# How tall is Mount Everest?

October 1, 2020 • 1:30 pm

If you asked me the height of Mount Everest, I could tell you without missing a beat: 29,029 feet (I don’t know it by heart in meters, but it’s 8,848 m).  That’s been the accepted height since the 1954 Survey Of India, which established the height using a number of observation stations and triangulation (trigonometry). Since then, there have been a few other measurements, all yielding heights close to the 1954 data: a 1999 National Geographic measurement gave 29,035 feet (seven feet higher), while a 2005 Chinese survey yielded 29,017 (that was the rock height, neglecting the roughly ten feet of ice and snow covering the summit).

There’s no doubt that Everest’s summit is the highest spot on earth measured from sea level (Chimborazo in Ecuador, however, is the highest mountain measured from the Earth’s center), but people want an exact figure. This article in the new National Geographic (click on screenshot) shows the difficulty of actually getting that figure.

First of all, the height of Everest keeps changing, both rapidly and slowly. Slowly because it’s still rising as the Indian tectonic plate collides with the Asian one—the event that created the Himalayas to begin with. That rise is about 0.5 centimeters per year. The more rapid changes are due to earthquakes: one in 1934 is supposed to have lowered the mountain by two feet. Then there’s the decision about whether to count the ice and snow blanketing the peak in its total height, for that blanket can be up to ten feet thick. (Triangulation of course includes that.)

Finally, there’s the tough decision about the baseline, taken as “sea level.” The problem is that calculating “sea level” is hard because it varies from place to place and time to time due to irregularities in the Earth’s shape, and so what they’d like is “what the sea level would be under Mount Everest if there were sea under Mount Everest”.  That involves making two models, as depicted in the figure below from the article, and it’s apparently the sum of the geoid height and the ellipsoid height is the mountain’s height. (It’s a bit complicated, and I can’t say I understand it fully, because sometimes the geoid height looks to be negative.)

The first of two recent sets of measurements were taken by a Nepalese survey team that climbed Everest in 2019, summiting in the middle of the night to avoid the rush of climbers.  Laser trigonometry as well as GPS technology established the summit height. They also used a method to determine the thickness of ice and snow on the summit. That “official” height is now known but hasn’t been revealed, for the Chinese get a say as well: the border between China and Nepal runs right through the summit, and so this spring, when all expeditions were canceled because of the pandemic, the Chinese used a combination of climbers and a surveying plane to get their own height (see below).

And politics are involved as well:

“There’s a lot of history here,” says Ed Douglas, a respected Everest historian who recently published a history of the Himalaya. Douglas notes that, like Nepal, China has long used Everest as a symbol of national identity. In 1960, Mao Zedong ordered a large state-run expedition of Everest. That team made the first successful ascent from the Tibet side of the mountain. During the 2008 Beijing Olympics, China imposed restrictions on climbers on the Tibet side of the mountain so that an official expedition could carry the Olympic torch to the top without incident.

Nepal, one of the poorest nations in Asia, has numerous reasons to keep its wealthy and powerful neighbor happy. During the last fiscal year, some 90 percent of foreign direct investment in the nation came from China, and during his state visit, Xi pledged \$500 million in financial aid. This comes in addition to the millions of dollars China has invested in Nepali infrastructure projects, including new airportsrailways, and hydropower plants.

There is precedent for Nepal and China coordinating on the issue of Everest’s height. After the Chinese completed their 2005 survey, Nepal and China announced a joint agreement to recognize both the new Chinese survey of the highest point of rock and the 1954 Survey of India elevation, which included the snowcap.

So we’ll have at least two new heights, and they’re very unlikely to be identical. But it doesn’t really matter, as Everest will remain the highest spot on Earth—calculated from an estimated sea level. That’s why I trekked in to see it twice, and why so many have tried, and many have died, trying to stand on the roof of the Earth. It’s a beautiful place to visit, and an excellent trek, and I’m content to not have climbed it. Seeing it was enough, for, believe me, you may think you’ve seen high mountains, but, like Crocodile Dundee’s knife, this is a mountain! I wish I could embed some of the photos I took on my trips, which are on 35 mm Kodachrome slides.

Here are two photos from recent measurement efforts. Photos and captions are from National Geographic:

From the recent Chinese expedition:

Below is an informative but scary chart from the Encyclopedia Brittanica, showing the peril of trying to climb it. Even I got cerebral edema climbing the small peak next to it, Kala Patthar, which is only 18,519 feet (5,644 m). That, and not base camp, is where you get the view of Everest in all its glory. (You can’t see anything from base camp.)

I made it up and down Kala Patthar on both treks, but the second time I got cerebral edema, wanted to lie down and sleep (my companion stopped me from that, knowing I’d die) and I repeatedly stumbled trying descend. I stopped at the Trekker’s Aid Post nearby for a checkup, and they told me what I had and that it would go away when I descended. (A doctor inhabits a quonset hut during the trekking season.)  I hiked down to 15,000 feet, and then I was fine.

Here, from Wikipedia, is the view of Everest from Kala Patthar. On both days I climbed the small mountain, it was perfectly clear like this, and the view was stupendous. (There was also plume of snow from Everest’s summit, showing high winds.)

h/t: Andrew Berry, a fellow Everestphile

# A lovely graph that tells our story

October 9, 2017 • 8:00 am

by Matthew Cobb

I came across this beautiful graph in an article in the journal Cell this week. It shows declining levels of genetic variability among 51 populations of humans across the planet, plotted against the distance of each population from East Africa:

The data in the figure are from a 2008 paper in Science by Jun Li and co-workers [JAC: reference at bottom; free access] looking at human genetic variation. They studied 938 unrelated people and  650,000 genetic variants, measuring the levels of heterozygosity in each population – this the frequency with which individuals had different copies of a each genetic variant.

This striking result is additional evidence that we originated in Africa and gradually moved around the planet, losing genetic variability as we went. The last places we reached in this survey – the Americas, show the smallest levels of variability.

This is exactly what you would expect: in species that have spread geographically, the ancestral populations have the highest levels of genetic variability. Populations that have moved into new areas tend to lose variability for two reasons. First, they initially contain just a subset of the variability present in the original population. This is probably the explanation for most of the effect on this figure, as many of the genetic variants they have studied will be in ‘junk’ DNA that has no effect on the phenotype. Where the variants are in genes that have an effect, variability can be lost again as the population is subject to new selection pressures in their new environment, which further reduces heterozygosity. Or, as the authors put it:

This trend is consistent with a serial founder effect, a scenario in which population expansion involves successive migration of a small fraction of individuals out of the previous location, starting from a single origin in sub-Saharan Africa.

The final reason why this figure is so pleasing is that it gives a straight line—that doesn’t happen very often in biology!

However, if we look closely, it’s not totally linear – in particular, African populations can show varying levels of variability that do not appear to be related to geographical distance from East Africa (in fact, from Addis Ababa). If you plotted only the African data, you wouldn’t be very impressed. This African variability may be for a number of reasons: the origin of humans may not have been precisely in East Africa, or humans have lived for far longer in Africa than anywhere else on the planet, and may have been subject to particular selection pressures reducing their variability (for example, in an isolated group). An explanation of those four African points at the top, which show essentially identically high levels of variability, may be that there were consistently high levels of gene flow between these groups, maintaining the variability.

Whatever the case, this figure underlines that we are a global species, spanning out across the planet, adapting and losing genetic variability as we traveled.

____________

Li, J. Z., D. M. Absher, H. Tang, A. M. Southwick, A. M. Casto, S. Ramachandran, H. M. Cann, G. S. Barsh, M. Feldman, L. L. Cavalli-Sforza, and R. M. Myers. 2008. Worldwide Human Relationships Inferred from Genome-Wide Patterns of Variation. Science 319:1100-1104.

# Jerry’s Nose

April 18, 2015 • 12:00 pm

Well, I’ve been accused of having a hypertrophied proboscis, especially by some anti-Semites who delight in that sort of thing, but I’m pleased that there’s a landmark in Newfoundland named after my schnoz. It’s part of a series of colorful place names in Newfoundland and Labrador (series list here). Here’s the notes on “Jerrys nose” (note that the link has an apostrophe):

Around here, there are hundreds of places and thousands of stories. There are many peculiarities surrounding Jerrys Nose – the lack of an apostrophe and the absence of anyone named Jerry are just the beginning. But there’s a beauty about this place that can’t be contained by punctuation. So how did it come by such a distinct name? Our friend Fred has a theory.

The series:

This year Newfoundland & Labrador Tourism launched “Place Names”. Supported by TV, digital, newspaper, and social media advertising, a series of digital vignettes – eight (8) in total – begins to tell the story of our colourful place names – engaging the target audience and differentiating the province once again as a tourism destination.

Filmed in 2014, the eight digital videos are categorized into different quirky themes: Love, People (Anatomy), Food, and Off-Kilter.

h/t: Merilee

# All countries shall have prizes

January 15, 2014 • 3:30 pm

Reader David sent me this map from Business Insider showing what each country leads the world in. A lot of it will be visible by clicking the image below to enlarge it, but go to the original map to read everything and see how some things were measured.

As Michael Kelly at BI notes:

A wonderful map created by William Samari, Ray Yamartino, and Rafaan Anvari of DogHouseDiaries illustrates what every country does better than every other country.

They collected the information from various sources and sprinkled in some quirkier rankings since many countries led the world in multiple things.

“Myanmar leads the world in ‘Speaking Burmese.’  That’s kind of a silly thing but still true,” Anvari told BI. “UK leads in fascist movements, but that’s all movements in history, not active movements.”

Most interesting to me: Nepal, Bulgaria, Costa Rica, Rwanda, Finland, the Netherlands, Australia, and. . . SWEDEN!