Friday, January 10, 2020

Small Multiples of Global Heating

Small multiple maps of global heating seem to have taken over from climate stripes as the most popular way to visualize global heating. Climate stripes are a very effective way to visualize how average temperatures have increased over time. The more recent multiple maps visualizations of average annual temperatures work in exactly the same way, showing how annual average temperatures are increasing as a result of global heating, except they substitute maps for stripes.

Multiple map visualizations of global heating have a couple of advantages over climate stripes. The maps themselves are obviously a clear indicator of the location whose average temperatures are being visualized. Multiple map visualizations of global heating (unlike climate stripes) also include the year for each map. This means it is much easier to tell which years have seen warmer or colder annual average temperatures on multiple map visualizations of annual average temperatures than on a climate stripes visualization of the same data.

In December Zeit released Too Warm Here, a tool which allows you to generate the climate stripes for any German town. Zeit's Too Warm Here also included a small multiple maps visualization of how temperatures have changed in the whole of Germany over the last 137 years.

In this small multiple maps visualization a small map of Germany is colored for every year since 1881 to show the average annual temperature for that year. The map visualizes very clearly how in the last 22 years Germany has experienced temperatures which are far hotter than the average annual temperatures.

Inspired by Zeit's small multiple map visualization of climate change in Germany I decided to create a similar visualization of annual average temperatures in the UK. My UK Warming Maps colors 50 small maps of the UK, to show the average temperature for each successive year from 1969-2018, using data from the UK Met Office.

50 years isn't quite long enough to clearly see the pattern of rising temperatures in the UK. However I think you can still on this small multiple map visualization how the UK has been witnessing hotter than average annual average temperatures on a far more frequent basis in recent years.

Australia's Bureau of Meteorology has now created their own small multiple map visualization of 110 years of Australian temperatures. This visualization uses 110 small maps of Australia, each one colored to show the average annual temperatures for the mapped year, to show the anomaly of mean temperature for each calendar year, compared to the average for the period of 1961–1990.

The record breaking temperatures experienced by Australia in recent years has been used to help explain the devastating bushfires that have been burning for the last few months in Australia. Another reason why the fires have burnt so extensively and for so long is because of the exceptionally dry weather that Australia has been experiencing.

The Bureau of Meteorology has created another small multiple map visualization which shows just how dry 2019 was. 120 years of Australian rainfall visualizes the decile rank of rainfall for each calendar year. In this visualization 2019 clearly stands out for its remarkable lack of rain compared to every over year in the last 110 years.

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