365 Days of Climate Awareness 164 – 2015 State of the World Climate

2015 World Climate Data

• Global atmospheric CO₂ concentration: 399.34ppm, +2.01 ppm from 2014
• Surface air temperature anomaly: +0.93°C/1.67°F, 4^th all-time 1880-2021
•  Precipitation 22.5 (0.4 in) mm below 1961-1990 global average 1033 mm (40.7 in)
• Global mean sea level 40.99 mm above 1993-2008 average, +10.99 mm from 2014
• Antarctic ozone hole: max. area 28.2 million km²; minimum O₃ 101 DU (Dobson Units)
• ENSO: Strong El Niño
• NAO: Positive (large pressure difference north to south: warmer in eastern US & northern Europe, cooler in southern Europe)

Larger Version

Global Conditions

• Above-average temperatures: South America; Africa; Indian Ocean islands; Europe; Middle East; Russia; Mongolia; China; Japan; India; Pacific Islands; Australia
• Above-average precipitation: Western Africa and the Sahel; Indian Ocean islands; UK & Ireland; Scandinavia; southeastern Europe; Turkey; China; Japan; India
• Below-average precipitation: South America; northern, eastern & southern Africa; Iberian peninsula; central & eastern Europe; Australia

At the time, 2015 was the warmest year on record. Nine of the then-top 10 warmest years globally  came after 2000, and the only execption was 1998. Central and southern Europe were visited by a severe heat wave which lasted nearly three months, was accompanied  by drought throughout much of the region, and produced temperatures as high as 40°C/104°F.

The sustained El Niño led to elevated ocean temperatures in the Pacific, and caused a jump in global eustatic sea level of over 1 cm. It brought most of its usual global temperature and weather impacts, including temperature and precipitation impacts from the Indian to Atlantic Oceans.

Atlantic Niño (top) vs. Atlantic Niña (bottom). 

But there is a lesser-known version of this oscillation, known as the Atlantic Niño or Atlantic Equatorial Mode. It is very similar in appearance—a patch of very warm water near the Equator, alternating with cooler surface water extending from Africa westward toward South America. Atlantic Niño’s weather impacts are far smaller than ENSO’s, though a positive (warm) event usually leads to dry conditions in central western Africa and the Sahel (the region south of the Sahara). There is no obvious link between the two, though Atlantic Niño tends to peak in boreal summer, while the much larger Pacific version is strongest in boreal winter.

Tomorrow:  2016 State of the Climate, North America.

Be brave, and be well.