20th February 2024
Global warming is defined by the IPCC as “an increase in combined surface air and sea surface temperatures averaged over the globe and over a 30-year period. Unless otherwise specified, warming is expressed relative to the period 1850–1900, used as an approximation of pre-industrial temperatures… For periods shorter than 30 years, warming refers to the estimated average temperature over the 30 years centred on that shorter period…” (1) https://www.ipcc.ch/sr15/ An IPCC Special Report on the impacts of global warming of 1.5°C 2018
The chart below shows a baseline which is the average (mean) of the combined surface air and sea surface temperatures for the period 1850-1900. The bred and blue columns shows the annual deviation around that base line. Between 1850 and 1900 the blue and red columns cancel each other out. The increasing number and height of the red lines thereafter show the extent of global warming.
The Green Tau 