The Government have done no specific work to assess the role of ornamental plants in mitigating the effects of climate change. However, the growth of plants captures carbon dioxide (carbon sequestration), so giving some mitigation for other emissions. Assessments of carbon capture have been made for forestry and non-ornamental crops in the UK, since they represent the majority of the land use. The data available would allow a crude assessment of the potential for carbon sequestration by ornamentals.
More generally, ornamentals are a significant component of green infrastructure, which can reduce air temperatures in built up areas by up to 2° C. Some studies suggest that surface temperatures can be reduced to a much greater extent. Incorporating deciduous trees, including ornamental trees, into building design can also help to reduce solar gain in summer reducing energy usage associated with air conditioning, while maintaining solar gain in winter. Apart from the role of green infrastructure in reducing the urban heat island effect, the shade provided by ornamental trees will also play a role in reducing the incidence of skin cancers that is otherwise likely to increase as a result of projected reductions in cloud cover. Green infrastructure also has a role to play in sustainable urban drainage systems, helping to alleviate the projected increase in flood risk.