  Mars was characterized by cataclysmic groundwater-sourced surface flooding
that formed large outflow channels and that may have altered the climate for
extensive periods during the Hesperian era. In particular, it has been
speculated that such events could have induced significant rainfall and caused
the formation of late-stage valley networks.
  We present the results of 3-D Global Climate Model simulations reproducing
the short and long term climatic impact of a wide range of outflow channel
formation events under cold ancient Mars conditions. We find that the most
intense of these events (volumes of water up to 10$^7 $km$^3$ and released at
temperatures up to 320 Kelvins) cannot trigger long-term greenhouse global
warming, regardless of how favorable are the external conditions (e.g.
obliquity and seasons). In any case, outflow channel formation events at any
atmospheric pressure are unable to produce rainfall or significant snowmelt at
latitudes below 40$^{\circ}$N.
  On the long term, for an obliquity of $\sim $45$^{\circ}$ and atmospheric
pressures $>$ 80 mbar, we find that the lake ice (formed quickly after the
outflow event) is transported progressively southward through the mechanisms of
sublimation and adiabatic cooling. At the same time, and as long as the initial
water reservoir is not entirely sublimated, ice deposits remain in the West
Echus Chasma Plateau region where hints of hydrological activity
contemporaneous with outflow channel formation events have been observed.
However, because the high albedo of ice drives Mars to even colder
temperatures, snowmelt produced by seasonal solar forcing is difficult to
attain.
