There's another hockey stick in the scientific literature, this one from the PAGES 2k Consortium
in Nature Geoscience. It used over 700 proxies from around the world and shows that climate is warming faster now than at any time over the last 2000 years. As Michael Mann
wrote on Twitter, it re-re-re-re-re-...-re affirms the hockey stick, and we can add it to
the list. Let's go to the figure:
The reconstruction only goes to the year 2000 -- we've now at 1.0 C of warming, and pushing higher.
Here's a different form of the results, presented in a
phys.org news release:
More from the
press release:
The results suggest that volcanic activity was responsible for variations before about 1850. After that, greenhouse gases became the dominant influence on global climate. By removing these influences in their analysis, the researchers also identified the magnitude of the random changes that cannot be traced to a specific cause. The team's data-based reconstructions also agreed with model simulations when evaluating these random changes.
As I've written
before, it's easy to show that hockey stick is the expected result in the absence of significant natural forcings:
- temperature change = (climate_sensitivty)*(change in forcing)
- CO2 forcing = constant*log(CO2/initial_CO2)
- Atmospheric CO2 has been increasing exponentially since the beginning of the industrial era.
- So if CO2 isn't changing, there is no temperature change -- the flat handle of the hockey stick.
- If CO2 is increasing exponentially, its forcing is changing linearly and hence so is the temperature – which is the blade of the hockey stick.
- The initial curve upward from the shaft was when CO2 was increasing superexponentially.
It'd be far more surprising is there
wasn't a hockey stick in the last 2,000 years.
**
Added 1:40 pm - PAGES 2k's calculations of 51-year trends, from the same paper:
**
Added 5:10 pm - Here's a map and proxy count of PAGES 2k's network, from their
Supplementary Information. In all
they used "...nearly 700 separate publicly available records from sources that contain indicators of past temperatures, such as long-lived trees, reef-building corals, ice cores, and marine and lake sediments. The data are sourced from all of Earth's continental regions and major ocean basins."