Each year, we hear that people are gaining weight and that chronic health problems like obesity, heart problems, and diabetes are on the rise.  It’s commonplace to ascribe these trends to personal lifestyle choices, such as the lack of exercise and diet, as well as the increasingly pervasive nature of fast food and processed, high-sugar foods.

However, there may be additional risk factors that are harder to control, such as genetics, and—as  a provocative new article in PLoS One (open access) suggests—birth order.  Specifically, first-born children might be more prone to these kinds of chronic health issues later in life:

Recent work has suggested that birth order may be a non-modifiable risk factor for obesity. Current evidence suggests that first-born infants grow faster than later-born infants. Dunger et al. suggest that the in-utero growth of first-born babies may be restrained as they have lower birth weight and accelerated post-natal catch-up growth, both of which are risk factors for obesity and cardiovascular and metabolic diseases, in adult life. However, whether first-born individuals have elevated metabolic risk in adulthood remains unknown. A recent study found that first-borns had a 4-fold risk of increased fat mass in early adulthood compared to later-borns. Neither of these studies evaluated the magnitude of metabolic risk induced by such greater weight and adiposity.

…Here we investigate the associations of birth-order with metabolic phenotype in early adulthood using data from a birth cohort of Brazilian young men. We tested two hypotheses. First, we wanted to confirm that first-born status was associated with low birth weight and faster infant growth. Second, we tested the hypothesis that metabolic risk was increased in first-borns compared to later-borns.

What did they find? What implications might their work have for public health given the kinds of global population changes we expect over coming decades?

Some results (excerpts):

• After adjusting for family income, maternal education, household assets score and maternal smoking in pregnancy, first-borns had significantly lower mean birth weight.
• First-borns also showed faster weight gains during infancy and had greater mean height and weight at 43 months.
• This greater weight and height tracked into early adulthood, with first-borns being significantly taller and heavier than later-borns.
• Total cholesterol and low-density lipoproteins were higher among first-borns.
• Our analysis suggests that low birth weight does not itself explain the increased metabolic risk associated with birth order. Rather, rapid post-natal weight gain appears most important, although such rapid growth is itself a response to low birth weight. Broadly similar growth patterns have been linked to the occurrence of type 2 diabetes and coronary events in adults.

So why do these patterns happen?  Here is their hypothesis:

The lower birth weight of first-borns can be attributed to materno-fetal physiological interactions. Following implantation, cells from the outer layer of the blastocyst, known as trophoblast, invade the maternal endometrium and alter the structure of the arteries that transfer blood to the placenta. Such modification decreases maternal resistance and increases placental blood flow. These changes then impact on the placental dynamics of subsequent pregnancies, such that second-born neonates are well known to have higher average birth weight than first-borns. Dunger et al. suggested that first-born children have higher glucose levels compared to later-borns, an effect most likely due to the combined effect of insulin resistance due to the increased adiposity and to the possible in utero programming of the insulin glucose axis. Thus, the increased adult body weight and adiposity of first-borns is likely to be induced at least in part by the maternal constraint of intra-uterine growth. However, other mechanisms may also be important. There is preliminary evidence in animals and in humans, that the novel experience of the first pregnancy could raise the level of apprehension in primigravid women, thereby potentially affecting the growth of the foetus via modulation of the vascular and endocrine functions of the feto-placental unit. Maternal emotional stress is an established risk factor for low birth weight, intrauterine growth retardation, preterm delivery and still-birth. Specifically, circadian cortisol secretion pattern appears to be distinctive in primiparous women and an alteration of the hypothalamus-pituitary axis (HPA) function could modify maternal glucocorticoids levels and affect foetal development. Possible mechanisms for birth-order effects on foetal growth merit further research.

And what potential implications might this have for the health of the global human population as we approach 9 billion people on the planet by 2050 and move through demographic transitions, such as reduced family sizes (emphasis mine)?

Our findings contribute to understanding of the early origins of adult disease. Our data show that a demographic factor relevant to all human populations can generate variability in both early growth and later metabolic risk. These findings also have important implications for understanding the increasing prevalence of the metabolic syndrome worldwide, where many populations are undergoing demographic change in response to economic development. Globally, there is a trend towards lower fertility rate, such that increasing proportion of individuals will be first-borns. In Brazil, for example, the average number of children per women (total fertility rate) dropped from 6.0 in 1960 to 1.8 currently.

They conclude with several important qualifications:

[A] number of questions still merit attention. For example, studies should describe in more detail the growth patterns that appear to lead to elevate metabolic risk, and identify the optimal time periods for intervention. Studies should also clarify the relative contribution of different possible underlying mechanisms (growth patterns, psychological factors) to the effects that we observed in these samples. Third, more research is required to establish the magnitude of the effect, whether it is similar in men and women, and whether it amplifies with age, as adverse metabolic profile consolidates. In these samples of young adults, the magnitude of the effect was relatively small, but degenerative diseases are expressed primarily from middle age and early-life effects tend to become more important through adulthood.

Siervo, M., Horta, B., Stephan, B., Victora, C., & Wells, J. (2010). First-Borns Carry a Higher Metabolic Risk in Early Adulthood: Evidence from a Prospective Cohort Study PLoS ONE, 5 (11) DOI: 10.1371/journal.pone.0013907

___

Photo credit: portfolium

The apparent bottom line for cell phone safety:

• Use texting instead of voice calling.
• Use an earpiece if you must voice call.
• Keep your cell phone at least an inch away from your body at all times while it’s on.

The full article is worth reading.  Below are a few excerpts of the review and Rogers’ interview with Davis:

In “Disconnect,” Devra Davis, a scientist and National Book Award finalist for “When Smoke Ran Like Water,” looks at the connection between cellphones and health problems, with some disturbing results. Recent studies have tied cellphone use to rises in brain damage, cheek cancer and malfunctioning sperm. She reveals the unsettling fact that many new cellphones now come with the small-print warning that they are to be kept at least one-inch from the ear (presumably for safety reasons) and many insurance companies refuse to insure cellphone companies against health-related claims. Most troubling of all, science has shown that children and teenagers are particularly susceptible to cellphone radiation, raising questions about its effects on coming generations.

What to you is the most compelling evidence that links cellphones to brain cancer?

The brain cancer connection is in fact a very complicated one. Cancer can take a long time to develop. After the Hiroshima bomb fell, there was no increase in brain cancer for 10 years, even 20 years afterward. Forty years later, there was a significant increase in brain cancer in people who survived the bombing. Now, for studies of people who have been heavy cellphone users (defined as someone who has made a half-hour call a day for 10 years), there is a 50 percent increase in brain cancer overall. And among the heaviest users there’s a two- to fourfold increased risk.

We’ve only really been using cellphones for 10 years. Isn’t it a bit early to be drawing these kinds of conclusions?

Well, that’s actually not true. Heavy use of cellphones in the United States is a very recent phenomenon for the general population. In the year 2000, fewer than half of us regularly used cellphones. Now almost all of us do. If there’s a 10-year latency, we still have to wait another five years in the United States to see any general population impacts.

You have to look at all of the evidence and not simply wait for proof of human harm or sick people or dead people. If the debate becomes, “Do we have sufficient proof of human harm?” that means we’re waiting another 20 years. That means we will potentially have an epidemic before we act to prevent harm. Now, some people could be very cynical and say, look, brain cancer is relatively rare so even if it doubles or quadruples it’s still rare. But it’s also, at this point, mostly incurable.

Why are young people so much more at risk?

Their brains are not fully protected with myelin. Myelin is a kind of fatty sheath that goes around neurons [brain cells] and helps to enhance judgment and a whole bunch of other things, like impulse control. Their skulls are also thinner, and a thinner skull admits more radiation. We now know that the young brain doesn’t mature until the mid-20s, later in boys than girls. We need to be much more vigilant about protecting the young brain because it is more vulnerable. We know that from work that’s been done on lead and a number of other agents.

If this research is really as convincing as it seems to be, then why hasn’t it created a widespread uproar?

Well, it has in France. Bills passed both houses of the French national government this spring that ban the marketing and creation of phones uniquely for children. It’s also had an impact in Israel, a country that is very sophisticated in its use of radar and microwaves, and Finland, both of which have issued warnings.

But think about the fine print warning that comes with BlackBerry Torch. It says, If you keep the phone in your pocket, it can exceed the FCC exposure guidelines. What’s that supposed to tell you? It sounds like that phone cannot safely be put in your pocket — well, where do they expect people to keep them?

….The book also describes the aggressive push-back by people affiliated with the cellphone industry against scientists whose findings point to safety concerns — including, in one case, a campaign to discredit someone’s findings by accusing them of manufacturing evidence. It’s pretty explosive stuff.

I think it might have started out as nothing more than companies wanting to make profits, and wanting to keep their products in a positive light. Companies are allowed to make profits; I’m not opposed to that. And I imagine people genuinely thought these kinds of dangers from radiation weren’t possible, because the physics paradigm [at the time] said it wasn’t. But it has since been morphed into something worse. Now even the insurance industry is listening to scientists. Many companies are no longer providing coverage for health damage from cellphones.

We need to be more sophisticated as a society in using experimental data where we have it. We have experimental data on sperm counts. We have experimental data on brain cell damage. We have experimental data on biological markers that we know increase the risk of cancer. These are the same debates that went out over passive smoking, over active smoking, over asbestos, over benzene, over vinyl chloride. They said we don’t have enough sick or dead people. The consequence was to continue exposing people. Is there anybody in the world who believes we should have waited as long as we did?

Read more.

___

Photo credit: liber

There’s a new paper in this week’s issue of Science that suggests that growing a landscape mixed with genetically modified (GM) Bt corn and non-GM hybrid varieties of corn can be mutually beneficial to all corn farmers.

Why?  They argue that the populations of GM corn knock down the populations of insect herbivores enough that, on a landscape scale, this effect spills over to nearby farmers growing non-GM corn, which raises yields and profits:

[W]e estimate that cumulative benefits for both Bt and non-Bt maize growers during the past 14 years were almost $6.9 billion in the five-state region (18.7 million ha in
2009)—more than $3.2 billion in Illinois, Minnesota, and Wisconsin, and $3.6 billion in Iowa and Nebraska. Of this $6.9 billion total, cumulative suppression benefits to non-Bt maize growers resulting from O. nubilalis [European corn borer] population suppression in non-Bt maize exceeded $4.3 billion—more than $2.4 billion in Illinois, Minnesota, and Wisconsin, and $1.9 billion in Iowa and Nebraska—or about 63% of the total benefits.

They suggest that the populations of non-GM corn also benefit the Bt corn farmers because the non-GM corn maintains a genetically diverse population of insects, helping prevent the evolution of herbivores resistant to Bt corn.

These results are interesting and —if they hold—could be an example of how GM crops bring environmental and social benefits.  A good outcome for all.

However, there are a couple of important things to consider:

(1) The notion of mixing crop types to minimize herbivory is the one of the fundamental tenets of traditional agroecology and organic agriculture, but instead of relying on GM crops, it could be done with a mix of hybrid crop varieties that doesn’t risk the potential environmental side effects of Bt corn or other unexpected outcomes of GM crops.  This is a major value judgment.   Does having one GM crop and a few dominant corn varieties count as diversity when the Midwest becomes a giant sea of maize?  As I explain in #2 below, probably not.  Could we achieve the same kind of insect pest management using a diversity of non-GM crops?  Yes—it happens all the time in midwestern organic farms.  Multi-crop organic farming is often more labor intensive than industrial agriculture, making the food produced more expensive.  But do we only care about cheap food?

(2) I’ve lived in southern Minnesota, where it’s a giant rotating monoculture of corn and soybeans.  If you look at Figure 1 in this paper, you will see that 50-75% (or more) of the corn grown in many regions of states like Iowa, Nebraska, and Minnesota is Bt corn.  When so much of your landscape is Bt corn, the evolution of resistance to Bt is most likely inevitable, as we saw in a previous post with the use of Roundup-ready crops like soybeans, which are often grown in rotation with Bt corn in these regions.   Acknowledging this fact of life, EPA recommends mixing GM and non-GM corn in an effort to delay the evolution of resistance, not prevent it:

To delay evolution of resistance, the U.S. Environmental Protection Agency (EPA) mandated that a minimum 20 to 50% of total onfarm maize be planted as non-Bt maize within 0.8 km of Bt fields as a structured refuge for susceptible O. nubilalis. Use of non-Bt maize refugia is an important element of long-term insect resistance management.

…Sustained economic and environmental benefits of this technology, however, will depend on continued stewardship by producers to maintain non-Bt maize refugia to minimize the risk of evolution of Bt resistance in crop pest species, and also on the dynamics of Bt resistance evolution at low pest densities and for variable pest phenotypes.

Hutchison, W., Burkness, E., Mitchell, P., Moon, R., Leslie, T., Fleischer, S., Abrahamson, M., Hamilton, K., Steffey, K., Gray, M., Hellmich, R., Kaster, L., Hunt, T., Wright, R., Pecinovsky, K., Rabaey, T., Flood, B., & Raun, E. (2010). Areawide Suppression of European Corn Borer with Bt Maize Reaps Savings to Non-Bt Maize Growers Science, 330 (6001), 222-225 DOI: 10.1126/science.1190242

___

Photo credit: Ian Hayhurst

Water security is making a bit of a splash this week.  CNBC ran this story on the water crises in western U.S. states, where the region is possibly closing in on a day of reckoning, as described by Felicity Barringer in the NY Times, and creating a climate of pessimism among some western water managers.

The scientific community is also weighing in.  C.J. Vörösmarty and colleagues published a review paper in this week’s issue of Nature in which they evaluate the worldwide risk of water security and threats to aquatic biodiversity (edited slightly to remove citations and statistics):

We find that nearly 80% (4.8 billion) of the world’s population (for 2000) lives in areas where either incident human water security or biodiversity threat exceeds the 75th percentile. Regions of intensive agriculture and dense settlement show high incident threat, as exemplified by much of the United States, virtually all of Europe (excluding Scandinavia and northern Russia), and large portions of central Asia, the Middle East, the Indian subcontinent and eastern China. Smaller contiguous areas of high incident threat appear in central Mexico, Cuba, North Africa, Nigeria, South Africa, Korea and Japan. The impact of water scarcity accentuates threat to drylands, as is apparent in the desert belt transition zones across all continents (for example, Argentina, Sahel, Central Asia, Australian Murray–Darling basin).

What is the disparity of risk between rich vs. poor nations?

Most of Africa, large areas in central Asia and countries including China, India, Peru, or Bolivia struggle with establishing basic water services like clean drinking water and sanitation, and emerge here as regions of greatest adjusted human water security threat. Lack of water infrastructure yields direct economic impacts. Drought- and famine-prone Ethiopia, for example, has 150 times less reservoir storage per capita than North America and its climate and hydrological variability takes a 38% toll on gross domestic product (GDP). The number of people under chronically high water scarcity, many of whom are poor, is 1.7 billion or more globally, with 1.0 billion of these living in areas with high adjusted human water security threat.

They also argue that as wealth increases in a nation, the apparent ability to deal with water security issues improves, leading to the perception that threat level is declining:

Contrasts between incident and adjusted human water security threat are striking when considered relative to national wealth. Incident human water security threat is a rising but saturating function of per capita GDP, whereas adjusted human water security threat declines sharply in affluent countries in response to technological investments. The latter constitutes a unique expression of the environmental Kuznets curve, which describes rising ambient stressor loads during early-to-middle stages of economic growth followed by reduced loading through environmental controls instituted as development proceeds. The concept applies well to air pollutants that directly expose humans to health risks, and which can be regulated at their source. The global investment strategy for human water security shows a distinctly different pattern. Rich countries tolerate relatively high levels of ambient stressors, then reduce their negative impacts by treating symptoms instead of underlying causes of incident threat.

Biodiversity threats from river use appear to be significant globally:

The worldwide pattern of river threats documented here offers the most comprehensive explanation so far of why freshwater biodiversity is considered to be in a state of crisis. Estimates suggest that at least 10,000–20,000 freshwater species are extinct or at risk, with loss rates rivalling those of previous transitions between geological epochs like the Pleistocene-to-Holocene.

And what about future prospects?

We remain off-pace for meeting the Millennium Development Goals for basic sanitation services, a testament to the lack of societal resolve, when one considers that a century of engineering know-how is available and returns on investment in facilities are high. For Organisation for Economic Co-operation and Development (OECD) and BRIC (Brazil, Russia, India and China) countries alone, 800 billion US dollars per year will be required in 2015 to cover investments in water infrastructure, a target likely to go unmet. The situation is even more daunting for biodiversity. International goals for its protection lag well behind expectation and global investments are poorly enumerated but likely to be orders of magnitude lower than those for human water security, leaving at risk animal and plant populations, critical habitat and ecosystem services that directly underpin the livelihoods of many of the world’s poor.

…with a not-so-comforting conclusion:

Left unaddressed, these linked human water security–biodiversity water challenges are forecast to generate social instability of growing concern to civil and military planners.

Vörösmarty, C., McIntyre, P., Gessner, M., Dudgeon, D., Prusevich, A., Green, P., Glidden, S., Bunn, S., Sullivan, C., Liermann, C., & Davies, P. (2010). Global threats to human water security and river biodiversity Nature, 467 (7315), 555-561 DOI: 10.1038/nature09440

___

Photo credit: suburbanbloke

Genetically modified organisms (GMOs) are back in the news.  A few days ago, NPR featured a couple of blog posts (here and here) considering whether the new GMO “supersized” salmon will be harmful to aquatic ecosystems.

A concern with GMOs is that—like the early adoption of pesticides—potential risks are being borne by the environment and consumers as we experiment with new species.  There’s a lot of potential for GMOs, and I hope that they all end up being harmless.  But there are potential downsides too that we are not able to assess very well at this point.  And we may be creating problems that we are not even aware of yet.

As more data come in, it’s not always an encouraging outlook.  A couple of recent examples:

Case #1: We saw a few months ago how weeds that were supposed to be eliminated by the agricultural herbicide, Roundup, are now evolving resistance to the chemical, meaning that Roundup-ready soybeans and other crops no longer work as designed.

Case #2:  In this week’s Early Edition of the Proceedings of the National Academy of Sciences, Jennifer Tank and colleagues examined what happens to transgenic corn residue (old crop parts left on fields that are not harvested).  One of the main transgenic varieties of corn is known as “Bt corn.”  Bt stands for the name of a microbe—Bacillus thuringiensis—that makes a protein toxin that destroys the functioning of guts in some insects.  Scientists have figured out how to move the Bt gene, and hence Bt toxin manufacturing capacity, from the bacteria to corn plants, thereby conferring general insect herbivore resistance to this crop (the main pest being the European corn borer).

This team asked:  What happens when corn stalks, cobs, and leaves end up in streams and rivers throughout the Midwest?  Their answer is eye-opening:

Widespread planting of maize throughout the agricultural Midwest may result in detritus entering adjacent stream ecosystems, and 63% of the 2009 US maize crop was genetically modified to express insecticidal Cry proteins derived from Bacillus thuringiensis. Six months after harvest, we conducted a synoptic survey of 217 stream sites in Indiana to determine the extent of maize detritus and presence of Cry1Ab protein in the stream network. We found that 86% of stream sites contained maize leaves, cobs, husks, and/or stalks in the active stream channel. We also detected Cry1Ab protein in stream-channel maize at 13% of sites and in the water column at 23% of sites. We found that 82% of stream sites were adjacent to maize fields, and Geographical Information Systems analyses indicated that 100% of sites containing Cry1Ab-positive detritus in the active stream channel had maize planted within 500 m during the previous crop year. Maize detritus likely enters streams throughout the Corn Belt; using US Department of Agriculture land cover data, we estimate that 91% of the 256,446 km of streams/rivers in Iowa, Illinois, and Indiana are located within 500 m of a maize field. Maize detritus is common in low-gradient stream channels in northwestern Indiana, and Cry1Ab proteins persist in maize leaves and can be measured in the water column even 6 mo after harvest. Hence, maize detritus, and associated Cry1Ab proteins, are widely distributed and persistent in the headwater streams of a Corn Belt landscape.

Who cares?  Streams and rivers are the breeding grounds to many insect species, including dragonflies, mayflies, and damselflies.  If there are toxins floating in these aquatic ecosystems that are good at killing insects, there is risk of disrupting food webs, including potential changes to bird species as well as many important recreational and sport fish that dine on insects:

Once maize detritus enters stream channels, this carbon source degrades rapidly via a combination of microbial decomposition, physical breakdown, and invertebrate consumption, and that energy may fuel stream food webs. Maize detritus in agricultural streams decomposes in ∼66 d …. Therefore, the material that we found during our synoptic survey had entered these streams relatively recently. Maize detritus is rapidly colonized by stream-dwelling invertebrates, and growth rates of invertebrates feeding on nontransgenic decomposing maize are comparable to those feeding on the deciduous leaf litter commonly found in forested streams

Perhaps this means that the Bt toxins might break down quickly and pose less harm? Doesn’t look like it:

Our data demonstrate that long after harvest, Cry1Ab is present in submerged Bt maize detritus; thus, stream organisms may be exposed to Cry1Ab for several months.

It’s also interesting to learn that low or no-till conservation tillage practices may exacerbate the corn residue inputs because greater material left on fields is susceptible to washing away:

The dried detritus left on fields after harvest, as part of conservation tillage, enters headwater streams as a result of surface runoff and/or wind events occurring throughout the year. During heavy precipitation, overland flow is the likely mechanism transporting this material to stream channels.

It may not even be a matter of leaving less residue; the toxins also appear to be draining through the soils:

Our results from tile drains indicate that tiles may be a mechanism by which Cry1Ab leached from detritus on fields or from soils can be transported to streams.
Cry1Ab released from root exudates or decaying maize detritus moves vertically through soils and can be detected at the base of 15-cm-long soil profiles for up to 9 h.

Their conclusion?  An illustration of how little we know at this point:

The question of whether the concentrations of Cry1Ab protein we report in this study have any effects on nontarget organisms merits further study.

Jennifer L. Tank, Emma J. Rosi-Marshall, Todd V. Royer, Matt R. Whiles, Natalie A. Griffiths, Therese C. Frauendorf, and David J. Treering (2010). Occurrence of maize detritus and a transgenic insecticidal protein (Cry1Ab) within the stream network of an agricultural landscape Proceedings of the National Academy of Sciences : 10.1073/pnas.1006925107

___

Photo credit: snake.eyes

Environmental Working Group (EWG) has updated their information on cell phone radiation and potential health risks.

As I alluded to in a previous post, conducting human health risk analyses for things like cell phone radiation exposure is difficult because it’s hard to determine how much exposure is too much, and it takes years to see what health effects might show up.

The research below suggests that links between cell phone radiation and health are now becoming evident.

And with more than 4 billion cell phone users worldwide (2/3 of the human population), we are unintentionally conducting one of the largest epidemiological studies of all time.

Learn more from EWG:

• Risks and research—executive summary
• Risks and research—full report (pdf)
• How much radiation does your cell phone emit?
• How to reduce radiation exposure

____

Photo credit:  http://www.flickr.com/photos/gibbons/ / CC BY-ND 2.0

• Use political tools to set emissions targets (e.g., 80% reduction by 2050);
• Invest heavily in green technology to drive green energy prices lower.  Only then will these technologies take hold. Carbon reductions are an important byproduct but not the main goal.

Of course these are not mutually exclusive, but they might as well be given the way they have played out on the political stage.

With a lot of people down on political solutions to deal with climate change, strong advocates of the latter approach may now gain the upper hand.  Folks like Shellenberger and Nordhaus have been arguing that green energy needs to be produced as quickly and cheaply as possible—forget all of the games with cap and trade or carbon taxes.   Tom Friedman has also argued the need for swift action on energy, while also endorsing political solutions like carbon taxes.

If you look for areas that are gaining or have the potential to gain traction, there seem to be two levers that may work:

• the link between fossil fuel dependency, climate change, economic stability, and national security;
• the fact that China is eating our lunch with respect to clean energy development.

Both of these general concerns have attracted Republican support for green energy and climate change mitigation, including Senator Lindsey Graham (R-SC).

This may be a signal of potential game changers and the clearest path forward that we’ve seen in awhile.

_____

Photo credit:  http://www.flickr.com/photos/worldeconomicforum/ / CC BY-SA 2.0

Little good news is coming out of Haiti these days.   There’s a deep social-environmental history that needs to be explored to understand why crises like poverty, AIDS, mudslides, and this week’s earthquake have been so devastating to the Haitian people.

I have written a bit about this history for one of the book projects I’m working on.  Below are a few excerpts, but before reading further, please consider helping with the humanitarian relief for earthquake victims:

• Doctors Without Borders USA
• AmeriCares
• An additional list of aid agencies can be found at the NY Times.

When hurricane Jeanne swept across the Caribbean, flooding rains killed over 3,000 people in the small nation of Haiti. Only 18 people died in the Dominican Republic on the same island.  Haiti has one of the highest population densities in the Caribbean. Its 8.7 million inhabitants live on less than half the land occupied by 9.4 million Dominicans, so population density is roughly two times greater.  Puerto Rico’s population density is as high as Haiti’s, but only seven people died in the storm.

Why, if Haiti’s population size is similar to the Dominican Republic’s and population density is the same as Puerto Rico’s, did Haiti suffer such a devastating loss of life?  Some argue that the loss of forests, with their capacity to prevent soil erosion, was a main reason why so many people were killed: heavy rains let loose massive mudslides on deforested hillsides.¹

Deforestation of Haiti’s landscape for agriculture and the manufacture of charcoal have left only 3% of the land surface forested.² Charcoal, produced by cutting trees and slow burning them in mud pits, meets about 85% of energy needs as cooking fuel.³ We see a ravaged countryside today and are tempted to blame this on Haiti’s high population density.  What is not as apparent, however, is how environmental degradation stems from a legacy of colonial resource extraction, slavery, corrupt governments, foreign intervention, and choices about energy, agriculture, and industry.

The mudslides and mortality did not occur in surrounding countries, which have less poverty and deforestation.  In fact, forest area is actually increasing in countries like Puerto Rico and the Dominican Republic where economic growth is rapid. Puerto Rico’s forest cover, for example, has risen from less than 10% to more than 40% in the last 60 years.¹ These forests are recovering on abandoned farmland with the transition from agriculture to industry.

It is therefore too simplistic to blame Haiti’s high population density and consumption of forest resources for the current state of the environment.  Human population growth drives environmental change but is seldom the sole factor behind environmental problems.  Instead, we need to figure out how population changes go hand-in-hand with social, economic, and technological changes so that we can explain environmental impacts.  Understanding and solving environmental challenges often requires simultaneous attention to demographic, economic, political, technological, and cultural values.

Haiti’s indigenous inhabitants practiced subsistence-based agriculture of corn, yams and cassava until their Columbus-era enslavement and genocide. Later, French colonists planted sugar cane in the well-suited warm, wet climate, and developed large, labor-intensive plantations. Throughout the 1700s, France imported thousands of African slaves to Haiti each year such that there were half a million working in 1789. During the colonial period, Haiti’s population was seven times larger than the Dominican Republic’s, which carried forward in time. Haiti exported tens of thousands of tons of sugar and most of the lumber from its forests back to France. The heavy exploitation of land for timber and sugar took a toll on the environment because of widespread land clearing, but it made Haiti one of the most profitable colonies in the Caribbean.

After Haitian independence in the early 19^th century, the nascent government was unable to support its own people in developing cash crops for export. To re-establish trade and diplomatic relations with France, Haiti’s government was forced to pay reparations for land and slaves lost during the revolution.  As much as 80% of Haiti’s budget went to pay these reparations, driving Haiti into significant debt from which it has not yet fully recovered.⁴

Today, Haiti is the poorest country in the Western Hemisphere, with the lowest combination of lifespan, education, and standard of living of any country outside Africa.⁵ Demographic, social, and economic changes happening elsewhere in the Caribbean are not happening as rapidly in Haiti. The abject poverty in which 80% of the population exists deteriorates the country’s environmental and political conditions and constrains economic development.  People are forced to choose between life in urban slums and life as poor, small-scale, subsistence farmers.  More than a million Haitians have emigrated to the United States and elsewhere since 1950.

In recent decades, many Haitian farmers have abandoned agriculture in search of greater profits from supplying charcoal to large urban and rural populations. With the collapse of agricultural and industrial exports, an unemployment rate of 33%, and sliding deeper into poverty, Haitians are forced to destroy remaining forests for charcoal fuel production. Consumption of natural resources just to stay alive is contributing to degraded environmental conditions.

Fertility remains high in Haiti because of high rates of mortality. Maternal, infant, and child mortality rates are high:  Sixty-eight infants and 52 mothers die for every 1,000 live births each year, and the under-five child mortality rate is 123 children per 1,000.  Haiti also suffers from the highest incidence of HIV/AIDS in the Western Hemisphere (5.6% of the population). The leading causes of death are diarrhea, respiratory infections, malaria, tuberculosis, and HIV/AIDS—diseases that are preventable or treatable in more developed countries.  However, 40% of Haitians have no access to health care.⁶ Haiti’s unstable governance, poverty, and environmental degradation exacerbate this need for large families as a social safety net.⁷ This is why simple approaches of reducing fertility, such as government support for contraception, have largely failed in Haiti.

Thus, Haiti’s changes in population and economic welfare, from its subsistence-based land use pattern, to an exploitative resource-extraction system, to a poor society where wealth, industry, and commercial agriculture have pulled out of the country, are not characteristic of the economic pattern—in which increasing economic development begets increased welfare—experienced by much of the developed world over past centuries.

Haiti is battling not only mudslides and earthquakes, but a colonial legacy that has predisposed its people to one devastating crisis after another.

References and Further Reading:

¹Aide, T.M. and H.R. Grau (2004) Globalization, migration, and Latin American ecosystems. Science 305:1915-1916.

²Kaiser, J. (2004) Wounding Earth’s fragile skin. Science 304:1616-1618.

³Collie, T. (2003) We know that this is destroying the land, but charcoal is what keeps us alive. South Florida Sun-Sentinel

⁴Hallward, P. (2004) Option Zero in Haiti. New Left Review 27:23-47

⁵Diamond, J. (2005) Collapse; How Societies Choose to fail or Succeed. Penguin.

⁶Farmer, P. (2004) Political violence and public health in Haiti. New England Journal of Medicine 350:1483-1486.

⁷de Sherbinin, A. (1996)  Human Security and Fertility: The Case of Haiti. Journal of Environment and Development 5(1):28-45.

_____

Photo credit:  http://www.flickr.com/photos/kretyen/ / CC BY 2.0

Happy New Year, everyone.  Sorry for the lag in posts, but there wasn’t a lot happening in the news or journals over the past week.

A few years ago, I saw a talk by Thomas Schelling (Nobel laureate in economics) who argued that we need to accelerate the economic development of poor countries so that they are able to cope with climate change.  This analysis is interesting, if not fraught with additional challenges, such as development in a carbon-based energy world hastening the very problem to which these nations are attempting to adapt.

In an article¹ in the Early Edition of the Proceedings of the National Academy of Sciences (open access), Anthony Patt and colleagues argued that the need for assistance by Least Developed Countries (LDCs) is dependent on vulnerability, which, in turn, depends on both exposure to climate change and how socioeconomic factors affect the sensitivity of LDCs to climate change.

To assess this hypothesis, they first examined how deaths caused by disasters (floods, droughts, and storms) varied across the level of development in several LDCs.  They used the UN Human Development Index—HDI, a composite metric of income, education, and life expectancy—as a proxy for development.

Here’s what they found…

As you might expect, they found that deaths declined with increased HDI, but interestingly, the relationship had a peak in the middle, suggesting that as the least-developed countries become more developed, they may actually exacerbate vulnerability to climate change at mid levels of HDI before eventually reducing vulnerability at high levels of HDI.

Next, they focused on Mozambique as a case study.  Using the model of deaths vs. HDI they developed for other countries, they projected how Mozambique’s HDI might change over the next 50 years.  To do this, they linked the HDI to different development scenarios outlined by the IPCC’s Special Report on Emissions Scenarios (SRES):

The A2 storyline describes high population and economic growth but low globalization, whereas the B1 storyline describes greater globalization
tied to improvements in environmental quality and sustainability, as well as lower population growth.

Under both scenarios, carbon increases in the atmosphere, but at different rates and to different degrees.  The authors assumed a linear increase in storms/disasters with rising temperatures, indicating that greater warming in the A2 scenario will lead to more disasters and more potential death than the B1 scenario where warming is not as great.

Following the B1 scenario caused the HDI to rise more quickly than the A1 scenario.  Simply put, society on a more-sustainable path (B1) leads to higher social welfare than under a more fossil-fuel intensive path with higher levels of human population (A2).

Similar to what they found by examining many countries, Mozambique will become more vulnerable to increased deaths as HDI rises over coming decades (by 2030-2040).  However, after 2050, vulnerability declined significantly in the B1 scenario, less so in the A2 scenario.

A few excerpts of their conclusions:

The results suggest that vulnerability may rise faster in the next two decades than in the three decades thereafter. Importantly, the overall need for adaptation measures will continue to rise… However,
assuming that their development paths fall somewhere close to the range bounded by the A2 and B1 scenarios, by the second quarter of the century LDCs will likely engage in a greater share of this adaptation autonomously, thereby reducing both their losses, and their need for financial assistance. This is especially the case if socio-economic conditions change in a manner close to that described in the B1 scenario.

….Looking beyond 2060 and the crossing of temperature thresholds such as 2 °C, it may well be that steadily rising climate impacts—such as sea level rise or the effects of cumulative changes on ecosystems—create problems that go well beyond the ability of any country, rich or poor, to adapt. Until that point, a primary argument for ramping up assistance slowly—namely, that adaptation needs can only increase as climate change continues—is incomplete, because it ignores the role that socio-economic development and the concurrent changes in adaptive capacity will have to play. Although there are important caveats to our results, they provide a first estimate of how vulnerability will unfold over the next 50 years, if one assumes, as do all of the SRES scenarios, that
incomes will continue to rise. They suggest that the urgency of efforts to reduce vulnerability, including the provision of international financial assistance, is high.

One thing the authors acknowledge is that nobody really has a good explanation for the humped relationship of HDI vs. deaths from disasters.  That’s an important part of their results, which suggests that the very poorest nations may experience more suffering in the initial steps of development.  Understanding this would make a great PhD in development economics.

¹Patt, A. et al. (in press) Estimating least-developed countries’ vulnerability to climate-related extreme events over the next 50 years. Proceedings of the National Academy of Sciences.

_____

Photo credit:  http://www.flickr.com/photos/breadfortheworld/ / CC BY-NC 2.0

One of the outcomes of climate warming is that species will have to move to remain within climatic zones that match their physiological tolerances.  Some common examples include the northward migration of boreal forest species into areas that are currently tundra and the upward migration of mountain species.

As Scott Loarie and colleagues note¹ in this week’s Nature (subscription required), we often think of mountain ecosystems as being particularly threatened because alpine species have nowhere to go.

To analyze this challenge, they looked at the spatial gradients of temperature across land masses of the world.  These data indicate how temperature changes over a known distance (temperature gradient = degrees C per kilometer).

Then, they used climate model model projections to determine how fast the temperature of a region will change (warming rate = degrees C per year).

By dividing the warming rate by the temperature gradient, they determined what they called the temperature velocity (kilometers per year)—which is basically represents how fast you (or another species) needs to move along the earth’s surface to maintain a constant temperature (check this division for yourself to see how the units cancel).

What did they find?

Here is the rank order of temperature velocities for biome types (from lowest to highest, with average velocity—km/yr— in parentheses)

• tropical and subtropical coniferous forests (0.08)
• temperate coniferous forests (0.11)
• montane grasslands and shrublands (0.11)
• Mediterranean forests, woodlands, and scrub (0.26)
• tundra (0.29)
• tropical and subtropical moist broadleaf forests (0.33)
• temperate broadleaf and mixed forests (0.35)
• tropical and subtropical dry broadleaf forests (0.42)
• boreal forest (0.43)
• temperate grasslands, savannas, and shrublands (0.59)
• tropical and subtropical grasslands, savannas, and shrublands (0.67)
• deserts and xeric shrublands (0.71)
• mangroves (0.95)
• flooded grasslands and savannas (1.26)

These data suggest that species in the latter categories will have to move much faster than those in former categories to keep up with climate change.

This make sense if you think about it because mountains have steep climate gradients where there is a lot of temperature change over little distance.  We can therefore say that these kinds of habitats have a bit of a buffer against climate warming—indeed, in most of these regions, species only have to be able to move 0.11 km/yr—about the length of a football field.  This runs counter to what most people have thought about mountain ecosystems being especially fragile to climate change.

However, when you look at globally conserved areas, the picture is less rosy.  The authors claim that only 8% of conservation areas have residence times greater than 100 years, meaning that existing climate will be gone in that time.  Put another way, in 92% of conservation areas, climate will be uncharacteristic of the region in less than a century.

This makes conservation extremely challenging—it means that the traditional notions of park boundaries no longer work because species will likely need to move by the end of the century.

There are a few important caveats that the authors point out.  One big one is that the fate of species depends on their breadth of physiological tolerance.  Species with the capacity to tolerate a wide range of climates will not need to move as rapidly (if at all) compared to those with narrow physiological tolerances.

This is an interesting way to show how fast the climate space will move over time, allowing biologists to work more on physiological tolerances to see what species or ecosystem types might be most vulnerable to warming and to develop adaptation plans for them.

¹Loarie, S. et al. (2009) The velocity of climate change. Nature 462: 1052-1057.

____

Photo credit:  http://www.flickr.com/photos/agrinberg/ / CC BY-NC-ND 2.0