WASHINGTON -- Mark this week down as the one that truly shifted the climate conversation in the nation's capital.

It was a week where Hillary Clinton's announcement that she opposes the Keystone XL pipeline played fourth fiddle -- and a potential government shutdown was barely even in the band -- climate change was the one unifying theme connecting the week's top stories.

First, Pope Francis called for climate action at the White House welcoming ceremony on Wednesday: "It seems clear to me also that climate change is a problem which can no longer be left to a future generation. When it comes to the care of our common home, we are living at a critical moment of history."

The leader of the Roman Catholic Church echoed that call in his address to Congress on Thursday, and more specifically called on the United States and its legislators to make a "courageous and responsible effort" on climate change.

And on Friday, Obama and Chinese President Xi Jinping announced an even stronger commitment to climate action ahead of upcoming United Nations negotiations in Paris, with China pledging to set up a cap-and-trade system by 2017. These developments come nearly a year after another major historic agreement between the two countries.

In a joint press conference, Xi said the two nations would "work together to push the Paris climate change conference to produce important progress." And China agreed to provide $3.1 billion in funding for developing countries to deal with climate -- one-upping the U.S.'s previous commitment of $3 billion .

The pope's message was a moral one, calling for compassion for poor and vulnerable populations most affected by climate change. It asked listeners to reflect on how environmental destruction of all types hurts the least powerful among us, and to create an economy that is "modern, inclusive and sustainable." And you don't have to be Catholic to care: Evangelical , Muslim and Jewish faith leaders have offered a similar message.

The U.S.-China agreement is a practical one: if the world's two biggest emitters can cut emissions, so can everyone else. And everyone else is trying. China's announcement overshadowed the news that Indonesia and South Africa -- two other major emerging emitters -- also put forward climate targets this week, bringing the total number of countries that have done so to 72 .

The week essentially negated two primary lines of opposition heard in Washington -- that there isn't a good reason to act on climate change, and that the U.S. would be acting alone. What little credence those arguments may have held is gone.

The confluence of events also cast the current situation in Congress in a starkly different light. Republican leaders have been working to undermine progress toward an international climate agreement. And they've opposed providing the $3 billion in climate aid that the Obama administration pledged to the Green Climate Fund -- a fund that many see as an essential way to bring along developing country support for a climate agreement. It's unlikely that opposition will go away easily, but the hollowness of opponents' arguments should echo louder now.

There will still be the Rep. Tim Huelskamps of the world, arguing that the pope's message doesn't matter because climate change is not "settled science," and the Rep. Paul Gosars, who will choose not even to hear the message because the pope talks "like a leftist politician."

And there will be the Sen. James Inhofes, who will decry, via a press release, that Obama should "spend more time working with Congress instead of developing press releases with the Chinese government."

But any shred of credibility those opponents might have retained is gone. And Congress will, eventually, realize that.