Here today, gone tomorrow: the IPCC’s new report predicts the sea-level rise flooding our backyard

The Intergovernmental Panel on Climate Change (IPCC) has just released part of its Sixth Assessment Report, unequivocally linking human influence to the warming of the atmosphere, land and ocean. It comes as unprecedented fires and floods act as a wake-up call for the Northern Hemisphere, but for some – like the island nations of the Pacific – the climate crisis has been a reality for decades.

Among a swathe of dire results, the new report found that the global mean sea level has risen faster over the past 100 years than in any other century in at least 3,000 years. In the last decade alone, sea levels across the world have risen an average of four millimetres per year – and this rate is now accelerating.

Even if we rapidly slash emissions, the seas will still rise by half a metre by the end of the century, the report says – though under higher emissions scenarios, this could swell to nearly two metres. And the water could continue to rise for centuries or even millennia, as the ice sheets disappear and the ocean absorbs heat from the atmosphere.

“Worldwide, unmitigated emissions will impact hundreds of millions of people over the 21st century and beyond,” warns Professor John Church, an oceanographer at the University of New South Wales (UNSW) and an author on previous IPCC reports.

But for those who live on islands and in coastal communities, the consequences of our actions have already arrived – and in just decades, these places could lose everything.

Vanishing islands: what’s at stake?

“Climate change is here, and it’s already harming the people of the Pacific most of all,” says Dr Nikola Čašule, Greenpeace Australia Pacific Head of Research and Investigations.

Islands are canaries in the coal mine for the climate crisis, the first to face the consequences in a measurable way. Some of the hardest-hit places are in the Australasian and Pacific region; the oceans are rising at a faster rate here than in many other parts of the world.

Professor Patrick Nunn, a coastal geographer from the University of the Sunshine Coast, has spent 25 years living and researching in the Pacific. He says that parts of the Western Pacific – like the Solomon Islands and Micronesia – are copping 10–12 millimetres of sea level rise each year, which is three to four times the global average.

“There is a type of island, called an atoll island or a reef Island, that is basically just a pile of sand and gravel on top of a coral reef,” says Nunn. “Most of that material is unconsolidated, therefore it’s very exposed or very vulnerable to erosion. And these islands do frequently get washed away.”

Islands are canaries in the coal mine for the climate crisis.

Sandy shorelines have already retreated in many locations in the Australasian region, confirms Dr Mark Hemer, a CSIRO scientist and lead author on the chapter about oceans in the new IPCC report.

“This sea-level rise will be experienced most alarmingly through more frequent and severe coastal flooding in low-lying areas, and coastal erosion, in response to extreme sea level events,” he says.

These flooding events will also flush saltwater into coastal freshwater aquifers, affecting groundwater that seeps into estuaries.

Pacific Island nations are no strangers to these effects.

“Already at 1.1°C of heating, the Pacific is seeing rising sea levels and destructive king tides, fiercer cyclones, crop failures due to drought and soil salinity, and the degradation of marine resources, like fisheries,” says Čašule.

These events are only expected to increase in frequency and severity.

Communities are already being forced to move to avoid the worst of these events, with 830 vulnerable communities listed for relocation in Fiji alone, according to a new report compiled by Greenpeace Australia Pacific and co-authored by Čašule. This report also highlights that the 14 Pacific Island countries produce just 0.23% of global greenhouse emissions, despite bearing the brunt of the consequences.

“All low-lying island communities, and especially developing economy ones, will be hit hard by a heating planet,” Čašule says. “There are no Pacific Island countries that will escape unscathed if the world doesn’t get serious about slashing emissions and phasing out coal, oil and gas.”

Similarly, residents of the Torres Strait Islands, scattered through the sea between Australia and Papua New Guinea (PNG), face the encroachment of an ocean they have lived companionably alongside for millennia.

Reports suggest that sea levels in the Torres Strait have risen six millimetres per year since 1993, which is twice the global average.

In 2019, eight influential Torres Strait Islanders approached the UN Human Rights Committee in Geneva, alleging that the federal government is violating their fundamental human rights, due to its failure to adequately tackle climate change.

But the Australian Government was reticent to address their concerns, and Prime Minister Scott Morrison declined an invitation to travel to the islands to see coastal degradation for himself. It remains an alarming reality for nations and cultures that have lived and prospered on these rocky, muddy or sandy isles for generations – whether the PM visits or not.

As Earth heats up and glaciers and ice sheets melt, the run-off is not evenly distributed across the globe.

According to Professor Ian McNiven, a specialist in Indigenous archaeology at Monash University, the earliest current evidence for human occupation of the Torres Strait Islands comes from Badu, where charcoal and stone tools were found in layers dating to around 9,000 years ago.

McNiven was an archaeological expert witness in a Torres Strait Island native title claim, presenting the Federal Court with evidence of the island’s cultural continuity from past to present. He is patently conscious of what islanders stand to lose to a swelling ocean.

“The most pressing thing for communities is are they going to lose where they can actually live in terms of their houses and infrastructure,” he says. “But also, a lot of the cultural heritage sites and archaeological sites are in low lying areas. Those vast archives of their ancestors’ activities – a lot of that is going to wash away.

“Sea level rise is going to rob people in many ways of their future, but it’s going to rob them of their past as well.”

Why do sea levels rise faster in some places than others?

The varied rates of rise around the globe hinge on a number of complex factors, according to UNSW’s Church.

Firstly, as Earth heats up and glaciers and ice sheets melt, the run-off is not evenly distributed across the globe.

“Because you’re changing the mass distribution on Earth [as the ice melts], you’re changing the Earth’s gravitational field,” Church says.

“Right near where the glaciers are losing mass, there’s less loading on the Earth. As the ice sheets lose mass, both in Greenland and Antarctica, [sea level] rise is smaller in the near field by an order of 20-30% than in the far field.”

The ‘near-field’ refers to the area around whether the ice sheets are; the ‘far-field’ refers to places like Australia and the Western Pacific. This effect is known as glacial isostatic adjustment (GIA).

The other major contributing factor to higher-than-average sea level rise in Australasia comes, according to Church, from weather patterns. Large-scale oceanic weather patterns like El Niño and La Niña, as well as longer-term ‘decadal’ patterns, have hastened sea level rise in the Western Pacific compared with the Eastern, because they force water westwards. Church says, however, that this pattern appears to be slowing.

Looming over each of these factors, holding the puppet strings, are human beings. The new IPCC report confidently links anthropogenic emissions and the warming of our planet. The majority of sea level rise since 1970, it says, is due to human influence – largely warming but also other behaviours like the alteration of water flows for terrestrial water storage.

And the consequences of our actions are not just island-specific – sea level rise will devastate parts of the mainland, too.

Sinking cities

Most Australian cities are built on river deltas, which are by design sinking into the ground due to sediment compaction over time. This sinking effect accelerates sea level rise in delta and estuary-based communities.

“In coastal cities, the combination of more frequent extreme sea-level events and extreme rainfall/riverflow events will make flooding more probable,” explains Hemer.

Despite the risks posed to our own major cities, Nunn says Australian politicians are burying their heads in the sand.

“No one’s moving Adelaide at the moment, no one’s moving Melbourne, or Sydney or Brisbane,” he says. “But the lowest parts of those cities will have to move eventually, because the sea level is rising, and nothing is going to stop the rise of sea level anytime soon.”

Church says that even seemingly small increments of sea level rise have dramatic impacts on extreme weather events like coastal flooding, which is a growing threat to communities on Australia’s east coast.

“The rule of thumb is something like [for] every 10-centimetre rise in sea level, you have roughly a factor-of-three increase in the frequency of high sea-level events,” he explains. “What that means is what is currently a one-in-100-year event, for the highest sea-level rise scenario, that will be occurring maybe several times a year by 2100.”

From Nunn’s perspective, modern society – which is inherently sedentary – has acculturated us to be resistant to change.

“When you look at the history of the Pacific Islands, one of the defining features of the cultures has been their mobility. People have moved continuously,” he says.

“And it’s really only since globalisation, colonisation that people in Pacific Island contexts have developed this idea that they can root themselves to particular places, and that those places are therefore somehow immune to change.”

Like it or not, the humans of the future will be forced to adapt.

Modern society – which is inherently sedentary – has acculturated us to be resistant to change.

“Politicians find the environment very inconvenient, and they often like to pretend that it’s some kind of unchanging backdrop to the human drama, but it’s not,” says Nunn. “Human societies evolve and environments evolve, and it’s a question of understanding how they will co-evolve that we really need to know about.”

Massive collaborative efforts like the IPCC aim to provide this exact information and outline potential paths forwards for world leaders – if they listen.

“Climate scientists have been sounding the alarm about global warming for decades and for decades too many leaders have failed to act – this is their ‘break glass in case of emergency’ moment,” says Čašule of the new report.

“The question for the world’s leaders is whether they have the will and courage to rein in the fossil fuel companies, rapidly phase out the burning of coal, oil, and gas, and make big cuts to emissions in the next decade. This is the only thing that will stop the worst of the potential scenarios the IPCC has laid out from becoming a reality.”

The responsibility lies largely on the shoulders of the highest-emitting nations, who will come together in November this year in Glasgow at the 26th UN Climate Change Conference of the Parties (COP26). The path they choose could literally cause countries to be lost beneath the waves.

“The world’s biggest emitting nations need to announce and implement emissions-reduction targets that are compatible with a 1.5-degree heating limit,” says Čašule.

“For Australia, this means decarbonising our electricity sector by 2030, and reaching net zero emissions by 2035. The action we take this decade will determine whether we succeed or fail in protecting the planet and being a good neighbour to the Pacific.”

LAUREN FUGE contributed additional reporting to this story.