Pope Francis’s six-day trip to the U.S., which begins on Tuesday, is highly anticipated — and not just among American Catholics. The pope’s progressive stances have earned him nearly unprecedented favor with liberal-leaning Americans, and his aggressive position on climate change has been one of his most applauded moves.

While the pope has made his concern about human-caused climate change known on numerous occasions, his position was largely summed up in his second encyclical, “Laudato Si,” released earlier this summer — a document that made headlines around the world for being the first papal encyclical based entirely around environmental issues. Now, as Pope Francis makes his way through Washington, New York City and Philadelphia, climate activists are expecting a reaffirmation of his commitment to environmental issues and to climate action in particular.

…there’s a lot that Pope Francis gets right about climate change — in particular, a deep understanding of the ways it will affect the most vulnerable people and places in the world.

In the past, the pope has received criticism for what some experts perceive as a somewhat simplistic understanding of the economics of climate change interventions, a field he’s professed is not his strong suit. In particular, his suspicion of carbon pricing has garnered negative feedback from experts pointing to its past success as an emissions reduction strategy. And some have pointed out that the arguments the pope presents in his encyclical hardly offer any new information to the climate change conversation.

But there’s a lot that Pope Francis gets right about climate change — in particular, a deep understanding of the ways it will affect the most vulnerable people and places in the world.

Here are some of the highlights:

Climate change is linked to every aspect of life on Earth. 

More and more, scientists are emphasizing the fact that climate change isn’t just about global warming. Temperatures will rise, yes, but they’ll also bring about a complex series of intertwined effects that will have consequences for many aspects of life on Earth. These include sea level rise, changes in global weather patterns, agricultural losses, declines in water quality and availability, reductions in biodiversity and even the potential for forced migrations and civil unrest.
In his encyclical, Pope Francis expresses an understanding of this complexity when he writes, “At the global level, [climate change] is a complex system linked to many of the essential conditions for human life.” And, indeed, this attitude is reflected throughout the rest of the document, which goes on to describe a number of interconnected environmental concerns, including pollution, water quality, deforestation and loss of biodiversity — all of which could be exacerbated by a changing global climate, or even help accelerate global warming.

And because humans depend on natural resources to support so many aspect of life on Earth, the pope also writes that the effects of climate change will not just manifest themselves in the form of environmental degradation: These implications will also be “social, economic, political, and for the distribution of goods.” In other words, all aspects of the planet, including the finest details of human infrastructure, have the potential to be affected.

Climate change is fed by vicious cycles.

Pope Francis also understands the global carbon cycle and the ways in which human activities can influence it. In his encyclical, he writes that warming “creates a vicious circle which aggravates the situation even more” — a statement backed up by considerable science.

As the pope goes on to describe, many of the consequences of climate change also have the added effect of contributing to more global warming in a sort of feedback loop. “The melting in the polar ice caps and in high altitude plains can lead to the dangerous release of methane gas, while the decomposition of frozen organic material can further increase the emission of carbon dioxide,” he writes. The release of this extra gas further accelerates warming, which then causes more melting and thawing — a vicious cycle. Less ice in the Earth’s polar regions also means that less sunlight is getting reflected back out into space. More sunlight being absorbed in these regions can cause more warming, which leads to more melting.

Francis also notes that climate change has the potential to affect some of the Earth’s most important carbon sinks, like forests and oceans. These sinks absorb carbon emissions that would otherwise go into the atmosphere. But as the pope notes, the effects of climate change can damage their ability to absorb carbon. For example, if droughts, fires or extreme temperatures cause forests to die off, they can no longer act as carbon sinks. Additionally, dead forests release all the carbon they previously contained into the atmosphere, leading to even more warming.