest year since records began in 1900. Across India, heavy rain
and flood-related incidents during the monsoon season claimed
around 800 lives. In August and September, above-normal
precipitation triggered the most devastating floods in more
than a decade in the Venezuelan states of Bolívar and Delta
Amacuro. In Nigeria, heavy rain during August and September
caused the Niger and Benue Rivers to overflow, bringing floods
that displaced more than 100 000 people.
Global fire activity was the lowest since at least 2003; however, high activity occurred in parts of North America, South
America, and Europe, with an unusually long season in Spain
and Portugal, which had their second and third driest years
on record, respectively. Devastating fires impacted British
Columbia, destroying 1.2 million hectares of timber, bush, and
grassland, due in part to the region’s driest summer on record.
In the United States, an extreme western wildfire season
burned over 4 million hectares; the total costs of $18 billion
tripled the previous U.S. annual wildfire cost record set in 1991.