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As well as comparing present-day melting with the past, they looked at how different global greenhouse gas emissions trajectories would impact melting over the coming century.

They modelled the IPCC’s best-case emissions scenario, called Representative Concentration Pathway (RCP) 2.6, and the worst-case emissions scenario called RCP 8.5.

Under RCP 2.6, emissions are drastically reduced starting now and we achieve net-negative emissions this century. That is, we get our emissions to zero and also draw greenhouse gases from the atmosphere through technology or by boosting natural sinks like forests and blue carbon.

Under RCP 2.6 we limit global average warming to within 2 degrees Celsius by 2100.

On the other hand, under RCP 8.5 we continue burning fossil fuels as per usual, making no substantial efforts to reduce our greenhouse gas emissions through to 2100.

Under the RCP 2.6 scenario, their models forecast that melting of the southwestern Greenland ice sheet would increase to around 8,800 billion tonnes per century on average by 2100 — about a forty per cent increase on today’s rate.

But under the worst-case RCP 8.5 scenario, they forecast the southwestern Greenland ice sheet could be losing up to 35,900 billion tonnes per century — an increase of nearly 600 per cent on today’s melting rate.

Although their study area didn’t encompass the entire ice sheet, Professor Briner said Greenland tends to melt fairly uniformly.

“Based on reconstructions of ice sheet changes over the past several decades, it has been shown that when the ice sheet loses mass in our study area, it loses mass across its entire surface,” he said.

“When rates of ice loss are high across our study area, they are high across Greenland.”

The study is an important demonstration of the difference that we can make by cutting emissions, according to David Etheridge from the CSIRO’s Climate Science Centre.

“The range of predictions shows a high sensitivity to emissions scenarios with the possibility to limit ice loss with low emissions,” Dr Etheridge said.

‘We still have time’ to slow down sea level rise

Modelling sea level rise was outside the bounds of this study, but the researchers tentatively suggest that the worst-case scenario melting from the southwestern Greenland ice sheet would add around 10 centimetres to sea levels this century.

If that was scaled to the entire ice sheet, that would likely be “doubled or tripled”, Professor Briner said. And that’s without accounting for any melting from the Antarctic ice sheet.

Research published earlier this month in Nature found that the Antarctic ice sheet will add 1.3 metres to sea level for every degree of warming up to 2 degrees Celsius above pre-industrial levels.

That research found that we have locked in at least two-and-a-half metres of sea level rise from Antarctica, regardless of what happens with our emissions from now on.

But it’s the rate at which the melting happens that we have some control over and is the crucial issue, according to Will Steffen from the ANU’s Climate Change Institute.

“We can still influence the rate at which Greenland melts and thus the rate that sea level rises. That’s the important message,” Professor Steffen said.

“We still have time to adapt if we slow it down.”

Rather than needing to adapt and shift coastal communities over decades, we can buy ourselves a century or more if we act to get emissions down immediately, Professor Steffen said.

When countries signed up to the Paris Agreement in 2015, the aim was to keep warming to 1.5C.

Given our lag in getting emissions down since then, Professor Steffen said he doesn’t think 1.5C is still realistically achievable, but keeping warming below 2C is.