FJehn

509Giessen, GermanyJoined Jul 2018

Bio

Hi, I’m Florian. I am enthusiastic about working on large scale problems that require me to learn new skills and extend my knowledge into new fields and subtopics. My main interests are climate change, existential risks, feminism, history, hydrology and food security. I hope to find a place where I can work on some (or all?) of these topics, apply my data science skills, work in a team and share my knowledge by writing articles and giving courses and presentations. If you have similar interests or know of an organisation I would fit in well, let’s get in touch!

Personal blog: https://florianjehn.github.io/

Comments
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Good idea. I'll look into this when I find the time and report back here. 

Our conversation kinda feels like to me that we are talking a bit past each other. As I understand your message you are saying that the shift in temperature focus is due to the Paris Agreement. This is also what we say in the paper. However, you disagree in the conclusions from that, by saying that this does not imply a focus shift. 

And this is the part I don't get. If the IPCC focuses on different things due to the Paris Agreement, how is this not a shift in research focus? Especially after you said in your post before that your statement is based on a strong increase in the mentions of RCP8.5, which I showed to not have happened. 

Concerning your statement: "I especially don't think it is true to say that the climate science literature is ignoring impacts of more than 3 degree". The paper does not claim that we ignore impacts of more than 3 degrees,  merely that our focus has shifted away from that. 

 

Could it be that our crux is that my model is something like:

  • Temperatures are more important to look at, because they are what ultimately decides the impact of climate change. Therefore,  a shift in them is really concerning.

While your model seems to me: 

  • Only RCPs are important and it does not really matter which temperatures they ultimately look at. As long as RCP8.5 is studied a lot, you cannot say that higher warming is underresearched. 

We also looked into the RCP mentions. Going from AR5 to AR6 RCP8.5 increases ~ 10 %. Same goes for RCP2.5. The change is mainly caused by RCP6.0 mentioned less. RCP4.5 roughly stays the same. 

As the RCPs weren't really used before AR5, we cannot compare it to anything before that. This is also one of the reason for using temperature, as we can look compare all reports and not only the last two. 

The shift in temperature mentions is way stronger than the shift in RCPs. Especially if you compare it to the reports before AR5. 

I think the shift in temperature focus is partly caused by a shift in RCPs, partly by more constrained values of equilibrium climate sensitivity and mainly by the focus on the Paris Agreement. 

I guess my main questions to you are: 

  • What do you think caused the shift in temperature focus?
  • What do you think this shift implies, if not a change in research focus?

Alright, that's settled then. Also looking forward to resolution!

I get your reasons and I hope I lose the 100 $. I also think the probable temperature for 2100 will continue to go down. However, we still have quite a long way to go to get to 2°C. 

The IPCC does not really attach probabilities to temperatures. Therefore, it is not really possible to directly go for the IPCC reports as resolution. One possibility would be the Internationale Energy Agency. They regularly publish estimates of likely temperature trajectories. Their current estimate is that with currently (in 2021) stated policies we'll get 2.6°C in 2100. We could use the median estimate for stated policies in their report for 2032.  

As they have been around since 1974, it seems likely they will continue to exist in until 2032. However, they might chance the way they do their reporting, so I am not sure if this is a great way to resolve this.

I don't see how this contradicts with the paper above. It does not say we should focus on RCP8.5 or a warming of 4.3°C. The main takeaway is the IPCC reports now focus on lower temperatures as they did before. I think this implies a shift in research. If you have another explanation for this I'd be happy to hear it. 

Thanks for your comment. Unsurprisingly, I am less optimistic. While I also think that climate news gotten better over the last years, I still think there is a big chance we end up at over 2°C. The Twitter thread you linked to says "It finds that, if all the countries of the world fulfilled their climate commitments, the world would most likely limit climate change to just under 2 degrees C." That's quite a big if. 

The post by John and Johannes mainly argues that extreme warming is not likely, which I also agree with. However, I see the research gap more in the range 2°-3.5°C. 

Finally, even if our median trajectory would aim below 2 °C, we still should do more research above 2°C . Climate damage does increase considerably for higher temperatures and due to uncertainties in the climate sensitivity we still could end up there. 

I'm happy to take on your second bet. Let me know how you want to implement that. 

I'd also consider the first one depending on the implementation. However, betting is easier if you have lots of money, which I don't. 

Thank you. I'll probably won't have the time to make a full post out of this, but this was strongly inspired by the series about 1848 in the Revolutions Podcast and especially this episode:  https://thehistoryofrome.typepad.com/revolutions_podcast/2017/08/707-the-hungry-forties-.html

So, if you are looking for additional information, you'll likely find it there. 

I'll use this post to add some other potato related thoughts I had some time ago, as this chance might never come up again in the EA Forum: 

 

Are the potato famine and the revolutions of 1848 an example for the fragility of the modern world?

Recently I came across the potato famine and how it contributed or even caused the revolutions of 1848. I wondered if this is an good example to show how cascading failures lead from an natural event to an agricultural crisis, to an economic crisis, to an financial crisis and finally resulting in a political crisis.

 So what happened?

In the 19th century potatoes became a staple crop in Europe, because they were easy to plant and harvest, cheap and filled you up quite nicely. However, there were very few varieties at that time and this made them vulnerable to disease. In 1845 a new potato disease spread all over Europe and destroyed much of the yearly harvest. This was especially a problem in Ireland (because they almost exclusively used potatoes), but most parts of Central Europe were at least a bit affected. This basically left Europe without potatoes until new varieties could be developed.

In 1846 bad weather also affected the wheat and rye harvest. This lead to rising prices all over Central Europe, as now all major food crops had considerably lower yields. These food shortages forced people to kill most of their livestock, as they did not have any feed for it. But as many people slaughtered their animals at the same time, prices for meat plummeted (though they were still way to high for poor people).

This agricultural crisis lead to an economic crisis, as everybody had to use most of their money for food. Therefore, there wasn't anything left to buy other consumer goods. This in turn increased unemployment considerably, as many people in the consumer goods industry lost their jobs. Especially in cities this was a problem, as many people had moved their in the last decades and could not find any jobs to sustain themselves.

So, after the agricultural crisis in 1845 and 1846 were followed with an economic crisis in 1846 and 1847, next came an financial crisis in 1847. The financial crisis was mainly driven by the bursting of a bubble around building railroads. In the 1830s and  1840s many railroad projects were started, but most were crap. The bubble burst in 1847 after states started to rise interest rates to consolidate their finances in the economic crisis. In addition, the food crisis diverted funds away from the railroads and this showed that most of the projects could only continue if they got more money continuously. When this did not happen they crashed and with them everyone who had invested their money. This again led to more unemployment as all the railroad companies closed and due to a lack of available loans many smaller businesses went bankrupt, making even more people lose their job.

So in 1848 you had a crashed economy, a debt crisis, still some famine and massive unemployment. Many people all over Europe faces several years of fear, hardship and poverty. They looked for someone to blame. This brought many people to politics. And finally in 1848 we can see revolutions in most states of Central Europe. Some being successful (France), while others failed (Germany). Still, it seems like an new potato disease basically started a chain of events that led to a drastic change of the political landscape in Central Europe.

Is it an important research topic to explore the availability of flammable materials in major NATO cities to assess the effects of nuclear war?

Today I read "Examining the Climate Effects of a Regional Nuclear Weapons Exchange Using a Multiscale Atmospheric Modeling Approach". It models the effect of a regional nuclear war between Pakistan and India. One quote stood out to me:

"The assumed 16 g cm−2 fuel loading and 100% burn rate for the fire is actually uncertain, and in fact, Reisner et al. (2018) assume only ∼1 g cm−2 fuel loading. Reisner et al. (2018) points out that Indian and Pakistani cities are built of concrete, and there fore, firestorms that erupted in fuel-rich Hiroshima and Hamburg would not occur. Our simulations, using 1 g cm−2, cause no global radiative forcing, because the BC emitted into the lower and middle troposphere is quickly removed by EAM."

This means the effects of a nuclear war are mainly determined by how bad the firestorms will become and this in turn is determined by how much flammable material is available in the bombed cities. However, the possible range for this parameter seems to be from "there is too little fuel to cause a nuclear winter" to "nuclear winter is basically certain". This seems like a pretty big research gap to me. 

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