Interesting AGU Papers

Some interesting papers (to me) from this week's batch of AGU TOCs:

• Wada et al, GRL: "Past and future contribution of global groundwater depletion to sea-level rise"
  
  Taking water from the ground sends it on its way to the oceans, but putting up dams in rivers keeps it from reaching the sea. Humans are doing more of the former, and the dams are about at capacity. So whatever rise is sea level has been suppressed will start to show up again eventually, and this paper says that time is soon:
  
  "Our results show that the contribution of groundwater depletion to sea-level increased from 0.035 (±0.009) mm yr−1 in 1900 to 0.57 (±0.09) mm yr−1 in 2000, and is projected to increase to 0.82 (±0.13) mm yr−1 by the year 2050. We estimate the net contribution of terrestrial sources to be negative of order −0.15 (±0.09) mm yr−1 over 1970–1990 as a result of dam impoundment. However, we estimate this to become positive of order +0.25 (±0.09) mm yr−1 over 1990–2000 due to increased groundwater depletion and decreased dam building. We project the net terrestrial contribution to increase to +0.87 (±0.14) mm yr−1 by 2050. As a result, the cumulative contribution will become positive by 2015, offsetting dam impoundment (maximum −31 ± 3.1 mm in 2010), and resulting in a total rise of +31 (±11) mm by 2050."
  
  
• Orsi et al, GRL: The Little Ice Age shows up in Antarctica too, though about half the cooling of Greenland.
  
• Weijer et al, GRL: A more realistic ocean model than of IPCC-class suggests any decline in the Atlantic Meriodional Current -- that's the one that sends heat to northern Europe -- would be more gradual but more persistent.
  
• Wakelin et al, JGR: The amount of carbon going from the atmosphere into the northeastern Atlantic Ocean (the North Sea, etc.) is ∼6 ± 1 × 10¹² mol C yr−1. (I just love that they can determine such things.) By way of comparison, there are now about 7 × 10¹⁶ mol C in the atmosphere, and humans emit about 4 × 10¹⁴ mol C yr−1. (Most of the carbon being absorbed by the oceans happens where the water is cold, at the high latitudes.)
  
• Chakrabarty et al, GRL: Black carbon in northeastern India is increasing daily temperatures in the lower atmosphere by about 2 C