Either Will Steffen thinks humans didn’t exist five thousand years ago, or he hasn’t heard of the Holocene. The Herald Sun tells us the extraordinary news that:
“Humans are living in the hottest temperatures they have ever lived and I can guarantee this will only get worse.”
Will Steffen also says the climate is “complex”, and “impossible to entirely predict”. I guess that means his guarantee that it will get worse comes direct from God, since it’s not possible through science. I don’t know why Matthew Dunn, technology editor of the Herald Sun, didn’t ask more about that — obviously that would be big news.
Otherwise, nearly every proxy that’s ever been proxied suggests there were a lot of warmer times in the period 5,000 – 8,000 years ago. Ice cores say it was hotter in Greenland, barnacles, corals, sea worms, and “swash” tell us sea levels were something like 2 meters higher in stable West Australia* and nearly 1m higher in Hawaii and Polynesia, oceans were 2 degrees warmer around in Indonesia, and 6,000 boreholes sunk in the oceans all over the world show it was a global deal. Australian Aboriginals apparently struggled through a 1,500 year mega drought about 6,000 year ago (see McGowan). CO2 Science lists references from South-East Asia to the Sahara, from Antarctica to America. I am barely skimming the surface.
It was even warmer 120,000 years ago when Antarctica was over 2 degrees hotter, and seas were 3 -5 m higher and even more in some places. I’m pretty sure that homo sapiens was around then, and somehow they survived the heat without electricity, cars, hospitals or four-bedroom houses.
Here’s a few graphs of the scores I could use. Greenland has been warmer many times over the last 10,000 years*. The Roman warming of the European region was also fairly significant. Those Romans didn’t get by with togas for nothing.
…
In Western Australia — one of the oldest, most stable pieces of land in the world — sea levels have been falling for 7,000 years.
Source: Lewis et al
Sea levels rise when the world warms, but crustal plate and local changes make it difficult to calculate the global sea level of the Holocene. But in many places where humans lived it’s been higher during the Holocene that what it is today. See also Nils Axel Morner on European sea levels in the last 7,000 years, and the case of Pevensey Castle in the UK. It just makes a mockery of the claim that humans haven’t had to deal with climate change before.
Thousands of boreholes, which are pretty useless for most climate details, put paid to the idea that the world was not, on average, warmer during the holocene optimum. With 6,000 of them drilled in sediments around the world, the one thing they are useful for is a very big broad ultra low resolution estimate of whether it was all-over-hotter or all-over-colder (see Huang and Pollack, 2008).
Huang and Pollack 2008
For anyone who still says that the warming was local and not global, as far as I can tell, there is no human who lives at the global average temperature, instead we all live locally, and the hotter zones in these graphs cover hundreds of years. What scientist would declare that Humans are living in the hottest temperatures they have ever lived?
REFERENCES
Christiansen, B. and Ljungqvist F. C. (2012). The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability. Climate of the Past, 8(2):765–786, 2012. [abstract] [PDF] [NASA copy] [Discussion on CA noted a lack of complete archives and code]
Hamish McGowan,Samuel Marx, Patrick Moss, Andrew Hammond (2012): Evidence of ENSO mega-drought triggered collapse of prehistory Aboriginal society in northwest Australia, Geophysical Research Letters, Vol 39, Issue 22. DOI: 10.1029/2012GL053916 [Abstract]
Holmgren, K., Tyson, P.D., Moberg, A. and Svanered, O. 2001. A preliminary 3000-year regional temperature reconstruction for South Africa. South African Journal of Science 97: 49-51.
Huang, S. P., H. N. Pollack, and P.-Y. Shen (2008), A late Quaternary climate reconstruction based on borehole heat
flux data, borehole temperature data, and the instrumental record, Geophys. Res. Lett., 35, L13703, doi:10.1029/2008GL034187 [PDF]
Lewis, S.E., et al., Post-glacial sea-level changes around the Australian margin: a review, Quaternary Science
Reviews (2012), http://dx.doi.org/10.1016/j.quascirev.2012.09.006 [abstract] (paywalled).
Ljungqvist, F. C., Krusic, P. J., Brattström, G., and Sundqvist, H. S (2012).: Northern Hemisphere temperature patterns in the last 12 centuries, Clim. Past, 8, 227-249, doi:10.5194/cp-8-227-2012, 2012. [abstract] [PDF] or try this [PDF] [CO2science discussion]
Yair Rosenthal1,*, Braddock K. Linsley2, Delia W. Oppo3 (2013) Pacific Ocean Heat Content During the Past 10,000 Years, Science 1 November,Vol. 342 no. 6158 pp. 617-621 DOI: 10.1126/science.1240837 [Sciencemag.org ]
* Edited for accuracy — Greenland has been warmer “for a lot of” changed to “many times”. Thanks to Craig Thomas #42 – Jo