The end is nigh
Permanent total cloud cover means that the planet is about to undergo thermal runaway. Soon the oceans will boil and Earth will be a cooler version of Venus.
For most of geological history there was no ice at sea level anywhere on earth and Earth was warmer than today. Temperature was well regulated by cloud cover. If Earth got warmer more water evaporated and more clouds formed. Clouds reflect sunlight back into space before it can warm the Earth. So there is a negative feedback loop stabilising the temperature.
The negative feedback ceases when cloud cover becomes total. The end is nigh.
In passing, global warming worries relate to melting the current ice and disrupting the present (unstable) interglacial climate. That would be pretty catastrophic, but life and probably even human life would survive.