“Was there anything that could have been done to prevent it?”

“We proposed several potential solutions to deal with the caldera threat, including the construction of a deep-well venting system. Congress vetoed the deal three years ago, claiming the $23 billion price tag was far too excessive for a tourist attraction. When we protested, news pundits on one politically slanted network accused members of the U.S. Geological Survey of using scare tactics to fund our department.”

“Obviously, a blast of this magnitude striking so early in the morning represents a worst-case scenario. We’re getting death estimates ranging from eight to ten thousand—”

“Ms. Matney, I don’t think you comprehend the magnitude of this event. It’s not the initial blast or the lava flow we have to fear; it’s the ash cloud. As it rises into the stratosphere it will span the entire globe, blanketing the atmosphere and blotting out the sun’s rays. Photosynthesis will cease, which means crops will fail, leading to mass starvation. The Earth’s temperatures will plummet, initiating another ice age. What we’re looking at is the opening act of a planet-wide cataclysm—an extinction event.”

The announcer couldn’t find her voice, forcing her colleague to take over the interview.

“Dr. Hurtienne, this is Tyler Bohlman. How long will this theoretical ice age last?”

“I can assure you, Mr. Bohlman, the ice age is not theoretical. Sixty-five million years ago an asteroid struck the Gulf of Mexico, wiping out the dinosaurs. It wasn’t the impact that caused the mass extinction, but rather the ash cloud that caused a radical change in climate. As for how long the ice age will last, the answer is anywhere from a thousand to a hundred thousand years.”

“Huh!” My eyes snapped open, my heart pounding in my chest. For a distressing moment I felt lost.

Jonas was snoring softly in his command chair, his congested breaths nearly concealing the faint sound of rushing water. Locating my headphones, I listened in on the sonar.

The sound was coming from the riverbed below the Manta, along the base of the ice sheet now walling us in. Deciding not to wake Jonas, I restarted the engines and dove the sub to the bottom.

The subglacial waterway hadn’t ceased; its outflow had been dammed by ice extending from the bottom of the glacier to within seven to ten feet of the riverbed. Reduced to a narrow bottleneck, the current was rushing beneath the ice sheet at a swift twenty-three knots.

It would be a tight squeeze, but the Manta could slip through. The danger lay in the fact that the extended bottom of the glacier was essentially river water that had frozen, rendering it unstable. Traversing the passage could cause the ceiling to collapse on the sub and trap us for all eternity.