- Beef (1 lb): 0.45 kg (454 g)
- Pork (8 lbs): 3.63 kg (3,629 g)
- Chicken (10 lbs): 4.54 kg (4,536 g)
- Tofu (20 lbs): 9.07 kg (9,072 g)
Though I agree with you that using metric system is better, here's what's important is the ratio, so the unit is not really relevant.
Ok Ok. Lemme convert that.
One kilo of beef is roughly equal to 8 kilos of pork, 10 kilos of chicken, and 20 kilos of tofu in CO₂ emissions.