Storm Daniel developed in the early days of September in Greece, causing serious flooding on 5-6 September before strengthening as it moved across the Mediterranean to northeast Libya over last weekend.

September is normally a dry month in Libya's Jebel Akhdar mountains around the coastal city of Derna, averaging just 1.5 millimetres of rain, but this week the area received a deluge of around 400 millimetres in just 24 hours.

As the massive run-off accumulated in the mountains, water levels rose alarmingly along Wadi Derna, which eventually runs through Derna to the sea. It overwhelmed a small dam about 20 kilometres south of Derna, before the torrent gathered speed and strength as it moved down towards the city. It burst over the 20-metre-high Derna waterfalls, seven kilometres out, and then reached the city outskirts as a huge torrent before hitting and breaching a much larger dam.

What has been described as a tsunami then overwhelmed and destroyed large parts of the city, demolishing four bridges, including the main coastal route, with much of the destruction taking place in just a couple of minutes. The death toll was appalling, with the Libyan Red Crescent reporting 11,300 dead on Thursday - and the toll may yet rise much higher.

The loss is already more than triple that of the 9/11 attacks that had taken place, by grim coincidence, 22 years to the day earlier. Those attacks had a massive impact across the Middle East and South Asia, as the United States and its coalition partners fought their 'war on terror' in response. Instead of an anticipated victory the consequences were multiple Western military failures, first in Afghanistan, then in Iraq, and lastly in Libya in 2011.

Libya never recovered, despite its oil and gas wealth, and it has remained in disarray, with a crumbling infrastructure unable to cope with tragedies such as Derna.

The flood may also have a much wider significance. It may not be traceable directly to climate change, but it is highly likely to bear some responsibility, since the chances of far more intense and damaging weather events have been predicted with increasing certainty for years.

After the disaster, the World Meteorological Organisation said: "As the planet warms, the expectation is that we will see more extreme rainfall events, leading to more severe flooding."

Over just the past two years we have seen all too many examples of floods, as well as severe fires. However, their political impact - even cumulatively - has been limited, failing to prompt the vigorous global decarbonisation programme that is essential to avoid irreversible climate breakdown.

Specific weather events have included the Lahaina fire in Hawaii in August this year, killing 115 people with others still unaccounted for, and damage caused by heat domes, which include the burning to the ground of Lytton in British Columbia by wildfires in 2021. But so far none has prompted change at the intensity and speed required, even though new technologies make that change far more feasible than even a couple of decades ago.

This brings us to the uncomfortable conclusion that it will take another huge tragedy like Derna to prompt the collective action of the powerful states that could prevent climate breakdown. But there will need to be two additional elements. One is that the disaster has to be even worse than Derna and the second - to be blunt - is that it has to hit a centre of population of one of the world's powerful and wealthy states. States may then be shocked into facing down the deeply entrenched power and influence of the world's fossil carbon industries.

In February 1953, a combination of weather factors led to a storm surge affecting the UK, the Netherlands and Belgium. Ultra-high tides combined with severe weather saw coastal and river defences repeatedly overrun, killing over 2,500 people, mostly in the Netherlands and eastern England.

Flood defences were much improved in the years that followed, but a weather event far worse than 1953 might even see those collapse, leading to tens of thousands of deaths and at last prompting the action needed. A single heat dome 'event' in the near future, in a large city of a heavily populated, wealthy state and combining severe heat with high winds, might also have a similar effect.

It doesn't have to be that way and even to talk like this may be depressing and even counterproductive. There is certainly every reason to push relentlessly for radical change, but we also need to face a political reality. It may now take the near-seismic shock of a climate catastrophe in western Europe or the United States far worse than Derna to bring about the change needed.

From openDemocracy