Winter World / A. G. Riddle

The ice is coming. It was the last thing we expected, but the world is freezing. A new ice age has dawned and humanity has been forced to confront its own extinction. Billions have fled the glaciers, crowding out the world's last habitable zones. They can run from the ice, but they can't escape human nature: a cataclysmic war is coming. 

In orbit, a group of scientists are running the Winter Experiments, a last-ditch attempt to understand why the planet is cooling. None of the climate models they build make sense. But then they discover an anomaly, an unexplained variation in solar radiation...and something else. Close to the burning edge of the sun, they catch a fleeting glimpse of something that shouldn't be there....

Suddenly humanity must face the possibility it is not alone in the universe. And the terrifying possibility that whatever is out there may be trying to exterminate us.