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.
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."