From Lauren Morello at the New York Times:
This sort of research isn't easy or simple, especially since the long-term record is problematic at best, but it's key if we want to understand our planet's climate and how its going to change over the next century. The ocean is a massive heat reservoir, constantly exchanging energy with the atmosphere and between its varying depths. It's clearly moving towards equilibrium with the atmosphere, and as it does that it's capacity to act as a heat sink for excesses in the atmosphere diminishes. That process won't resolve itself for centuries, but it's a major reason we can expect much faster global warming (as measured at the surface) as we get closer to the latter half of the 21st century.
The upper ocean warmed considerably over the past decade and a half, according to a new study that attempts to make sense of conflicting analyses of the amount of heat stored in the world's seas.
Between 1993 and 2008, the study finds, the upper 700 meters of the oceans absorbed about 0.6 watts per square meter of energy. That is roughly equivalent to the power of 2 billion copies of the atomic bomb the United States dropped on Hiroshima, Japan, during World War II, said lead author John Lyman, an oceanographer at the University of Hawaii's Joint Institute for Marine and Atmospheric Research.
"Ocean heat content is a very good indicator for how the entire planet is warming," he said, because the seas serve as a massive planetary heat sink. "A percentage of the incoming radiation [from the sun] is trapped on our planet by greenhouse gases, and it turns out that about 80 to 90 percent of that heat is trapped in the ocean."
Lyman's research team, whose work was published yesterday by the journal Nature, found a warming trend six times larger than the uncertainty inherent in the ocean heat data they analyzed.
This is but a piece in the puzzle that continues to boggle the mind even today, after decades of study. It's relatively easy to figure out that carbon dioxide and some other gases trap heat leaving the atmosphere, but allow it to pass on the way in. Hence the nickname 'greenhouse gas'. What isn't easy is figuring out where all that trapped heat ends up going. Global warming heats up the entire planet, not just the thin layer of atmosphere right above ground level that we can easily measure.Between 1993 and 2008, the study finds, the upper 700 meters of the oceans absorbed about 0.6 watts per square meter of energy. That is roughly equivalent to the power of 2 billion copies of the atomic bomb the United States dropped on Hiroshima, Japan, during World War II, said lead author John Lyman, an oceanographer at the University of Hawaii's Joint Institute for Marine and Atmospheric Research.
"Ocean heat content is a very good indicator for how the entire planet is warming," he said, because the seas serve as a massive planetary heat sink. "A percentage of the incoming radiation [from the sun] is trapped on our planet by greenhouse gases, and it turns out that about 80 to 90 percent of that heat is trapped in the ocean."
Lyman's research team, whose work was published yesterday by the journal Nature, found a warming trend six times larger than the uncertainty inherent in the ocean heat data they analyzed.
This sort of research isn't easy or simple, especially since the long-term record is problematic at best, but it's key if we want to understand our planet's climate and how its going to change over the next century. The ocean is a massive heat reservoir, constantly exchanging energy with the atmosphere and between its varying depths. It's clearly moving towards equilibrium with the atmosphere, and as it does that it's capacity to act as a heat sink for excesses in the atmosphere diminishes. That process won't resolve itself for centuries, but it's a major reason we can expect much faster global warming (as measured at the surface) as we get closer to the latter half of the 21st century.
