Buy one and refill it; Don’t keep chucking out the disposable variety. The plastic your pen is made of is just as harmful for the environment as the plastic bottles we’ve been weened off of in recent years.
Of course, not all pens are refillable. The solution is the DBA 98 Pen. It’s produced at a wind-powered facility, uses potato-based packaging, non-toxic ink and compostable plastic. All that adds up to a 98% biodegradable pen. Pick up a 3-pack for $9.