I believe that effect would be even less noticeable.

quick math tells me that if we include urea (0.85M) and salt (0.71M) then freezing point of urine should be about -4.2C, in close to worst case scenario, which decreases roughly linearly as it is diluted. meaning that this is temperature where urine starts freezing, but below that point there is some amount of liquid where all urea and salt concentrates. just for water-salt mix some amount of liquid will remain down to -22C

i guess this gets more important at higher tempetatures

What about a fart? I always fart when I pee.

Not exactly. The specific heat of ice is about half of the specific heat of water.

So 6 tonnes of urine at 37°C would take 12 tonnes of ice from -37°C to 0°C.

That's still ice, though, and it takes way more energy to thaw ice that to warm ice from -37 to 0.

Actually, I'll just do the math.

6 Mg piss * 37°C * 4.18 J/g°C = 929 MJ

Let's say ambient ice temp is -20°C.

20°C * 2.05 J/g°C * X + 333.55 J/g * X = 929 MJ

X ~2.5 tonnes of ice melted.

Not too bad. I suspect the change in albedo is the real problem.