The Biden administration should not allow the Chinese regime to use climate change as a bargaining chip to extract concessions in other areas, according to China experts. The warning comes as the United States formally rejoined the Paris agreement on Feb. 19. President Joe Biden has described climate change as an “existential threat” and vowed to do more to reduce carbon emissions. But analysts are concerned that this may lead the United States to become cozier with the Chinese regime.  While Biden officials have broadly indicated they would continue the Trump administration’s tough-on-China posture, they have also pointed to “cooperative” aspects of the U.S.-China relationship.   On the campaign trail, Biden said he’d work with the regime in areas of common interest, such as climate change and preventing nuclear proliferation.  Experts fear that U.S. cooperation on climate change could lead the administration to give ground in other key domains such as human rights, …