Record sea surface temperatures suggest that Earth is heading into “uncharted territory” when it comes to sea level rise, coastal flooding and extreme weather. By the end of March, the surface temperature of the world's oceans was higher than anything we've seen in the 40 years since satellites measured it. The records were "off the charts" and as the heat refused to abate for over a month, the Earth marched into "uncharted territory," scientists said. Ocean surface temperatures – like those on land – are being increased by global warming, but can fluctuate from year to year as weather systems come and go. But 2km below the surface, this variability is almost nowhere to be seen. The rising heat down there has been relentlessly rising for decades, thanks to the burning of fossil fuels. “The ocean’s capacity to trap heat is enormous,” says Dr Paul Durack, a scientist specialising in ocean measurements and modelling at the US Department of Energy’s Lawrence Livermore National Laboratory. “The ocean is capturing more than 90% of the energy imbalance we are creating due to anthropogenic climate change.” The ocean is much less reflective than land and absorbs more direct energy from the sun. But as greenhouse gases trap more of the energy that is reflected back – allowing less to escape into space – the ocean is struggling to match the heat in the atmosphere above it. A technical table in the latest UN climate assessment chapter shows the unfathomable heat gains. Between 1971 and 2018, the ocean gained 396 zettajoules of heat. (Graham Readfearn, The Guardian)