I'm not sure that was the intent of the press release because it doesn't actually use the words "ice age," "trigger " or "instantaneous," but that's my take on it. See if you agree.

With a title that belies its importance, "Winter monsoons became stronger during geomagnetic reversal," the press release (see full release below) explains that galactic cosmic rays (high-energy particles from space) increased "dramatically" during the Matuyama–Brunhes magnetic reversal of 780,000 years ago. Such an increase (called the Svensmark Effect) could induce more low cloud formation and influence the Earth's climate via the umbrella effect.