[Brybry]

So in ~5 years they've launched 5113 satellites[1]: 2 * 400 kg + 60 * 227 kg + 1665 * 260 kg + 2987 * ~300 kg + 399 * 800 kg = 1663 metric tons

So if they all burned up today it would be around a 6% yearly increase, globally? (1663 / 5200 * 5). And that's probably the most forgiving estimate I could come up with, I think your ~20% number is more accurate for future projection purposes given most of the mass was launched in a much shorter timespan.

Then the real question is what effect does space dust have on the earth's atmosphere (if any).

[1] https://en.wikipedia.org/w/index.php?title=List_of_Starlink_...

[sjducb]

There are two more things to consider. 1) The whole satellite doesn’t burn up. Most of it crashes into the ocean. 2) much of the burning up happens in the thicker lower atmosphere where we’re already putting lots of material from jet engines and factory chimneys.