A satellite has been launched with a mission to map the world's oceans, lakes, rivers and other waterways. It has been dubbed SWOT – Surface Water and Ocean Topography. It went into space just before dawn. Data from the satellite will help scientists to monitor how climate change is adversely affecting water levels. The broadcaster PBS said: "SWOT is needed more than ever, as climate change worsens droughts, flooding and coastal erosion." NASA said SWOT was of "pivotal" importance. It said: "We're going to see Earth's water like we've never seen it before."

The satellite is the size of a sports utility vehicle. It took 20 years to make and cost $1.2 billion. High-precision radar will measure the height of water on 90 per cent of Earth's surface. It will survey millions of lakes and 2.1 million kilometres of rivers. It will identify areas of water loss that could threaten populations and coastlines. A NASA 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 understand, "the critical role the oceans play in climate change".