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READ: Data Exploration - Nuclear Weapons

After 1945, the superpowers engaged in a race to obtain the most and best nuclear weapons. How should we measure the threat posed by the spread of these weapons?
The data exploration article below uses “Three Close Reads”. If you want to learn more about this strategy, click here.

First read: preview – what do we have?

This will be your quickest read. It should help you get the general idea of what this chart is about and the information it contains. Pay attention to:
  • Labels and titles. What is the title? How are the axes labeled? Is anything else on the chart labeled?
  • Data representation. How many variables are there and what are they? What are the scales? What time period does the chart cover? Is the chart interactive?
  • Data source. Where did the data for this chart come from? Do you trust it? Who created the chart?

Second read: key ideas – what do we know?

In this read, you will pay attention to the information that most helps you understand the chart and the information it is trying to convey. Pay attention to:
  • Claim(s). What can you say about the data? What story does it tell? Can you make any claims about this data? Does it change when you zoom in compared to when you look at the data as a whole?
  • Evidence. What data from the chart supports this story? Does this change if you change the scale or variables?
  • Presentation. How does the way this chart is presented influence how you read it? Has the author selected certain variables or scales that change the conclusions that can be drawn? Is there anything missing from this chart?
By the end of the second read, you should be able to answer the following questions:
  1. What story does Chart 1 tell about the spread of nuclear weapons? How does this story change if you click the Relative toggle on the bottom left?
  2. Can you identify any ways in which Chart 1 is misleading? How would it change if Russia (red) were on top and the US (blue) were on the bottom?
  3. Looking at Chart 1 and 2, what was the most dangerous period of the Cold War, in terms of the threat of nuclear war?
  4. Using Charts 1 and 2 as evidence, do you think nuclear war has gotten more or less likely since the end of the Cold War?
  5. What information does Chart 3 provide that the other two do not? What does it tell you about the links between the Cold War and decolonization?

Third read: making connections – what does this tell us?

The third reading is really about why the chart is important and what it can tell us about the past and help us think about the future. Pay attention to:
  • Significance. Why does this matter? Does this impact me, and if so, how? How does it connect what is going on in the world right now? How does it relate to what was happening at the time it was created?
  • Back to the future. How does this data compare to today? Based on what you now know, what are your thoughts on this phenomenon 25 years, 50 years, and 100 years from now?
At the end of the third read, you should be able to respond to these questions:
  1. Why do these charts matter? What does the history of nuclear proliferation tell us about human networks, communities, and production and distribution?
  2. Using these charts, make one prediction about how nuclear weapons tests or stockpiles will change in your lifetime. What evidence from the charts supports your prediction? What evidence challenges it?
Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading.

Nuclear Weapons Data Introduction

By Max Roser and Mohamed Nagdy
Adapted by Mike Papritz and Trevor R. Getz
After 1945, the superpowers engaged in a race to obtain the most and best nuclear weapons. How should we measure the threat posed by the spread of these weapons?


Nuclear weapons technology was developed during the 1930s and 1940s. During World War II, the United States used the first nuclear weapons against Japan, detonating them over the cities of Hiroshima and Nagasaki. The devastating power of the bombs forced the Japanese surrender. Since then, controlling and regulating nuclear weapons has been an important issue in international relations.
After 1945, more and more nuclear weapons were made and tested in the Cold War arms race between the United States and the Soviet Union. The Cold War was the period between 1947 and 1991, when the two superpowers struggled against each other to gain global power and influence. One way in which they attempted to “win” the Cold War was to accumulate more and better nuclear weapons than their opponent. There are two common ways of understanding the development of nuclear weapons. One way is to view the stockpile of nuclear weapons each country has. The other is to analyze the number of nuclear tests each country conducted.

Nuclear weapons over time

One way of quantifying the proliferation (rapid increase and spread) of nuclear weapons is to look at the stockpiles maintained by different countries. The number of states with confirmed nuclear capabilities now includes the United States, Russia, United Kingdom, France, China, India, Pakistan, Israel, and North Korea. Chart 1 shows the total estimated number of nuclear warheads possessed by each of these states over time. The x-axis represents time, from 1945 (the year of the first nuclear weapon use) to 2014.

Nuclear testing

Another way to understand the development of nuclear weapons is to look at how many times different countries conducted tests of those weapons. Chart 2 illustrates those tests, by country, over time. In addition, the map below marks the locations of all atomic tests since 1945. Decolonization and the Cold War were entangled struggles, and the arms race is no exception. As you’ll notice in this map, many nuclear tests were detonated in the colonies of imperial powers.
These charts leave us with lots of questions. Is the world moving toward smaller stockpiles and fewer nuclear weapons? Or just less testing? Will these trends reverse? Who pays the cost of nuclear weapons testing? What will the future hold?
Author bios
Max Roser
Max is the founder and director of Our World in Data. He began the project in 2011 and for several years was the sole author, until receiving funding for the formation of a team. Max’s research focuses on poverty, global health, and the distribution of incomes. He is also Programme Director of the Oxford Martin Programme on Global Development at the University of Oxford, and Co-executive Director of Global Change Data Lab, the non-profit organization that publishes and maintains the website and the data tools that make OWID’s work possible.
Mohamed Nagdy
Mohamed worked with OWID as a research assistant in 2015. He helped expand content on the growth and distribution of incomes, economic development, violence, and education. Mohamed graduated from the University of Oxford with a MPhil in Economics.

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