Sunday, 17 April 2011

The Science and the rhetoric of climate change in the Bolivian Amazon

Este Blog está en Ingles porque mi esperanza es que sea un espacio de discusión entre investigadores que pertenecen a varias disciplinas y de varios países. Y, aunque a mi también me cueste mucho, el idioma de la ciencia es el Ingles. Pero me doy cuenta que los Bolivianos (y quizás no solo ellos) podrían estar interesados en muchos de los temas que se encaran aquí y que el ingles puede ser una barrera a su participación. Por lo tanto me comprometo, desde el próximo post, a escribir en ambos idiomas. Mientras tanto, los Castellano hablante que tengan ganas de traducir los viejos posts al Español son muy bien venidos. Podéis poner la traducción en la sección de los comentarios y yo luego me encargaré de ponerla a continuación del texto principal. Espero que haya muchos voluntarios/as.

Development organizations are calling for funds to finance projects aimed at the mitigation of climate change risk in the Llanos de Moxos. 
Oxfam International in its web writes: “Climate change will increase both the intensity and frequency of extreme weather events, such as flooding or droughts. Beni, a district of Bolivia prone to alternate flooding and drought, is an example of a region where people are being forced to adapt to the changing climate.” A few weeks ago, AlertNet pointed out that climate change represents a threat to people in lowland Bolivia: “Widespread flooding in Bolivia, which prompted the government to declare a national emergency last week, shows the vulnerability of one of South America's poorest countries to changing weather patterns linked to climate change.” In the same article: "Roger Quiroga, emergency coordinator for Oxfam GB in Bolivia, described Beni as one of the "largest lakes in the world" during the annual rainy season, when 150,000 sq kms is covered, an area equivalent to the size of Ecuador or Nicaragua."
These projects often receive important press coverage, like that of the most important News media of the world: 
James Painter -  BBC News wrote: “If, as predicted by many experts, the cycles of El Nino/La Nina are going to increase in intensity and frequency, then the [Oxfam’s] project has the capacity to help poor families cope better with the extreme weather events and unpredictable rainfall that are to come.”

So, I decided to dig a bit deeper on what these many experts are actually predicting. 
The first step is to see how big the floods actually are. Hamilton et al. in the Journal of Geophysical Research  measured, for the Llanos de Moxos, a maximum flood extension of 92,094 Km2
and an average flood extension of 29,460 Km2, 5 times smaller than that asserted by Oxfam!!
The second paper I want to draw your attention to is Aalto et al. Nature  425, 493-497 (2003). Here he states that “transient processes driven by the El Niño/Southern Oscillation cycle control the formation of the Bolivian flood plains and modulate downstream delivery of sediments.” This basically means that the extreme flood events are related to El Niño. Thus, the frequency and intensity of future floods depend on how global warming will affect El Niño. 
I looked then for studies that assess this issue and I found a paper by Collins et al. published in 2010 in Nature Geoscience (3, 391-397). Title: The impact of global warming on the tropical Pacific Ocean and El Niño. Quote: “despite considerable progress in our understanding of the impact of climate change on many of the processes that contribute to El Niño variability, it is not yet possible to say whether ENSO [El  Niño  Southern Oscillation] activity will be enhanced or damped, or if the frequency of events will change.” Well, it seems that there is no scientific basis for claiming that climate change will cause more severe floods in the Llanos de Moxos.
 Ok, but what will happen on average? Maybe there will be more floods because there will be more total rainfall regardless of El Niño effect. So I looked for climate models at the IPCC website site but I didn’t know how to deal with them…too many models and scenarios to choose from…and I am not a climatologist. So I looked at papers of people who have already done this work like Mayle et al. and Malhiet al.…and what have they found out? That the increase of temperature will be coupled with a decrease in precipitations! It seems that the big problem might be coping with prolonged drought rather than severe floods.
If there is a climatologist out there, I would like to know his/her opinion!
Meanwhile…I wonder if overstating the effects of climate change  might be contributing to the growth in the number of climate skeptics, like my virtual friend Guidorzi :-)

La Ciencia y los cuentos sobre el cambio climático en la Amazonia Boliviana.
En este post tomo el proyecto de Oxfam en lo Llanos de Moxos como un ejemplo del mal uso que a menudo se hace de los datos científicos. Oxfam está construyendo campos de cultivo elevados (camellones) en los alrededores de Trinidad –Beni -Bolivia con un doble objetivo: proveer las poblaciones locales con una antigua herramienta productiva usada por los pre-Colombinos, supuestamente más efectiva del chaco (agricultura del “quema y roza”) y mitigar el riesgo de las graves inundaciones que supuestamente en el futuro golpearan los llanos de Moxos a causa del cambio climático. Bueno, ambos objetivos carecen de base científica. He discutido el porqué lo camellones pre-Colombinos de los Llanos de Moxos nunca fueron más productivos del chaco en un articulo que acaba de ser publicado en el Journal of Archaeological Science (y que he mandado a Oxfam hace meses sin recibir respuesta), y no voy a discutir ese aspecto ahora. Lo que quiero evidenciar aquí es que el ciclo de las inundaciones/sequías catastróficas del Beni está relacionado (aunque menos estrechamente de lo que parece) con el ciclo del El Niño/La Niña. Por lo tanto, la manera de cómo el cambio climático afectará las inundaciones de los llanos depende (en parte) de cómo cambiará la frecuencia y/o la intensidad del Niño. Bueno, los estudios científico actualmente disponibles nos dicen que NADIE tiene la menor idea de lo que pasará al Niño en el futuro. Otro factor que afectará el régimen de lluvias en los Llanos es la cantidad de vapor que se forma en la Amazonia,  y este valor es muy sensible a la deforestación. Pero de esto hablaremos mas adelante. Bueno, si no estáis de acuerdo o queréis añadir o preguntar algo, podéis hacer clic en “comments” aquí abajo :-)



  1. Dear Umberto, hoping that Alberto Guidorzi is reading too: what I can think, as a non-climatologist a little bit acquainted with the meaning and the use of scientific measures, is simply that the extension of data we can trust on to build our models is, by far, too short even to hope than any climatological model can offer any kind of sound and reliable worldwide and/or long-term forecast.

    Maybe in some decade climatology will become a quite predictive science, and in some century it will be reliable close to the limits of indetermination principle, but now I simply don't understand how people can honestly claim that this reliability is already obtained.

    Do you think that some meteorologist is presently able, at least, to simultaneously and exactly forecast the regimes of hydrometeores, temperature, pressure and wind on each and every point of the world with a spatial resolution of, say, 5*5 km and a temporal horizon of, say, one week? But such accuracy, or something better, is just the tiniest piece of what you need to forecast climatic changes even on a single and well-defined 100*100 km area. Bets on all the winners of next Olympic games are more reasonable!

    Not even Hari Seldon could have been forecasting the climate's future of the whole world by using present models, datasets and technologies.

    Unfortunately, too many economical and political issues have been dogmatically linked to some overoptimistic (and/or bombastic) claims of a very little number of noisy and pretending Dulcamaras... and now we are here.

  2. hola umba (and everybody else) - great topic, has been out there for a long time... sorry I keep this short (wrote 2 comments already which disappeared upon submitting, grrr, maybe someone is watching us?): I very much agree that things are not at all as easy as stated in Aalto et al (which gives us a good idea how to publish a Nature paper), and this has been an ongoing issue since. Throw into the discussion Ronchail et al 2005 (Journal of Hydrology) who try and tackle the problem with data from both sides of the continent, thereby giving credit to the multiple controls on regional climate/precipitation... its certainly not enough to think in terms of warm or cold. In conclusion (short version): 1) we probably cant take our "understanding" of modern climate as an analogue, and 2) this is exactly why we need to go back to the Beni and figure out the TERRESTRIAL (fluvial, flood, inundation) evidence ;-) (thanks to Leo, Anna and Beda jeje). Looking forward! Cheers to you all, H

  3. Lunch break at the 12th Swiss Global Change. Great presentation from David Thompson - Colorado State Univ. "Anthropogenic influence on atmospheric circulation". He said that human activity (CO2 increase and depletion of the ozone's layer) is even more clear on the global atmospheric circulation than on temperature variation. With respect to the tropics, tropical region is widening. However, in his opinion, there is no evidence of the ENSO following any trend.
    I will add something to the Henne's comment later on.

  4. Henne, I agree that Ronchail et al 2005 (and even more Ronchail & Gallaire 2006) is an important piece of the puzzle. I left it out because I wanted to keep things as simple as possible :-)
    However, I think the most important aspect of their work is the analysis of the spatial distribution of the rainfall during El Niño and La Niña. During El Niño is raining less in the Andes and more in the Llanos and during La Niña is happening the contrary: more rain in the Andes and less in the Llanos. This explain why Aalto et al. got a positive correlation between La Niña and the high sedimentation. I don't quite understand why you think he is wrong. During La Niña, there is less rainfall in the llanos and the Mamorè overflow is less constrained; at the same time, as is raining more in the Andes, the Mamorè has more water. For me it is quite a good model. What's your disagreement with that?

  5. I'll give a look to that communication. Human activities effects on air circulation are quite more realistic than those on global climate, as of course they are more closely linked to local or regional variations in the usage of land and on the local emission of heat. A new artificial hydroelectric basin is enough to change the climate of the surrounding area. By the way, a technical and not-ideological discussion about the environmental effects of an intensive use of wind generators could be useful...

    Amigo Umba, lo siento, pero mi castellano no es bastante para contribuir a las traducciones. No confío en escribir algo en español, pero me gusta leerte.

  6. Querido Umba, al respecto de la comunicación que encabeza este último post y tu amable invitación a participar en la traducción de tus posts anteriores.......ARE YOU TALKING TO ME?????? (La Choca - y de pasada tu mujer medio inglesa)