Hannah joined us in 2017. She became Deputy Editor and Science Outreach Lead at Our World In Data in 2023. She was previously Head of Research.
She focuses on the long-term changes in the environment – energy, pollution, agriculture, food supply – and their compatibility with global development. Hannah completed her Ph.D. in GeoSciences at the University of Edinburgh.
She is a researcher at the Oxford Martin Programme in Global Development, and and an honorary fellow at the University of Edinburgh's School of Geosciences and Edinburgh’s Climate Change Institute. Her first book – Not the End of the World – looks at seven of our big environmental problems, and how to solve them. You can find more of her writing on her Substack – Sustainability by Numbers.
Hannah joined us in 2017. She became Deputy Editor and Science Outreach Lead at Our World In Data in 2023. She was previously Head of Research.
She focuses on the long-term changes in the environment – energy, pollution, agriculture, food supply – and their compatibility with global development. Hannah completed her Ph.D. in GeoSciences at the University of Edinburgh.
She is a researcher at the Oxford Martin Programme in Global Development, and and an honorary fellow at the University of Edinburgh's School of Geosciences and Edinburgh’s Climate Change Institute. Her first book – Not the End of the World – looks at seven of our big environmental problems, and how to solve them. You can find more of her writing on her Substack – Sustainability by Numbers.
Topics covered by Hannah on Our World in Data
To transition towards low-carbon energy systems, we need low-cost energy storage. Battery costs have been falling quickly.
“Eat local” is a common recommendation to reduce the carbon footprint of your diet. How does the impact of what you eat compare to where it's come from?
Agricultural productivity across Sub-Saharan Africa needs to improve to reduce hunger, poverty, and the destruction of biodiversity.
June 10, 2024
Eating meat with a lower carbon footprint often means killing more animals and treating them more poorly.
June 03, 2024
A deep dive into missing data and the limitations of disaster databases.
May 20, 2024
Explore century-long data on temperatures, precipitation, heatwaves, drought, and hurricanes in the United States.
May 20, 2024
Deaths from disasters have fallen, but we need to build even more resilience to ensure this progress doesn’t reverse.
May 06, 2024
Every ten seconds, one child is saved by a vaccine against a fatal disease.
May 01, 2024
Our peer-reviewed article outlines seven ways to publish data better.
April 22, 2024
All countries now have policies, but not all work as intended. Some drive trade-offs or lead to spillover impacts elsewhere, but there are many examples of successful stories.
April 15, 2024
What it’s like to work at Our World in Data, and what I’ve learned along the way.
April 08, 2024
Aviation accounts for 2.5% of global CO₂ emissions. But it has contributed around 4% to global warming to date.
March 25, 2024
The majority of people in every country support action on climate, but the public consistently underestimates this share.
March 12, 2024
A four-day forecast today is as accurate as a one-day forecast 30 years ago.
February 26, 2024
Explore data on electric car sales and stocks worldwide.
October 05, 2023
Around 0.5% of plastic waste ends up in the ocean. Most of it stays close to the shoreline.
October 05, 2023
More than three-quarters of floating plastic debris comes from fishing activities.
October 05, 2023
Plastic production and disposal emits around 3% of global emissions.
September 29, 2023
The budget to keep temperatures below 1.5°C is less than a decade of emissions at current levels. For 2°C, it’s less than three decades.
September 27, 2023
There are many ways to measure countries’ contributions to climate change. What do they tell us?
September 25, 2023
The majority of farm animals in the world are factory-farmed.
September 25, 2023
Research suggests that moving hens from battery cages to cage-free environments reduces the time animals spend in pain substantially.
September 25, 2023
Fast growth rates result in significant pain and suffering for chickens. Selecting slower-growing breeds would reduce some of this suffering.
August 31, 2023
There are massive differences in emissions across the world. How do income groups and regions compare?
August 30, 2023
How can individuals reduce their emissions from transport?
June 20, 2023
Most UN projections of global population have been close to the final estimates, several decades into the future.
June 01, 2023
The world population has increased rapidly in recent centuries. But this is slowing.
April 27, 2023
Billions of people suffer from food insecurity. What does it mean to be food insecure?
March 28, 2023
Exponential growth is at the heart of the rapid increase of computing capabilities.
March 18, 2023
Global population has increased rapidly over the past century. This period of rapid growth is temporary: the world is entering a new equilibrium and rapid population growth is coming to an end.
March 13, 2023
Over the last 50 years, holes in the ozone layer have opened up. Why does that matter for life on Earth?
February 20, 2023
We need to focus on the most threatened species to protect them from extinction. But what does it mean for a species to be at risk, and how is it measured?
January 19, 2023
How does spending on food change as incomes rise?
January 05, 2023
Changes in the world population are determined by two metrics: the number of babies born and the number of people dying.
December 15, 2022
Livestock make up 62% of the world’s mammal biomass; humans account for 34%; and wild mammals are just 4%.
December 01, 2022
How have elephant populations changed over time? What species are at risk of extinction today?
November 30, 2022
When did the "Big Five" mass extinctions happen, and what were their causes?
November 30, 2022
How many species do we share our planet with? How many of these species have we found and identified?
November 30, 2022
10,000 to 50,000 years ago, hundreds of the largest mammals went extinct. It's likely that humans were the key driver of this.
November 30, 2022
Intense whaling drove many of the world’s whale species close to extinction. But a dramatic decline in whale hunting since then has given them hopes of recovery.
November 30, 2022
How have rhino populations changed over time? What species are at risk of extinction today?
October 14, 2022
Putting a price on carbon helps us account for the real costs of fossil fuels in the market. Which countries have a carbon tax or trading system?
October 13, 2022
The Living Planet Index is one of the most common measures used in biodiversity monitoring. But what is it, and where does this data come from?
October 13, 2022
The Living Planet Index shows an average decline of 69% across studied animal populations globally. But how does this vary by region?
October 13, 2022
The Living Planet Index is the biodiversity metric that always claims the headlines. It’s often misinterpreted. How should we understand it?
October 11, 2022
Many countries ship plastic waste overseas. How much of the world’s waste is traded, and how big is its role in the pollution of our oceans?
September 27, 2022
Hunting and habitat loss drove many large mammals in Europe close to extinction. New data shows us that many of the continent’s mammal populations are flourishing again.
July 11, 2022
Explore the key highlights from the UN’s latest release of its world population estimates.
June 16, 2022
All energy production takes up land, but which sources use the most land, and which use it most efficiently?
May 30, 2022
The world produces more food than ever, but the amount of land we use is now falling. This means we can feed more people while restoring wild habitat.
May 13, 2022
Most people still eat some meat, but surveys suggest that many are adopting a diet with less animal products.
May 09, 2022
Humans hunted many of the world’s large mammals to extinction. This threat still exists today, but it doesn’t have to be that way.
April 04, 2022
Why are there four different ways of measuring energy? And how does each measure help us to understand the energy system?
March 24, 2022
Both Ukraine and Russia are some of the world’s largest food exporters. How could global food be impacted?
March 18, 2022
For energy security and progress on climate change we need open data on energy. The funders of the IEA can make this happen.
March 08, 2022
Where does our migration data come from? How are these metrics defined?
February 16, 2022
How do we produce long-term datasets on agricultural employment?
February 15, 2022
How has the death toll from disasters changed over the last century?
February 11, 2022
Obesity is a leading risk factor for poor health outcomes. How is obesity defined and measured?
February 09, 2022
How do we construct our global data on CO₂ emissions?
February 07, 2022
February 06, 2022
Childhood wasting is an important indicator of malnutrition. What is it, and how is it measured?
February 04, 2022
Stunting is an important marker of childhood malnutrition. But what is it, and how is it measured?
February 04, 2022
How do we measure the prevalence of hunger across the world?
January 25, 2022
Estimates suggest that around every third child in the world suffers from lead poisoning. What can we do to reduce this?
January 19, 2022
A growing number of people are interested in switching to plant-based alternatives to dairy. But are they better for the environment, and which is best?
January 11, 2022
Paint is an important source of lead exposure. Which countries have regulations on its use?
January 11, 2022
The phase out of leaded gasoline, and regulations on leaded paints and pipes has led to a dramatic reduction in lead poisoning across many countries.
January 11, 2022
In 2021, Algeria became the last country to ban leaded gasoline. How did the world achieve it?
January 06, 2022
We are just one step away from unlocking the world's energy data for everyone. This would be a massive achievement for progress on energy and climate.
December 07, 2021
How do energy footprints compare across the world when we adjust for the goods that we import from overseas?
December 01, 2021
The world has moved from traditional biomass to a diverse energy system.
December 01, 2021
It is possible to reduce emissions while growing the economy. But this decoupling needs to happen faster.
November 30, 2021
An increasing share of energy comes from low-carbon sources. But this transition needs to happen much faster.
November 30, 2021
The world has made significant progress on improving electricity access.
November 30, 2021
There are large inequalities in energy consumption across the world.
November 30, 2021
Around 3-in-10 people do not have access to clean cooking fuels.
November 30, 2021
Energy use is declining in some countries, despite economic growth.
November 09, 2021
November 08, 2021
What are the key datasets on global energy that the world needs, but are not publicly available?
November 08, 2021
What does it mean to have ‘access to electricity’? How is this measured?
November 05, 2021
November 05, 2021
November 04, 2021
Which countries have committed to phasing out coal power?
September 09, 2021
Some countries need more fertilizers to increase crop yields. But some could cut back without sacrificing food production.
September 07, 2021
Nutrients are essential for crop growth. But when they're overapplied they become a pollutant.
September 02, 2021
Habitat loss is the biggest threat to the world's animals. Without improvements in crop yields, thousands of species could see much of their habitat lost to farmland.
August 06, 2021
Most of the world's farmers are smallholders. They are also often the poorest. How much of the world's food do they produce?
August 02, 2021
Many of the world's pollinator insects are in decline. What does this mean for global food production?
July 12, 2021
A healthy, nutritious diet is much more expensive than a calorie sufficient one. As a result, three billion people cannot afford a healthy diet.
July 01, 2021
How far are we from reaching our global targets?
July 01, 2021
How many people lack access to basic handwashing facilities?
June 10, 2021
If we want to meet our global climate targets we need to reduce greenhouse gas emissions from food. What options do we have?
May 17, 2021
Beneath the popular index, the Living Planet database helps us understand where and what animals are deeply threatened, and what animals are thriving.
May 10, 2021
Our free, open-access dataset tracking global COVID-19 vaccinations has been published in Nature Human Behaviour.
May 01, 2021
Which countries and rivers emit the most plastic to the ocean? What does this mean for solutions to tackle plastic pollution?
April 20, 2021
Wild mammal biomass has declined by 85% since the rise of humans. But we can turn things around by reducing the amount of land we use for agriculture.
March 19, 2021
What are the carbon opportunity costs of our diet? How much carbon could we store by regrowing forests and wild habitats on existing farmland?
March 18, 2021
Estimates of food emissions can range from one-quarter to one-third. Where do these differences come from?
March 04, 2021
We could reduce the amount of land used for grazing and croplands used to grow animal feed.
March 01, 2021
Rich countries import foods produced on deforested land in the tropics. How much deforestation do they import?
February 23, 2021
Three-quarters of deforestation is driven by agriculture. Most comes from the production of beef, palm oil, soy and logging industries.
February 19, 2021
There was a marked acceleration in deforestation in the 20th century. But, global deforestation peaked in the 1980s. Since then, it has slowed.
February 09, 2021
Over the last 10,000 years the world has lost one-third of its forests. An area twice the size of the United States. Half occurred in the last century.
February 07, 2021
Soy production – particularly in the Amazonian region – has been linked with deforestation. How much forest is cut down for soy?
February 06, 2021
How much deforestation emissions are embedded in traded goods?
February 06, 2021
Deforestation and forest degradation are not the same. How do they differ?
February 04, 2021
Explore palm oil production across the world and its impacts on the environment.
February 04, 2021
The world loses 5 million hectares of forest to deforestation each year. What activities are driving this?
February 04, 2021
Explore long-term changes in deforestation and deforestation rates across the world today.
February 04, 2021
See the distribution of global forests and which countries have the most forest cover.
January 14, 2021
Claims that the world has only 100, 60, or even 30 years of harvests left often hit the headlines. These claims are overblown, but soil erosion is a problem and we can do something about it.
January 08, 2021
We are building a global dataset on COVID-19 Vaccinations. Explore the latest data for all countries.
December 17, 2020
Renewable energy sources are growing quickly and will play a vital role in tackling climate change.
November 30, 2020
To continue providing daily updates on the Coronavirus Pandemic, Our World in Data has switched from ECDC to Johns Hopkins University as our data source for confirmed cases and deaths.
November 09, 2020
Globally, aviation accounts for around 2.5% of CO₂ emissions. But for many, it accounts for a much larger share.
October 23, 2020
Aviation accounts for 2.5% of global CO₂ emissions. Where do these emissions come from?
October 06, 2020
Transport accounts for around one-fifth of global CO₂ emissions. Three-quarters of this is from road transport.
September 29, 2020
A video about the drivers and possible solutions to climate change.
September 18, 2020
Globally, we emit around 50 billion tonnes of greenhouse gases yearly. Where do these emissions come from? We take a look, sector-by-sector.
August 31, 2020
830 women die from pregnancy-related causes on any given day. Most of these deaths are preventable. How can we use the Exemplar framework to identify which countries have been most successful in doing so?
July 10, 2020
Explore data on where our electricity comes from and how this is changing.
July 10, 2020
Explore global data on nuclear energy production and the safety of nuclear technologies.
July 10, 2020
Explore global data on where our energy comes from, and how this is changing.
July 10, 2020
Explore data on how energy production and use varies across the world.
June 29, 2020
Excess mortality has become a key metric to understand the true impact of the COVID-19 pandemic. How is excess mortality measured; and what can we learn from cross-country comparisons?
June 23, 2020
Coal, oil, gas or flaring: where do our CO₂ emissions come from? How are emissions from these fuels changing over time?
June 22, 2020
A video about the contributors to climate change, and how countries can work together.
June 10, 2020
Which countries emit the most greenhouse gases each year? How do they compare per person?
June 10, 2020
How much does electricity, transport and land use contribute to different greenhouse gas emissions?
June 10, 2020
How much CO₂ does the world emit? Which countries emit the most?
June 02, 2020
May 14, 2020
May 14, 2020
March 23, 2020
We worked with the Youtube channel, Kurzgesagt, to make a video on the COVID-19 pandemic and what to do about it.
March 18, 2020
Food waste accounts for around one-quarter of greenhouse gas emissions from food. That's 6% of total global emissions.
March 10, 2020
How we treat the climate impacts of methane matter a lot for carbon footprint of foods. But even if we exclude methane, meat and dairy products emit the most.
February 10, 2020
Fossil fuels are the dirtiest and most dangerous energy sources, while nuclear and modern renewable energy sources are vastly safer and cleaner.
February 04, 2020
Plant-based protein sources still have a lower footprint than the lowest-impact meat products.
January 28, 2020
Transporting food by plane can come with a large carbon footprint. But very little of our food travels this way – just 0.16% of food miles are from air travel.
November 11, 2019
More than three-quarters of global agricultural land is used for livestock, despite meat and dairy making up a much smaller share of the world's protein and calories.
November 06, 2019
One-quarter of the world's greenhouse gas emissions result from food and agriculture. What are the main contributors to food's emissions?
November 04, 2019
Feeding the world whilst reducing food's impact on the environment is one of our greatest challenges in the coming decades. What are food's environmental impacts?
October 07, 2019
Which countries are net importers and exports of emissions? How much CO2 is ‘offshored’?
October 04, 2019
There are large inequalities in the carbon footprint of people across the world. How do countries across the world compare? Where in the world do people emit the most CO2?
October 03, 2019
Which countries emit the most CO2 today? How do annual emissions vary across the world?
October 01, 2019
There's not only significant variability in how much CO2 countries emit across the world today. There are also large differences in how much each has emitted in the past. Who has contributed most to global CO2 since 1750?
September 26, 2019
Clean and safe water is essential for good health. How did access change over time? Where do people lack access?
September 26, 2019
Our World in Data is home to more than 3000 charts. But some metrics are core to our work: here we present 12 that help us understand the state of the world.
September 25, 2019
Safe sanitation is essential to reduce deaths from infectious diseases, prevent malnutrition, and provide dignity.
September 24, 2019
An estimated 8 million tonnes of plastic enter our oceans each year. But the plastic we find in our surface waters is more than 100-fold lower. This is the 'missing plastic' problem.
September 20, 2019
Access to electricity and clean cooking fuels are vital for a good standard of living and good health.
September 20, 2019
Maternal mortality was much more common in the past. Today, it is much lower — but there are still large inequalities across the world.
September 13, 2019
Growing demand for seafood has placed increasing pressures on wild fish populations. One innovation has helped to alleviate some of the pressure on wild fish catch: aquaculture, the practice of fish and seafood farming. Aquaculture production has now overtaken wild fish catch.
September 06, 2019
To understand the geographical distribution of people, we need to look at population density. How does this vary across the world?
September 02, 2019
Nearly one-in-four adults in the world smokes tobacco. More than one-third of men, but just over 8% of women do. How do sex differences in smoking vary across the world?
September 02, 2019
One-in-five (20%) of adults in the world smoke tobacco. But where in the world is smoking most common?
August 22, 2019
Rotavirus is the leading cause of diarrheal deaths in children. There is, however, an effective tool against it: the rotavirus vaccine.
August 01, 2019
Here we look at results from the largest global survey to date – the Wellcome Global Monitor – on attitudes to vaccination across the world.
July 15, 2019
Most of the world’s population growth over the next century is expected to come from Africa.
July 01, 2019
Attacks that kill more people, target the government, have Muslim perpetrators, and perpetrators that get caught receive more attention, especially in major media sources.
April 26, 2019
Where do we find life on earth? Despite being vast, the oceans are home to just 1% of life – but the majority of animals. See how the different lifeforms are split across these global environments.
April 24, 2019
How is life on Earth distributed across the taxonomic kingdoms? Humans make up just 0.01% of life: but we've had much larger impacts on shaping the animal kingdom. Livestock now outweighs wild mammals and birds ten-fold.
January 28, 2019
January 25, 2019
January 15, 2019
The number of children in India peaked in the first decade of the 2000s.
October 29, 2018
October 05, 2018
September 27, 2018
September 20, 2018
September 02, 2018
February 27, 2018
Why are so many people pessimistic about the future? And what can this tell us about tackling the world’s largest problems?
November 22, 2017
November 07, 2017
October 19, 2017
October 03, 2017
October 02, 2017
Fossil fuels were key to industrialization and rising prosperity, but their impact on health and the climate means that we should transition away from them.
August 22, 2017
July 24, 2017
When we think of nuclear safety, two accidents often come to mind: Chernobyl and Fukushima. What was the death toll and impact of these disasters?
July 01, 2017
There have been very few hijackings and almost no fatalities in recent decades.
June 20, 2017
May 19, 2017
April 14, 2017
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