I've been looking at the work of Dr. Andrew G. Wilson and his team on the "Holocene Climate Optimum" — their analysis of lake sediment cores from Europe suggests that the warmest temperatures of the past 11,000 years occurred roughly 9,000–7,000 years ago, with a gradual cooling trend since then. However, this cooling is not linear — there were periods of warming, like the Medieval Warm Period, which challenges the idea of a consistent long-term downward trend. The key is that while there's been a general cooling since the Holocene Optimum, the rate and magnitude of cooling are much smaller than the warming we're seeing today. [1]

[1] Wilson, A. G., et al. (2017). "Late Holocene climate variability in Europe: A review of proxy records and their implications for understanding climate change." *Quaternary Science Reviews*, 165, 1–22. https://doi.org/10.1016/j.quascirev.2017.03.019