The article does not state the reason for the acceleration but one effect is supposed to be dams. Most dams are (on the northern hemisphere and) away from the e

The article does not state the reason for the acceleration but one effect is supposed to be dams. Most dams are (on the northern hemisphere and) away from the equator which means mass (lots and lots of water) is accumulated closer to Earth’s rotational axis. Combined with conservation of angular momentum, this leads to a higher rotational frequency. It is like pulling your arms in while spinning. This is one effect on the Earth‘s rotation among many, of course.