Improving observations of ocean heat content show that Earth is absorbing
more energy from the sun than it is radiating to space as heat, even during the
recent solar minimum. The inferred planetary energy imbalance, 0.59 \pm 0.15
W/m2 during the 6-year period 2005-2010, confirms the dominant role of the
human-made greenhouse effect in driving global climate change. Observed surface
temperature change and ocean heat gain together constrain the net climate
forcing and ocean mixing rates. We conclude that most climate models mix heat
too efficiently into the deep ocean and as a result underestimate the negative
forcing by human-made aerosols. Aerosol climate forcing today is inferred to be
1.6 \pm 0.3 W/m2, implying substantial aerosol indirect climate forcing via
cloud changes. Continued failure to quantify the specific origins of this large
forcing is untenable, as knowledge of changing aerosol effects is needed to
understand future climate change. We conclude that recent slowdown of ocean
heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols
and a deep prolonged solar minimum. Observed sea level rise during the Argo
float era is readily accounted for by ice melt and ocean thermal expansion, but
the ascendency of ice melt leads us to anticipate acceleration of the rate of
sea level rise this decade.Comment: 39 pages, 18 figures; revised version submitted to Atmos. Chem. Phy
