Oceans, such as the
Pacific pictured here from space, are absorbing much of the warming the
planet is currently experiencing. NASA/ Roger Ressmeyer/ Corbis
The rate of heat building up on Earth over the past decade is
equivalent to detonating about 4 Hiroshima atomic bombs per second.
Take a moment to visualize 4 atomic bomb detonations happening every
single second. That's the global warming that we're frequently told
isn't happening.
There are periods when the ocean heats up more
quickly than the surface, and other periods when the surface heats up
more quickly than the oceans. Right now we're in a period of fast ocean
warming and overall, global warming is continuing at a very fast pace.
The confusion on this subject lies in the fact that only about 2
percent of global warming is used in heating air, whereas about
90 percent
of global warming goes into heating the oceans (the rest heats ice and
land masses). But humans live at the Earth's surface, and thus we tend
to focus on surface temperatures. Over the past 10–15 years, Earth's
surface temperature has continued to rise, but slowly. At the same
time, the warming of the oceans – and the warming of the Earth as a
whole – has accelerated.
This was the conclusion of a
scientific paper I co-authored
last year, in which our team found more overall global warming (of the
oceans, air, land, and ice combined) over the past 15 years than during
the prior 15 years. Just recently,
another paper
published in the journal Geophysical Research Letters found that the
warming of the oceans since the turn of the century has been the most
sustained in the past 50 years. They also found that, consistent with
my team's research, about 30% of overall global warming has gone into
the deep oceans below 700 meters due to changing wind patterns and ocean
currents. This accelerated deep ocean warming is also unprecedented in
the past 50 years.
We often hear from the media that the (surface
air) warming has slowed or paused over the past 15 years. This isn't a
puzzle; climate scientists are well aware of several contributing
factors, as
a recent Reuters article – "Climate scientists struggle to explain warming slowdown" – eventually discussed. The accelerated warming of the oceans is likely the main contributor.
During
years with La Niña events, more heat is transferred to the oceans, and
surface temperatures are relatively cool as a result. The opposite is
true during El Niño years. During the 1990s, there were more El Niño
than La Niña events, which resulted in more surface air warming. One of
the strongest El Niño events of the century happened in 1998, which not
coincidentally was 15 years ago.
When people say 'no warming in 15 years', they're
cherry picking
the timeframe to begin in an abnormally hot year. It's like arguing
that your car must have broken down because it hasn't moved in the 15
seconds while you've been stopped at a red light. The argument selects a
short timeframe that's not representative of the whole.
Since
2000, there has been a preponderance of La Niña events, which has acted
to temporarily bury more global warming in the oceans.
A new study
published in Nature Climate Change found that by taking into account
the short-term changes caused by factors like El Niño and La Niña
cycles, they could accurately forecast the slowed warming at the surface
several years in advance. The paper concluded,
"Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown."
Reuters
did not talk to the authors of this study, or ask any other climate
scientists about this surface warming slowdown that they're supposed to
be puzzled about. Actually that's not quite true. Just a week earlier,
Reuters interviewed the lead author of that paper in an article with
the headline "
Oceans may explain slowdown in climate change". The article noted,
"Experts
in France and Spain said on Sunday that the oceans took up more warmth
from the air around 2000. That would help explain the slowdown in
surface warming but would also suggest that the pause may be only
temporary and brief."
Reuters didn't connect the dots
between these two articles, telling us one week that oceans help
explain the surface warming slowdown, and the next week claiming the
slowdown is puzzling climate scientists. However, these 'slowdowns'
happen on a regular basis. You can find one every 5 to 10 years in the
surface temperature data, as illustrated in a graphic I created
nicknamed '
The Escalator'.
During periods with more La Niñas, surface temperatures temporarily
flatten out. But global warming does not. As long as humans continue
to increase the greenhouse effect by burning massive quantities of
fossil fuels, the planet will continue to warm, as is clear from the
acceleration of global warming since 2000.
• This is the first
post for my new blog with John Abraham, Climate Consensus - the 97%,
hosted by the Guardian. I'm also a writer for
Skeptical Science, and an environmental scientist by trade. You can follow me on Twitter
@dana1981.
