SEA levels are indeed rising – but is the draining of water on land, not climate change, the main culprit?
A band of scientists from Japan and the US claim unsustainable water use on the ground has contributed almost half of the 1.8mm rise in sea levels recorded annually between 1961 and 2003.
The research also explains a large portion of the sea level change that remained unaccounted for in the latest report by the UN’s Intergovernmental Panel on Climate Change, which could only attribute 1.1mm per year of the rise to climate facts such as glaciers and ice caps melting, the loss of ice masses in Greenland and Antarctica, and the thermal expansion of oceans.
The scientists say the unsustainable sources of underground water worldwide – 97 per cent of which is wasted and flows into the ocean – added 1.05mm every year to the world’s sea levels in the second half of the 20th century.
Even after being offset by the construction of new dams, which prevent some water reaching the oceans, sea levels were pushed up by more than 3cm by the wasted water.
Thermal expansion of the oceans contributed just 0.42mm a year, glaciers and ice caps melting 0.5mm a year and the loss of ice masses in Greenland and Antarctica 0.19mm a year, the IPCC’s fourth assessment report in 2007 said.
But the new investigation, released today, looked at underground water extraction, dams, water held in farmed soil and water taken for irrigation from major inland bodies like the Aral Sea, finding they were major contributors to rising sea levels.