Deep ocean contributions to sea level rise and Earth's energy budget
Event: 2014 Ocean Surface Topography Science Team Meeting
Session: Science Results from Satellite Altimetry: Regional and basin-scale processes and sea level rise
Presentation type: Type Oral
As the dominant reservoir for the uptake of heat in the climate system, the world's oceans provide a critical measure of global climate change. Here, we quantify ocean warming in the context of global mean energy uptake and sea level rise for the recent years between 2005 and 2013. Four different analyses of in situ observations (Argo floats) are examined to estimate the thermal expansion of ocean waters from the surface to 2000m depth. The in situ observations yield a thermosteric global mean sea level trend of 0.9+/-0.15 mm/yr, of which the warming in the 700-2000m layer accounts for 42%. The in situ data-based thermal expansion together with estimates of ocean mass increase from satellite observations (GRACE) imply a net global mean sea level rise of 2.9+/-0.18 mm/yr. The agreement between this combined estimate and direct satellite measurements of global mean sea level rise (2.78+/-0.32 mm/yr over this period) leaves little to no room for possible warming in the ocean below 2000m. Nevertheless, taking errors from all sources into consideration, we find an upper bound of 0.59 mm/yr in thermal expansion and 0.35 W/m2 in net warming -expressed as a net radiative imbalance at the top of the atmosphere- for this deep ocean layer. From 2005 to 2013, the combined analysis suggests that the full-depth ocean has rates of thermal expansion of 0.77 ± 0.28 mm/yr and warming of 0.64 ± 0.44 W/m2.