What's the worst thing we do to the earth and how can we atone for our impact?

Why discuss climate change in a personal finance and investing blog?
Because climate disruption is affecting our lives and our finances and imposing massive costs on future generations.
So... what's the worst thing that middle class Americans do? We fly on airplanes. Flying has a large carbon footprint. Besides flying less, we can buy carbon offsets for our flights.
Writing in The Wall Street Journal (2/13/19) Scott McCartney explains that the expansion in air travel has a huge environmental impact. 

Just How Green Are U.S. Airlines? Carriers want fliers to see them as eco-friendly—but while their planes are more efficient, their greenhouse-gas emissions are rising overall

Even though planes are more efficient, more people are flying. Biofuels are a tiny drop in the bucket. So what can a passenger do? 

Buy carbon offsets for your flights.  

"Offsets are credits that enable polluters to avoid cutting their own emissions by investing in projects such as tree planting that take carbon dioxide out of the atmosphere. Many observers see offsets as the key to reducing emissions without crippling U.S. industry with high costs, though some environmentalists worry that certain offset projects won't deliver the promised benefit to the environment." from: Carbon Offsets: A Q&A. What are they? How would they work? And will they really reduce emissions? By Rob Curran

"United and Delta offer carbon calculators and links to making contributions to environmental groups with cash or miles to offset your particular emissions on a trip. Airlines say usage is very low."( So far American, the largest carrier, does not offer an offset program.)

Usage is low because most passengers don't know about them and you really have to search the website to find how to calculate and pay for the offset. 

How much should I expect to pay? One example: a round trip flight between Atlanta and New York would be less than $5.