The animated spiral presents global temperature change in a visually appealing and straightforward way. The pace of change is immediately obvious, especially over the past few decades. The relationship between current global temperatures and the internationally discussed target limits are also clear without much complex interpretation needed.
Please feel free to use this graphic elsewhere – a link back here would be appreciated! Thanks for all the interest!
Data: HadCRUT4.4 from January 1850 – March 2016, relative to the mean of 1850-1900, available here
1. Features you can see:
1877-78: strong El Nino event warms global temperatures
1880s-1910: small cooling, partially due to volcanic eruptions
1910-1940s: warming, partially due to recovery from volcanic eruptions, small increase in solar ouput and natural variability
1950s-1970s: fairly flat temperatures as cooling sulphate aerosols mask the greenhouse gas warming
1980-now: strong warming, with temperatures pushed higher in 1998 and 2016 due to strong El Nino events
2. Why start in 1850? Because that is when the HadCRUT4 dataset starts, as we don’t have enough temperature data before then to reliably construct global average temperature
3. Are temperatures ‘spiralling out of control’? No. Humans are largely responsible for past warming so we have control over what happens next.
4. What do the colours mean? The colours represent time. Purple for early years, through blue, green to yellow for most recent years. The colour scale used is called ‘viridis’ and the graphics were made in MATLAB.
[Thanks to Jan Fuglestvedt for the idea to make a spiral.]