The Klingon Invasion (The Chimes At Midnight)

In an alternate timeline in which Spock died in childhood and James T. Kirk died while saving his son David Marcus from the Klingon Commander Kruge in 2286, no mission was undertaken by the Enterprise crew to retrieve a pair of Humpback whales from Earth's past. Instead, the Cetacean Probe ravaged Earth unopposed for a period of about a week before finally moving off. In the aftermath, Earth's atmosphere was ionized, destroying the ozone layer, and torrential storms rained down across the planet, blocking out the sun and preventing agriculture. Dr. Carol Marcus attempted to use a less powerful version of the Genesis Device to restore the Earth's atmosphere to its previous state; however, the Klingons chose to use the opportunity to invade Earth.