Notes |
Abstract (paragraphs 1-3)
The year was characterized by a transition from a
waning La Niña to a strengthening El Niño, which first
developed in June. By December, SSTs were more than
2.0°C above average over large parts of the central and
eastern equatorial Pacific. Eastward surface current
anomalies, associated with the El Niño, were strong
across the equatorial Pacific, reaching values similar
to the 2002 El Niño during November and December
2009. The transition from La Niña to El Niño strongly
influenced anomalies in many climate conditions, ranging
from reduced Atlantic basin hurricane activity to large
scale surface and tropospheric warmth.
Global average surface and lower-troposphere temperatures
during the last three decades have been progressively
warmer than all earlier decades, and the 2000s
(2000–09) was the warmest decade in the instrumental
record. This warming has been particularly apparent in
the mid- and high-latitude regions of the Northern Hemisphere
and includes decadal records in New Zealand, Australia,
Canada, Europe, and the Arctic. The stratosphere
continued a long cooling trend, except in the Arctic.
Atmospheric greenhouse gas concentrations continued
to rise, with CO2 increasing at a rate above the 1978
to 2008 average. The global ocean CO2 uptake flux for
2008, the most recent year for which analyzed data are
available, is estimated to have been 1.23 Pg C yr-1, which
is 0.25 Pg C yr-1 smaller than the long-term average and
the lowest estimated ocean uptake in the last 27 years.
At the same time, the total global ocean inventory of
anthropogenic carbon stored in the ocean interior as of
2008 suggests an uptake and storage of anthropogenic
CO2 at rates of 2.0 and 2.3 ±0.6 Pg C yr-1 for the decades
of the 1990s and 2000s, respectively. Total-column ozone
concentrations are still well below pre-1980 levels but
have seen a recent reduction in the rate of decline while
upper-stratospheric ozone showed continued signs of
ongoing slow recovery in 2009. Ozone-depleting gas concentrations
continued to decline although some halogens
such as hydrochlorofluorocarbons are increasing globally.
The 2009 Antarctic ozone hole was comparable in size to
recent previous ozone holes, while still much larger than
those observed before 1990. Due to large interannual
variability, it is unclear yet whether the ozone hole has
begun a slow recovery process. |
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