By now everyone has heard of Greta Thunberg, the Swedish teenage environmental activist on climate change whose campaigning has gained international recognition. She has organized "school strikes" for students to bring climate change to the forefront of issues and in September she spoke bluntly and powerfully to the United Nations General Assembly.

Whether one agrees with her style and tactics or not, we Catholics are certainly united with her in our concern for climate change and our need to take greater care of the earth, what Pope Francis calls "our common home." For us, as Catholics, our concern for creation is one of the seven principles of Catholic Social Teaching, so our perspective is not only practical, or political, but also theological.

The Church has called our attention to environmental and climate issues as far back as 1990 with Pope John Paul II's message for the World Day of Peace. Pope Benedict spoke eloquently on care for the environment, even earning him the title of "The Green Pope" at one point. And, of course, Pope Francis has become the first Pope to issue an encyclical on the topic, "Laudato Si, On Care for Our Common Home."

And our U.S. bishops have issued their own statement on environmental responsibility in 2001, entitled "Global Climate Change: A Plea for Dialogue, Prudence and the Common Good." In that document, they teach that, "At its core, global climate change ... is about the future of God's creation and the one human family. It is about protecting both 'the human environment' and the natural environment." They go on to say, "Care for the earth is not just an Earth Day slogan, it is a requirement of our faith".

Perhaps Pope Francis put it best in "Laudato Si" when he wrote, "A true ecological approach always becomes a social approach; it must integrate questions of justice in debates on the environment, so as to hear both the cry of the earth and the cry of the poor. Everything is connected."

This is an especially critical matter because, as in many other issues, those who are most drastically affected are the poor. The experience of Catholic Relief Services, as an example, is that those who are struggling on the margins of society are absorbing the largest impact of changes to the climate and the environment.

Working with the poor around the world, CRS testifies to the effects of the changing climate on poor and vulnerable. Farmers that CRS serve are losing their crops due to erratic rainfall or warm temperatures. Families they serve are struggling to keep their homes as the water around them rises.

I have seen that in Guatemala, when farmers can't grow their own corn because of climate changes, they are forced to migrate to other areas of the country, into neighboring countries, or even farther in order to be able to make enough money to put food on the table.

In El Salvador, I spoke with coffee growers who have consistently had to move "up the mountain" because the warm temperatures have limited the area that is best for growing coffee beans.

CRS has provided resources to help them reduce the effects of climate change, but since the administration has cut off aid to Central America, many of those programs are being reduced or eliminated.

Our Catholic faith calls us to advocate that our country takes climate change as a serious threat and to provide financial international aid to help the poorest around the world adapt to the changing environment. Let your senators and members of Congress know that you support those efforts.