365 Days of Climate Awareness 144 – 2005 State of the World Climate

 

2005 World Climate Data

• Global atmospheric CO₂ concentration: 378.98 ppm, +2.03 ppm from 2004
• Surface air temperature anomaly: +0.67°C/1.21°F, 9^th all-time 1880-2021
• Precipitation 0.87 mm below 1961-1990 global average
• Global mean sea level: 3.11 mm above 1993-2008 average, +4.86 mm from 2004
• Antarctic ozone hole: max. area 27.2 million km²; minimum O₃ 103 DU (Dobson Units)
• ENSO: Neutral, with signs of incipient La Niña by year’s end

Global Conditions

• Above-average temperatures: Russia; Scandinavia; Brazil; China; India; central, south and southwestern Asia; Australia
• Below-average temperatures: the Balkans
• Below-average precipitation: eastern Australia; western Europe; northern and central South America (esp. Amazon Basin and Paraguay); Australia
• Extreme precipitation: eastern Europe; Russia (esp. winter); Germany; Switzerland; Saudi Arabia (Medina); southern Argentina; China; southern Asia

Larger Version

2005 continued the recent run of top-10 years for global air temperature. El Niño years tend to correlate with increased rain in the tropics, and decreased rain in the higher latitudes. 2005 began with a weak, fading El Niño and this pattern continued with it (including northern hemisphere snow cover, which was 24.7 million km², nearly a million below the 1961-1990 average of 25.6 million km²).

Questions about the constancy of the thermohaline (density-driven) circulation of the ocean, and specifically in the Atlantic Ocean (AMOC: Atlantic Meridional Overturning Circulation), have become increasingly prominent with time. And with good reason: the AMOC transports an estimated 1.3 PW (1.3 petawatts = 1.3 x 10¹⁵ watts = 1.3 million billion watts) of heat northward. Global warming has led to increased melting of Arctic and Greenland ice. This cold but fresh water tends to flow southward in the upper water column, impacting the North Atlantic Current as it flows northeastward. As of 2005, analysis showed fluctuations in the AMOC to be within historical limits, though the dataset was still young.

More recent reanalysis of satellite data suggests that the AMOC system is in fact slowing down. (Not all researchers agree: they argue that the observed variability is still plausibly random). The slowdown, measured via satellite altimetry, is thought to be due more to weakening wind patterns connected with positive NAO events (where the pressure contrast between Iceland and the Azores is greater) than Arctic meltwater. In recent decades the NAO has trended positive, which supports this interpretation.

Tomorrow: 2006 State of the Climate, North America and Europe

Be brave, and be well.