The Responsibility100 Index ranks FTSE 100 companies on their commitments and actions towards key social, environmental and ethical issues.

We split the FTSE 100 into 8 sectors.

Companies are ranked according to their ‘Walk’ score, which tracks performance across 6 key pillars: Equality, Climate, Good Business, Justice, Poverty & Wellbeing and Skills & Education.

The ‘Talk’ score records the sustainability organisations a company has joined and the targets they have set, and exists to assess whether the actions of a company reflect its commitments.

Unilever ranks 1st on the Index, up from 3rd last year. It has secured this spot as a result of strong scores by climate and social measures, including low Scope 1 and 2 emissions, comprehensive Scope 3 reporting, almost 100 per cent of waste recycled, and a low gender pay gap.

Airtel Africa, a telecommunications company, is new to the FTSE 100 and ranks bottom of the Index. Sparse reporting and weak inclusion – only one in eight senior managers are women, for example – hurt its overall ranking.

Having ranked top of the Index last year, Severn Trent has fallen to 12th place. One reason is our improved fines methodology, which found that Severn Trent received fines totalling £2 million in the last year, most of them related to sewage pollution incidents.

Auto Trader has improved the most year on year, rising 42 places to 15th in the Index. Major reasons for its success include more women in senior management, becoming an accredited Living Wage provider, and meeting the Parker Review Target, which calls for at least one board director from an ethnic minority.

FTSE 100 companies emit 3.4 billion tonnes of CO2 equivalent including Scope 1, 2 and 3 – around 7 per cent of global emissions. Hover over a company to see their emissions.

However, less than 10 per cent of these emissions are covered by Science Based Targets, which require deep emissions reductions while minimising the use of offsets.

This sets the UK’s biggest listed companies on a pathway that if followed by the rest of the world would overshoot the limit of 1.5C of warming agreed in Paris in 2015 – to 2.8C

A third of companies pay their CEO more than 100 times the average worker. CRH, a building materials company, pays its CEO 289 times its average UK wage. The company operates in 29 countries worldwide, and declined to say whether the global ratio was higher or lower.

The trend of decreasing representation of women as they gain seniority within companies also persists, contributing to the FTSE 100 average gender pay gap of 15.9 per cent (although that gap has narrowed from 17.6 per cent last year).

Though gender representation on FTSE boards has improved, there are still no women in C-Suite or Chair roles at 47 companies.

Nearly 80 per cent of companies fail to provide a figure for their ethnicity-based pay gap.