We're going to see how we can use 2D GIS media layers to visualise climate change. So we need to do that in ArcGIS Online Map Viewer. Before we do that, we're going to download the image we want to use for our potential media layer. So we need to go to a browser and type in triftglacier since 1864. So we go to Images and look at this one here in Wikipedia, and if we click that and then visit that page, scroll down a little bit and you'll see it again here, we just double click 'til we see a high-quality image that we want to use as our media layer. So we save the image that we're going to use shortly as a media layer. We just need to remember where we saved it of course. Next we go back to Map Viewer, and what we need to do before we add the media layer is find the area where the media is going to be located, so we're gonna search that here in the Search panel, and I'm gonna type Triftsee, because that's the lake which is featured in the map. So click the Triftsee that's associated with Switzerland, the code is CHE, and we go straight to it, and we're now ready to add our media layer. So we need to tell the map where to find the image that we saved few moments ago. So we click Your Device and we look for the image that we saved, and here it is, Triftglacier Since 1864. So we double click that to load the image as a media layer that we're gonna need to align in a panel called Add Media Layer. Now, the next steps are a little bit fiddly, but we have to use these image handles, especially the corner ones, to make the image the correct size to match the map underneath. We can also make our image a little bit less visible or more visible by using this Transparency slider here. That can come in very handy. So I'm gonna place it around about there, about a quarter of a way, and we're just gonna zoom out just a little bit, and then I'm going to stretch the image until I can see that the lake is more or less the same orientation and alignment as the lake on the map. So as I say, this can be a bit fiddly, but it can also be quite satisfying. It's a bit like doing a sort of jigsaw puzzle really. So you can see that now I'll just make my lake a little bit more visible for a moment, and don't worry if you don't make it exact, it's an approximation, but this is georeferencing in action, so it's a very important skill for us to learn. Now, I probably need to make it a little bit bigger, and it's important to use the corner points because that keeps the overall orientation of the image more accurate than if you use the sideways ones. So we're nearly there. You can see it is a bit fiddly. You can do this without a mouse, but a mouse is a very helpful thing to have 'cause it gives you a little bit more control. So very nearly there, and that's a fairly good approximation. So if I've got to that stage, I'm going to click Update and close. Then we can check our georeferencing using the Transparency slider to show the media layer against the base map underneath. A useful thing to try at this point as well is to change the base map. So if we change it in this case to Imagery, and then we can use the Transparency slider to check our georeferencing against that, and we can see once again, it's a pretty good match. So now is a good time to save our work. So we click Save and Save as, and we're gonna call this map Trift Glacier. I'm gonna put Demo, which you don't need to do, just to show that I'm demonstrating this, and I'm going to save that, and the next time I make any changes and save that, I won't have to give it a new title. It will already be saved. We're now in a good position to use our georeferenced media layer to do some analysis to see what's happened with regard to climate change and the Trift Glacier. To do this, we're gonna check in the Layers panel. We've got the properties on show. We do, but if we didn't, we could just click Show Properties. There they are on the right. Then we're gonna hide the Layers panel and look for the Map Tools button on the right and click that. The first tool we're going to use is Measurement, and we're gonna measure distance, which is the first icon, and we're going to measure in small steps, the distance from the 1864 extent right up to the 2020 extent. So we're gonna follow the valley as best we can. If you follow the river, it's quite a good idea, and what we can do is make sure we're going up the middle of the valley that way, and if we then follow the route through the lake and then up towards where the 2020 extent is, I'm taking these small steps each time, and when I've reached the end of that transect, I double click to see what the distance is, and we can see it's around about four kilometres. In a similar way, we have another tool which measures the area of ice that's lost. So we look at the blue line, which is the boundary of the 1864 glacier, going back to the yellow line, which is the 2020 boundary, and we can approximate the area of ice that's been lost. So again, it's a stepping technique. We just go around the area, and it doesn't matter it's not perfect, and you can see it does seem to be going the wrong way, but it actually isn't. You'll see what happens when we get to the end. So we're going inside that line there. I'm doing this very, very roughly, and I'm following the inside of the 1864 glacier there, cutting a few corners. You can do it much better than I can. I'm absolutely sure of that. So, what we're doing is finding out the area that's been lost due to climate change and getting very nearly there. I'm just following that line up the other side of the glacier, and when we get to the yellow line, I'm gonna go along that just to get some idea. I could go a little bit further over, but I'm not gonna do that. Just go up to there, so we get roughly some idea of how much area's being lost. So we double click and find that the area of ice that's been lost is 2. 81 square kilometres. Now georeferenced media layers' already proven to be pretty useful, but we can extend its use and make it even more powerful by saving it as a media layer. So we click Layers, then the three dots, Save As, and we're going to save it as Trift Glacier ML, ML standing for media layer, and then we can use that in other maps and apps.