The latest UN report on the effects of climate change makes for grim reading, especially for those in Asia. A staggering 143 million people will likely be uprooted over the next 30 years by rising seas, drought, searing temperatures and other climate catastrophes, according to the UN's Intergovernmental Panel on Climate Change. Governments all over the world will be scrambling to deal with the fallout.

One in three migrants in the world today comes from Asia, which leads the world in the number of people being displaced by extreme weather, largely storms and flooding, according to the report. With rural villages emptying out and megacities like Jakarta at risk, scientists predict migration flows and the need for planned relocations will only grow.

By one estimate, as many as 40 million people in South Asia may be forced to move over the next 30 years because of a lack of water, crop failure, storm surges and other disasters. Rising temperatures are of particular concern, said Stanford University environmental scientist Chris Field, who chaired the UN report in previous years. Relatively few places on Earth are simply too hot to live now. But it's beginning to look like in Asia, there may be more of those in the future and the report urges governments to think really hard about the implications of that.

At the moment, no nation offers asylum or other legal protections to people displaced specifically because of climate change, though the Biden administration has studied the idea. People leave their homes for a variety of reasons including violence and poverty, but what's happening in Bangladesh demonstrates the role climate change also plays. Scientists predict as many as 2 million people in the low-lying country may be displaced by rising seas by 2050. Already, more than 2,000 migrants arrive in capital Dhaka every day, many fleeing coastal towns.

The migration flows can be slowed if countries like the United States and European nations act now to drop their greenhouse gas emissions to zero. Otherwise, richer countries that produce more emissions should offer humanitarian visas to people from countries that are disproportionally affected.

Dealing with climate migrants will become a major policy issue for Sub-Saharan Africa and Latin America as well over the next few decades, according to the UN report. Most people will be moving from rural areas to cities, especially in Asia where two-thirds of the population could be urban in 30 years.

The migration doesn't have to cause a crisis.

In the northern part of Dhaka, for example, officials are building shelters for climate migrants and improving the water supply. They also are working with smaller cities to be designated "climate havens" that welcome migrants. The influx of a new work force offers smaller cities an opportunity for economic growth. And it prevents migrants who may be fleeing villages threatened by rising seas from seeking refuge in a city with scarce water supplies and basically "swapping one climate risk for another." Given the outlook, in coming years, helping prepare cities for the influx of migrants will be key. In the battle against climate change, they are the new frontline.