The U.S. credibility chasm on climate change

• The Paris agreement called for warming to be limited to "well below 2 degrees" Celsius, or 3.6 degrees Fahrenheit, relative to preindustrial levels.
• However, the world is currently on course for 3 degrees Celsius, or 5.4 degrees Fahrenheit, of warming, which raises the odds of potentially disastrous consequences.

The big picture: The U.S. has been playing a game of "red light, green light" on climate change for decades. The country played a leading role in brokering the Kyoto Protocol in 1995, but walked away from that agreement in 2001.

• Then the U.S. helped spearhead talks on the Paris agreement during Barack Obama's presidency, only to leave that agreement under Donald Trump and rejoin when Biden took office.
• Considering this timeline, other countries — including China, which is by far the world's top emitter today — question the word of the Biden administration when it says the U.S. is fully committed to climate action.
• Some Chinese leaders have recently signaled they don't see the U.S. as being in a strong position to prod it to cut emissions after walking away from Paris.
• For example, on Friday, Chinese Foreign Ministry spokesman Zhao Lijian said of the U.S. return to the Paris agreement: "Its return is by no means a glorious comeback but rather the student playing truant getting back to class."

Quick take: Kelly Sims Gallagher, a Tufts University professor who helped broker a climate deal with China during the Obama administration, tells Axios the U.S. has a lot of work to do.

• "Trust was broken when the United States withdrew from the Paris Agreement," she said. 
• "The way to rebuild the trust is for this Administration to first explain how the United States will achieve its Paris target and then also provide a concrete plan for enhancing ambition by 2030."

Context: The White House summit will be a major test of just how much credibility the U.S. lost on the global stage, and specifically within the uniquely fraught realm of climate negotiations, when Trump walked away from Paris and worked to gut domestic efforts to cut emissions.

Driving the news: The Biden administration wants countries to agree this week to cut emissions significantly by 2030, on the way to net zero by 2050.

Scientists have shown that in order to keep the Paris agreement's most stringent temperature target of 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, of warming in play, emissions must be slashed deeply by 2030.

• The U.S. is expected to unveil an emissions reduction commitment on the order of a 50% emissions cut relative to 2005 levels by 2030, but it's unclear how many other nations will announce anything new ahead of November's U.N. climate talks in Glasgow.

Yes, but: Even if the talks are successful, it's unknown whether new emissions targets will actually happen, considering the lack of an enforcement mechanism to punish countries that don't live up to their word.

• University of Washington statistician Adrian Raftery, who has analyzed how nations are not on track to meet even existing commitments, said the targets are "somewhat untethered from what's likely to occur."

The intrigue: The joint communique released by the U.S. and China Saturday night indicates that there may be a window for progress between the world's top two emitters, despite the tensions in that relationship overall.

What they're saying: Rachel Kyte, a former World Bank official who advises the U.N. secretary-general, said policy makers will be looking to the U.S. to back up whatever new targets it offers with a detailed plan on how to get there.

• “The credibility is all wrapped up with actions not words," said Kyte, now the dean of The Fletcher School at Tufts University. "All eyes are on the plan.”

Ben Geman contributed to this story.

Go deeper: U.S. and China agree to take joint climate action