"[t]he influence of  so-called greenhouse gases on near-surface temperature - is not yet  absolutely proven.
"[t]he influence of  so-called greenhouse gases on near-surface temperature - is not yet  absolutely proven.
global warming:55
before the industrial revolution, naturally occurring amounts of greenhouse gases caused the air near the surface to be warmer by about 33 °c (59 °f) than it would be in their absence.