Carbon dioxide equivalent emissions, which accounts for the climate impact of all greenhouse gases, is referred to as ‘Carbon’ in our assessments. The construction carbon impact of HS2 Phase One is reported in the relevant Environmental Statement*. This assessment presents a reasonable worst-case scenario assuming fossil-based diesel for heavy plant and related transport. It does not reflect HS2 Ltd’s target to cut construction carbon emissions by 50% against industry baselines. The Environmental Statement was produced to accompany the then High Speed Rail (London - West Midlands) Bill, and in the 4 years since publication, technological improvements and adoption of best working practices, including the adoption of plant and facilities that do not use fossil-based diesel, will have superseded many of the findings therein.