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Ice in the Antarctic is melting faster than ever, with around 200 billion tonnes a year returning to the ocean. Meltwater from the Antarctic alone is pushing global sea levels up by about 0.6mm per year - three times as much as in 2012.

Most of the losses are happening in western Antarctica, where warmer ocean waters are beginning to undermine glaciers that end at the sea.

Globally, sea levels are now rising at 4.5mm per year.  That's a huge increase from the middle of the 20th Century, when seas were rising by just 1.4mm per year.

About 1.3mm per year of that sea level rise is cause by thermal expansion, because sea water expands as it gets warmer.  But melting ice, in particular from Antarctica and Greenland has increased considerably.  Ice melt from Greenland contributed about 5% to sea level increases in 1993, but this had risen to 25% by 2012.

In worst case scenario models, scientists have predicted that ocean levels could rise globally by 0.9m to 1.5m by 2100.  The last time global average temperatures were 2-3C higher than they are today , sea levels were 25 metres higher.  Back then, 14,000 years in the past, global sea levels rose at a rate of around 1 metre every 20 years.  The Paris Climate Agreement aims to limit temperature increases to 'well below' 2C above pre-Industrial levels, but many countries are still struggling to come up with proposals on how to meet that target.

A metre in 20 years doesn't seem too bad until you realise that at least 10% of the world's population lives on land that will end up under those rising seas.  The sooner we all start to really tackle climate change, the better it will be. 

Photo by David