Adopt a Climate Change Indicator

Created by Annette Schloss, Coordinator, Picture Post Network

The effects of climate and climate change are everywhere. We all know about melting polar ice caps, rising sea level, and changing weather patterns, but what do we know about what is happening in our local area?

Pictures taken regularly over time can show us change that we might not be aware of otherwise. By calculating a greenness index on vegetation in a set of pictures, you can determine the timing of seasonal changes, known as phenology, and if the timing has shifted in recent years. Just like in research, the more data you have, - in this case the more pictures over time, the more you will begin to see important patterns in the changing seasons.

Greenness Index

Researchers developed this greenness index to study the effects of climate change on forested ecosystems. Picture Post now lets you calculate the index with Picture Post pictures right on the Picture Post website! The index uses the red, green, and blue colors in the image to characterize the relative “greenness” using this relationship:

Greenness Index = Green / (Red + Green + Blue)


  • Review the Adopt a Season activity.
  • Capture budburst and green up in the spring and the change in autumn leaf color by taking pictures daily during times of rapid change.
  • Capture plants’ response to heavy rain by taking pictures within a day or so of a storm event.
  • Capture plants’ response to drought by taking pictures every few days during periods of no rain.

The graphs below show seasonal changes in greenness in vegetation at Picture Post 6, Menotomy Rocks Park in MA.

Greenness was calculated in the area inside the small box drawn on the images. Images can be viewed on the graph by moving your mouse over the graph. The Help Video shows you how. Data can be downloaded for use in other analysis programs.

green down pic 2
green down pic 3
green down pic 4

Go Further

Researchers created the Phenocam network to study greenness around the world. You can find the Phenocam site nearest your post and compare what is happening in your local area with the Phenocam site. Do you see differences? What might be causing them?

Learn more about Phenology as a Climate Change Indicator

USA Phenology Network
Project budburst


Toomey, M., et al., 2015. Greenness indices from digital cameras predict the timing and seasonal dynamics of canopy-scale photosynthesis. Ecological Applications, 25:99-115, PDF

Sonnentag, O., K. Hufkens, C. Teshera-Sterne, A.M. Young, M. Friedl, B.H. Braswell, T. Milliman, J. O'Keefe, and A.D. Richardson. 2012. Digital repeat photography for phenological research in forest ecosystems. Agricultural and Forest Meteorology, 152: 159-177, PDF

Richardson, A.D., J.P. Jenkins, B.H. Braswell, D.Y. Hollinger, S.V. Ollinger, and M.-L. Smith. 2007. Use of digital webcam images to track spring green-up in a deciduous broadleaf forest. Oecologia, doi10.1007/s00442-006-0657-z. PDF