It is written,
Revelation 16:8 (KJV)
{16:8} And the fourth angel poured out his vial
upon the sun; and power was given unto him to scorch men
with fire. {16:9} And men were scorched with great heat,
and blasphemed the name of God, which hath power over
these plagues: and they repented not to give him glory.
I believe that global warming is primarily due to natural cycles of the planet. However, I believe that man's greed, degradation, and exploitation of resources exacerbates the issue. Ultimately, we might be reading a prophecy of this very thing that will eventually come upon our world.