A controversial new study claims we may breach the 2 degrees Celsius (3.6 degrees Fahrenheit) climate change increase threshold by the late 2020s — almost two decades earlier than current projections.
The study, published Feb. 5 in the journal Nature Climate Change, claims global surface temperatures had increased by 1.7 C (3 F) above pre-industrial averages by the year 2020.
However, other scientists have questioned the findings, saying that there are major flaws in the work.
There are dozens (are we over 100 yet?) paleoclimate proxies that have made it into the literature at this point. Some tell us about temperature in a single point, others for big regions. This is just one of many.
There’s something of an index of them here