As a leading figure in the fight against climate change, Hare has utilised his expertise to influence global climate policy and negotiations. He is the CEO and Senior Scientist of Climate Analytics, an organisation dedicated to synthesising climate science and policy analysis to support vulnerable countries in climate negotiations.

Hare's career is marked by his involvement with the Intergovernmental Panel on Climate Change (IPCC), where he has been a key contributor to several assessment reports. His work with the IPCC has earned him recognition as part of the team that won the Nobel Peace Prize in 2007. Hare's research focuses on the impacts of climate change, mitigation strategies, and the development of scientifically-based climate targets, particularly aiming to limit global temperature rise to 1.5°C above pre-industrial levels.

Hare's achievements extend to the academic sphere, where he frequently publishes and speaks on climate issues, contributing to the broader understanding and urgency of climate action. His work underscores the critical need for informed and effective climate policies, emphasising the intersection of science, policy, and advocacy in addressing the global climate crisis.

In 2022 Hare was a member of the UN Secretary General's High Level Expert Group on theNet Zero Emissions Commitments of Non-State Entities, to develop standards for net-zero emissions pledges by non-State entities. 

Bill was a recipient of a Murdoch University Distinguished Alumni Award in 2018.