Tropical storms and heavy rainfall have caused devastating flooding and landslides across much of South and Southeast Asia in recent days, with officials saying more than 1,250 people have been killed across Indonesia, Sri Lanka and Thailand alone and that many others are still missing.

Two cyclones and a typhoon, all different kinds of tropical storms, contributed to the disaster, which left towns and villages buried under mud across Sri Lanka, Thailand and the Indonesian island of Sumatra, with recovery efforts expected to continue for weeks.

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Sri Lanka has declared a state of emergency after the flooding and landslides, which displaced more than 1.1 million people. The country is facing a “humanitarian crisis of historic proportions”, Sampath Kotuwegoda, the director general of the Disaster Management Centre, told Al Jazeera.

Jessica Washington, reporting from Indonesia, the worst hit by the floods, said she saw landslides everywhere in North Sumatra province. “I have covered natural disasters, and usually, there is an area where landslides are contained, but this time, landslides have affected all the villages that we saw as we made our way here,” she said from North Tapanuli.

So what caused the record floods and landslides, and what can be done to mitigate future natural disasters?

What caused the floods and landslides?

As reports of the devastating floods began to spread, online search trends showed that people were interested in what was driving the extreme weather that caused some of the worst disasters in decades in multiple countries simultaneously.

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Communities across South and Southeast Asia, in countries including Indonesia, Sri Lanka, Thailand, Vietnam, Malaysia and the Philippines, have all been inundated in recent days, following weeks of heavy rains and deadly tropical storms across the region.

The most recent floods were made worse in some countries by tropical storms, including Typhoon Koto, which caused severe flash floods and landslides in the Philippines, as well as Cyclone Senyar, which hit Indonesia’s northern Sumatra severely, and Cyclone Ditwah, which caused devastation in Sri Lanka.

One common thread across the region is that communities were struggling to respond to the sheer volume of rainfall, which caused knock-on problems, including landslides, says Steve Turton, an adjunct professor of environmental geography at Central Queensland University in Australia.

“All around the world where we get these tropical systems, whether you call them typhoons or hurricanes or tropical cyclones, they are producing more rain than they’ve ever produced,” Turton told Al Jazeera. “And that’s because of climate change.”

While Cyclone Senyar, Cyclone Ditwah and Typhoon Koto were not categorised as severe storms due to their wind speeds, says Turton, they all produced “a lot of rain”.

“And that’s due to the warming of the atmosphere and the warming of the ocean, that’s feeding these rainstorms,” he added.

“Warmer oceans fuel stronger rain bands around tropical cyclones, and a warmer atmosphere holds more moisture and releases it in more intense bursts,” Roxy Matthew Koll, a climate scientist at the Indian Institute of Tropical Meteorology, explained.

It is a phenomenon called La Nina, which is a natural climate pattern in which the Pacific Ocean becomes cooler than usual in the east and warmer in the west, causing winds to strengthen and push more warm water and moisture towards Asia.

This pattern loads the atmosphere with extra moisture over Asia that often leads to heavier rainfall and higher flood risk, Koll told Al Jazeera.

While the impact of increased rainfall is well understood, Turton notes that when it comes to other unusual aspects about this past week’s storms, including how Cyclone Senyar and Typhoon Koto may have interacted, it will be necessary to wait for more specific research, known as attribution studies, to be conducted.

One recent attribution study from the Grantham Institute for Climate Change and the Environment using the Imperial College Storm Model (IRIS) has already found that climate change increased the amount of eyewall rain from Typhoon Fung-wong, which made landfall in the Philippines last month, by an estimated 10.5 percent.

What can be done to respond?

While visiting disaster-affected communities in North Sumatra on Monday, Indonesian President Prabowo Subianto said climate change is a problem that Indonesians will need to “confront”.

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“Regional administrations must also be prepared to face the impacts of climate change,” he said.

Shweta Narayan, campaign lead at Global Climate and Health Alliance, a consortium of health professionals and civil society organisations around the world, said the governments and cities have “failed to prepare at all to deal with the consequences of the extreme weather events”.

“There is a massive disconnect between the reality and the sheer deliberate ignorance among policymakers,” she said. “And the price is being paid by people.”

After decades of warnings from climate scientists, many governments and climate change activists are eager to move to more practical responses to help reduce the severity of current and future climate change-induced disasters as much as possible.

Climate activist and founding director of the Satat Sampada Climate Foundation, Harjeet Singh, told Al Jazeera that the science on attributing individual disasters to climate change is settled, and that it is now time to move on to responding.

“People across South and Southeast Asia are living the data,” he said, noting that the evidence should now lead to accountability.

“We don’t need to wait for event-by-event attribution to know that climate change is increasing the scale and frequency of these impacts,” he said.

“Countries that grew wealthy by burning fossil fuels have a legal and moral obligation to urgently deliver grant-based finance” to help countries respond, Singh added.

The latest storms came less than a week after the United Nations Climate Change Conference (COP30) ended in Brazil, without delivering the responses that countries experiencing climate change harms have repeatedly called for.

This includes grant-based funding to help them respond to increasingly costly disasters, rather than loans, which further contribute to their debts, says Singh, as well as more urgent cuts to fossil fuel emissions.

Yet, despite facing significant uphill battles, countries experiencing the worst of climate, including island nations, are continuing to search for ways to address the crisis.

Earlier this year, the world’s top court, the International Court of Justice (ICJ), ruled that states must act urgently to address the “existential threat” of climate change by cooperating to cut emissions, following through on global climate agreements, and protecting vulnerable populations and ecosystems from harm.

“Failure of a state to take appropriate action to protect the climate system … may constitute an internationally wrongful act,” said ICJ President Yuji Iwasawa, in response to the case which was brought to the court by developing countries led by Vanuatu.

The advisory opinion could also influence the growing number of climate change lawsuits making their way through courts around the world.

Those legal challenges include a case recently launched by survivors of the 2021 Super Typhoon Odette in the Philippines, who announced last month that they are suing British oil giant Shell for its role in causing the climate crisis through courts in the United Kingdom.

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On Monday, the International Federation of Red Cross and Red Crescent Societies called for an “urgent need for stronger legal and policy frameworks to protect people in disasters”.

“These floods are a stark reminder that climate-driven disasters are becoming the new normal, and investment in resilience and preparedness is critical,” Alexander Matheou, IFRC director for the Asia Pacific region, said in a statement.