It is not currently possible to reduce emissions to zero on a global level. There presently isn't enough renewable (or zero carbon) electricity to meet the global energy demand. There isn't anywhere near enough zero carbon forms of transport that can be practically used to meet the needs of international trade. No matter what you do to reduce your energy consumption and carbon footprint you are almost certainly going to still be responsible for some carbon emissions - not just from your direct energy usage, but indirectly from things you buy and services you use.
By supporting carbon offsetting projects, you are supporting the solutions to climate change, through choosing to help fund more renewable energy production; help fund improved efficiencies in developing countries; help fund teams working to reduce deforestation (which currently contributes around 20% of global greenhouse gas emissions); and helping plant more trees to capture and store carbon that has already been emitted into the atmosphere.