2009年11月12日

India's lost water

Water resourses are at a premium in many parts of the world, and India is one of them.

Indirect evdence suggests that groundwater in being consumed faster than it is being naturally replenished in northwest Indea, but assessments of large-scale rates of depletion are difficult to construct from ground-based measurements.

Gravity observations from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites, combined with land surface models, have been used to produce a time series of groundwater strage variations in India.

The analysis reveals a progressively more severe reduction in groundwater in Northwestern India between 2002 and 2008.

Groundwater has been depleted at a mean rate of 4.0 cm of water per year averaged over the northern Ibdian states of Rajasthan, Punjab and Haryana.

The authors consider unsustainable consumption of groundwater for irrigation and other anthropogenic uses as the most likely cause.


### DataBace ###
nature Vol.460 925-1050 Issue no.7258 20 August 2009
Letter p999 / Satellite-based estimates of groundwater depletion in India / M Rodell et al.

posted by 0≠素子(由理政宗) at 15:35| earth | このブログの読者になる | 更新情報をチェックする

2009年11月06日

Holocene carbon cycle

A new atmospheric δ^13 C record derived from measurements of air trapped in the EPICA Dome C Antarctic ice more, combined with a simple carbon model, provides a high-resolution view of the carbon cycle during the Holocene, the current interglacial period that started about 11,000 years ago.

Previous reconstructions had revealed significant chenges in atmospheric CO2 concentrations, but the processes responsible for these changes were unclear.

The new data suggest that the 5 p.p.m.v. decrease in atmospheric CO2 during the early Holocene resulted from an uptake of about 290 gigatons of carbon by the land biosphere together with carbon release from the ocean in response to carbonate compensation of the terrestrial uptake at the end of the last ice age.

The 20 p.p.m.v. increase of atmospheric CO2 during the later Holocene can be mostly explained in terms of carbonate compensation of earlier land biosphere uptake and coral reef formation, with a minor contribution from a small decrease of the land biosphere carbon inventory.


### DataBace ###
nature Vol.461 439-558 Issue no.7263 24 September 2009
Letter p.507


posted by 0≠素子(由理政宗) at 22:53| climate | このブログの読者になる | 更新情報をチェックする
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