A new high-resolution dataset from multiple orbiting missions has shown the global sea level to have risen by an average of 3mm per year over the past 18 years.
Speaking last week at the five-yearly radar altimetry symposium, appropriately held in Venice, the European Space Agency's head of Earth observation applications Maurice Borgeaud detailed the findings, attributed roughly equally to water expansion due to rising temperatures and the melting of glaciers and polar ice sheets.
The meeting followed the 20-year anniversaries of the launch of the first European Remote Sensing satellite, ERS-1, and of the joint French-US TOPEX/Poseidon mission. Both carried radar altimeters, and have been followed by missions including TOPEX/Poseidon follow-ups Jason-1 and -2, in 2001 and 2008, and ESA's ERS-2, Envisat and CryoSat.
However, Pascale Ultré-Guérard, head of Earth observation for French space agency CNES, stressed the importance of data continuity - an issue thrown into stark relief earlier this year when ESA lost contact with Envisat and declared the mission over. That satellite had already survived five years beyond its minimum design life, but its replacement by the Sentinel series of spacecraft will not begin until first launch, currently scheduled for 2013.
ESA will launch its next radar altimeters with the Sentinel-3 mission within Europe's Global Monitoring for Environment and Security (GMES) programme.