Today, our journey takes us to Neko Harbor, one of the prime locations in this region to view glaciers. These towering walls of ice are a majestic sight, and a humbling reminder of the fragility of the natural systems that human beings depend upon for life as we know it.

As we began our journey, I wrote about the threats we face as Antarctica's glaciers melt and the world's oceans rise. Yet beyond the physical impacts that rising seas pose to coastlines, glaciers are important for many other reasons. We need them in order to preserve one of the basic necessities of life: clean drinking water.

Let's take a step back. As the global population tops 7 billion, nearly 800 million people do not have access to clean and safe drinking water. The climate crisis could make this problem worse.

As sea levels rise, saltwater can contaminate sources of freshwater near coastal cities and towns. When too much saltwater seeps into lakes, rivers or the soil, the water becomes undrinkable and unusable for agriculture.

Nearly 635 million people - one out of every 10 people in the world today - live in low-lying coastal areas that are susceptible to inundation and disruption of the water supply.

Saltwater intrusion has already affected the Shandong Province in China, and water resources on the Caribbean Islands. In the United States, the water supplies of both San Francisco and New York City could be compromised as sea levels rise and the salty oceans intrude on the drinking water.

But the impact of melting glaciers does not end with rising seas. Glaciers also make up the primary water supply in several mountainous parts of the world. In the Andes, shrinking glaciers could impact the water supply for millions of people. The Bolivian cities of La Paz and El Alto depend on glaciers for about a third of their water supply.

From the ice melting in Antarctica, to rising sea levels flooding Bangladesh, to the prospect of a compromised drinking water supply in New York City, the world's glaciers tie together our greatest challenges of the 21st century. This is a problem that binds all of us together, wherever we live. That's why it's incumbent upon all of us to solve the climate crisis.