I've been looking at some recent studies on orbital forcing and solar variability. The Earth's climate has always been in flux, driven by Milankovitch cycles. Over the past 10,000 years, we've been in a relatively stable interglacial period, but there have been smaller cooling phases, like the Neoglacial period. It's not a straight line down, but there's definitely a long-term cooling trend when you look at the bigger picture. Check out this study on orbital forcing: [NASA's Milankovitch Cycles](https://climate.nasa.gov/science/12-milankovitch-cycles/)