A new paper that reveals Holocene Climate History, a period that covers the last 12,000 years, has been published within Nature.
Titled “Holocene global mean surface temperature, a multi-method reconstruction approach“, it confirms that modern temperatures are likely higher than any time in the Holocene and the history of civilisation.
Let’s take a brief look.
The Climate History Study
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Background
During the two millennia prior to the 20th Century, global mean surface temperature (GMST) cooled at a rate of roughly −0.15 °C per 1000 years. Not well known, however, is: when did the multi-millennial cooling begin, and has recent global warming exceeded the maximum global mean surface temperature of the Holocene?
The only previous GMST reconstruction for the Holocene based on multi-proxy data showed maximum warmth around 7000 ± 2000 years ago followed by multi-millennial global cooling. This cooling trend occurred while the atmospheric concentrations of greenhouse gases were increasing. Liu et al. coined the term “Holocene temperature conundrum” to highlight the contradiction between the cooling indicated by proxy evidence versus the warming simulated by global climate models, a trend reinforced in the most recent generation of climate models.
This paper now brings to the table a far more extensive database of paleo temperatures. It is the most comprehensive global compilation of previously published Holocene proxy temperature time series currently available.
What is in it?
It includes a total of 1319 paleo-temperature records from 470 terrestrial and 209 marine sites where ecological, geochemical and biophysical proxy indicators have been used to infer past temperature changes.
Different sources have made different assumptions, hence variations existed. To resolve they applied five different statistical methods to the Temperature 12k database to reconstruct global and latitudinal temperatures over the past 12,000 years.
The Reveal
This is now the long view of where things stand – the best possible record of global temperatures over the last 12,000 years …
The inset displays an enlarged view of the past 2000 years.
Bottom line: Right now it is hotter than at any other time in the last 12,000 years.
Cue: But what about the famous medieval warm period when the Vikings colonised Greenland?
That was not a global hot period, it was regional and restricted to just northern Europe. On a global scale it is hotter now than at any other time over the last 12,000 years.
Our CO2 emissions are impacting the global climate. Doing nothing is really not an option.