September 2026 Science Summary

 Greetings,

I've got four new articles this week. I continue to play with using AI to help me spot weak spots and interesting aspects of papers I review (after my initial review to avoid bias).

If you know someone who wants to sign up to receive these summaries, they can do so at http://subscribe.sciencejon.com (no need to email me).

WILDLIFE MIGRATION & CROSSINGS:

I didn't properly review Williamson et al. 2024. But had to share my delight at learning that there are "giant" hummingbirds in Chile which were documented migrating in a loop up to 8,335km long! Also to quote the paper, the migration "included a 3-wk, ~4,100-m ascent punctuated by upward bursts and pauses, resembling the acclimatization routines of human mountain climbers, and accompanied by surging blood-hemoglobin concentrations". Also they are big for a hummingbird, but still weighing only up to 31g (~2.5 strawberries).

Abra et al. 2026 conducted a BACI study on the impact of wildlife crossings under the BR-262 highway between Anastacio and Corumba in the Brazilian Pantanal. They found that underpasses combined w/ fencing reduced caiman mortality but not mortality of capybara or crab-eating fox, likely b/c of gaps in the fencing due to poor maintenance. They also found evidence of both a) a wide array of species using the underpasses (even though we know from research elsewhere that some species prefer overpasses) and b) of roadkill impacting some key species like giant anteater and jaguarundi.


WATER MANAGEMENT:
Wight et al. 2026 looks at how well capping water use works across 47 cases around the world (but ~1/2 in the US). They find that enforcement is of course critical (which in turn requires water users to all have permits and be regulated and monitored), so is adaptability (changing extraction in response to water levels every few years). 89% of cases with the best performance had a top score for enforcement, but the reverse doesn't hold true and they provide several examples of enforcement of an insufficient cap w/o adaptability failed (e.g., the Colorado River basin). Note that there are many kinds of caps and some cases used multiple options at once. Barriers include lack of water management staff and monitoring data, lack of support from water users (issues around trust, control, and livelihoods), and lack of authority for enforcement. They recommend clarity and transparency about the problem, the cap, and how it would work (including monitoring and defining success vs. failure), as well as trying to co-create a solution to get buy-in from water users (since everyone loses if supply continues to dwindle). See a related blog about a relatively simple water management framework https://www.sustainablewaters.org/a-simple-yet-powerful-fram...


CLIMATE ADAPTATION:
Vitorino et al. 2026 interviewed Pantaneiros (broadly, including fishers and farmers, not just ranchers) in 2012 and 2024 to see how perceptions had changed (although they didn't interview the same households). By 2024 almost everyone had noticed changes in temperature (substantially higher) and rain (slightly lower, although streamflow from upstream is also declining according to other papers). 90% reported adapting their practices in response. But some of those adaptations might be bad ideas - like reducing the number of crop species planted to a few that are easier to grow makes farming simpler but can potentially increase risk of crop failure vs. diverse farms. Also, moving closer to rivers could create higher flood risk in wetter years even though the overall trend is getting drier.

REFERENCES:
Abra, F. D., Goebel, L. G. A., Desbiez, A., Yogui, R., Costa, R., Laps, R. R., Ribeiro, Y. G. G., Guilherme, L., Mello, R. De, Cunha, L., Ascens, F., Pino, E. G. R. Del, Guazi, P. A. P. M., Ascenç, S. R. S., Nogueira, A. C., Oliveira, J. C. L. De, Barros, D. S., Varanis, E. N., Gregory, T., … Prist, P. R. (2026). From roadkill monitoring to evidence-based wildlife mitigation in the Brazilian Pantanal. 70. https://doi.org/10.1016/j.gecco.2026.e04347

Vitorino, B. D., da Frota, A. V. B., Arruda, M. A. do N., Vacchiano, M. C., Nunes, J. R. da S., & da Silva, C. J. (2026). Effects of climate change: an overview of perceptions, vulnerabilities and adaptations in the northern Pantanal wetland integrated with long-term climate data. Climatic Change, 179(8), 173. https://doi.org/10.1007/s10584-026-04268-4

Wight, C., Richter, B. D., Ayala, G., Blevins, L., Carter, K., Carter, S., Coughlin, B., Delzell, S., Diment, L., Fabiano, A., Farrell, C., Hanway, S., Heitmeyer, E., Herock, E., Jackman, S., Jenkins, R., Kelley, C., McNichols, A., Novak, D., … Yohannes, E. (2025). Taking stock of caps on water use: fostering sustainability or falling short? Water Policy, 27(1), 17–39. https://doi.org/10.2166/wp.2024.071

Williamson, J. L., Gyllenhaal, E. F., Bauernfeind, S. M., Bautista, E., Baumann, M. J., Gadek, C. R., Marra, P. P., Ricote, N., Valqui, T., Bozinovic, F., Singh, N. D., & Witt, C. C. (2024). Extreme elevational migration spurred cryptic speciation in giant hummingbirds. Proceedings of the National Academy of Sciences, 121(21), 2017. https://doi.org/10.1073/pnas.2313599121

Sincerely,

Jon

P.s. The picture above shows a trick I used to stay cool when biking in hot weather. It's a backpack with a mesh back and space for air to flow when riding, and I sometimes put a camelbak full of ice water in it so it feels kind of like air conditioning when I ride. Last time I did this the heat index was 113 but it didn't feel too unpleasant. Please be cautious if trying this out though - the risks of heat stress are real!

September 2025 science summary

Hi there,

This month I've got three articles on water scarcity, and two on fire and human health in South America. But before I get to the science, here are a couple of very old blog posts and more pictures...

In case you want more pics like the one above, here's an album full of similar pics of snowy mountains and clouds I took on the flight from Punta Arenas (Chile) to Santiago. This was the most beautiful plane flight I've ever taken.

Also, way back in 2013 I wrote an article about how I came to appreciate house centipedes (along w/ nematodes) for their ecological role in pest control, and recently was tickled to see people are still reading and commenting on it 12 years later! Here it is if anyone is curious: https://blog.nature.org/2013/02/08/everyday-nature-how-i-came-to-love-house-centipedes

Finally, the Washington Post and New York Times recently did their own taste tests about real sugar / high fructose corn syrup (including Mexican vs. American Coke) BUT neither was double-blind and neither involved multiple samples of each to improve statistical confidence in the results. Here's one way to do a more rigorous test if you're interested: https://sciencejon.blogspot.com/2012/10/does-real-sugar-make-mexican-coke-taste.html

If you know someone who wants to sign up to receive these summaries, they can do so at http://subscribe.sciencejon.com (no need to email me). OK, with that, here are the science summaries (finally):

FIRE AND HUMAN HEALTH:
dos Santos et al. 2025 found that the smoke plumes from the 2020 Pantanal fire combined with heatwaves, lack of rain to wash smoke particles from the air, and COVID to drive an increase of 21% in premature non-COVID deaths in São Paulo state (see Fig 5) – not counting nonlethal hospitalizations. In other words, improved fire management in the Pantanal could benefit even city dwellers far away. Fig 2 shows the smoke plume trajectories, Fig 3 shows the resulting PM2.5 (small particulate matter air pollution) levels, and Fig 7 is a nice schematic of how the different hazards combine to drive excess mortality. The authors call for more widespread integrated fire management, and continued reductions in sugarcane burning.

Palmeiro-Silva et al. 2025 is an opinion piece arguing that with wildfires increasing across South America, we need to do more to consider human health impacts of fire prevention and management. Using the 2024 wildfires in the Pantanal and the Amazon as a case study, they note that in addition to impacts on the environment and obvious human health impacts like death and air pollution, economic and mental health impacts are also important. They call for better and faster communication to affected communities, co-development of fire plans with local residents, and coordination across multiple sectors to address wildfires via a comprehensive fire risk reduction strategy.


WATER SCARCITY:
Womble et al. 2025 covers several potential ways to address water scarcity (via mandatory cutbacks, several types of water markets focused just on water consumption, and strategically considering impact on fish habitat when selecting places to buy water from). Fig 3 shows the room for improvement from the perspective of fish, often with relatively little extra cost. But an interesting twist is that depending on how the market is structured, the cost and incentives to consider fish habitat varies a lot. The default least cost "authorized market" authorized by the 2019 legislation is not great for fish (the "strategic portfolio" would cost 55% more) but for other markets the extra cost is from <1% to 8% higher to improve fish habitat. Specifically: "strategically investing <1% more funding than a least-cost plan nearly doubles fish habitat improved to intermediate status in an authorized water market with aggressive water-use reductions" and "investing 8% more than a least-cost plan ... nearly triples restored intermediate habitat in an expanded water market with aggressive water-use reductions, more water-user participation and more protections for restored flows". Finally - just 10 transactions yield 1/4 of that potential tripled habitat benefit at 1% of the cost. My overall take-aways are that there could be a lot of secondary effects of market structure, and that a little bit of focused spending to improve fish habitat can have a huge impact!

Given the outsize impact of alfalfa in the SW states, Waring et al. 2025 has some potentially useful ideas about how IF you had a well-designed water market, alfalfa irrigation could be reduced to save water (compensating farmers for reduced yield). Essentially they would cut and sell alfalfa fewer times each year b/c it goes dormant under low water, which they estimate could reduce 16-50% of alfalfa’s water use. See Table 3 for why that’s a big range – it depends on how many fields participate, how many cuttings participating fields have under BAU, and assumptions of irrigation efficiency. Almost half the fields have a short season (3-4 cuttings), which is why in Table 3 you see that scenarios like 3 and 5 that reduce participation by short-season fields result in a lot of missed opportunity. Fig 2d shows the % of total water consumption in each state due to alfalfa from Jul-Oct (note consumption is the amount of water evaporated and transpired from both rain and irrigation, unlike withdrawal which is the volume of irrigation water applied). 

Coelho et al. 2025 shows the trend for overall streamflow and flooding in the Pantanal, and also shows how three upland basins (Jauru, Taquari, and Miranda) connect to their floodplains and the Upper Paraguay (UP) River. I find Fig 11 to be pretty compelling in showing the drying trend for the Pantanal, and Fig 3 shows how the three upland basins flow into their respective floodplains and then to the UP river channel.


REFERENCES:
Coelho, M. E. M. S., Chaves, H. M. L., & Fonseca, M. R. (2025). Trends, Patterns, and Persistence of Rainfall, Streamflow, and Flooded Area in the Upper Paraguay Basin (Brazil). Water, 17(10), 1549. https://doi.org/10.3390/w17101549

dos Santos, D. M., de Oliveira, A. M., Duarte, E. S. F., Rodrigues, J. A., Menezes, L. S., Albuquerque, R., Roque, F. de O., Peres, L. F., Hoelzemann, J. J., & Libonati, R. (2024). Compound dry-hot-fire events connecting Central and Southeastern South America: an unapparent and deadly ripple effect. Npj Natural Hazards, 1(1), 32. https://doi.org/10.1038/s44304-024-00031-w

Palmeiro-Silva, Y., Llerena-Cayo, C., Blanco-Villafuerte, L., Rojas-Rueda, D., Borchers Arriagada, N., Vela-Clavo, Z., de Camargo, T., Rusticucci, M., Valdes-Velasquez, A., & Hartinger, S. M. (2025). The 2024 South America ablaze: health impacts and policy imperatives for protecting population health in an era of wildfires. The Lancet Regional Health - Americas, 48, 101160. https://doi.org/10.1016/j.lana.2025.101160

Waring, E., Dahlke, H. E., Abatzoglou, J. T., Medellín-Azuara, J., Yost, M. A., Bali, K. M., Naughton, C. C., Putnam, D. H., Sabie, R., Kishore, S., Santos, N. R., & Viers, J. H. (2025). Reimagining alfalfa as a flexible crop for water security in the Southwestern USA. Science of The Total Environment, 990(June), 179851. https://doi.org/10.1016/j.scitotenv.2025.179851

Womble, P., Gorelick, S. M., Thompson, B. H., & Hernandez-Suarez, J. S. (2025). A strategic environmental water rights market for Colorado River reallocation. Nature Sustainability. https://doi.org/10.1038/s41893-025-01585-x


Sincerely,
 
Jon
 
p.s. The pic above is one of the many beautiful snow covered mountains I saw in Chile between Punta Arenas and Santiago (in June so during winter). More pics are here: https://www.flickr.com/photos/jaundicedferret/albums/72177720327724315/with/54674270850

Where does your water come from?

Do you know where your water comes from? Many people don't, and it's important if you want to know how secure your water supply is. This new map shows you where the water comes from for almost 500 cities around the world, and for 27 of those cities we have maps showing how much of the place your water comes from is unprotected. The goal is to inspire people to realize that protecting nature near them helps to ensure their continued access to clean water. You can see the map here: http://www.nature.org/all-hands-on-earth/water


The report explaining how the data behind the map was generated is here: http://www.nature.org/idc/groups/webcontent/@web/@northamerica/documents/document/prd_056889.pdf

While I didn't have anything to do with generating the data, I'm pretty proud of how the map was put together, so for those interested, here's how it works. We wanted an easy to use interface (Google Maps being the best choice for simplicity), a really easy way for non-techies to update the data (Google Fusion Tables is great for this), but we also wanted to have full control over the look and feel of the base map (which is much harder to do with Google).

I found some existing code that lets you combine Esri map services (which we can easily customize the look of) with the Google Maps javascript API: http://google-maps-utility-library-v3.googlecode.com/svn-history/r172/trunk/arcgislink/docs/reference.html. That way we get the best features of each of the three publishing options without some of the baggage (fusion tables by default has an awkward interface, Esri products are harder to update and the interface isn't quite as nice, Google Maps has limited base map options).

Since we had two kinds of popups for different cities, we used two different Fusion Tables:

• The blue dots are cities with just a text description: https://www.google.com/fusiontables/DataSource?docid=19fmls00Ab-remGe5-80zFbQEws47wyK1DzQd0io
• The red dots are cities with nice maps: https://www.google.com/fusiontables/DataSource?docid=195lWSBIoJmn4L2Q2wq9iRAA1wvQioRD9-CAfN0k

The update process is pretty simple: to add more cities to the map, you just go to Fusion tables and import a spreadsheet with the new cities to add more rows. Google uses the concatenated "City, State" column to map each city (for international cities we use the format "City, Country").

You can simply view the source code of http://www.nature.org/all-hands-on-earth/water to see how it was accomplished, but I also have some simpler examples to help you get started if you want to replicate this approach:

• http://maps.tnc.org/wheredoesyourwatercomefrom/google_esri_example.html (uses an Esri base map, Google fusion tables data, and has a few extra features like limiting the zoom level and displaying the Esri logo) and 
• http://maps.tnc.org/wheredoesyourwatercomefrom/google_esri_simplest.html (uses a Google base map w/ fusion tables and a single Esri map service).

The quickest, easiest way to save water

My latest blog post is essentially an analysis showing that you could shut off your water at home (no toilet, no shower, no washing machine, etc.) and still have less impact than switching from beef to soy once per week. Here's the full article: http://bit.ly/TMjfg6

If you don't like soy you can still have a big impact by switching to other types of beans / lentils / legumes, and an even bigger impact by switching to grains (just be aware that nuts actually have a pretty high water footprint). If you want to look up the water footprint of specific foods, you can browse through a few of them at http://www.waterfootprint.org/?page=files/productgallery, and see a comprehensive list at http://www.waterfootprint.org/Reports/Mekonnen-Hoekstra-2011-WaterFootprintCrops.pdf


For people who don't eat burgers: any 1/3# serving of beef (steak, roast, etc) you swap out for a 1/3# soy burger still saves you about 579 gallons each time. Eating the soy burger instead of a 1/3# serving of pork saves 196 gallons (almost 3 days of home water use), and the soy burger saves 130 gallons over 1/3# serving of chicken (over two days of home water use). If you drink milk, every half gallon of soy milk you buy instead of cow's milk saves 377 gallons of water, which works out to a savings of 47 gallons of water per cup of soy milk. Coconut or oat milk also have low water footprints, but almond milk has a water footprint almost as high as cow's milk.

People interested in the water footprint (how much total water something takes to produce) of various animal products and some plant alternatives should check out http://www.waterfootprint.org/?page=files/Animal-products

It was pointed out to me (in a comment on http://blog.nature.org/2012/10/the-quickest-easiest-way-to-save-water/) that the water use for beef I cited is a global average, and that in the US our beef has a lower water footprint. There is another paper calculating water footprint of livestock by nation (http://www.waterfootprint.org/Reports/Report-48-WaterFootprint-AnimalProducts-Vol1.pdf), and they found that the water footprint for a 150g beef burger in the USA would be 562 gallons rather than 621 . That translates to a savings of 520 gallons of water for each soy burger consumed instead of an American beef burger. That still works out so that eating a soy burger instead of an American beef burger once per week saves more water than the average total indoor water use for a week.

Also, hopefully this goes without saying for people who know me, but unlike some similar figures you may have heard (usually from vegetarian advocacy organizations) this one is based on some really solid science and calculations. While one can debate the methodology used, the water footprint numbers have been validated by other authors (Zimmer & Renault 2003, Oki et al 2003). If you want to check or replicate my work you can download the spreadsheet where I made my calculations (which includes the citations) from http://fish.freeshell.org/green/WaterFootprint.xlsx

Tips for More Eco-Friendly Clothing

Not sure whether bamboo or organic cotton is better for the environment? Confused by all the competing claims about "green" clothing? I sure was before researching and writing this piece.
http://bit.ly/Ns2GDe