New research provides a significant reconstruction of global temperature increases since the last ice age. This work does not appear to be controversial, and should set new standards from which to measure the progress of climate change. There are three websites you can go to for details, starting with a brief introduction at Phys.org: https://phys.org/news/2021-11-global-temperatures-years-today-unprecedented.html. A subscription service called Ars Technica has free access to an extended review with additional chart work plus commentaries from science outsiders who have nothing but praise for the quality of research behind this project: https://arstechnica.com/science/2021/11/scientists-extend-and-straighten-iconic-climate-hockey-stick/. You can also read the full study itself, published by Nature, which has been given open access through a special arrangement. It has still more charts worth looking at, plus all the details and some valuable insights into the warming trend of the last few centuries, encompassing the entire industrial era: https://www.nature.com/articles/s41586-021-03984-4.epdf.
There are a few things in the reconstruction that differ from what we have always been told, starting with the one that is getting the most attention—the highly revised historical temperature trend of the entire Holocene interglacial period. There are a some other, less dramatic, things that could be missed, which I think are worth knowing and deserve special commentary, as follows: 1. The total amount of global warming between the end of the glacial period and full realization of the Holocene interglacial turns out to be 7C, a number one or two degrees greater than what most estimates have said in the past. 2. The warmup period did not even begin until about 17,000 years ago, or 3,000 years later than most estimates. 3. The warmup period did not completely end until about 6,000 years ago, rather than 8000. For all those 6000 years the trend has been almost perfectly flat, on a globe-wide basis, despite numerous regional disparities. 4. I cannot see any sign of temperature increases between 1750—or the beginning of the industrial era—and the early 1910s. If anything, temperatures dropped a bit during that period, perhaps because of excessive cooling due to the high sulfur emissions of increasing amounts of very dirty coal burning.
There is a good chart inside the Nature study showing details of the trend from 1850 through 2019. It has no new sign of any warming trend prior to the early 1910s. This means we no longer really need to think of “pre-industrial” as the true starting point of the modern era of global warming, at least not for practical measurement purposes. The sharp, early move up to 1945 is validated, followed by three decades of decline until around 1973. The main brunt of global warming, amounting to roughly one degree, on a track of no less than 0.2C per decade, has all been registered since the early 1970s. This reconstruction of the modern trend can be compared with existing charts that we are already accustomed to over the same period, one of which is displayed below. Apart from the different baseline period, I can see practically no difference at all in the basic data points, which means we can feel more confident than ever that the numbers in hand that we deal with are truly reliable. Future projections, unfortunately, are not so dependable.
Carl