The most common comment on the ‘Warming Stripes’ visualisations is: ‘what happened before 1850’?
I’m glad you asked.
We have a new reconstruction of global temperature going back to the year 1AD thanks to the work of the PAGES2k team. This reconstruction includes data from a wide variety of proxy records such as tree rings, cave deposits, corals, etc.
The warming over the past 50 years is stark compared to the variations that have occurred naturally over the last 2000 years. It is not normal.
The PAGES2k reconstruction also comes with uncertainty estimates, and so can be visualised in a more standard way, with key relevant global events added, such as large volcanic eruptions, the Maunder solar minimum and historical dates of scientific discoveries.
The data show that the modern period is very different to what occurred in the past. The often quoted Medieval Warm Period and Little Ice Age are real phenomena, but small compared to the recent changes. In this example, the reference period is 1850-1900, which is often used as an approximate ‘pre-industrial’ level.
The invention of the efficient steam engine in 1790 by James Watt kick-started the industrial revolution and our reliance on burning fossil fuels for energy. This has brought many benefits to humankind, but we are now experiencing the side effects of that development.