The Earth is fine... Mankind however, is in danger of imminent extinction.

The Golden Age

The late 20th century saw many advances in technology. World-wide communication was instantanious, access to a wide breadth of knowledge and entertainment was almost universal. Cultures that once would have never interacted, now competed for their 15 seconds of popular attention span. Nations joined forces and cooperated to an extent never before experienced in human history.
Science was greatly benefiting from the glut of information and cooperation. Energy research saw strong advances in storage capability, leading to exciting developments in both the commercial and military sectors. Agriculture created ever increasing amounts of staple foods using engineered seeds that could produce many times the "natural" crops once available.

Mankind flies too high

Ever increasing masses of humanity resulted in staggering demands for food and water. For years science was able to come up with solutions. Better agricultural processes, wastewater recovery technology, and engineered crops managed to produce the necessities of life for the teeming masses that populated Earth.
That precarious balance abruptly shifted during an event now commonly refered to as "The Blight". Whether the result of terrorist action or natural forces finally finding inherent vulnerabilities in the engineered crops is still a subject of debate. Either way, one fatal summer saw half the worlds grown food supply lost to an insiduous plant infection.
No nation had the reserves available to handle the loss of this much of the food supply. Within a few weeks, rumors started spreading, accusations were made, angry retorts and much political posturing fueled the flames of discontent.
Global unity dissolved within the month, followed shortly by an ever increasing number of regional conflicts as the remaining food supply was consumed.
Hunger fed the conflicts, until the globe was consumed by war. Any chance at rebuilding the lost agricultural capability was destroyed as every political force lashed out to protect what little production they might have had left.
With hunger came war and disease. As people become ever more desperate, might made right, and those with the power grabbed what they could to promote their own survival. The end of mankind was at hand.
Mankind was now just a handful of struggling survivors, subsisting on the meager scraps left from what had been civilization just a couple years before.

Clinging to existance

Civilization was still a fresh memory, but the global infrastructure that fueled the civilized lifestyle no longer existed. Communities existed based on what could be locally procured. Technology now existed only as recycled components from pre-blight products. Food production was limited to some local farms and ranches that had stockpiles of "heritage" seeds or a natural climate that could support livestock. Water supplies consisted of rainfall and local watersheds, the vast aqueduct systems that supplied the large urban areas having been destroyed by warfare or rural "activists" taking the water to supply their local communities.
The global wars had destroyed much of the remnants of the pre-Blight world. Most of the developed areas were reduced to wasteland, and sparsely inhabited rural areas were now empty without the production chains that once supported them. The worlds population was a small fraction of what existed pre-Blight, and dropping rapidly. Local food production was still in the process of being established. Agriculture hadn't yet been re-established and the vast pre-blight factory farmlands were now dust bowls. Bio-weapons, chemical warfare, and good old industrial waste had polluted much of the ariable landscape.
The global environment was in flux. The devastation brought on by the end of civilization changed weather patterns and dust clouded skies across the Earth. The ecologies once shaped and controlled by the hand of Man now struggled to find a new balance. Some species died off as their environments disappeared, some found new footholds and prospered within the chaos.

Hope Springs Eternal

Fortunately for mankind, a well connected think tank called (booga Wooga, I'll call them "Minerva Corp" for now) was conducting a series of pre-Blight experiments related to modifying gravitational waves. Nothing much came of the experiments, and the results ended up returning inconclusive data.
Shortly afterwards, one of the primary scientists ("Dr. Soensoe") was reminiscing with a colleague who had been on sabbatical. The colleague had been performing some underwater archeology off the coast of Spain at the site of a recently discovered submerged ancient city. The colleage reported strange events happening at the site, glowing lights and water vortexes abruptly appearing and dissapearing over the spans of several hours, then stopping without any explanation.
In a flash of insight that would make the fate of Minerva Corp and quite possible mankind, Dr. Soensoe remembered his gravitational experiments and was able to correlate the timing to that of the strange events at the archeology site.
As the Blight struck and destroyed the world (as we knew it), Dr. Soensoe managed to get permission to join the archaological expedition. Working with a small team of assistants and some local divers hired to perform the heavy lifting, he was able to immediately recreate the previously noticed anomalies. Further experimentation determined that the glowing lights were actually generated by an arrangement of large stone blocks at the site of an ancient temple.
The disappearance of a diver while finding of the glowing stones lead to determining that the vortexes were in fact localized to a specific area. Apparently as the original experiment triggered certain gravity waves, the stones would glow, and a volume of nearby water would simply disappear.
Needless to say, this was "Big News"... but at that time the Blight had reached public awareness, and geeks playing science wasn't exactly what people cared about anymore.
Minerva Corp realized they had something important with this discovery. As the world collapsed, they made a concerted effort to restock the research ship. Several more ships were moved to the area and a team of the brighest minds available started to explore the new discovery, sheltered from the dissolving world around them.
The flottila of research ships became an isolated community, crewmen reached into the ocean for provisions, and sneaked onto the nearby shore for supplies as needed. Meanwhile the scientists conducted experiment after experiment to determine what was actually happening with the glowing stones.
The breakthrough occured after several months of fruitless experimentation. In a fit of frustration, Dr. Soensoe had the early gravity wave experiment reran. The stones glowed and the water churned as expected, but this time between the stones was the original missing diver, minus his diving gear. Upon recovering the body of the unfortunate air-breather, they noticed some rather odd discrepancies. The diver appeared to have been alive and healthy, with several months worth of beard growth and some primitive tools tucked into what appeared to be the remnants of his dive belt.
Realising that the unfortunate diver had not simply "disappeared", but had in fact lived for several months in an out of water enviroment, the team reapproached the experiments with the hypothesis that the glowing stones actually transported the affected area to a human habitable place. Further experimentation led them to discover that the stones would only activate at a finite interval, apparently they would only "turn on" every 15 minutes or so.
They isolated the affected area, and built a chamber covering the ancient temple site. Once people could approach the stones without protective diving gear, the transportation experiments began. Several rocks and ration packages were successfully "disappeared" and recovered before the first official scout traveled through the stones.

A breath of fresh air

The scout successfully returned, and brought back amazing news. He reported appearing on a grassy hill overlooking a lush forest, topped by an array of stones that matched the ones at the archeology site. Even more amazing, the air was clear, the grass was abundant, and birds flocked about in abundance. The only sign of human life was an abandoned encampment down by the treeline, presumably established by the lost diver several months before.
The decision was made to explore this unusually lush area. A small group of personnel used the stones and started setting up an encampment on the new found landscape.
Finding the remnants of the diver's equipment, the group were able to quickly determine that the abandoned emcampment had belonged to him. No other signs of human life were apparent, but the explorers greatly enjoyed the clear sunny day. No one could figure out where on Earth they were, nowhere still existed where nature had survived and still flurished to such an extent.
The first nightfall brought the group insight. Those who stayed up to watch the stars in the unusually clear night sky couldn't find their favorite constellations, the rising of a second moon on the horizon suddenly demonstrated that they were no longer on their own familiar planet.
Finding itself holding the keys to a fresh unspoiled world, Minerva Corp wasted no time in securing the original archeology site. Working in concert with some of the regional governements, they established a supply line from the mainland to the flotilla. The original chamber was soon covered by a large dome, and airlocks providing access via submersiable watercraft.
While exploration teams scouted the new world, Minerva Corp started shipping equipment and personnel through the stones. A small outpost was established, and the new world (now named "Eden") became the first extraterrestrial human colony.
News of the discovery eventually leaked out. Minerva Corp found the flotilla besieged by refugees, desperate for a chance they not longer had on the dieing Earth. The underwater location of the glowing stones (by now, commonly referred to as "The Gate") prevented casual access, but as the news spread, increasingly powerful organizations began to push for access to this new world.
The cycle time on the Gate limited the amount of people and material that could be transported. Minerva Corp began selling tickets to the new world, at an astronomical price. Lottery centers were established on the mainland, there anyone could apply for a chance to freely travel through the gate. The refugees surrounding the flotilla were warned off, and a strictly enforced perimeter was established. Minerva Corp used it's control over Gate travel to force concessions with many of the surviving governments and corporations. Almost overnight, Minerva Corp went from being a medium sized research company to effectively controlling what was left of human civilization.

Discovering the Gate Network

Establishing the Nexus

The Diaspora

Current Day