A U.S.-French satellite has been launched with a mission to map all the world's oceans, lakes, reservoirs, rivers and other waterways. The satellite has been dubbed SWOT – Surface Water and Ocean Topography. It went into space just before dawn on Friday. Scientists hope data from the satellite will help them to monitor how climate change is adversely changing water levels. The U.S. broadcaster PBS said: "The satellite is needed more than ever, as climate change worsens droughts, flooding and coastal erosion." A NASA spokesperson spoke of the mission's importance. She said: "It's a pivotal moment.…We're going to see Earth's water like we've never seen it before."

The SWOT satellite is about the size of an SUV (sports utility vehicle). It took 20 years to develop, at a cost of $1.2 billion. High-precision radar equipment will measure the height of water on more than 90 per cent of Earth's surface. It will survey millions of lakes, as well as 2.1 million kilometres of rivers. Scientists will identify potential areas of water loss that could threaten local populations and coastlines. NASA said SWOT is a marked technological upgrade from its predecessors. A spokesperson said: "SWOT will give us a ten-fold improvement in the [accuracy] and spatial resolution of our measurements of water height." It will help scientists to better understand, "the critical role the oceans play in climate change".