Typhoon Haiyan has left an estimated 10,000 dead and hundreds of thousands homeless in the Philippines. And it has once again underscored for many development experts a cruel truth about climate change: It will hit the world’s poorest the hardest.

“No nation will be immune to the impacts of climate change,” said a major World Bank report on the issue last year. “However, the distribution of impacts is likely to be inherently unequal and tilted against many of the world’s poorest regions, which have the least economic, institutional, scientific and technical capacity to cope and adapt.”

That is the firmly established view of numerous national governments, development and aid groups and the United Nations as well. “It is the poorest of the poor in the world, and this includes poor people even in prosperous societies, who are going to be the worst hit,” said Rajenda Pachauri of the Intergovernmental Panel on Climate Change, speaking to reporters in Brussels back in 2007.

The reason is twofold. First is the geography of climate change itself. The higher the latitude, the bigger the temperature increase. And generally, the farther from the equator, the wealthier the country — meaning rich countries like Norway and Canada might see a disproportionate impact from global warming.

Photo

Photo

But poorer, lower-latitude regions are expected to face desertification and more-intense storms. The increase in the sea level might be 15 to 20 percent higher in the tropics than the global average, meaning flooding for coastal cities in regions like southern Asia.

Droughts are also expected to increase significantly in lower-latitude areas, including in Africa and the Middle East. (The United States and Australia might also be hard hit, as the map below shows.)

Photo

Photo

Moreover, in many countries, the vulnerable poor might cluster in areas where climate change might have a disproportionate impact, like flood zones and dry rural areas. Here’s the World Bank on the topic earlier this year:

As the coastal cities of Africa and Asia expand, many of their poorest residents are being pushed to the edges of livable land and into the most dangerous zones for climate change. Their informal settlements cling to riverbanks and cluster in low-lying areas with poor drainage, few public services, and no protection from storm surges, sea-level rise, and flooding. These communities – the poor in coastal cities and on low-lying islands – are among the world’s most vulnerable to climate change and the least able to marshal the resources to adapt, a new report finds. They face a world where climate change will increasingly threaten the food supplies of Sub-Saharan Africa and the farm fields and water resources of South Asia and South East Asia within the next three decades, while extreme weather puts their homes and lives at risk.

The second, more significant reason is that the poorer the country, the harder it might be for it to respond to a changing climate.

Let’s take the example of a typhoon. Before a storm hits, building sturdy, secure houses and ensuring that a population has a plan for evacuation are critical to preserving life and property. Right after a storm, highways, search-and-rescue teams, helicopters, tractors, firefighters, hospitals and surgeons become critical for doing the same. Afterward, insurance, savings and a well-financed government response become necessary for rebuilding lives and cities. When it comes to such disasters, money matters.

The same goes for many other phenomena related to climate change caused by human activity. If a given area is getting drier and hotter, a subsistence farmer is going to face greater struggles than a diversified agricultural conglomerate. A shrinking water supply might be harder for Pakistan to manage than California. The same might be true for rising oceans.

For that reason, many poorer countries hold rich countries like the United States responsible for climate change, and want them to help pay for its effects. Carbon emissions, for instance, are correlated with income. The Philippines emits 0.9 metric tons of carbon per capita. The United States emits 17.6.

Nations like Bangladesh, Palau and the Philippines have all made the case. “Each destructive typhoon season costs us 2 percent of our G.D.P., and the reconstruction costs a further 2 percent, which means we lose nearly 5 percent of our economy every year to storms,” said a Filipino climate negotiator last year. “We have received no climate finance to adapt or to prepare ourselves for typhoons and other extreme weather we are now experiencing. We have not seen any money from the rich countries to help us to adapt.”

Without a global pact to stop warming and an overarching plan to mitigate its effects, the concern for development experts is that extreme weather might stall or even erase years of progress for the developing world. Hurricanes and floods will wash communities away. Drought will crush farms and increase hunger.

“Poverty reduction and climate change are linked,” said Dr. Jim Yong Kim, the president of the World Bank, in a commentary this year. “We have powerful new evidence that even if climate change falls short of the much-discussed 4°C warmer world, we could witness the rolling back of decades of development gains and force tens of millions more to live in poverty.”

He concluded: “If we don’t confront climate change, we won’t end poverty.”