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.
On February 2, 2013, Kyle met his own death in the way he had killed so many others. That day, on a shooting range in Texas, former Marine Eddie Ray Routh, 25, shot and killed Kyle and his friend, Chad Littlefield. The motive remains unclear, but it is thought Routh was suffering from post-traumatic stress disorder.