There are no shortcuts when it comes to figuring the planet's warming rate. Cloud records remain unreliable. The physics are confusing. Global climate models fail to agree. And no patch of clouds has been more confounding for researchers than the durable, low clouds flopping off California's coast. Now, for the first time, scientists are embarking on a campaign to probe these clouds from below. To improve their clouds in silicon, they've found, they must first go to sea.