Mount Mid-Life-Crisis

Using data science to gain new insights from the Himalayan Database. Who is summitting Mount Everest?

Image by David Mark from Pixabay

You surely heard about people queueing in the death zone to summit Mount Everest in May this year. The viral photo by Nirmal Purja stirred up the media, producing a sour debate about how complicated the situation on Mount Everest nowadays is, not only because of the crowds, but also a flood of inexperienced climbers and unreliable agencies. Not being a mountaineer myself, I got intrigued: how come there is so many people there? Who are they? I got more deeply interested in the topic and not much later, through the excellent blog of Alan Arnette, who extensively and frequently covers mountaineering activities in the Himalayas, I learned about the Himalayan Database.

The Himalayan Database is a truly unique project, existing because of determination of Elizabeth Hawley, a journalist based in Kathmandu, whose ambition was to track all the mountaineering activities in the Himalayas since 1905. In a way, you can say that nobody could claim that they had summitted the peak without her approval! Although she unfortunately passed away in 2018, she had gathered a small group of enthusiasts around the project who continue and extend her work. The database is regularly maintained and updated, and no expedition can go back home without entering their details into it.

The database features data about members — people who pay to climb — and hired staff— people who are paid to assist the members as Sherpas or cooks, or who are mountain workers conserving the route. The database also contains information about the expedition details (who took part, route taken, sponsor and agency, casualties, summit bids, reasons of expedition termination, further notes as free text…) and people involved (name, age, gender, profession, nationality, use of oxygen or other special equipment like skis, death/injury…) for all Himalayan peaks. The data is to much extent curated, but every now and then there are missing values, so not all the analyzed numbers can be 100% cross-checked against each other. While the database have been featured in a couple of analyses, including even a whole book, The Himalaya by the Numbers, containing all kinds of general statistics and stories, I felt that data science can bring many more new insights (also because I believe in a world beyond bar plots). As the database is now available freely online as an SQL file, I unleashed the power of Python et al. and for the past several weeks have been on a truly fascinating journey through this dataset.

There has been already some body work done on the exploratory analysis of the database. See for example blog posts of Alan Arnette, Power BI dashboard by Sandeep Nakarmi and two editions of The Himalaya by the Numbers accessible online (2007, 2011). Here I am not going to reproduce this work, but build on their insights.

For the case of storytelling, I am going to publish my insights as a series of data stories, so stay tuned for more!

High traffic on the summit is a problem of the whole decade

In order to see what has been happening on the summit over past years, I plotted all the summit days as a heatmap, where a row corresponds to all the summits in a given year, while a column corresponds to a particular date. I aggregated all the successful summit bids from the database and color coded them — darker blue means more people on a given day. On the left side there is a bar plot with the sum of all the successful summit bids in a given year. On the right side — a bar plot counting all the days when there was at least one person on the top.

A background note: generally the best season to climb the Everest is in spring. There is another summit window in autumn, but it is very unpopular among commercial expeditions. Therefore I limited myself here to the time window of 14th of April–15th of June, as this covers all the summit dates between 1980 and 2019. In 2014 and 2015 there has been very few summits due to avalanches and an earthquake which made the way up dangerous or even impassable.

It is a calendar, but looks like a Himalayan version of Minesweeper

We can see here a couple of things.

First of all — the Everest has seen days where there were more than 100 people on the top already as early as 2003, and the previous record has been set in 2012, with 266 people on the top. You can also see that there has been no dramatic increase in the number of summitters between 2018 and 2019 — it has been in a steady growth since long ago, with numbers exceeding 600 people in a year as early as 2007.

2019 has been special, however, not only because it broke the record with 357 people on the summit on the 23th of May (note that this is — assuming an unrealistic, best case scenario of a steady flow of people across 24 hours — almost 15 people every hour, so a new person every 4 minutes for the whole day! In reality, we will see later that the mountaineers summit during much smaller time window in the day, which makes the traffic even more insane). If you look closer, on the preceding day there were 224 people on the top — which means that around 66% of all the summits in that season were done on just these two days! Reuters Graphics has recently published an excellent piece discussing the meteorological factors leading to such an outcome.

Let me also comment briefly on other insights. In the 1980s and 1990s summit attempts by different expeditions were spread across the whole season — there were successful bids as early as in April. These were mostly exploratory expeditions, who had time and resources to be there longer and try out things. Moreover, they didn’t have the access to such accurate weather prognosis as we have now, 30 years later. Nowadays most of the expeditions have commercial character. Their participants often do not have the time capacity to wait for a time window over many weeks — they arrive during the optimal time of the year and they try to summit whenever the first opportunity comes. Additionally, they may need to rely on the fixed ropes prepared by the so called Ice Doctors — mountain workers taking care of the route — which are often not ready until the beginning of May. Here you can see in the data how the overall summit window decreases over the years. For the last few years all the summit bids have concentrated within a barely 3–week window, between the 10th and 30th of May. And although the number of days with at least one successful summit bid stays more less comparable over the years, at around 10–15 days per season, large groups of people relying on a small available time window make the mountain much more vulnerable to random crowding. 2017 and 2018 have seen very comparable number of people and days available, but due to more stable weather and some other random factors, the people distributed their summit bids more equally.

Be on the top for the sunrise

Now that we know on which days in the year most people are summitting, what can we say about the summit times? I filtered the database for the records containing this information and grouped them to get an average hourly profile of traffic on the top in a given year. The top and bottom graphs are the averages of profiles for the relevant years. I also indicate the sunrise and sunset times in May.

As we can see, the summit times have gradually shifted over the years to much earlier times in the day. 25 years ago most people summitted around the mid-day. In recent years, around 25% of the people summit even before the sun rises, and almost all mountaineers are gone from the summit by 12pm. It means that most of the people on the top show up within an 8–12 hour window, further contributing to the clogging of the route.

This happens not only because the summitters would like to observe the sunrise from the top of the world. Summitting early is much safer. The descent is generally more difficult than the ascent, as there is no adrenaline rush and the body is weakened by the ascent and prolonged stay in the death zone above 8000 m. Descending from the danger zone during the daylight dramatically increases chances of coming back home without any casualties.

This overall shift to the earlier, safer summitting times also signifies that over the past decades the mountaineering community has accumulated vast knowledge about the route and different safety factors. More on this later.

Middle-aged wealthy guys are flooding the mountain

As we have seen before, over the years there has been a steady increase in the members arriving and summitting the mountain. I wanted to know more about who these people are.

Of course, the majority of mountaineers approaching the Everest defines as male (steadily decreasing since 1980, currently at 80% male). I was interested in how old they are and how it has changed with time. So I created an age profile of the population of members for each year since 1950 and plotted it against the time (below, heatmap on the left). I also looked at the average population pyramids aggregated for the three periods: 1980–1987 (the end of so called “transitional period”, as defined in The Himalaya by the Numbers), 1988–1995 (beginning of the “commercial period”), and 2016–2019.

We can see that in the 1980s, most people coming had 30+/-5 years old, the sweet spot between the physical capacity of a human body and having enough experience, maturity and mental power to tackle the mountaineering challenges. In the early 1990s, there has been quite a growth of arrivals more less uniformly distributed along the same age groups as in the 1980s. If you compare it with the population pyramid for the recent 4 years though, you can see that the median age has shifted towards 40 years old. Comparing to the 1980s, in recent years there has been almost the same number of people around 30. The majority of the growth has been driven by the older population. This trend has been steady in time since the 1990s, and it is illustrated on the heatmap by the ever increasing highest age and a lack of darkening in either age group. Notice also a peculiar recent trend: mountaineers attempting to climb Everest just before or on their 18 birthday.

To quantify this trend, I split the population in three main age groups: (1) below 35 years old, (2) 35–50 years old, (3) above 50 years old. Let’s see how these three population segments changed over time since 1980 in two cases: members who arrive at Mt Everest (left), and members who summit successfully (right).

Between 1980 and 1990, the number of people has been increasing equally across all the age groups. Since 1990, the number of <35-year-olds arriving has been more less constant. From 1995 on, the rise in arrivals and summits has been driven by the population above 35. Since that year, this age group has been the majority arriving AND the majority successfully summitting. And since 2007, the increase of arriving climbers has been driven almost exclusively by the group of >50-year-olds, as the amount of arriving 35–50-year-olds has stabilized at around 250 every year.

So in absolute numbers it is mostly the middle-aged men, wealthy enough to pay or fundraise 45 000 USD on average for the adventure, who flood the mountain and are the source of dangerous crowds at the camps and near the summit.

Almost everyone makes it to the summit nowadays

If you compare the two plots above, you can see that in the recent years the number of people who summit is actually not far from the number of people attempting to climb, in a huge contrast to how it used to be in the 1980s. Let’s look at the summit rates in a given year among these three age groups.

Astonishingly, the summit rates has reached now a whopping 80% for everyone below 50 years old, and exceeded 50% for >50-year-olds! It is also fascinating that the summit rates has been increasing since 1990 in an almost linear fashion. Despite the 35–50-year-olds being possibly less fit than the younger members, they summit at almost the same rate as <35-year-olds. The >50-year-olds fall behind, but not much, with the bigger gap in summit rates opening only around 2005.

If climbing Mount Everest is such a difficult achievement, as we are inclined to think — all in all, it is the top of the world — how come the summit rates are so high?

One thing is that the typical Everest expedition shifted its character from being an exploratory to being commercial. The expeditions follow well-known, standardized, secured routes, there is a vast body of knowledge about possible dangers and pitfalls waiting on the way, the mountaineering gear is technically many times better than 30 years ago. All this enables people with relatively less fitness (although, still with an above-average fitness!) and experience to be successful.

But there is also a dark side to it: people who invested a lot of their own savings to pursue their goal are more motivated to push for summitting, sometimes dangerously breaking the safety boundaries, and some agencies and guides are not willing to advise against it, or not able to provide adequate support. There is also a group of people who attempt the climb not because they are mountaineers by passion or experience, but because they will have very tangible benefits once they get to the top and back: social recognition, financial rewards, honors and medals.

It is also known that inexperienced climbers are to much extent babysit by their Sherpas until the summit and back. It is actually reflected in the data, and to qualitatively illustrate this, I designed a visualization that looks globally at the ratio of Sherpas to members plus their summit bids in different years.

Here one row is a single expedition, and a square denotes one person belonging to this expedition. Black line in the middle separates the expeditions where at least one person successfully summitted the top from the expeditions which never made it to the summit. A person who summitted is colored with a darker hue. Members are shown in shades of blue, on the right side of each pyramid. Their hired staff — on the left, in gray.

We can see that up until 2005, around half of the expeditions didn’t make it to the summit at all, and in those which succeeded, it was mostly the members alone who made a successful summit bid. The expeditions also didn’t hire as many Sherpas as nowadays.

Since 2005, the amount of expeditions arriving at the Everest has been more less constant. However, an increasing majority of the expeditions has been successful in summitting the top. It also visible that over time bigger and bigger fraction of members belonging to a single expedition makes it to the top. Moreover, most of the expeditions nowadays have ca. 1:1 ratio between the members and the hired staff, even with the tendency to have more Sherpas than members. And similarly, almost all the hired staff makes it to the top with their members, which didn’t use to be the case in the 1980s, 1990s and even early 2000s. In 2019 there was barely any expedition where a member wouldn’t have a Sherpa with them on the summit.

Mount Mid-Life-Crisis

So what does it all tell us?

In the 1980s, the expeditions had more exploratory character: they involved younger members, less Sherpas, and were spread over many weeks in the spring season. Thanks to these years of exploration, people in a way figured out how to climb the mountain the right way. As a result, the expeditions could become more standardized and commercially available. Nowadays almost all summit during the optimal time at the end of May, follow the same ascent routes, involve older members who aren’t professional mountaineers, and have much bigger ratio of Sherpas to members in an expedition.

Despite the widely criticized fact that there is many inexperienced, not physically fit expedition members out there, and that many expeditions are organized by new agencies without proper Himalayan expertise, most of the members successfully make it to the top and the casualty rate is very small compared to other Himalayan peaks (11 out of 900 is a 1.2% death rate in 2019).

On one hand, this means that good equipment, knowledge about the route and good planning, enough hired staff and good preparation can compensate for the lack of experience, physical fitness and presence of the crowds. On the other hand, it also looks like the Everest, despite being the highest and perceived by the media as really dangerous, is now a relatively easy technically— and safe, as for a 8000er— mountain to climb.

And the queue to the summit? This analysis shows that the crowd on Mount Everest seems to be composed in big part of middle-aged wealthy men and their high-altitude babysitters. But having said that, it’s good to remember that they actually made it to the top and back — an achievement that I, a data nerd with a sedentary lifestyle, could never reproduce myself.

What’s next?

This is not the end though. In the next stories I will look at the following questions:

Is it more dangerous to climb with the new or less experienced agencies? Which of them have the biggest casualty rate?

Are there more casualties related to the lack of experience and poor preparation nowadays?

How does having a previous Himalaya mountaineering experience influence the summit bid success?

What happens on different routes?

Are some countries more successful in their summit bids than the others?

What about other Himalayan peaks?

… and more — stay tuned!