The Committee on Climate Change (the CCC) has recommended that the UK emissions be reduced to zero https://www.theccc.org.uk/publication/net-zero-the-uks-contribution-to-stopping-global-warming/ by 2050. The strategy/recommendations rely very significantly (ie about 50%) on 'offsetting' the emissions that will continue at 2050. This would be done through burning biomass (timber and grasses) and capturing and burying the carbon dioxide separated from the exhaust and, in a separate category, the removal of carbon from the air by mechanical systems and tree planting and soils. Mechanical separating and burial (carbon capture and storage or CCS) has been tried on a relatively small scale but has not even been piloted in the UK. These processes also required energy as does the mechanical extraction of carbon from air. Tree planting is a very good thing (carbon sequestration could be seen as a a 'co-benefit' (see http://www.wwwnationalforestgardening.org/ to enhance the benefits) but there are uncertainties about how effective trees would be in the short term when emissions are still at their maximum and most dangerous (ie not being avoided during the decade which matters most). There are also questions about how the carbon is kept in the timber and forestry products. These reservations need to be very closely analysed and the CCC challenged to back up its recommendations with research and monitoring. In fact the UK Green Building Council also seems to have accepted that carbon offsetting could enable the building of new housing to continue at scale to minimise the impact of embodied carbon.
The expression "offsetting is an excuse for business as usual" has started to appear in carbon conversations. For the last twenty years we have been able to pay (eg Climate Care) a premium on air tickets to enable trees to be planted or low energy light bulbs to be fitted. The idea of relying of offsetting to enable the building millions of houses during a period (ie 12 years) when net emissions should be moving close to zero requires a huge leap of faith. Whether or not it is a legal requirement, the CCC takes into account the financial consequences of its recommendations and is unlikely to support or promote measures which significantly disturb or disrupt the status quo. It may be that a genuinely net zero carbon economy will have to be very different in many important respects and the transition should include and element of 'planning'. By reducing the reliance on offsetting (which should not mean any reduction in tree planting) there would be a greater incentive for 'businesses to become unusual' and promote and adapt to the new low carbon conditions.