It's not just the actual farming (if you can call it that) that makes industrial agriculture so detrimental. In almost every case, land use changes -- say, deforestation, or paving over green space for suburban expansion -- result in more surface warming. One exception: When deforestation occurs to create more agricultural land. That's right, deforestation results in surface warming, with the exception being conversion to agriculture. Wait, what?
The difference here is that we're talking surface warming, rather than changing atmospheric conditions, and, while chopping down a forest might make it feel cooler, forests have a much greater potential to sequester carbon dioxide than does monocultural, industrial agriculture (and there goes the baby with the bathwater). The bottom line: The effect of land use conversion on rising surface temps is an underestimated component of global warming, and just because it feels cooler today than it did yesterday does not mean big-time climate change is right around the corner.
More on agriculture and global warming
How To Stop Global Warming and Hunger At the Same Time
Greenhouse Gases Could Be Used To Grow Organic Food
A Tale of Two Will Allen's: "Industrial Agriculture One of Most Polluting & Dangerous Industries"
More Cities Means More Warming, Sure - But More Agricultural Land Means More Cooling?
Organic Agriculture Could Significantly Reduce The Carbon Footprint Of Orange Juice
Organic Farming Could Stop Global Climate Change