Hi Reddit, We’re Margaret Kosmala and Koen Hufkens at Harvard University and Josh Gray at Boston University. We’re part of a research group that has been putting automated cameras on weather towers and other elevated platforms to study the the seasonal timing of changes in plants, shrubs, and trees – called ‘phenology’. Because this timing of when plants leaf, flower, and fruit is very sensitive to changes in weather, plant phenology alerts us to changing climate patterns. Our network of about 300 cameras (’PhenoCams’) take pictures of vegetated landscapes every half hour, every day, all year round. (That’s a lot of pictures!) With the data from these images we can figure the relationships between plant phenology and local weather and then predict the effects of future climate using models. We also use images from satellites to broaden the extent of our analyses beyond the 300 specific sites where we have cameras. And we use citizen science to help turn our PhenoCam images into usable data, through our Season Spotter project. Anyone can go to Season Spotter and answer a few short questions about an image to help us better interpret the image. Right now we are running a “spring challenge” to classify 9,500 images of springtime. With the results, we will be able to pinpoint the first and last days of spring, which will help calibrate climate change models. UPDATE: We’re done with our Season Spotter spring images, thanks! Since it’s fall in half the world, we’ve loaded up our fall images. We have another 9,700 of those to classify, as well. We’ll be back at 1 pm EDT (10 am PDT, 6 pm UTC) to answer your questions; we’re looking forward to talking to you about climate change, plants, and public participation in science! UPDATE 1 pm Eastern: We’re now answering questions! UPDATE 3 pm Eastern: Josh has to leave for a meeting. But Koen and Margaret will stick around and answer some more questions. Ask away if you have more of them. UPDATE 5 pm Eastern: Koen and I are done for the day, and we’ve had a lot of fun. Thank you all for so many insightful and interesting questions! We’ll try to get to more of the ones we missed tomorrow.