Burning coffee and reducing carbon dioxide

Some of the most meaningful advances in environmental problems fly under the radar.  So if “Development of a biomass charcoal combustion heater for household utilization” doesn’t sound like a groundbreaking paper, consider a catchier title: “Smart folks offer plan to reduce greenhouse gas emissions and provide energy with renewable resources.”

That’s the idea of a new study published in Industrial & Engineering Chemistry Research.  And it’s relevant because Asian countries like Japan have millions of households with charcoal heating – so by improving the efficiency of these heaters, it will reduce the amount of carbon dioxide burned and the amount of biomass used.

The two main ways the researchers achieved greater efficiency were using a thin layer of charcoal and fuel that converted a high ratio of the mass to heat.  Additionally, the fuels come from sustainable sources: waste from wood processing, coffee beans, and soybean fiber.  Most of the biomass stoves in the U.S. have an efficiency of 46-54%, while the new design reaches efficiencies of 60-81%.

To reduce carbon dioxide emissions, we need smart ways to get more from our limited resources.  This study, along with similar efforts to increase the efficiency of some of the dirtiest engines in developing countries, probably won’t make headlines.  But it represents some of best hope for rapidly reducing our impact on the environment and slowing climate change.

Click here to read the article.

Corn’s ecological footprint

High-yield corn agriculture in America provides obvious benefits, but a new study shows it’s also correlated with environmental problems – some of which can be detected by fishers thousands of miles away.  While using the words corn and nitrogen in the same sentence may sound as boring as a discussion of tractor tires, the issue is actually one of the most important environmental issues around.

High-yield corn production requires fertilizer to provide nutrients for the plants.  As reported in the journal Frontiers in Ecology and the Environment, this practice is also linked with higher nitrogen in nearby rivers: much of the nitrogen fertilizer washes away from the fields and winds up in streams that feed larger rivers.  Broadly speaking, this creates two major problems.

First, the excess nitrogen in the water fuels “dead zones” in rivers and in oceans.  Just as the nitrogen helps corn grow in fields, it also helps algae grow in water.  But because algae has a much more rapid life cycle – it grows and dies quickly – algal blooms create masses of decaying algae in a short period of time.  As algae decompose, oxygen is rapidly depleted, and fish and shellfish are unable to survive in these areas.  

Secondly, though we need nitrogen, we need a delicate balance of it to sustainably enjoy crops and fish.  Excessive nitrogen can be as problematic as scarce nitrogen.  This issue has received less attention than global warming and carbon footprints, but scientists are increasingly concerned about the impacts of using nitrogen unwisely.

The new study showed a strong correlation between intensive corn production and nitrogen in rivers, indicating this type of agriculture is associated with the two problems described above.  But where more types of crops were grown, the levels of nitrogen in rivers decreased.  

The study authors suggest their findings should play a role in determining agricultural policies to curb nitrogen runoff. Some existing practices which can help reduce runoff include increasing buffers between cropland and surface water, changing in crop rotation, and using native plants in some parts of fields to help keep the nitrogen from leaving the fields.

The article is free to read on the journal’s website.

Can ecologists live ethically?

Conservation biologists are great at using science to illuminate the often hidden world of animals and providing guidance to help save them.  But can the same biologists practice what they preach?

That’s the question raised by Giovanni Bearzi in an essay in the current issue of the journal Conservation Biology.  ”When swordfish conservation biologists eat swordfish” is Bearzi’s piercing but necessary exploration of how even the best informed minds can fail to live up to their own ethical standards.

The essay goes beyond simply finding examples of internal inconsistency in conservation biologists – it’s about a greater struggle to reconcile what is expedient and what is morally correct.  In this sense, it’s an ancient human conflict, but applied to the realm of modern environmental issues.  The essay is accessible to a lay audience and freely available on the journal’s website.

For all that appears in the popular press about green lifestyles, this essay stands out as more inquisitive and though-provoking than nearly any other I’ve seen lately.  Click here to read it.

Kermit’s last meal

Frog legs aren’t just a characteristic French meal and the source of a common derogatory term used by the English to describe the French – they’re also an enormous source of meat in parts of Asia.  Exactly how many frogs are taken from the wild is unknown, which was part of the reason a team of researchers set out to quantify the trade in frogs.  (Their article, “Eating frogs to extinction” will appear shortly in the journal Conservation Biology.)

Worldwide, amphibians are among the most threatened animals.  Habitat loss is part of the problem, but the spread of chytrid fungus, which is wiping out vast swaths of amphibian populations, has made the situation much more severe.

Beyond conservation, there are other reasons to be concerned about losing frog populations: in many areas of the world – particularly wet, swampy areas – frogs provide insect control.  From a human health or agricultural perspective, controlling insects naturally is critical because insects spread some of the most deadly human diseases and can ruin productivity of agricultural land.

The study authors advocate for greater documentation of the species being harvested (many are wild frogs, though some are farmed) and greater documentation of frogs harvested and consumed within a country’s borders, since these are rarely counted.  Only with a better idea of the number of frogs harvested can conservation biologists start to measure the true impact on frogs and the insect populations they eat.

Finding 21% of Nemo

Few examples linking the global economy with the global environment are as clear and direct as overfishing. A recent article in the journal Conservation Biology highlights this link: as incomes in mainland China have increased, consumers have exerted a greater demand for live fish from tropical coral reefs.  

The study focuses on declines in spawning aggregations, which are critical because they are large gatherings of many fish in a small area – ideal for successful reproduction, but also easy pickings for harvest.  And unlike North American salmon, whose harvest is heavily regulated or restricted as they gather to spawn, many of these spawning fish are going to feed the growing demand for them in restaurants.

The authors were able to collect the most data for Nassau grouper, a large fish that takes years to reach sexual maturity and a popular dish in some parts of the world.  Spawning aggregations of this species were reduced to the point that it is now classified as threatened.

More broadly, the authors found declines in 79% of the aggregations for which there were sufficient data.  The declines noted in the study are an example of what fish biologists call recruitment overfishing: taking so many fish that the population cannot replace itself.  Combined with the growing trend of harvesting fish before they are sexually mature, these practices destroy the natural capacity of reef fish to provide enduring, sustainable harvests.

Click here to read an abstract of the article.

Ocean acidification’s newest foe: fish poop?

Another reason to appreciate marine fish: they produce carbonates within their intestines, and these carbonates are vital for marine life but disappearing through global warming.  

One of the by-products of global warming is ocean acidification, or the decrease in pH throughout the sea. This acidification harms the ability of organisms as diverse as algae, corals, and shellfish to form calcium carbonate skeletons.

In the latest issue of the journal Science, researchers report that 3 to 15 percent of all carbonate in the oceans is produced in the intestines of bony fish and then excreted.  Additionally, the carbonate excreted by fish dissolves in the water more readily than other sources.  Another major source of carbonates comes from the shells of dead organisms, but these tend to dissolve in the depths of the oceans, while fish-produced carbonates dissolve in the upper layer.

So as increased carbon dioxide makes oceans more acidic, marine life has a new ally in the form of fish feces. (In the interest of complete accuracy, the carbonates are formed in fish intestines but are not actually feces – only roommates with feces.)

An abstract of the article is available here.

Predicting climate change’s impact on agriculture

At a global scale, a warmer climate does not provide better growing conditions for food crops.  In a study published in the current issue of the journal Science, the IPCC’s climate projections for the 21st century are compared with historical examples of warm summers to show the destructive impact of high temperatures.

The authors (an atmospheric scientist and an economist) show the IPCC’s models indicate a strong likelihood that by 2100, the median summer temperatures in many areas will be equal to or higher than the warmest summers during the past century. Essentially, what was an exceptionally hot summer in the 20th century will be standard at the end of the 21st.

The authors discuss warm years in the past 100 years as an example of agriculture’s general response: in 2003, a heat wave in Europe sent production of key grains down by double digits in France and Italy, and 1972 saw a general failure of the wheat harvest in Russia.

Additionally, it’s important to realize a warmer summer isn’t just a gentle increase in temperature – it’s often the result of periods of intense heat which can kill crops before they’re mature.  Perhaps more important is the relationship between warm weather and precipitation, since drought and heat waves are a fatal combination. Precipitation patterns also change as temperatures increase, often resulting in hotter temperatures with more sporadic rainfall.

On the whole, the study’s outcome is bleak, particularly for tropical regions already stressed by increasing populations and degraded land.  Here, as for most of the rest of the world, a warmer planet is more likely to produce scarcer harvests than abundant harvests.

To read the abstract of the article, click here.

Evolving against our best interests

Call it survival of the littlest.  A new study published in the Proceedings of the National Academy of Sciences provides evidence that harvesting wild populations of fish and wildlife can be counterproductive – for the animals and the people who hunt them.

The study is troubling because it shows how harvesting the biggest individuals in a population can lead to future generations that are smaller.  It’s also a reversal of the normal selection pressure – predation – in which the youngest (and sometimes oldest) members are eaten most often.  When human pressure is intense, it creates an evolutionary force producing the opposite of what we want: smaller populations less capable of replenishing themselves.

For instance, many game species like bighorn sheep have a minimum size restriction, so only the largest individuals can be taken.  The same pattern is often found in commercial and recreational fisheries, where fish have to be a certain minimum length to be legally harvested.  When this pressure is high enough, it has the effect of selecting against larger (and typically older) individuals, leaving the smaller and younger individuals to survive and reproduce.

Commercial fishing usually harvests the larger members of a population.  This type of pressure favors fish that grow to a smaller size, because smaller fish aren’t harvested as much – so they survive and reproduce.  But in many fish species, smaller females produce far fewer offspring than their larger and older counterparts.  So harvesting the biggest individuals, while productive in the short term, can lead to future harvests with smaller and fewer individuals.

While these trends have been noted before (particularly for fish, as noted in an earlier post), the study examines a wide range of organisms in which the negative impacts are occurring.

The article’s abstract is available on the journal’s website.

Farming biodiversity

We use vast swaths of our planet to grow the food we eat.  What impact does that have on the species in and around that land?

It’s a simple question with huge implications for biodiversity.  In South Asia and Southeast Asia, it’s also an urgent question, as increasing agricultural demands make the tropical forests there among the most threatened in the world.  Are the species there doomed, or is there hope for balancing biodiversity and increased agriculture?

A study in the Proceedings of the National Academy of Sciences suggests there’s hope.  The study’s authors examined bird diversity in southwestern India, a region with high biodiversity and an extensive history of agriculture.  Where arecanut palm is grown,  90% of the bird species found in neighboring intact forests were also present.  In contrast, peanut fields and rice paddies have essentially no native birds or other wildlife during parts of the year.

Beyond showing the coexistence of birds and food plants, the study is important because it helps to identify the factors that help to promote this coexistence.  The authors point to the vertical structure arecanut palms provide, but which rice paddies and peanut fields do not.  (In other words, rice paddies are essentially two-dimensional, whereas acrenut palms are much more three-dimensional, like native forests.)  Additionally, farmers rely on bordering forests to provide mulch for their crops.  There’s an incentive to preserve these forests, and native species use this habitat.

The article also highlights critical ecological issues that aren’t explicitly tied to global warming.  If we manage to tackle climate change, there are many other problems facing a planet with a population of six billion.  Understanding how we can produce the resources we need to survive without destroying everything else is one of those big problems.  This paper provides a step in the right direction.

Click here to read the open access article.

We’re out of cod. Try the gelatinous zooplankton.

Very quietly, ocean ecosystems are showing signs of changing dramatically, and it’s not because of global warming.

Big fish like cod and tuna have been fished for centuries, but the increasing burden of recent decades may be too much.  In a study in the November issue of the Canadian Journal of Fisheries and Aquatic Sciences (CJFAS), two biologists showed a large population of Canadian cod is projected to essentially vanish within 40 years – even if fishing stops tomorrow.

The scary implication is that past overfishing – taking unsustainable levels of fish – can cause fish populations and the ecosystems in which they live to fundamentally change.  In the case of the Canadian cod, mortality rates are the critical factor causing the collapse.  The Canadian government heavily restricted or closed fishing for the cod populations in 1993, so populations should be increasing.  Instead, they have kept falling.

In 2002, David Conover and Stephan Munch published a study in the prestigious journal Science showing how harvesting only the largest fish in a population could produce smaller fish in the next generation.  The same idea may explain what’s happening to cod: past fishing has created intense selection pressure on smaller fish that mature earlier in life.

Not all cod populations show the same trend, so it would be premature to suggest Atlantic cod face imminent extinction.  But the trends in the population in CJFAS study are indicative of what can happen elsewhere: poor management and overharvest select for future generations that are smaller and less capable of recovering.  

And when cod disappear, other organisms fill the void.  This creates a different ecosystem, and one that may be less productive from our point of view.  There’s a real possibility fish like cod are being replaced by skates, rays, and smaller invertebrates in oceans worldwide.  

This is why fisheries policy matters.  It’s also a great example of a global environmental problem we can change, one day at a time.  Fish are only caught to feed our demand, so our purchases shape the future of the oceans.  In this sense, sustainable seafood is one of the wisest investments.  Get a handy guide to sustainable seafood from the Monterey Bay Aquarium.