13 August 2025. Climate | Palestine

The impact of sea level rise on the world’s cities // Britain, Gaza, and terrorism laws [#J2T 647]

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1: The impact of sea level rise on the world’s cities

The investment writer Joachim Klement pointed me via his newsletter to a paper that attempts to quantify the impact of sea level rise on cities by 2100 at different degrees of climate change.

Allan Hsiao’s paper is short (literally five pages plus references), but it’s for the American Economic Association, so it also has its share of equations. The killer table is below, though, and Klement summarises it like this:

Analysing satellite data, he can rank the 30 largest cities by the percentage of infrastructure at risk from sea level rise. The table below shows that for a sea level rise of 1m, Osaka, Jakarta, and Tokyo face the largest possible loss of infrastructure. But once you go to 2m or 3m sea level rise, the cities that are much more at risk are Chinese and Southeast Asian cities, such as Bangkok and Shanghai, which are particularly affected.

Source: Allan Hsaio

The notes say that the percentage shows the proportion of infrastructure that is submerged at different levels of Sea Level Rise (SLR). The tipping point seems to be around 1.5 metres, which sounds fine in theory since the base case IPCC projections are for around a one metre increase by 2100, but that doesn’t allow for subsidence (often caused by water extraction), or the possibility of cascading climate change. Hsaoi summarises his conclusions at the start of the article:

How exposed are cities to the threat of sea level rise? I quantify this exposure worldwide with a focus on urban infrastructure. I document three facts. First, Asian cities are highly exposed. Second, poorer cities and neighborhoods are less exposed. Third, exposure accelerates as sea level rise passes 1.5 meters.

The actual method is pretty complicated, and involves a huge amount of data—this is one of those studies that would have been unimaginable in the days before computers. The dataset is also available separately on his website.

But broadly, he starts with the IPCC sea level rise projections, and uses multiple maps and satellite data to break cities into ‘cells’ of 30 square metres. A set of rules is applied to each cell to decide if it is inundated, and if so, what the impact is on adjacent cells.

The model captures permanent risk under SLR (sea level rise). SLR is a relative quantity: Inundation depends on land elevation above sea level, and so it occurs whether the sea rises or the land sinks. Cities thus experience SLR as the sum of global mean SLR and local land subsidence. ­ Fast-subsiding cities experience each SLR scenario before slow-subsiding cities do.

But the model doesn’t capture risk from storm surges or tidal surges—the modelling for this would be much more complex. But that does mean that you have to allow for the possibility that in practice these maps might be worse.

And here’s a couple of his maps, for the worst affected cities at one metre sea level rise and two metre. On the left: Osaka at a one metre rise in sea level, on the right Bangkok at a sea level rise of two metres.

(Source: Allan Hsaio)

As well as just assessing impact, Hsaio is also interested in the social equity of all of this, and that requires more analysis:

For a given SLR scenario, I compute the percentage of education, health, and transport infrastructure at risk of inundation in each city. Education infrastructure is schools, health is hospitals and clinics, and transport is highways and primary roads... I define infrastructure exposure as the average of these education,health, and transport percentages.

Being a finance guy, Klement wonders about this from the perspective of insurance companies, since, as he points out, there are large chunks of Miami that are largely uninsurable already. Hsaio’s more interested in policy response.

Hsiao has also done more specific work on Jakarta, which experiences frequent flooding. There are some interesting conclusions here, broadly that a strong government commitment to sea defences (in Jakarta’s case a sea wall) creates a moral hazard, because it

attracts coastal residents, slows inland migration, and lowers the incentives for inland development. The consequence is continued spending on coastal defense and large damages should it fail.

Insurance doesn’t work because places that don’t flood don’t want to pool with places that do (“Zurich doesn’t want to pool with Jakarta”). Alternatives that might place more of the financial burden on people who choose to live in coastal areas might work, but is open to political lobbying. And once you’ve decided to go with sea defences, and people decide to live behind them, you face political pressure to keep on strengthening the sea defences.

Taking the bigger, global picture, Joachim Klement thinks this leaves us with three options.

1. We do nothing and hope that our models are correct in forecasting sea level rise of 1m or less (I call this the ‘what could possibly go wrong’ choice).

2. We continue to accelerate the decarbonisation of our economy to ensure that we have a margin of safety in place, in case our forecasts are overly optimistic (but that would require the coordinated efforts of all countries in the world, including the US).

3. We increase our efforts in climate change adaptation to make sure that when sea levels rise, our infrastructure doesn’t drown.

He seems to think we’ll go for option 1. And judging by our current responses to climate change, he’s probably right.

But it is maybe also noticing this as part of a wider change—the normalisation of climate change effects in our policy discourse. Similarly, The Conversation had an article by Paul Behrens in the last week about the impact of climate change on food prices. (H/t to Ian Christie for the link). Just a quick couple of extracts from that here:

Climate change is pushing up the prices of the food that we buy and therefore changing what we eat. One-third of UK food price increases in 2023 resulted from climate change, according to research by agricultural economists. This extra cost contributed to food price inflation and the UK’s cost-of-living crisis.

This trend, he says, is likely to continue. But we can make changes to our diets that reduce the impact:

The scientific consensus shows that the biggest opportunity we have for reducing food’s environmental impacts across many countries is increasing the amount of plants we eat and reducing meat and dairy intake... The plant-rich diet we investigated isn’t vegan. It’s not even vegetarian, although it does include a reasonable (and healthier) amount of meat and dairy.

The wider point here is that we’ve now reached a point where climate change has become a fact of life. One of the problems with this is that people in different silos are used to thinking of their climate change problems as being different from other people’s, rather than connected.

Another one—this isn’t my point, but it came up in a work meeting and I can’t credit it, at least yet—is that climate change people are used to thinking of themselves as insurgents, or, in Three Horizons language, as the Horizon 2 innovators. But all of this is now firmly in the domain of the people who maintain our Horizon 1 systems, and this requires a whole new language.

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2: Britain, Gaza, and terrorism laws

Shortly after the British Home Secretary (or interior minister) Yvette Cooper pushed through an order under the UK’s anti-terrorism legislation in the House of Commons to declare that the non-violent group Palestine Action was a terrorist group, the following poem appeared on the Scots website Bella Caledonia. It is by Dougie Strang, and I have taken the liberty of reproducing it in full here.

Poem That Avoids Arrest

Or: Authoritarian Laws Accelerate Absurdism.

Snort

Apple

Paste

Sprout

Plasticine

Parents

Inept

Pastoral

Section

Tacit

Purple

Tension

Steal

Pronoun

Aspect

Realise

Plastic

Opponent.

I was struck by it because this kind of absurdism is a strategy that has been used historically by critics in authoritarian countries, and the proscription of Palestine Action is certainly an authoritarian act.

(Protestors in London on Saturday)

I also need to be absolutely clear that nothing that I say in this piece should be taken as my expressing support for Palestine Action, whatever my personal views, since doing this would make me liable for a jail sentence of up to 14 years.

So I probably need to back up a bit here, especially for overseas readers. There’s almost too much to say.

Here’s a description of Palestine Action taken from Wikipedia, unedited:

Palestine Action is a British pro-Palestinian direct action network. Founded in 2020 with the stated goal of ending Israeli apartheid, the organisation also became active in the Gaza war protests in the United Kingdom, in the wake of the ongoing Gaza war.

The group disrupts the arms industryin the United Kingdom with direct action, as the organisation accuses the arms industry of being complicit in the Gaza Genocide. Key targets have been British factories of Israeli weapons manufacturer Elbit Systemsand RAF Brize Norton base. In their campaigns, Palestine Action have used protest, occupation of premises, destruction of property, and vandalism, which sometimes resulted in its members being arrested. Palestine Action describes its actions as "non-violent yet disruptive", saying it has never hurt a human being.

The UK’s Terrorism Act was passed in 2000, initially, in effect, as a by-product of the Good Friday Agreement that largely ended the conflict in Northern Ireland, because a number of violent and armed groups continued to operate in the North.¹ After 9/11 it was extended to cover other groups, and most of these are Islamic in some shape or form.

The penalties under the Act are severe, not just for people who are members of proscribed groups, but also for people who promote them or support them. Britain’s anti-terrorism legislation is notably sweeping.

And so police forces around the country have been hard at work arresting people who have displayed signs showing support for Palestine Action, as well as people who might be showing support for Palestine Action, but in ways that are ambiguous, as well as people who are clearly not supporting Palestine Action but who are protesting against genocide in Palestine, including one protestor who was holding up a satirical article from the widely distributed magazine Private Eye. (Well, yes, police offices are not famed for nuance.)

It’s also worth going back into some of the history here, since if the UK had simply prevented businesses from exporting arms made in UK factories to Israel, Palestine Action—in its current form—would have no reason to exist.

Yvette Cooper, it turns out, couldn’t decide if Palestine Action should be proscribed or not, partly because the UK security experts she consulted didn’t think it was a terrorist organisation. She dithered for months.

The eventual decision was trailed in advance, and there were news reports that Home Office civil servants, who are not known for militancy, had said internally that they were concerned about the legislation being used in this way. One unnamed civil servant was quoted as saying,

[I]t’s being widely condemned in anxious conversations internally as a blatant misuse of anti-terror laws for political purposes to clamp down on protests which are affecting the profits of arms companies.”

The proscription order was pushed through Parliament in a single order which also named two organisations that are more clearly the sorts of organisations the Act was intended to deal with, which made it hard for MPs to vote against it.²

There’s a good account of all of the political and legal process by Tanzil Chowdury at the Critical Legal Thinking blog, by the way.

(Source: Private Eye, the following week. That’s the British Home Secretary on the right.)

One result was a large demonstration last weekend in London, and protests elsewhere, that can only be described as large scale civil disobedience, with more than 500 people arrested for holding signs saying “I support Palestine Action”.³

Afterwards, both the Home Secretary and later the Prime Minister’s office doubled down, with the Home Secretary doing that security hand waving thing that is the special prerogative of interior ministers everywhere: if only we knew what they knew, we’d all know that they’d made the right decision. Here’s the actual quote, though:

“Many people may not yet know the reality of this organisation, but the assessments are very clear – this is not a nonviolent organisation. UK national security and public safety must always be our top priority,” Cooper said.

Well, in general, politicians probably ought to leave distinctions between violent and non-violent protest to philosophers, at least until we establish that aircraft engines have feelings.

But the UK anti-terrorism legislation is not based on a distinction between “violent” and “nonviolent” organisations. The tests are all intended to be a lot tougher than this and more complicated.⁴ In a blurry statement like this, Cooper is really just covering up a serious error of judgment. Because, on balance, you’d want your average Home Secretary to be able to tell the difference between terrorism, violence, and nonviolence.

There are multiple things going on here, and this piece is already getting long, but let me try to strip them apart. The first is just obvious state overreach, as a group of United Nations rapporteurs pointed out.⁵

The second is also obvious: that—as the police response has already demonstrated—it has a chilling effect on protest. Jennie Jones introduced an amendment to the proscription order in the House of Lords that pointed this out, although it wasn’t carried.⁶ When in 2007, the independent reviewer of terrorism legislation, Lord Carlisle, reviewed the Terrorism Act at the request of Parliament, he referenced submissions that said that anti-terrorism legislation should intrude only minimally on people’s rights of protest and participation, under national and international law.

But he concluded (only in Britain, of course) that in our unwritten constitution the best defence against this were the powers of political discretion in the system. Absolutely, old chap.

Further, while the Terrorism Act does include reference to “violence against property” (which is the inference that the Government’s handwaving is inviting us to make) it’s striking that throughout his report Carlisle assumes that this refers to the bombing of buildings or systemic attacks on essential infrastructure.

(Source: Tom Dale, Twitter/X. Byline Times has an interview with Chris Romberg.)

The third is that there has been a number of trials of Palestine Action activists, and the outcomes have been all over the map. In one case, activists were acquitted after using a “necessity” defence.⁷ In another, the jury failed to agree, and a retrial on some charges is scheduled. In another, defendants were found guilty on a single charge and given non-custodial sentences. In one case, activists were jailed for 12 months. In some cases, judges have acknowledged in their remarks the defendants’ concerns over the genocide in Gaza.

There are also reports that the UK subsidiary of Elbit Industries, Israel’s largest arms manufacturer, has had to close offices and a factory in the UK because of effective disruption by Palestine Action. So it’s hard to avoid the conclusion that the proscription of the organisation is to save Elbit Industries further inconvenience. Certainly the company has lobbied the government hard for retrials and tougher sentences.

Finally, there is the wider effect on attitudes towards politics. Tom Dale, who has covered the Middle East and reported on Twitter/X on the weekend’s demonstration in London, tweeted:

Overwhelming sense, as another woman is carried away, is what a small-minded, self-harming act this proscription was for the Labour government.

There are a couple of issues in the politics of this. The smaller one is that Yvette Cooper has received funding from pro-Israeli lobby groups, along with around half of the Labour Cabinet. (She is also a member of Labour Friends of Israel.) With better judgment, she might have recused herself from the decision.

The larger one is that Gaza has become a faultline in in British politics that extends far beyond the country’s Muslim communities. In general, Britons are strongly opposed to Israel’s actions in Gaza. The age division is sharp: younger people are far more likely to support Palestine (although more than half of those arrested recently were over 60.).⁸

When I talked to someone who was on the demonstration in London on Saturday, they told me that the overwhelming mood was one of anger: that people had to be on the streets protesting as children were starting to die of starvation in Gaza because of the de facto Israeli blockade.

As Hattie Simpson put it in a New Statesman piece,

[T]he alienation playing out is not merely a question of young voters versus older voters. It’s about a disconnect between political instincts rooted in moral urgency, and a leadership perceived as coldly transactional in the pursuit of votes.

Some of this reminds me of the Blair government’s decision to invade Iraq in the face of widespread scepticism, unreliable evidence, and large scale protest (even Cooper’s language about “assessments” and “national security”). The moral case this time is far stronger. And the damage to our ideas about the value of democracy and about how politics works is accordingly far more corrosive.

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j2t#647

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1. One of the things I learnt as a journalist was that one had to be careful about describing groups as being “terrorist”; sometimes it was an accurate description; sometime it was a form of propaganda.

2. From a BBC News report: “the order also proscribes Maniacs Murder Cult, a white supremacist, neo-Nazi organisation and the Russian Imperial Movement, a white supremacist, ethno-nationalist organisation.”

3. There’s an obvious point here that supporters of actual terrorist organisations tend to try to remain anonymous and unknown to police, but that might have passed the government by.

4. Including whether acts of violence are intended “to influence the government”. Palestime Action insists it has no interest in influencing the government: it simply wants to disrupt the supply chain of arms being used to attack Gaza.

5. “While there is no binding definition of terrorism in international law, best practice international standards limit terrorism to criminal acts intended to cause death, serious personal injury or hostage taking, in order to intimidate a population or compel a government or an international organisation to do or to abstain from doing any act,” the experts said. “The UK supported this approach in voting for Security Council resolution 1566 in 2004,” they said. “Mere property damage, without endangering life, is not sufficiently serious to qualify as terrorism.”

6. Someone attending a Prom concert at the Royal Albert Hall at the weekend was initially turned away from the door by an over-zealous attendant because they were wearing a tiny Palestine flag as a lapel pin.

7. The defence that property damage was justified to prevent greater harm.

8. The Labour Party knows this first hand: as the New Statesman has reported, its youth membership has fallen to 30,000 from 100,000 under Starmer, with Gaza driving this.