This picture is from a display at a local attraction. It caught me by surprise. In the resources that I use to teach climate in class, the graph I use finishes at the point 290ppm and labels it "today". That graph does date from the 1990s I think. I was shocked to see that the new graph has reached 400ppm. And I have found the source of this graph: NASA
https://climate.nasa.gov/climate_resources/24/graphic-the-relentless-rise-of-carbon-dioxide/ I know that the data going back 450000 years comes from air trapped in bubbles in ice. See the start of the film The Day After Tomorrow for footage of this going on. But now we seem to be a long way above any level from the last half a million years.
