Typhoon Haiyan, one of the strongest storms ever recorded, struck the Philippines in November 2013 with winds of up to 190 mph (305 kph). At least 10,000 people died in one Philippine province alone.
Humans to blame for scale of devastation caused by Typhoon Haiyan, say experts
Population rise, poverty, poor housing and climate change make much of Philippines vulnerable
Associated Press in Washington
Typhoon Haiyan was an example of nature's fury at its most extreme.
But some experts say that although meteorology and geography contributed to the vast scale of the unfolding disaster in the Philippines, the lion's share of blame belongs to the human factor.
Poverty, shoddy construction, a booming population, and perhaps to a lesser degree climate change, all combine to make the Philippines the nation most vulnerable to the deadly effects of powerful typhoons, according to several scientific studies.
And Typhoon Haiyan was an extremely powerful storm. It produced a storm surge two storeys high and some of the highest winds ever measured in a tropical cyclone. An untold number of homes were blown away and thousands killed.
"You have a very intense event hitting a very susceptible part of the world. It's that combination of nature and man," said MIT tropical meteorology professor Kerry Emanuel. "If one of those ingredients were missing, you wouldn't have a disaster."
The 7,000 islands of the Philippines sit in the middle of the world's most storm-prone region, which gets some of the biggest typhoons because of vast expanses of warm water that act as fuel and few pieces of land to slow storms down.
Half the storms on an informal list of the strongest to hit land in the 20th and 21st centuries ended up striking the Philippines, according to research by Jeff Masters, who is meteorology director of the Weather Underground.
Storms often hit after they've peaked in strength or before they get a chance to, but Haiyan struck when it was at its most powerful, based on US satellite observations, Emanuel said.
But humans probably played a bigger role than nature in the making of the catastrophe, meteorologists said. University of Miami hurricane researcher Brian McNoldy figures that 75 to 80 per cent of the devastation can be blamed on the human factor.
Meteorologists point to extreme poverty and huge growth in population - much of it in vulnerable coastal areas with poor construction, including storm shelters that didn't hold up against Haiyan.
Video: Grim search for bodies goes on in Philippines
More than four out of 10 Filipinos live in a city of more than 100,000 that is vulnerable to storms, according to a 2012 World Bank study. The population of Tacloban, the Leyte provincial capital devastated by Haiyan, nearly tripled from about 76,000 to 221,000 in just 40 years.
About one-third of Taclo- ban's homes had wooden exterior walls. And one in seven homes had grass roofs, according to the census office.
Those factors - especially flimsy construction - were so important that a weaker storm would have still caused almost as much devastation, McNoldy said.
"You end up with these kind of urban time bombs, where cities have doubled, tripled, quadrupled in size in 50 years" without good building standards, said Richard Olson, director of the Extreme Events Institute at Florida International University. "It is, I hate to say, an all-too-familiar pattern."
Scientists say man-made global warming has contributed to rising seas and a general increase in strength of the most powerful tropical cyclones.
A 2008 study found that in the northwestern Pacific where Haiyan formed, the top 1 per cent of the strongest tropical cyclones over the past 30 years are getting on average about 1.5km/h stronger each year - a phenomenon some scientists suspect is a consequence of global warming.
"As you warm the climate, you basically raise the speed limit on hurricanes," said Kerry Emanuel, an atmospheric scientist at the Massachusetts Institute of Technology.
As the planet warms because of carbon dioxide and other heat-trapping gases, the difference between sea and air temperatures increases. It is this difference that fuels these kinds of cyclonic storms. "The strongest storms are getting stronger," said James Kossin of the National Climatic Data Centre, co-author of the 2008 study. Haiyan "is what potentially could be a good example of the kind of the things we're finding".
Similarly, the Philippines has seen its sea rise about one centimetre in the past 20 years - about triple the global increase, according to Steven Nerem of the University of Colorado.
Higher sea levels can add to storm surge, creating slightly greater flooding.
Naderev Saqo, the chief representative of the Philippines at an ongoing global climate change conference in Warsaw, was in no doubt about the link between climate change and the disaster in his homeland. "What my country is going through as a result of this extreme climate event is madness; the climate crisis is madness," Saqo said. "We can stop this madness right here in Warsaw."
His declaration of a hunger strike, coupled with the scope of the disaster, moved many of the delegates to tears.
Yet scientists say there is not enough data to draw conclusions about this or any other single storm.
In addition, the effect of climate change on storms in the Pacific is especially difficult to study because no governments fly research planes into storms to gather data.
Just as human factors can worsen a disaster, they can also lessen it, through stronger buildings, better warnings and a quicker government response.
Emanuel said poverty- stricken Bangladesh had much bigger losses of life from cyclones in the 1970s than it does now. The international community built strong evacuation shelters that get used frequently, he said.
"The Philippines is one of the most disaster-prone places on earth," said Kathleen Tierney, director of the Natural Hazards Centre at the University of Colorado. "They've got it all. They've got earthquakes, volcanoes, floods, tropical cyclones, landslides."
Additional reporting by The New York Times
The world responds with typhoon aid
Australia announced a A$10 million (HK$72.6 million) package, including medical personnel and non-food items such as tarpaulins, sleeping mats, mosquito nets, water containers and hygiene kits.
Britain announced a £10 million (HK$124 million) package to aid up to 500,000 people, including temporary shelter, water, plastic sheeting and household items, as well as military aid.
The European Commission said it would provide €8 million (HK$83 million) to help worst-affected areas.
The mainland is providing US$100,000 and the Chinese Red Cross a further US$100,000.
Indonesia is to dispatch aircraft and logistical aid including personnel, drinking water, food, generators, antibiotics and other medication.
Japan will give US$10 million in aid, including goods such as tents and blankets. A 25-strong emergency medical relief team has already been dispatched and will be followed by a 40-person team from its Self-Defence Forces.
New Zealand said it would give NZ$2.15 million (HK$13.7 million) in aid.
South Korea will provide financial aid worth US$5 million and dispatch a 40-member disaster relief team.
The United States is providing US$20 million in immediate humanitarian assistance and has already sent a team of about 90 Marines and sailors, part of a first wave of promised US military assistance. The arrival of a US aircraft carrier will speed up the distribution of aid and ensure injured survivors can be evacuated to hospitals in unaffected parts of the country. The US Agency for International Development is sending emergency shelter and hygiene materials. It is sending 50 tonnes of food. The US embassy is sending US$100,000 for water and sanitation support.
The Vatican pledged €3 million, adding to US$150,000 given by the Pope and €100,000 by Catholic charity Caritas.
Medecins sans Frontieres is sending 30 people, plus 200 tonnes of medical items.
How to help
Through the Philippines consulate
Catholic Relief Services
UN World Food Programme