How is the climate changing and why?

The global mean temperature in 2008 was the lowest since about 2000. Given that there is continual heating of the planet, referred to as radiative forcing, by accelerating increases of carbon dioxide and other greenhouses due to human activities, why isn’t the temperature continuing to go up? The stock answer is that natural variability plays a key role and there was a major La Niña event early in 2008, but this does not answer the question of where the energy has gone. Was it compensated for temporarily by changes in clouds or aerosols, or other changes in atmospheric circulation that allowed more radiation to escape to space? Was it because a lot of heat went into melting Arctic sea ice or parts of Greenland and Antarctica, and other glaciers? Was it because the heat was buried in the ocean and sequestered, perhaps well below the surface? Was it because the La Niña led to a change in tropical ocean currents and rearranged the configuration of ocean heat? Perhaps all of these things are going on? It turns out we can’t answer these definitively. Observations and attribution studies are inadequate. Has global warming really slowed or not?

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