As a climate change expert at the World Bank, Arame Tall is deeply familiar with the facts and figures of global warming. She understands how rising seas and changing weather cycles are affecting her home country of Senegal — from a retreating coastline in the city of Dakar where she grew up, to her mother's hometown of Diourbel, where drought and floods have forced people to abandon their peanut farms.

But even with all that knowledge, Tall was still shocked when her own nephew attempted to flee the country for a better life in Europe. "To the whole family's astonishment, he disappeared one night, and we looked for him," she told me. "He couldn't be found."

Earlier this year, 18-year-old Amadou had reached the boat that was supposed to smuggle him out of Senegal and into Spain. The captain warned of heavy rain that was forecast at sea and said the trip might not be safe. Afraid for his life, Amadou disembarked.

"Everybody else who got on that boat never came back," Tall told me. "And they were confirmed to have sunk in the Atlantic. So he escaped. But you always wonder, what if he had actually taken that boat?"

There is an expression in Wolof, one of Senegal's main languages: Djawou bou soppekou. It literally means, "The weather is changing."

Today, we are launching a project to look at how the ripples of climate change are radiating outward. Beginning in Senegal, my team and I are setting out to connect the dots on three major stories that I have often covered as distinct issues over the years.

Follow our live travel blog for the trip from Africa to Europe

How climate change, migration and xenophobic politics are linked

My most ambitious reporting trips as a host of All Things Considered have tended to return to a few consistent themes.

1. I've watched rising seas swallow islands in the Sundarbans of India, and tracked efforts to slow climate change at U.N. summits in Glasgow, Scotland and Paris, France.
2. I've followed in the footsteps of migrants walking hundreds of miles from Venezuela to Colombia and from Syria to Germany.
3. I've tried to understand the rise of political extremism in places as diverse as Indonesia and the United States.

Lately, I've started wondering about the ways in which these three broad themes weave together. What is the connection between climate change, the movement of people around the globe, and the rise of xenophobic politicians? That's the overarching question we're hoping to answer with this reporting trip.

The links among these three global trend lines are not hard to find. Many right-wing political leaders make attacks on migrants an overt part of their pitch. Donald Trump launched his presidential campaign with the racist claim that Mexico was sending rapists to the United States, and one of his most frequent applause lines as president was that he would build a wall along the southern U.S. border. In Sweden, members of an anti-immigrant political party that I reported on when they were outsiders in 2015 now have a shot at controlling the government. And in Italy, voters just chose a prime minister who has called for a naval blockade of Africans.

We also know that climate change is speeding up the movement of people around the world. Exactly how fast is difficult to specify.

"When we say 'climate migrant,' we don't really know what we're saying," Jay Balagna of the RAND Corporation told me. "There's such a wide range of definitions."

If you define climate migrants only as people whose homes are swallowed by rising seas, the number might be a few million by the middle of this century. On the other hand, U.N. experts have argued that climate change exacerbated the conditions that led to the civil war in Syria. So under more sweeping definitions, the number of "climate migrants" around the world could quickly climb much higher. And of course, we don't know how aggressively the world will move to limit carbon emissions and avert the worst possible impacts of climate change.

To complicate matters further, there is rarely only one reason someone decides to leave their home country for a more promising life elsewhere.

"So is it one plus one equals two? No, not necessarily," Tall says. "But in our lived experience in African countries, we've seen a dramatic shift in the number of climate related disasters that have been hitting us across the continent."

As Kayly Ober of Refugees International told me, climate change can be a "vulnerability multiplier," exacerbating other factors (such as corruption and poverty) that were already making life difficult to sustain.

But where human rights advocates see climate change as a vulnerability multiplier, opponents of migration see a threat multiplier. Some far-right extremists have used worst-case-scenario forecasts of climate migration as excuses to attack immigrants.

In El Paso, Texas, a mass shooter in 2019 killed more than 20 people and wounded more than 20 others. He told authorities he was targeting Mexicans, and he left behind a manifesto that read in part: "The decimation of the environment is creating a massive burden for future generations ... If we can get rid of enough people, then our way of life can be more sustainable."

Most climate displacement tends to be within a country, or at least a region. People will rarely abandon their homeland unless they see no other option. But in every hemisphere, there is also cross-border movement. Bangladeshis leave flooded coastal communities to become guest workers in the Middle East; El Salvadorans whose farms have stopped producing food make their way through Mexico to find jobs in the United States; and people from the Sahel region of Africa flee the encroaching desert, traveling north to pursue a better life in Europe.

We want to bring you along for the journey

That last route is the one that we will be following over the next three weeks. Our itinerary will take us to three countries, following a path that countless migrants have taken before us: from Senegal, through Morocco, to Spain.

Our stories from the trip will be broadcast on the radio and published on NPR.org during this year's U.N. climate summit, which is taking place in Egypt in November.

We also want to take you with us as we experience this journey, giving you opportunities to follow our travels in real time. So, we have launched a live travel blog that offers daily behind-the-scenes updates from our whole team.

The last time I flew to Senegal was aboard Air Force One. I was a White House correspondent covering Barack Obama's trip to Africa in 2013. I accompanied the president as he visited Goree Island, a port where boatloads of people captured and condemned to slavery were shipped to the West. It was the last place many touched African soil.

After gazing out the door of no return, Obama reflected on what he took away from that view, telling reporters, "We have to remain vigilant when it comes to the defense of people's human rights. Because I'm a firm believer that humanity is fundamentally good. But it's only good when good people stand up for what's right."

This project is focused on a different kind of mass exodus, though it too raises questions about human rights and the goodness of humanity. When I spoke with Tall about her research into climate change and her own family's experiences in Senegal, she used an expression that I had never heard before. As she described the extreme weather events forcing people to relocate, she said, "No one will sit on a sinking ship." The phrase struck me, and I asked her if this was a well-known Senegalese expression. She seemed surprised by my question. It's a concept that is simply obvious where she grew up, she said. "It's common sense where I come from."