The emissions from many gas mowers (and other gas-powered tools) are full of greenhouse gases. Some older or poorly running mowers even create more pollution than many cars! Some of the alternatives have become much better in recent years. There are rechargeable electric mowers that give you nearly an hour of mowing time per charge, and even robotic mowers that mow for you! You'd be surprised with the number of 'greener' options there are for powered lawn tools.