Beads of sweat were running down Bixi's forehead. He was working hard down here deep in the quarry, cutting out marble. The marble was highly prized by craftsmen for many hours walk around. The objects made from this marble were traded even further. The quarry was not very wide, perhaps 30 man lengths, but it was about a hundred man lengths deep. Access was via timber stairs, secured into a three-sided shaft that ran from top to bottom. Making the quarry deep rather than wide preserved the trees around the quarry.
The marble people had been quarrying here for generations. They were descendants of the Amazon tribes that had migrated out of the Amazon rain forests after the long winter centuries ago and come upwards into this part of northern America and beyond, multiplying and repopulating America as they went. The long winter and the ash clouds had lasted years and left few survivors apart from tropical hunter-gatherers who knew how to live without the amenities of civilisation. The new populations of America took clues from the remnants of the civilisations before the big war to build their own civilisation.
Bixi thought of this as he was cutting through the marble. Then he heard a crack and felt the ground move under him. A moment later he was dead.
About a walk hour away, Tigreh, a young tool maker of the marble people, was visiting Xibaisoa, the woman he loved, an ornament maker in another village. Perhaps one day he would take her home to his village as his wife. They were chatting in front of her parents' hut when they heard hissing sounds coming from the village of the marble people.
"What is this?" asked Xibaisoa.
"I don't know," Tigreh answered. "I have never experienced anything like this before. I need to go back."
"I am coming with you." Xibaisoa quickly said. She briefly disappeared into the hut to tell her parents.
Xibaisoa and Tigreh started walking. After a few minutes the hissing stopped. They were walking quickly and reached half way in about three quarters of the time it usually took.Then, after descending a short rise, Xibaisoa said, "I am breathing as if I had been running. But we are only walking quickly."
"I am also breathing more quickly," answered Tigreh, "That's very strange. Let's walk more slowly."
After a hundred steps or so, Xibaisoa said, "We are walking more slowly but my breathing is getting worse."
At that moment, they spotted a dead rabbit on the path. Tigreh looked at the rabbit carefully. There was no sign of injury or disease. Tigreh and Xibaisoa looked at each other.
Tigreh said, "Something is not right here. What could have killed this rabbit?"
"Maybe the rabbit also had trouble breathing," Xibaisoa answered. "I wonder if this has something to do with the hissing we heard earlier."
"I hope the people in the village are alright." said Tigreh but he didn't look like he thought they would be.
They continued talking about the rabbit and their breathing and what it might mean for the village and then they noticed that their breathing improved, so they both decided to walk on carefully. Whenever they found themselves breathing more quickly, they stopped for a while. They saw more dead animals.
Suddenly Tigreh screamed. There was a woman of about fifty years lying on the track.
"I know her," Tigreh said. "She lives in our village. Mushroom and berry collector." Tigreh felt the top of her chest. "She is not breathing. I think she is dead like the animals. No injury of any kind."
Tigreh and Xibaisoa kept going. As they approached the village, they saw more dead people and it became clear that not a single person in the village had survived. Tigreh's grief was indescribable. His parents, his two brothers and his sister were among the dead. Two more men of the marble people arrived who also found their dead relatives.
It was customary among the marble people to bury their dead but there were just too many. So, for the moment they decided just to bring all the bodies to a spot they chose just outside the village to identify and count them. They looked into the quarry.
"The stairs to the bottom are gone." said Tigreh.
"There is big hole down there." added Xibaisoa.
"The hole is very deep. I can't see the bottom." observed Xopisi, one of the other two, a man of about forty years.
"Neither can I," agreed Tigreh, "It's probably about a man length and a half at the quarry floor but it gets wider the deeper it goes."
"Did you notice the trees near the quarry?" asked Xibaisoa, "They seem to have fallen down and away from the quarry."
"Some sort of explosion must have come from that hole." said Xopisi.
Tigreh was looking carefully at the quarry walls and the shaft where the stairs had been. "How do I get down there?" he wondered.
"The stairs are destroyed and it's too far and too dangerous to climb down there with ropes," Xibaisoa quickly responded, "Anyway, there is no body down there."
"We don't know what's in that hole," Xopisi added, "Our quarrying probably disturbed it. Whatever it is, it might kill you, too."
"I don't believe a living thing did this," Tigreh objected, "We need to find out what happened."
"We have enough dead people to collect and bury. Let's do that first before we put more lives at risk." Xibaisoa said, alarmed.
"But we have to figure out what to do about the quarry," replied Tigreh, "Quarrying is our livelihood. You too need the marble for your ornaments."
"You are both right," Xopisi said in a calm voice, "We have to figure out what to do about the quarry but we don't have to do it right now. We'll collect our dead and then we'll go to the other villages, the ones that need the marble, and work out a plan. Maybe we will get help from the other villages."
Tigreh thought for a few moments. "You are right." he finally agreed.
They continued with their task of carrying the bodies to their chosen spot. Four more marble people as well as three people from neighbouring villages arrived. Eventually 127 dead marble people and four dead people from other villages lay in neat rows. Seven marble people were standing there alive. Four more were known to be travelling and six were unaccounted for.
The seven marble people and the other four were talking about what to do next when some people from another neighbouring village arrived. It turned out that in that village most had also died. In the coming days, it became clear that there were quite a few villages were people had died from a sudden inability to breathe properly. But there were other villages which were closer, all on somewhat higher ground, including Xibaisoa's, where all the villagers had experienced was the loud hissing sound.
The marble people had never heard of carbon capture and storage. They had no way of knowing that centuries ago the previous civilisation pumped vast amounts of compressed carbon dioxide into disused mines. Now these storage sites were like giant land mines, ready to kill not only those who innocently disturbed them but also many who were walk hours away.