There are a number of places on the Internet where you can purchase “carbon offsets” by planting trees or other activities to take out of the atmosphere as much carbon dioxide (CO₂) as you are responsible for putting into the atmosphere. Giving Green (www.givinggreen.earth) a nonprofit organization has rigorously investigated organizations that claim to provide carbon offset, and has made three recommendations.

• Climate Works (www.climeworks.com) specializes in direct air capture. Direct air capture take CO₂ out of the ambient air and permanent stores the CO₂ deep underground. It’s expensive, however. Very, very expensive at about $1,000 per ton of CO₂. Considering that the average American is responsible for 16 tons of CO₂ a year, it’s unlikely that many people will avail themselves of Climate Works services. They are, however, the gold standard for direct air capture.
• Tidewater (https://tradewater.us/) is a much cheaper option. They find old refrigerators worldwide and captures and destroys the greenhouse gases in these refrigerators for $15 per ton of CO₂ equivalent.
• Burn (https://burnstoves.com/) makes and distributes fuel-efficient stoves to women in Kenya. The reduced wood fuel means less deforestation, less money spent on fuel, and fewer emissions in houses for $10 per ton of avoided CO₂.This not only helps the environment, and protects trees, but also makes the lives of women in Kenya easier. That’s a pretty good deal.

Giving Green also makes recommendations on which national organizations are the most effective at getting policy changes made. Their two recommendations are pretty much polar opposite. 

• Clean Air Task Force (www.catf.us) uses an “inside the beltway” approach. They provide research and advocacy at the national level, taking “a pragmatic approach in an effort to garner support from politicians across the spectrum.”
• Sunrise Movement Education Fund (https://actionnetwork.org/fundraising/donate-to-sunrise-movement-fund), supports the Sunrise Movement, a climate activism group that seeks to mobilize popular support and political will for a more aggressive climate-change policy under the Green New Deal framework.

These are the recommendations of Giving Green who has spent a fair amount of time researching what organizations can help you offset your carbon footprint, and what organizations are effective in bringing about policy changes to address climate change. Hope this is helpful.