In Memory of Hans Rosling

This is a public letter to Ola Rosling, son of the amazing Hans Rosling.

[It is also a response to the recent alarming special report from the United Nations IPCC on global warming. Please read and share.]

Hans Rosling was a hero — a humble, funny man with a charming Swedish accent, who found his love in life as a public-health advisor and ambassador of statistics and numbers. Hans is one of the few children who never had the misfortune of growing up. With his wit, innocent wonder, sword-swallowing bravado, and data-based graphics, he dazzled audiences with his talks. A few of my favorites I hope you’ll watch:

Hans died of cancer in early 2017. His last project, which he did with his children, was to write this incredible book, which I hope everyone will get and give more copies to their friends:

You can buy this book at,,, and other bookstores.

While reading it, I had the pleasure to have an email conversation with Ola, Hans’ son, who developed the visualization software, cofounded the foundation, and played a big role in creating the book with his father. Ola now carries the message of factfulness to people around the world.

This essay is for Ola and anyone else who wants to understand the world using facts as tools.

The important message of Hans’s book, and of the work I’ve been doing for the last decade, is that the world is generally better off than we think. Using example after example, Hans shows that we are working our way out of poverty, overcoming long-held myths about population, education, health, longevity, and more. The world is not being destroyed, the poor are not getting poorer, and the middle class is growing around the world.

However, this essay is about the few things I believe Hans and Ola got wrong. At the end of the book, Hans lists five global threats we should worry about: 1) global pandemic, 2) financial collapse, 3) world war, 4) climate change, 5) extreme poverty.

With all due respect to Hans and the team, I believe three of those things should not be on the list: financial collapse, global war, and global warming. After an amazing book of factfulness and optimism, I believe this chapter gets the answer no better than the chimps — that is, no better than randomly choosing answers — on prioritizing our efforts to making the world a better place.

My goal here is to show that the world is in even better shape than Hans thought. I will leave the financial system and war for another essay. To keep things simple, I will focus here on Hans’ claim that global warming is a top threat to humanity.

Note: This same essay could equally apply to Steven Pinker’s book, Enlightenment Now.

Global Warming

The Roslings and many other data scientists, rationalists, and statisticians are concerned about global warming. It’s not hard to see how they have drawn that conclusion. CO2 is a greenhouse gas. CO2 has been rising steadily. Temperatures have also risen (though not steadily). The obvious conclusion is that one is driving the other. But I also believe that the data are in poor condition, cherrypicked, and manipulated, reports are misleading, and the process of peer review and reporting have been undermined by politics. Here, I want to show Ola and others that there is good reason to doubt the causes and the future forecasts, and that reasonable people can change their minds when they see new evidence.

I’ll do it using this graph taken directly from the UN’s latest IPCC report on global warming:

The first thing to notice is the scale: in the last 170 years, we observe fluctuations in global temperature in the range of just over 1 degree Celsius and an average increase of about 0.8 degrees. I will break this graph down into five sections. For reference, here is the accurate data on CO2 in the upper atmosphere, known as the Keeling curve:

That looks pretty scary. Let’s look at both correlation and causation.

In this period, we recorded temperatures using glass thermometers and notebooks. Most of these thermometers were in the US and Europe, and they probably weren’t very well calibrated. Much of the recordkeeping didn’t even start until 1880.

During these years, what can we say about global temperature? Not much. It fluctuated about half a degree, with no significant change over this period.

Whoah! Look at this:

That looks like some pretty serious global warming to me! 1948 was an extreme el Nino year, but here we have four decades of serious warming before that. Here’s a newspaper from that time:

Reports from fishermen, seal hunters and explorers all point to a radical change in climate conditions and hitherto unheard-of temperatures in the Arctic zone. Exploration expeditions report that scarcely any ice has been met as far north as 81 degrees 29 minutes. Soundings to a depth of 3,100 meters showed the gulf stream still very warm. Great masses of ice have been replaced by moraines of earth and stones, the report continued, while at many points well known glaciers have entirely disappeared.

Very few seals and no white fish are found in the eastern Arctic, while vast shoals of herring and smelts which have never before ventured so far north, are being encountered in the old seal fishing grounds.

That newspaper article was published in 1922 — after maybe ten years of warmer temperatures than before. Humans didn’t really start contributing CO2 to the atmosphere until around 1950, yet temperatures rose steadily for 40 years. If, somehow, this warming period were attributable to CO2 increase, then the ensuing 80 years should have seen a tremendous acceleration to match the huge amount of CO2 that followed.

That didn’t happen. Not so much warming here:

Looks like business as usual. As greenhouse gases increased, temperature did not. Proponents of global warming have tried to explain away this inconvenient “pause,” saying CO2 really started increasing after this period of mild cooling (that followed the inexplicable warming in the first half of the century). Does that make sense to you? Here’s what the New York Times had to say:

This is the period during which Al Gore and James Hansen raised the battle cry and alerted us all to the unnatural warming:

It does look like the earth warmed in this period. What caused it? Let’s look back on a few thousand years of global surface temperatures to get some perspective. Here’s a peer-reviewed study from Nature Magazine showing various ways to look at temperature data for the past 2,000 years:

From A global multiproxy database for temperature reconstructions of the Common Era, Nature Magazine

In the above graphs, dark blue is the most likely number for each year; gray represents the uncertainty. And look, no matter how you slice this data, you can see that temperatures were as high or higher in the past 2,000 years, before man’s influence.

Here’s a clearer version from Fredrik Ljundqvist:

So what caused the dramatic warming at the end of the 20th century? There could be a CO2 effect, it could be big, but it could also be nonexistent. It’s not clear that “all climate scientists agree” that man is heating the planet.

Now it gets interesting, because satellite temperature readings are more accurate and consistent than readings from weather stations on land. Let’s look at the US data from the University of Alabama at Huntsville for global lower-tropospheric temperatures.

This is the UAH v6.0 satellite data adjusted for satellite drift and other factors (adjustments are reasonable if they correct biases in measurement; they are unreasonable if they achieve a predetermined conclusion). Here we can see about 0.4 degrees of increase in 40 years (or 0.1 degree per decade), most of which occurred from 1979 to 2000 (brown trend line). We’ve had much less warming for the past 20 years (about 0.04 degree).

This is not much warming.

And yet, here is CO2 during that same period:

So — temperatures rose from 1970 to 2000, since then not very much, while CO2 has been increasing massively over the past twenty years. If this trend continues, we could see another 1 degree of warming in the next 100 years. That’s pretty close to what we saw in the previous 100 years, when there was very little CO2 from human activities.

If you are wondering how this could have happened, watch Tony Heller’s explanation of how government agencies distort the data:

So, what does this graph from the UN IPCC really tell us?

It tells us we’ve had three fairly flat periods and two periods of about 0.4 degrees of warming each, one of which was before CO2 was much of an influence. Now, the proponents of global warming have an explanation for why CO2 doesn’t directly drive temperatures, but another way to say it is that global temperatures just aren’t cooperating with their theory and models. Didn’t Al Gore predict the Arctic sea would be free of summer ice by 2013?

Here’s what the recent UN report stated:

Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. (high confidence)

How do they conclude that humans have already caused one degree of warming? Can you see that? I can’t. It doesn’t add up to me. If you look at alarming data, you’ll reach alarming conclusions — as Hans did. But I think the data has been heavily manipulated. As Richard Lindzen explains, the global temperature fluctuates all by itself on different time scales. Sometimes it declines, sometimes it rises. Despite thousands of climate researchers and more precise measurements, we still probably don’t know exactly why. I don’t think we have reliable models of future temperature. Is this a good reason to spend trillions of dollars decarbonizing, when so many other things need our urgent attention?

For those interested, I have a longer essay on climate change and its political origins at Over 200,000 people have read it. I encourage you to read it critically and don’t take my word for anything. I’m just showing a) there might be room for questioning the popular conclusions, and b) there are actually hundreds of PhD scientists with climate, physics, chemistry, oceanic, and aeronautics backgrounds who don’t buy the UN projections. You can call them skeptics, which scientists should be, or you can call them rational optimists who are willing to go where the data takes them.

Ola, you are right to work on ignorance, pandemics, and poverty. You have much more influence than I do. You stand on the shoulders of a giant man who was always questioning assumptions and was thrilled to be wrong, so he could dive into the details and figure things out, Feynman style. If your dad were to realize the consensus might be wrong, wouldn’t he be the first to admit it? Wouldn’t he be brave enough to show up at Davos with hard questions and a presentation on what he has learned? Wouldn’t he call Bill Gates and ask him to spend a week on this together? Wouldn’t he want you to try to get to the bottom of this?

I’m not asking anything easy here. Anyone who challenges the UN and NASA and the New York Times is going to be attacked and ostracized. Take heart, Ola — we are here for you. We’ve been through it already. From Judith Curry to Matt Ridley to Lord Monckton to Richard Lindzen (below, and please see this excellent lecture) to Bjorn Lomborg — we are willing to come together and challenge the status quo, because if the data leads us that way, we must go that way.

You can ignore this public letter, forget that small section of the book, and go back to the business of Gapminding. Or you could help us create a forum where we can all use scientific, rather than political, methods to learn what’s really happening. That is surely the more difficult path. Wouldn’t your father want to you to take it? If so, you have my email address. I look forward to our conversation.


David Siegel

PS —the story continues.

David Siegel is a serial entrepreneur in London. He is the CEO of two blockchain companies — the Pillar Project and 2030. He is the author of The Token Handbook.

Provocateur, professional heretic, slayer of myths, speaker of truthiness to powerfulness, and defender of the Oxford comma.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store