Many people who are trying to reduce their carbon footprints ask me about buying offsets. I do buy offsets to offset flights and the other parts of my travel that use fossil fuels (e.g. long drives where the battery on my Volt runs out).
Buying good offsets is not as good as (e.g.) taking the train or GO bus, but it is much better than nothing. I have found good offsets available at Less Emissions.
Carbonzero.ca allows you to buy individual projects. There are several I like, such as http://www.carbonzero.ca/projects/patriotes-school-board-energy-conservation-project-csp, http://www.carbonzero.ca/projects/canada-solar-heated-swimming-pools-aggregation-project, http://www.carbonzero.ca/projects/onqc-food-waste-valorization-project, and http://www.carbonzero.ca/projects/niagara-landfill-gas-energy-project.
For the reasons I reported to the Legislature, I generally don’t buy forest offsets; see details in http://docs.assets.eco.on.ca/reports/climate-change/2017/From-Plan-to-Progress-04.pdf.
I hope this helps! Thank you for taking action to reduce your footprint, as we all must.