Wood Romances

If you look at any reconstruction of global mean temperatures covering the entirety of the Holocene, you'll see that the 21st century is warmer than the mean reconstructed temperatures for any point during the Holocene. Now proxy-only reconstructions (Kaufman, Shakun, Marcott) show a warmer Holocene Thermal Maximum than data assimilation approaches (Osman, Erb), and the CI for the HTM is wide enough in Kaufman's reconstruction to allow a small possibility that some years were warmer during the HTM were than they are today, but the evidence is clear that the recent warming spike is unprecedented in the Holocene, and temperatures are likely warmer today than any time during the Holocene.  Attempts by contrarian influencers to undermine this conclusion have been substantial but unconvincing and frequently disingenuous. For instance, Javier Vinós manipulated Marcott's proxy data to make the difference between the Little Ice Age (LIA) and the HTM about 2x warmer than what was ...

Note: 1/15/2025. Graphs are updated to include 2024 when available. You sometimes hear that, at least on certain time scales, CO2 and global temperature (GMST) don't correlate very well or even that the two go in opposite directions. The implication drawn from this is that CO2 can't be the primary driver of climate changes. What I want to show here is that this claim is categorically false. On virtually all time scales in the Phanerozoic, CO2 and GMST correlate very well, especially when taking into consideration that GMST correlates with the log of CO2.  The best way for me to demonstrate this point is to simply show the correlation. Where I can, I convert CO2 to forcings (using RF = 5.35*ln(CO2/280)) and and plot CO2 forcings on the x-axis and GMST on the y-axis. This gives us two advantages: first, it allows us to calculate the r^2 for that correlation, and second, the slope of the correlation gives us an indication of sensitivity - that is, the temperature response to chang...