She remained inScotland for her PhD, researching malnutrition and global food systems. She created a scalable framework to understand food system pathways and identify losses, allocations, and conversions.[4] In particular, she looked to understand whether it was possible to feed a growing population without damaging the environment.[5] Ritchie isvegan.[6]
Ritchie started her career as a lecturer insustainability at theUniversity of Edinburgh. She developed teaching programs focused on sustainability.[7] She left Edinburgh to start a research position at theUniversity of Oxford, where she developed data visualisations to communicate information.[5]
Ritchie's early work considered food systems and how it was essential to adapt to meet theSustainable Development Goals.[8] For example, she has argued that for most foods, thecarbon footprint is barely impacted by transport.[9]
In 2017, Ritchie joinedOur World in Data as Head of Research. Her work focuses on environmental sustainability, including topics such as climate change, energy, food and agriculture, biodiversity, air pollution, and deforestation.[10] During theCOVID-19 pandemic, she built the Our World in DataCOVID-19 information dashboard.[11] In 2023 she became Deputy Editor and Lead Researcher.[10]
In 2024, she was elected to Scotland’s Just Transition Commission, "an independent advisory body that provides scrutiny and advice on how to deliver a just transition to a low-carbon economy in Scotland".[12]
In 2024,Chatto & Windus published Ritchie's first book,Not the End of the World,[13] which explores her optimism for large-scale problem-solving and endingclimate change.[14][15]
In 2025, Ritchie published a second book, titledClearing the Air.[16]
She also authors a newsletter titled "Sustainability by Numbers," with over 60,000 subscribers.[17]
In 2022 Ritchie was named Scotland's Youth Climate Champion at the Holyrood Green Giant Awards in recognition of her contributions to theclimate-change movement.[19] In 2024, Ritchie was recognised for lifetime achievement with honorary fellowship of theRoyal Statistical Society.[20]
Hannah Ritchie, "What We Learned from Acid Rain: By working together, the nations of the world can solve climate change",Scientific American, vol. 330, no. 1 (January 2024), pp. 75–76. "[C]ountries will act only if they know others are willing to do the same. Withacid rain, they did act collectively.... We did something similar to restore Earth's protectiveozone layer.... [T]he cost of technology really matters.... In the past decade the price ofsolar energy has fallen by more than 90 percent and that ofwind energy by more than 70 percent.Battery costs have tumbled by 98 percent since 1990, bringing the price ofelectric cars down with them....[T]he stance ofelected officials matters more than their party affiliation.... Change can happen – but not on its own. We need to drive it." (p. 76.)
