Rise in Rainbows

Climate Scientists predict an annual increase in rainbows by 4-5% by 2100

A study published in Volume 77 of the scientific journal Global Environmental Change detailed that climate change will lead to an increase in rainbows by 4-5% by 2100.

Rainbows are an atmospheric optical phenomena that occur when light refracts off rain droplets, climate change will directly alter rainbow distribution and frequency by changing rainfall and cloud cover patterns. 

Utilising the photograph platform ‘flickr’ scientists downloaded photographs taken between 2004-2019 with the word rainbow in the hashtag, description, or title. The scientists then cleaned the dataset to ensure all photos were unmodified and included the date, time, and geolocation.

After searching through over 121,550 photographs, the final dataset consisted of 7,094 photographs across all continents except Antarctica. The photographs were all collected between Feb.11, 2004 and Dec. 7, 2013.  

Using a model (data simulation) where the occurrence of a rainbow was the dependent variable, and the sun angle, liquid precipitation, and cloud cover were independent variables. The model was then tested using data on the variables from 1996 to 2005 and resulted in an 85% success rate before the predictive data was entered.

Above: Dataset - the colour on the map directly corresponds with the number of data points (rainbows spotted) in that specific location.

The results stated that by 2100, changes in cloud cover and liquid precipitation directly caused by greenhouse gas emissions will lead to an increase in days where rainbows are viewable.  

Above: map of the change in days with rainbows from 2000 to 2100. Black Polygons indicate “hotspots” of change.

Rainbows have been highlighted in human culture through art, music, mythology, literature, spirituality, and folklore throughout history. Climate change is predicted to have a direct impact on both tangible and non-tangible aspects of human existence.