books.google.com - A major international assessment released in 2007 concluded that the Earth's climate had warmed unequivocally over the past century, and that elevated levels of so-called "greenhouse gases" (GHG) were likely responsible for a major portion of the observed warming. Elevated concentrations of GHG in the...https://books.google.com/books/about/Climate_Change.html?id=OxkYQjGwQYoC&q=ecological&utm_source=gb-gplus-shareClimate Change
