How much colder would that asteroid make my planet?

I've seen some posts here (for example this one) for the effects of certain sizes of impactors, but I'm not finding any definite answer and all my google and google scholar searches have not turned up any proper answer. I'm looking at an asteroid a bit over 1km in diameter, possibly 1.6km, iron density (7.8kg/m^3) hitting at 16km/s at a 45° angle. Basically think Mistastin impactor. That's the basis for it. (Highest recorded surface temperature and all).

Now I'm wondering how much cooler the weather would get and for how long. Because this is essentially early days for my species and they're basically where we were at around 4 million years ago and I need to know how big the changes to vegetation might be and all that to know how it would affect them.

Follow-up question: how do you think they'd fare if, around the equivalent of their 4,000 BC they got hit by an 8 km impactor, rock density, 17 km/s (think Popigai).

Thanks!! :D

posted about 5 years ago

Nierninwa‭

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