Greenhouse gases are the cause of Greenhouse effect.The greenhouse gases which include CO2, Methane etc. trap the heat in the Earth's atmosphere and don't allow it to escape.
The weapon is fitted with a Leupold Mark 4. The rifle is also similar in appearance to the TAC-338 rifle that Kyle used in real life. McMillan TAC-338A sniper rifle with Harris bipod, Leupold Mark 4 scope, and AN/PVS-22 Universal Night Sight - .338 Lapua Magnum. Kyle taking aim with the rifle. Right side of the rifle.
As the name suggests, the Silph Scope was made by Silph Co. , which Team Rocket later invades. The Silph Scope was initially stolen by Team Rocket, and is obtained from the Rocket Hideout after the player defeats Giovanni.