Phytosphere

All life on Earth is held hostage by a desperate and ruthless alien race in this "hard-hitting apocalyptic thriller" from award-winning author Scott Mackay (Booklist).
The Tarsalans came to Earth hoping to settle on the planet alongside a sympathetic human race. But after years of delicate negotiations, their patience reaches the breaking point and they decide to make their case for immigration terrifyingly clear—by enveloping the planet in a green sphere which blocks out all sunlight.
Without energy from the sun, the Earth—and every living thing on it—is doomed.
Soon, civilization breaks down as the instinct for individual survival shreds humanity's common bonds. It appears mankind may destroy itself even before the Phytosphere does.
The only hope against catastrophe lies in the troubled connection between two brothers—one stranded at a lunar base on the moon, the other trapped on the dying Earth…
"Deftly juggling hard sci-fi and a bleak tale of post-apocalyptic survival" Scott Mackay once again offers an electrifying sci-fi tale of "high-tech intrigue and old-fashioned suspense" (Publishers Weekly).