365 Days of Climate Awareness 168 – 2017 State of the World Climate

2016 World Climate Data

• Global atmospheric CO₂ concentration: 405.22 ppm, +2.16 ppm from 2016
• Surface air temperature anomaly: +0.99°C/1.78°F, 1^st 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 43.15 mm above 1993-2008 average, +2.16 mm from 2015
• Antarctic ozone hole: max. area 23.0 million km²; minimum O₃ 114 DU (Dobson Units)
• ENSO: Mostly neutral, weak La Niña early and late
• NAO: Alternating positive and negative

Larger Version

Global Conditions

• Above-average temperatures:  The Caribbean; northern and eastern South America; Africa; Indian Ocean islands; Europe; the Middle East; Russia; Mongolia; China; Japan; southeast Asia; India; Iran; Micronesia; Australia
• Below-average temperatures: southern South America
• Above-average precipitation: Northern & southern  South America; northern Africa; eastern and southern Europe; Russia; Mongolia; China; Japan; Australia
• Below-average precipitation: Amazon Basin and eastern South America; sub-Saharan and southern Africa; Micronesia

The Arctic experienced a near-record warm year. As with eastern Antarctica, this can lead to increased snowfall, since during wintertime conditions are often too cold and dry for snow. The year began and ended extremely warm, with nearly average summer temperatures in between. The Arctic is warming at nearly twice the rate of lower latitudes—a process known as Arctic amplification.

There are several principal reasons for this: (1) reduced albedo due to reduced snow and ice cover, both in time and spatial extent; (2) increased atmospheric water vapor (due partly to increased warmth); (3) increased heat storage in the Arctic Ocean; (4) decreased cloudiness in summer (lower albedo) and increased in winter (insulative effect); (5) lower long-wave heat loss relative to the tropics due to colder temperatures.

The Antarctic does not experience the same dynamics. Antarctic snow does not melt away like the snow in northern Canada and Alaska do, in austral summer, so its albedo remains consistently high. Since Antarctica is isolated from other continents by an oceanic ring, the continental mass remains cooler. And due to the global dynamics of the atmosphere, cyclone activity in the southern hemisphere is far lower than in the north, resulting in lower overall heat transport from the equator toward the south pole.

In 2017, the total ACE for the northern hemisphere was 487 x 10⁴ kts²; for the southern hemisphere, it was 93 x 10⁴ kts². Using ACE as a measure, 60-75% of cyclone activity tends to occur in the northern hemisphere, indicating a far greater heat transport from equator to pole by major storms in the north than in the south. As the Ferrel cells expand and pole-to-equator heat transport becomes more efficient, Artic amplification is likely to grow even more pronounced.

Tomorrow: 2018 state of the climate, North America.

Be brave, and be well.