... then they start talking about km^2 of lost surface area. Which if you read the paper they cite, it says "Between 1984 and 2015 permanent surface water has disappeared from an area of almost 90,000 square kilometres, roughly equivalent to that of Lake Superior, though new permanent bodies of surface water covering 184,000 square kilometres have formed elsewhere." On top of that, shallow lakes fluctuate wildly in surface area. The great Salt Lake for example. VS Lake Tahoe which can drop 10 ft and the surface area loss is tiny.
Yes of course the relationship between volume and area depends on the lake depth, are you suggesting the paper implied anything else? The Great Salt Lake has dropped rather dramatically in the last ten years, so much so that it has already changed pretty much all recreation and commercial activity on the lake - the primary boat dock closed because the marina was completely dry and by last year the shores had moved inward, by kilometers in some cases. Unusual precipitation this year has brought levels up a little, but this might only be a blip in the downward trend. The known reasons include drought conditions, unusually high temperatures, and greater upstream use. The Great Salt Lake’s recent history very much backs up the claims of this paper, no?
This, and why 1992-2020? How many of these large lakes are distributed in say, Midwest America/Canada. What were the precipitation levels in that region just a few years prior? Why did they need to involve climate models when we have observable data?
Given the significant use of satellite data, I imagine the start point was chosen based on when some classes of data became available from recently launched satellites. An earlier time may not have sufficiently comparable data.
They used a technique for water segmentation described in an earlier paper [1]. The validation dataset for that method goes back to 1992...
"All applied images have 30-m spatial resolution and were acquired during October 1, 1992 to October 31, 2018. The period was set with regard to the availability of the validation dataset"
[1] Yao, J. Wang, C. Wang, J.-F. Crétaux, Constructing long-term high-frequency time series of global lake and reservoir areas using Landsat imagery. Remote Sens. Environ.232, 111210 (2019).
I think this might be just because their comment is borderline useless - it is so condensed that one can hardly make any sense of it.
So what did they want to say? Is it "Science, it works?" like in XKCD comic #54? Or are the quotes around science the actually important thing, casting doubt on it? It's hard to tell because they did not bother to spend a few seconds to actually write it out.
Beside that there is more to papers than just their abstract. If you are curious, you can check section "Global LWS trends and drivers" for the answers to your questions.
The intention was to get people to read the main thesis critically. That quote is sort of a tell about the quality of this paper, and the more I dig into this paper the more it confirms this is isn't good science.
