New York City Mayor Michael Bloomberg on Thursday bemoaned President Barack Obama's "disappointing" first term in office. He complained the Democrat "devoted little time and effort" to pragmatic, centrist problem-solving while wielding "partisan attacks." He charged he has "embraced a divisive populist agenda focused more on redistributing income than creating it."

And then the billionaire entrepreneur endorsed Obama over Mitt Romney.

Why? Bloomberg, in an op-ed on Bloomberg View, cited several factors—including the Democratic Party's support of abortion rights and gay marriage—but spent much of his piece fretting about climate change in the wake of deadly superstorm Sandy. Climate experts have warned that the world can expect more hurricanes like Sandy in part because of global warming.

[Related: Post-Sandy, climate change skeptics denying reality, lawmakers say]

"One sees climate change as an urgent problem that threatens our planet; one does not. I want our president to place scientific evidence and risk management above electoral politics," the mayor wrote.

"Our climate is changing. And while the increase in extreme weather we have experienced in New York City and around the world may or may not be the result of it, the risk that it might be—given this week's devastation—should compel all elected leaders to take immediate action," he added.

The mayor praised Romney, the GOP challenger, for his "history of tackling climate change" as governor of Massachusetts—notably by signing on to a regional cap-and-trade agreement. "But since then," Bloomberg noted, "he has reversed course."

"I believe Mitt Romney is a good and decent man, and he would bring valuable business experience to the Oval Office. He understands that America was built on the promise of equal opportunity, not equal results.

"In the past he has also taken sensible positions on immigration, illegal guns, abortion rights and health care. But he has reversed course on all of them, and is even running against the health-care model he signed into law in Massachusetts.

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"If the 1994 or 2003 version of Mitt Romney were running for president, I may well have voted for him because, like so many other independents, I have found the past four years to be, in a word, disappointing," he wrote.

While "neither candidate has specified what hard decisions he will make to get our economy back on track while also balancing the budget," the mayor said, Obama has a chance to build a bipartisan consensus.

"If he listens to people on both sides of the aisle, and builds the trust of moderates, he can fulfill the hope he inspired four years ago and lead our country toward a better future for my children and yours," Bloomberg said. "And that's why I will be voting for him."