Are We Still Coming Out of the Little Ice Age?

Once common refrain I hear among contrarians is that current warming shouldn't be considered exceptional or caused human activity because we're just "coming out of the Little Ice Age." The problem with this can be seen immediately by looking at the Pages2K reconstruction of global temperatures.


There was likely a cooling of global temperatures that led to the LIA, normally thought to be from 1450-1850. All treatments of the LIA that I'm aware of place the end of the LIA at 1850. So since 1850 it's more accurate to say that we came out of the LIA in 1850, not that we're coming out of the LIA in 2024. Beyond this, the years between 1850 and 1900 were essentially flat. I calculated the trend with uncertainty for the three GMST datasets for 1850-1900:

HadCRUT5:         -0.012 ± 0.023°C/decade (2σ)
Berkeley Earth:    0.011 ± 0.028°C/decade (2σ)
NOAA:                  -0.006 ± 0.019°C/decade (2σ)

As you can see, there was essentially no warming for 50 years following the end of the LIA. Global temperatures began to increase and accelerate with our GHG emissions. In fact, the correlation between CO2 and GMST is quite high, meaning that CO2 is a very good predictor of global temperatures. And yes, I know that correlation does not equal causation, but causation has been established elsewhere. Here I think it's fair simply to say that "coming out of the LIA" is not consistent with the data we have, but human activity (GHG emissions partially masked by aerosols) is very consistent with the data we have.

Here's the same graph plotted as CO2 radiative forcing and and a linear fit with global temperatures. The slope of this correlation corresponds to a TCR of 0.632*3.71 = 2.3 C, though this assumes that other forcings are negligible.

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