Eyal Frank

Humans killed millions of vultures. Now people are paying the price. The near-extinction of vultures in India has had severe consequences.

A truly heartbreaking article linking the deaths of children from rabies to the collapse of vultures in India

www.washingtonpost.com/climate-envi...

Reboot Development: The Economics of a Livable Planet New World Bank report: Find out about how policymakers can connect the dots across land, air, and water sectors to drive strong, sustainable economic growth at the national-level and unlock major glob...

New WB report offers a fantastic summary of current challenges and where economics can help fill in knowledge gaps: www.worldbank.org/en/publicati...

We could argue that full adaptation (=no heat stress milk declines) is possible by fully insulating cows from the environment and having complete climate control, but that type of full confinement introduces other stressors that reduce milk supply. /n

Two final notes. We also find that the damages occur when the cows are predicted to be most productive (in terms of their age and number of calf births). This means that the most productive cows are the least resilient to heat stress. 19/

The important takeaway here is that we often raise the scope to adapt to more extreme weather when seeing the potential damages of such events. However, economically viable adaptation might not be enough to fully offset such damages. 18/

Bottom line is that cooling helps, but does not fully offset the decline due to heat stress. On mild warm days, the decline in milk production can be halved, but as heat stress increases, so does the mitigation capacity. 17/

Importantly, we do not interpret these estimates as causal. Adaptation might have happened in the farms that were likely to benefit the most; hence, these should be seen as upper bounds for the gains to such adaptation. 16/

To do so, we surveyed 306 farms and asked when they installed their cooling equipment (read: fans and sprinklers, not air conditioning). We use the variation in the timing of the installation to report how the damage curve changes with and without such cooling equipment. 15/

Once we establish that high heat stress lowers, on average, the daily output of a cow by 10%, we quantify how much adaptation can mitigate those damages. 14/

Our study provides more evidence on how important it is to take humidity into account when examining climate change impacts, as demonstrated by yet another recent study on human health. 10.1126/sciadv.adq3367 13/

Warm and humid conditions can have negative effects on milk production for several days. We use our very large sample to test how lagged days above specific thresholds affect milk production. It can take up to 11 days for cows to recover from heat stress exposure! 12/

In short, higher wet-bulb temperature means a higher heat stress level. We estimate the binned response curve of the logged milk production versus wet-bulb temperatures. Each hour spent in high heat stress conditions lowers milk production. 11/

For a given day with the same dry-bulb temperature (say 30 degrees Celsius, x-axis), milk production can decline a little or a lot, depending on the relative humidity (going from low to high on the y-axis). Milk losses range from 0 to 10%! 10/

It matters because higher values of wet-bulb temperature mean less capacity to cool off by sweating or panting—crucial for us on team mammal. 9/

To study how milk production responds to high temperatures, we use wet-bulb temperature instead of just dry-bulb temperature (also commonly referred to as just temperature). Wet-bulb temperature captures information on dry-bulb temperature and relative humidity. 8/

(3) Cows in Israel are the most productive in the world, and farmers are at the technological frontier, especially when it comes to the use of cooling to mitigate heat stress. 7/

(2) Farmers face fixed prices that are set by the Israeli Milk Council, so we can focus solely on the supply side. 6/

(1) There is a wide temperature gradient from south to north, capturing the variety of climate conditions across other large milk-producing countries. 5/

Our study uses data on the daily milk production of *each* cow in Israel from 2009 to 2020, for a total of 320 million cow observations. Israel is a useful testing ground for how cows are affected by heat stress, and how farmers adapt for several reasons: 4/

Several papers in the applied micro literature on climate change impacts have documented how high temperatures will have a negative impact on agriculture, but they have mostly focused on crops (10.1038/s41586-025-09085-w). Our focus is on livestock, specifically dairy cows. 3/

First, this (www.science.org/doi/10.1126/...) is joint work with clairepalandri.github.io, economics.agri.huji.ac.il/ayalkimhi, Yaniv Lavon, Ephraim Ezra, and www.ram.sites.tau.ac.il. 2/

New paper published in Sci. Adv. on the limited scope for dairy farms to adapt to humid heat stress. The tl;dr is cooling equipment helps, but only mitigates up to half of the milk losses—which we interpret as an upper bound. Details below! 1/

Hopefully, if you made it this far, you appreciate bats a bit more than you did a few minutes ago.

Not every decline in wildlife populations will result in severe damages. There is a distribution of impacts we will experience from biodiversity losses. These findings tell us about how far the tail of the distribution can extend, and how the density in that tail is not zero!

The results also highlight how damages and losses from biodiversity declines can occur well before species become fully extinct in the wild. It is enough they become locally functionally extinct, and can no longer play the role they had in the ecosystem

More broadly, my findings tell us something about how we benefit from natural enemies interactions in ecosystems, and how those help to stabilize the functioning of those systems—providing us with tangible benefits.

I also examine how farm production and operations are affected by the decline in bat populations, but those results are more suggestive. Interestingly, Ando and Manning found that agricultural land rental rates fall in WNS affected counties (doi.org/10.1086/720303)

More recent work finds higher infant mortality from elevated pesticide use as well (see for example doi.org/10.1093/rest... and drive.google.com/file/d/10NPw...)

My results suggest that a 1% increase in insecticide use leads to a 0.25% increase in IMR. To anchor this magnitude with just one example (I offer more in the paper), work by Chay and Greenstone (2003) found that a 1% decline in air pollution led to IMR going down by 0.3%.

These are large effects, but it is imporant to remember that the change in biological pest control is large, and so is the response by farmers.