CNN Business A common site on the Canadian prairies at seeding time. Two big tractors with air seeders and chemical tanks attached, ready to roll. A PinP photo. The United Nations released a dire warning recently: Climate change is here and it's a clear and present danger to our entire planet. Of course, we didn't need another report to tell us that — we see it in extreme and unusual weather, disappearing wildlife and falling farm yields. But there is one major cause of this global catastrophe that doesn't get the attention it deserves: industrial-scale chemical agriculture. Story here.