Gradually you come to full awareness and you are eventually met by someone who speaks English with an odd accent which is vaguely Australian in general who has come to ask you some questions. They is 173cm tall, has olive skin, dark green hair in a sensible bob haircut, is dressed in a green shirt, green pillbox style hat, dark green and black jacket with insignia on the breast and shoulder, medium green leggings and boots and looks like a broad shouldered woman, though they correct you if call them a woman as they are not "Stemline Binary". They are accompanied by an guard in black armor a a truncheon who watches things quietly and brings you a meal (tea, vegetable soup and noodles, they'd change the menu at your request). Their name is doctor* Kayin Thail, they're a Precatacylist historian and they inform you that it is Imperial Year 1538, or 4265 CE.
Basically during the 21st century climate change was left unaddressed which gradually led to increased political and economic instability which culminated in 2103 with the Catacylsm War. Billions died in the war and billions more died in the aftermath, leaving only about 250 million or so alive by 2120. Society regressed to a large degree to mostly preindustrial levels without the boon of fossil fuels. But enough information survived so that a recovery was possible by a federation of towns in what was once Queensland Australia to gradually pick up the pieces and rebuild from the Dark Age. It was a step by step process requiring careful management of resources, gradually developing thermal solar and hydropower capacity while fighting off nomadic barbarians and city states to the south over the span of centuries, but ultimately they gained enough capacity to steamroll their foes, unify Australia and from their unify the world under the banner of the Imperial Commonwealth (name translated) ruled from Khenber (built on the remains of Canberra). Over the last two centuries they've begun to really reach out into the Solar System and have developed colonies on the moon, the asteroids, mars and venus, though the total population off world remains at less than a million people.
The Society which arose from the ashes is distinct from modern society in a large number of ways. It has overtaken modern earth technologically and now the bulk of it's power is generated by fusion reactors. Much of it's economy (in praticular heavy industry) is operated by governmental bodies, though there is still a market element and a lot of effort is put into sustainable development. The government has democratic elements, but also a strong technocratic element as well. Cities tend to have large numbers of apartment buildings and electric commuter railways. Electric Automobiles as something that your average worker could afford have only become common in the last two centuries, but single family suburbs don't exist. Arcologies are beginning to be built. It also has put into place a program which involved the genetic modification of humanity through various incentives for parents to remake humanity into a species of functional hermamphrodites with triple the lifespan, which is near universal in Australia, Asia and South America (the first areas conquered by the Imperial Commonwealth) and less so in the latter frontier regions. There are some remnants of Judaism, Shintoism, Christianity, Islam and Hinduism that identify as such, but all of them have evolved to some degree over the past twenty two centuries (Judaism is still the most recognizable). More information is provided on a tablet with information translated into English. The Imperial Commonwealth's population is about four billion people.
But getting back to your story, about six months ago workers building a new set of apartment blocks found a pre-catacylsm chamber with a pod powered by a small Radioisotope Thermal Generator which contained a person in it. Inside it was you, they found instructions for safely decanting it's contents and now you are out. Basically Kayin is in the opportunity that a real world that a historian from out time would have if they managed to unfreeze a Roman from the time of Julius Caeser. The people of the Imperial Commonwealth largely look upon the USA, PRC, EU, British Empire, USSR, Napoleon and so forth in similar ways that we'd look at the city states of Greece and the Roman Empire. They show sympathy for your loss and never seeing your friends, children, parents and siblings again, friends and, but despite this they would still like to interview you to learn more about our world. After you are cleared to leave the hospital in a couple of weeks, they'd move you into a 128 square meter apartment in Khenber.
How would you describe the 21st century world to Kayin?
Spoiler
Zor