Good morning, Hank.

It's Tuesday. So listen, I have an idea inspired by  early modern humans.

But to explain it, I need to share with you two things  I recently learned that I found surprising. Okay, so the average US resident  eats around 220 servings of beef per year. That is not a surprising fact  to me because I live in the United States.

You often see like three or four beef  purveyors at a single intersection. What surprised me was learning that  we used to eat much more beef. Like in the 1970s, Americans ate  something like 275 servings of beef per year.

So while we still eat about  twice as much beef as they do in, say, Germany or the United Kingdom,  our beef consumption is declining, albeit slowly. The other thing I learned  is that if humans don't dramatically reduce their beef consumption,  it will be impossible to limit ourselves to 1.5 degrees Celsius  of post-industrial global warming. Beef produces around ten times  more greenhouse emissions per gram of protein than poultry, and  about 20 times more greenhouse emissions per gram of protein than  plant based proteins, like beans.

I mean, putting everything else aside,  it’s just wildly inefficient. Beef cows use around 60% of the world’s  agricultural land, but produce 2% of the world’s calories and only 5%  of the world’s protein. Also, beef cows are currently the world’s  leading cause of deforestation.

So when thinking about climate  change, we often tend to focus on technologies, you know, like electric  cars and solar panels and batteries and all of that is super important, of course.  But I think we don't talk enough about social norms. Like in the US we've  just sort of agreed that most cars should be SUV's or pickup trucks,  which is why the average American car produced today weighs 1000  pounds more than the average American car produced in 1985.  We've also just kind of agreed that our houses should be 1000 square  feet bigger than the ones we built in the 1980s. And when your houses  and cars get bigger, they also get more energy intensive.

That's not a  technological problem, that's like a social norm problem. So while we  definitely need new technologies to limit climate change, I think we also  need to change some social norms. And that can be really hard.  Like, currently in the world, about 13% of all human deaths are at least  partly caused by one drug.

And that drug is called tobacco. And I used  quite a lot of tobacco when I was younger, even though I understood  that there were serious health risks associated with it. Because smoking  was cool.

Like, it is almost impossible to explain to young people of today  just how cool smoking was. In the 20th century, everybody cool smoked.  Like, jazz singer Billie Holiday - smoker. Physicist Albert Einstein - smoker.  NASCAR driver Dick Trickle, which, yes, was his real name - smoker.  In fact, he smoked cigarettes live on television during NASCAR races.  [Announcer] You know, he has a cigarette lighter in the car.  He just reached for it. [John] But then smoking became  less cool, partly through government regulation that made tobacco more  expensive, partly through really good anti-smoking marketing campaigns.  And now smoking has dropped in the United States, and so has death from  smoking related causes.

So norms feel permanent.  Like, there was no part of me in high school that thought smoking  would ever not be cool. But norms can nonetheless change, and when  they do, it can be really powerful. Which brings me back to beef.  I need to reduce the amount of beef that I eat.

And in thinking about how  to do that, I've been thinking about feast days, a phenomenon we find  throughout the world and throughout history, from Mesoamerica to the  Islamic world to Europe. On certain agreed upon holidays, communities  will come together and feast, potentially eating things that on  other days would be verboten, like only eating meat on saint days  or whatever. And so in our family, over the next year, we are going to  attempt to recreate this ancient social norm with Beef Days.  Four times a year, on agreed upon dates we will celebrate great  achievements in human history with a beef day, a day where we eat beef.  We'll also have two annual flex days - days where we eat beef because  we want to eat beef.

And then, other than that, the 359 remaining  days, we won't eat beef. If we stick with it, our family will  reduce our beef consumption by around 90%. And Hank, I'd like  to invite you and anyone else who's interested to join us.  I should say that there are advanced forms of Beef Day.  One can, for example, abstain from both beef and dairy products,  except for on beef days.

And then, of course, there's the most advanced  version of all - vegetarianism, where people abstain from beef  and all other forms of meat all year round, including Beef Days.  I feel like vegetarians should be especially celebrated on Beef Days,  and all the vegetarians should be congratulated and thanked and  encouraged to feast on whatever is considered a feast. Now, I want  to be clear that Beef Days are not, like, a solution to climate change.  Many, many technologies and norms will have to come together to  accelerate the speed at which we are decreasing greenhouse  emissions. But I think it might help our family a bit.

There is only one  question that remains for me. What should be our beef days?  What dates should we pick? What sacrifices and achievements  and gifts that humanity has given the world should we honor with  our most sacred Beef Days?

Let me know in comments what  Beef Days you would propose, and we'll choose some from  your suggestions. Hank, I'll see you on Friday.  Hi, P. S. this Saturday at noon eastern time, we'll be hosting a  livestream here on the Vlogbrothers channel to talk about some of the work  Partners in Health is doing, and also to honor a young Nerdfighter  named Amit, who died of cancer and left part of his estate to  Partners in Health.

We're going to try to raise money to match his gift  and also dive deep into PIH’s theory of change. So hope to see  some of y'all there. Bye.