25/01/2022

(The Conversation) 5 Ways Climate Change Boosts Tsunami Threat, From Collapsing Ice Shelves To Sea Level Rise

The Conversation -

Shutterstock

Author
is Adjunct Research Fellow, Curtin University.
The enormous eruption of the underwater volcano in Tonga, Hunga Tonga-Hunga Ha'apai, triggered a tsunami that reached countries all around the Pacific rim, even causing a disastrous oil spill along 21 beaches in Peru.

In Tonga, waves about 2 metres high were recorded before the sea level gauge failed, and waves of up to 15m hit the west coasts of Tongatapu Islands, ‘Eua, and Ha’apai Islands. Volcanic activity could continue for weeks or months, but it’s hard to predict if or when there’ll be another such powerful eruption.

Most tsunamis are caused by earthquakes, but a significant percentage (about 15%) are caused by landslides or volcanoes. Some of these may be interlinked – for example, landslide tsunamis are often triggered by earthquakes or volcanic eruptions. But does climate change also play a role? As the planet warms, we’re seeing more frequent and intense storms and cyclones, the melting of glaciers and ice caps, and sea levels rising. Climate change, however, doesn’t just affect the atmosphere and oceans, it affects the Earth’s crust as well.

Climate-linked geological changes can increase the incidence of earthquakes and volcanic eruptions which, in turn, can exacerbate the threat of tsunamis. Here are five ways this can happen.

1. Sea level rise

If greenhouse gas emissions remain at high rates, the average global sea level is projected to rise between 60 centimetres and 1.1m. Almost two thirds of the world’s cities with populations over five million are at risk.

Rising sea levels not only make coastal communities more vulnerable to flooding from storms, but also tsunamis. Even modest rises in sea level will dramatically increase the frequency and intensity of flooding when a tsunami occurs, as the tsunami can travel further inland.

For example, a 2018 study showed only a 50 centimetre rise would double the frequency of tsunami-induced flooding in Macau, China. This means in future, smaller tsunamis could have the same impact as larger tsunamis would today.


2. Landslides

A warming climate can increase the risk of both submarine (underwater) and aerial (above ground) landslides, thereby increasing the risk of local tsunamis.

The melting of permafrost (frozen soil) at high latitudes decreases soil stability, making it more susceptible to erosion and landslides. More intense rainfall can trigger landslides, too, as storms become more frequent under climate change.

Tsunamis can be generated on impact as a landslide enters the water, or as water is moved by a rapid underwater landslide.

In general, tsunami waves generated from landslides or rock falls dissipate quickly and don’t travel as far as tsunamis generated from earthquakes, but they can still lead to huge waves locally.

In Alaska, US, glacial retreat and melting permafrost has exposed unstable slopes. In 2015, this melting caused a landslide that sent 180 million tonnes of rock into a narrow fjord, generating a tsunami reaching 193m high – one of the highest ever recorded worldwide.

Scientists survey damage from a megatsunami in Taan Fiord that had occurred in October, 2015 after a massive landslide. Peter Haeussler, United States Geological Survey Alaska Science Center/Wikimedia

Other areas at risk include northwest British Columbia in Canada, and the Barry Arm in Alaska, where an unstable mountain slope at the toe of the Barry Glacier has the potential to fail and generate a severe tsunami in the next 20 years.

3. Iceberg calving and collapsing ice shelves

Global warming is accelerating the rate of iceberg calving – when chunks of ice fall into the ocean.

Studies predict large ice shelves, such as the Thwaites Glacier in Antarctica, will likely collapse in the next five to ten years. Likewise, the Greenland ice sheet is thinning and retreating at an alarming rate.

Icebergs colliding with the seafloor can trigger underwater landslides. Shutterstock

While much of the current research focus is on the sea level risk associated with melting and collapse of glaciers and ice sheets, there’s also a tsunami risk from the calving and breakup process.

Wandering icebergs can trigger submarine landslides and tsunamis thousands of kilometres from the iceberg’s original source, as they hit unstable sediments on the seafloor.

4. Volcanic activity from ice melting

About 12,000 years ago, the last glacial period (“ice age”) ended and the melting ice triggered a dramatic increase in volcanic activity.

The correlation between climate warming and more volcanic eruptions isn’t yet well constrained or understood. But it may be related to changes in stress to the Earth’s crust as the weight of ice is removed, and a phenomenon called “isostatic rebound” – the long-term uplift of land in response to the removal of ice sheets.

The end of the last ice age saw a huge increase in volcanic activity as ice melted. Whether the same could happen from climate change today remains to be seen. AP Photo/Marco Di Marco

If this correlation holds for the current period of climate warming and melting of ice in high latitudes, there’ll be an increased risk of volcanic eruptions and associated hazards, including tsunamis.

5. Increased earthquakes

There are a number ways climate change can increase the frequency of earthquakes, and so increase tsunami risk.

First, the weight of ice sheets may be suppressing fault movement and earthquakes. When the ice melts, the isostatic rebound (land uplift) is accompanied by an increase in earthquakes and fault movement as the crust adjusts to the loss of weight.

We may have seen this already in Alaska, where melting glaciers reduced the stability of faults, inducing many small earthquakes and possibly the magnitude 7.2 St Elias earthquake in 1979.

In 2018, back-to-back earthquakes shattered highways and rocked buildings in Alaska, briefly triggering a tsunami warning for islands and coastal areas south of the city. Marc Lester/Anchorage Daily News via AP
Another factor is low air pressure associated with storms and typhoons, which studies have also shown can trigger earthquakes in areas where the Earth’s crust is already under stress. Even relatively small changes in air pressure can trigger fault movements, as an analysis of earthquakes between 2002 and 2007 in eastern Taiwan identified.

So how can we prepare?

Many mitigation strategies for climate change should also include elements to improve tsunami preparedness.

This could include incorporating projected sea level rise into tsunami prediction models, and in building codes for infrastructure along vulnerable coastlines.

Researchers can also ensure scientific models of climate impacts include the projected increase in earthquakes, landslides and volcanic activity, and the increased tsunami risk this will bring.
Links
at No comments:

(AU NEWS.com.au) Deloitte Sustainability Report Finds More Australian Businesses Concerned About Climate Change

NEWS.com.au - Ellen Ransley

Australian business leaders are more alarmed about climate change than ever, with a report finding a big opinion shift in just eight months.

Opposition Leader Anthony Albanese says he wants Australia to be a part of the global effort in combatting… climate change. “Australia can’t solve climate change by itself. But what we can do is be a part of the global solution,” Mr Albanese said. “Working with like minded countries like the Biden administration in the United States.” 8min 03sec

The 2022 Deloitte CxO Sustainability Report, which surveyed 102 Australian business leaders, found that almost three quarters of them now believe the world is at a tipping point for responding to climate change.

Comparatively, just half of Australian businesses held that view last May.

In addition, almost all Australian executives say their companies have already been impacted by the changing climate. More than half say their organisation is being impacted by the regulatory and political uncertainty associated with climate change.

Two thirds of the business leaders expect climate change to have a “high or very high impact” on their organisation’s strategy and operations over the coming three years.

But, despite the increase in concern, the vast majority of business leaders are optimistic that there’s still time to act and make change.

A new sustainability survey from Deloitte has found more Australian businesses are concerned about climate change than ever before. Picture: AAP

The Sustainability Report surveyed 2000 business leaders across 21 countries, and found Australia was among the top ten countries in the world most concerned about climate change.

Deloitte Global chief executive officer Punit Renjen said the survey showed there had been a shift in a demand for combating climate change.

“The battle against climate change isn’t a choice, it’s billions of choices,” he said.

"No action is insignificant, but certain activities and decisions ‘move the needle’ more than others, and those bolder actions from business leaders are needed now – while there’s still time to limit the damage. It’s time to prove we’re up to the challenge.”

Deloitte Global CEO Punit Renjen said there had been a significant shift in the perceived threat of climate change, with more businesses prepared to do their bit to tackle the challenge.

The report found 89 per cent of Australia’s business leaders believe that with immediate action, the worst impacts of climate change can be limited.

With Australian companies 10 per cent more likely to be implementing the tougher, “needle-moving” actions defined by Deloitte’s analysis, Deloitte Australia chief executive Adam Powick said climate change was a “national agenda” that business leaders needed to own and seize upon.

“Climate change is both a critical challenge and critical opportunity for Australia,” he said.

“It’s great to see the positive engagement of Australian business leaders on this topic and the desire to work together to make a meaningful and positive impact.

“If we are bold, decisive and co-ordinated, we can mitigate downside climate risks and help attract investment, create new jobs and support our regional communities.”

Links - Deloitte Climate Change

at No comments:

(AU ASPI) Out Of The Cave: Climate Change In An Election Year

Australian Strategic Policy Institute - 
On the politics of climate change, Australia crawls slowly from the cave.

To mix the cave metaphor, we’ve passed peak troglodyte.

Light has pierced the dark. Troglodytes still growl and glower, but those who ignore or deny the science have declining power.

Sceptical language still shapes the politics of climate. Yet the troglodyte effect has less impact in this election year than it has had for 15 years.

The crawl from the cave reflects shifts on the political spectrum. Render this spectrum as running from denial and scepticism towards the central position of acceptance of the science. Going beyond acceptance, the spectrum reaches belief and action.

Denialists think global warming isn’t happening or simply ignore it, while the sceptics always want more convincing evidence.

The denialist–sceptic forces have pushed Australia into the policy cave with versions of former prime minister Tony Abbott’s 2009 line that climate change is ‘absolute crap’. Warming might be good for us, Abbott wrote in Battlelines, and there’s no point imposing ‘certain and substantial costs on the economy now in order to avoid unknown and perhaps even benign changes in the future’.

Note that the formal position of Australia’s political parties all along has been to accept the science on the warming of the planet. In politics, though, accepting a policy position doesn’t confer priority or action.

Our problem has been the step beyond the tick and nod of acceptance to the belief stage. Reaching belief means that understanding becomes a truth that defines reality. In politics, belief rearranges priorities, shifts policy and demands cash: action happens.

Action hurts because this is a wicked problem, compounded by the push of the mining industry and the noise of the Murdoch media empire.

We have been stuck in the ignore-deny cave because Australia is an emissions superpower, standing with Russia and Saudi Arabia among the greatest exporters of fossil fuels.

The resource blessing can be a ‘coal curse’. The cave is comfortable because the fossil fuel industry seeks a ‘grip on Australian hearts and minds’. Mining has muscle to match its riches—throwing its weight against Kevin Rudd and his mining tax in 2010 and killing the Hawke government’s land-rights legislation in the 1980s.

The miners, our most powerful industry, seldom have to make an overt entry into the political ring; Rupert Murdoch’s News Corp Australia is there every day.

News Corp’s defining voice is the national broadsheet, The Australian, while the capital city tabloids do the yapping and Sky News does the TV ranting. The empire has reach, setting up an echo chamber that touches the ears of every politician. The rest of Australia can take or leave The Australian, but for Canberra it’s a constant read in the same way the ABC is a constant soundtrack.

The Australian editorialises that it accepts the science of global warming. As Murdoch has long maintained, ‘The planet deserves the benefit of the doubt.’

Just as consistently, what it publishes amounts to a scepticism that treats scientists and environmentalists as the enemy. The tag ‘covert denialism’ was pinned on The Australian by Robert Manne back in 2011 and still fits the facts.

The Weekend Australian of 15–16 January shows how covert denialism works. On page 8, an AFP piece by a Washington correspondent states that the nine years spanning 2013–2021 rank among the 10 hottest on record:
The impacts have been increasingly felt in recent years—including record-shattering wildfires across Australia and Siberia, a once-in-1,000-years heatwave in North America and extreme rainfall that caused massive flooding in Asia, Africa, the US and Europe.
Hefty evidence, indeed, but the paper knows how to turn the temperature. Turn to the op-eds published in the ‘Inquirer’ section for the tonal change.

On the first page, environment editor Graham Lloyd has the lead item on how Australia is weathering the climate storm: ‘Australia has benefited from the effects of two La Nina years, much to the chagrin of climate catastrophists’. Those catastrophists, Lloyd argues in his first paragraph, faced ‘an inconvenient set of realities’ because weather systems plunged Australia’s average temperatures in 2021 to the lowest levels in a decade.

By the third paragraph, things get lyrical: ‘[N]ature is not broken, the natural cycles continue to operate and that resilience persists on land and at sea.’

Deeper into the item, Lloyd quotes from the US study that made the news pages, noting the finding that global average temperatures last year were 1.1°C warmer than the late 19th century average, at the start of the industrial revolution.

Such science gets a cold shower when you turn the page to find a headline about ‘50 years of climate panic’, by Bjorn Lomborg, whose latest book is False alarm: how climate change panic costs us trillions, hurts the poor, and fails to fix the planet.

Lomborg, too, starts by scorning those who fear ‘climate catastrophe’, deriding ‘panic and poor policies’ that are fuelled by ‘overblown predictions and emotional forecasts’ about the planet’s ‘last chance’. His first paragraph puts quotation marks around ‘climate catastrophe’ and ‘catastrophic’, but they don’t indicate irony or sarcasm so much as define the target to be hit. Classic stuff from The Australian’s favourite ‘skeptical environmentalist’, who has been penning variations on the same column for two decades: don’t worry, get smart, spend on adaptation and innovation.

Australia is emerging from the cave for many reasons. Even News Corp did an editorial campaign last year about reaching zero emissions. Murdoch’s top editor called it an ‘evolution’ of policy but it had a mea culpa tinge.

The Murdoch empire is catching up with the rest of Australia, as tracked by Lowy Institute polls showing increasing climate concern. Expect the covert denialism to dial down. Perhaps.

After 15 years of argy-bargy, our main parties of government—Liberal and Labor—are closer on climate policy than they have been since the 2007 election, when they agreed on the need for an emissions trading scheme. (A counterfactual is that if John Howard had held his seat and held government in 2007, we’d have got the ETS and not gone as deeply into the cave.)

Scott Morrison got the coalition to agree to net-zero greenhouse gas emissions by 2050. Governments receive little credit for what doesn’t happen (especially internal government disasters), so the prime minister doesn’t get much cachet for edging the Libs and Nationals out of the cave. More than a political pirouette, ScoMo did bomb disposal while zooming down the mountain on one ski.

Morrison said the policy got through the Nats party room by only two votes. So only two votes away from blowing apart the coalition. ‘I did have to put it on the line,’ the prime minister notes, ‘and it was very close.’  The National Party is roiled but roughly reconciled, especially by promises of cash rewards for the bush.

Australia is about to cram two political years into one.

The first ‘year’ will be bookended by the budget on 29 March and the federal election in May. Morrison needs every day he can get, so I’m sticking with the prediction that the election will be held on 21 May, the last day possible for a half-Senate and House of Representatives poll.

The Liberals can’t wedge Labor on climate policy as they did in the 2019 election. The two parties are standing too close together.

Labor has long suffered the agony of having its vote eaten from the left by the Greens. Now the Libs face a similar test in nominally safe seats, attacked by independents. The government says the independents are coming from the left, but on climate they reflect the centre of public opinion.

Whether Scott Morrison or Anthony Albanese, Labor or Liberal, the government that gets to work in June will have to do more than accept the science—it will have to believe and act.

Links
at No comments: