Environment

Despite its efforts for nearly two decades to raise doubts about the science of climate change, newly discovered company documents show that as early as 1977, Exxon research scientists warned company executives that carbon dioxide was increasing in the atmosphere and that the burning of fossil fuels was to blame.

The internal records are detailed in a new investigation published Wednesday by InsideClimate News, a Pulitzer Prize-winning news organization covering energy and the environment.

The investigation found that long before global warming emerged as an issue on the national agenda, Exxon formed an internal brain trust that spent more than a decade trying to understand the impact of rising CO2 levels in the atmosphere – even launching a supertanker with custom-made instruments to sample and understand whether the oceans could absorb the rising atmospheric CO2 levels. Today, Exxon says the study had nothing to do with CO2 emissions, but an Exxon researcher involved in the project remembered it differently in the below video, which was produced by FRONTLINE in association with the InsideClimate News report.

In 1978, the Exxon researchers warned that a doubling of CO2 levels in the atmosphere would increase average global temperatures by 2 to 3 degrees Celsius and would have a major impact on the company’s core business. “Present thinking holds that man has a time window of five to ten years before the need for hard decisions regarding changes in energy strategies might become critical,” one scientist wrote in an internal document.

The warnings would later grow more urgent. In a 1982 document marked “not to be distributed externally,” the company’s environmental affairs office wrote that preventing global warming would require sharp cuts in fossil fuel use. Failure to do so, the document said, could result in “some potentially catastrophic events” that “might not be reversible.”

Some on the Exxon internal research team saw the potential for a greater impact in their work. “This may be the kind of opportunity that we are looking for to have Exxon technology, management and leadership resources put into the context of a project aimed at benefitting mankind,” Harold N. Weinberg, an Exxon manager, wrote in a March 1978 internal memo.

But in the mid-1980s, collapsing oil prices, among other pressures, pushed Exxon to change course, according to the Inside Climate News investigation, widening a gulf between its research arm and the company’s executive suite. The report notes that by the 1990s:

Exxon helped to found and lead the Global Climate Coalition, an alliance of some of the world’s largest companies seeking to halt government efforts to curb fossil fuel emissions. Exxon used the American Petroleum Institute, right-wing think tanks, campaign contributions and its own lobbying to push a narrative that climate science was too uncertain to necessitate cuts in fossil fuel emissions.

“Let’s agree there’s a lot we really don’t know about how climate change will change in the 21st century and beyond,” Lee Raymond, the company’s former chairman and chief executive officer told an audience in a 1997 speech to the World Petroleum Conference.

In a written response to the InsideClimate News investigation, an Exxon spokesman said that, “At all times, the opinions and conclusions of our scientists and researchers on this topic have been solidly within the mainstream of the consensus scientific opinion of the day and our work has been guided by an overarching principle to follow where the science leads. The risk of climate change is real and warrants action.”

While it’s impossible to know where the climate change debate would be today without Exxon’s early decision to shift course on the science, the about-face was a lost opportunity in the overall effort to slow the rise of CO2 emissions, according to one climate researcher interviewed by InsideClimate News.

“All it would have taken is for one prominent fossil fuel CEO to know this was about more than just shareholder profits, and a question about our legacy,” said Michael Mann, the director of the Earth System Science Center at Pennsylvania State University. “But now because of the cost of inaction – what I call the ‘procrastination penalty’ – we face a far more uphill battle.”

From frustrated snowboarders to migrating birds arriving at shriveled wetlands to wildfires raging through national parks, the Sierra Nevada’s lack of snow has transformed just about every aspect of life in California. Farmers, fish, forests, gardeners, hikers, boaters, and more depend on Sierra snow for water.

But now it’s clear that the “snow fail” in the 400-mile long mountain range has reached epic proportions: This year’s snowpack is the driest it’s been in at least 500 years, according to new research published Monday.

This stark finding comes from an analysis of more than 1,500 California blue oak tree rings dating back to the early 1500s, when Spanish explorers were just beginning their conquest of the state.

Researchers who examined cores from the long-lived oaks to calculate the water content of each year’s snowpack were stunned to find that no other year was even close to as dry as 2015. Temperature data show why: The state was slammed with a drought-and-heat double whammy.

“What happened in 2015 is that very low precipitation co-occurred with record high temperatures. And that’s what made this snowpack low so extremely low,” says Valerie Trouet, a tree-ring research specialist at the University of Arizona in Tucson and co-author of the study published in Nature Climate Change.

The researchers had expected the 2015 results to be bad, ‘but we didn’t expect it to be this bad,’ Trouet says.

The 2015 Sierra snow water equivalent, a measure of water content, was just 5 percent of average over the past half-millennium, the researchers found. The next-closest lows were 2014 and 1977; both years the water content was 25 percent of average.

The team, which also included scientists from the National Atmospheric and Oceanic Administration in Colorado and the University of Arkansas at Fayetteville, calculated snow water content from the width of the tree rings. California blue oaks are “really really reliable recorders of the amount of rainfall that falls in the winter season,” Trouet says, because they produce wide rings after wet winters.

The researchers had expected the 2015 results to be bad, “but we didn’t expect it to be this bad,” Trouet says.

In fact, the water content of the Sierra Nevada snowpack could actually be at its lowest in 3,100 years, she said, based on a different analysis also reported in the study. That statistical method has a higher margin of error, but confirms that the 2015 snowpack is off-the-charts.

The result has been a summer of steep water cuts and exploding wildfires, billions in economic damage, and stressed wildlife-and perhaps a preview of what’s to come under climate change.

“Snow Melting Into Music”

Stretching from the grapevine snaking into Los Angeles to forests about 300 miles shy of the California-Oregon border, the Sierra Nevada’s reach encompasses Yosemite’s waterfalls, Lake Tahoe (the largest alpine lake in North America), Mount Whitney (the highest peak in the lower 48 states, and other renowned landscapes. Naturalist John Muir called them the Range of Lights and wrote “the snow is melting into music” to describe the voluminous fresh water running off its peaks.

Their snowpack is crucial to water supplies throughout California, including semi-arid Los Angeles and other southern cities, the San Francisco Bay Area, and Central Valley farms.

The storied Sierra snow is normally so saturated that skiers and snowboarders call the heavy powder “Sierra Cement.” This dense icing slowly melts into rivers and streams throughout the spring and summer; feeding reservoirs, flooding wetlands, and refilling the water table. (Read more here in National Geographic Magazine’s When the Snows Fail.)

For those who grappled daily with last winter’s scant snows, the centuries-long record may come as a surprise, but its severe effects do not.

“The past season’s suspension of operations was certainly the earliest on record, which doesn’t come as a surprise, given the [new findings of a] 500-year low of snowpack in the Sierra,” Thea Hardy, spokeswoman for the Sierra-at-Tahoe ski resort near South Lake Tahoe, said in an email.

Week after week it just kept not snowing and it was getting hotter and hotter.

The 2,000-acre resort, which has often stayed open into May during its nearly 70 years in business, shut down in mid-March. It was one of many California winter recreation spots that closed far earlier than usual this year.

Much of the precipitation that did fall last winter came down as rain, at lower elevations.

Ski instructor Sophie Castleton experienced that problem first-hand.

“Week after week it just kept not snowing and it was getting hotter and hotter,” says Castleton, who worked last winter at Alpine Meadows, near the California-Nevada border town of Truckee. “A lot of times it looked like it would snow, but then it would turn to rain and there would be puddles around the lifts.” That resort also closed early, and Castleton felt bad for her several colleagues who had come from South America and Australia to work.

Water managers are also keenly aware of the epic snow fail. The California Water Project, which oversees 154 reservoirs in the state, is able to deliver only 20 percent of the water its customers request, says Doug Carlson, information officer for the Department of Water Resources.

Californians have cut their water use by a whopping 31 percent and are for the most part getting by this summer with short showers, yellow lawns, and infrequently flushed toilets. (Read here what drought veterans say about this four-year dry spell].

Stressed Wildlife and Raging Wildfires

Wildlife is far less flexible, complicating management, Carlson says. Native salmon fry, for instance, need cool water to survive. Water in dwindling reservoirs heats up more quickly, which can be deadly to the young fish.

The lack of snowpack could turn California’s summer and fall wildfire season into a year-round event. Unseasonal winter blazes, such as last February’s fire near Bishop, are now torching Sierra elevations that used to be blanketed with snow. The 2015 statewide wildfire count is up more than 1,500 over last year, with a huge one now threatening Kings Canyon, home to the giant sequoias that are among the oldest living things on the planet.

No sure reinforcements for the snowpack are in sight. Predictions of a major El Niño event this winter likely mean heavy rains in Southern California, but the outlook for the Sierra and its indispensable snowpack are uncertain.

The drought probably will keep coming back as global temperatures climb, Trouet and other scientists say.

A new report by the Public Policy Institute of California’s Water Policy Center gives a glimpse of the toll: At least 18 species of native California fish, including salmon and steelhead trout, face imminent extinction if current conditions continue another two or three years. The 5 million birds migrating along the Pacific Flyway annually risk starvation and disease. Cities will fare better, but strict conservation will have to become a permanent way of life. Farm losses could top $2.8 billion a year.

A grim prospect. But Hardy, like many Californians, say they’ll adapt.

“We’ve learned that adapting to the effects of light snow years is just as important as riding out long, fruitful seasons,” the ski resort spokeswoman says. Whatever happens, she says, “we plan on taking advantage of every inch of snow that we receive.”

by Lynda Brown

Earlier this year, US soil microbiologist Elaine Ingham, of Soil Foodweb Inc. fame, caused several gasps at the Oxford Real Farming Conference with her controversial lecture, ‘The Roots of your Profits’. I recommend anyone interested in joined-up thinking about health to listen to this and view her slide presentation.

Put bluntly, Ingham’s message is that if you are interested in health, you have to be interested in soil. This lecture, and her work in general, brilliantly explains why.

Time to take a deep breath, prepare to have conventional thinking about soil turned on its head and find out why soil biology should matter to you.

Soil vs dirt

As most of us have realised, soil is not merely a prop for plants or ‘ terra firma ‘ for the biosphere; it is an infinitely complex underworld and inter-dependent web of micro-organisms such as bacteria, fungi, protozoa, nematodes and micro-arthropods to name a few.

It is this hidden world that allows our planet and our society to thrive. It is every bit as important to our health as breath itself.

But far from nurturing the soil that feeds us, agriculture often destroys it. Every time the soil is disturbed, or artificial fertilisers and pesticides are applied, soil life is killed and soil structure compromised.

Soil erosion, the leaching of water and nutrients, anaerobic conditions, pests and diseases all follow. The system gradually collapses and eventually the soil – now bereft of soil life – is degraded so much it becomes mere dirt.

It’s a self-perpetuating cycle of destruction, and farmers then have to devote their energy to dealing with the destructive knock-on effects.

Myth bashing

For Ingham, agriculture should be the art of nurturing soil life. It’s essential to understand what makes the life in soil tick – and conversely what destroys it – as well as how to manage soil life so it works to overcome the challenges that producing food presents. Get your soil biology right – ensuring the ‘good guys’ (aerobic micro-organisms) flourish and are in balance – and the rest falls into place.

Forget the latest farm app: the most essential piece of equipment a farmer or grower can have is a microscope. And the one skill she or he needs above all else is how to make aerobic compost and compost teas. It is these that contain the necessary microorganisms for soil health. Applied correctly, this is the only magic bullet you’ll ever need. It’s as simple as that.

But Ingham also goes further. She has no time for wasting money on soil tests, pointing out that during her lifetime the number of plant nutrients considered to be essential has increased from 3 to more than 40. Who can say what a plant needs, except the plant itself?

Applying this mineral or that fertiliser, Ingham says, is also a waste of money. Assays of plant tissues reveal that the nutrients present bear no relationship whatsoever to any soluble artificial nutrients applied. A plant requires all nutrients to a greater or lesser extent, and only it knows what it needs and when – the trick is having all those nutrients in a bio-available form in the soil at all times.

She also blows away the myth of pH, the measure of soil acidity or alkalinity. Since when, she asks, has nature said a pH 6.5 is ideal for crops, when they grow successfully in ranges from 5.5-11? Soil pH varies so widely even along a root hair that an average value is meaningless. It isn’t the soil pH that needs analysing, it’s the soil’s microbial life.

Even more controversially, Ingham points out that all soils on the planet have enough (inorganic) nutrients locked up in their mineral particles (that is, particles derived from rocks) to feed plants for the next 10,000 billion years. What?!

The only reason the Green Revolution worked is that it fed dirt, not soil. Sustainable intensification? Forget it. It won’t work because it can’t: it still relies on the chemical inputs that destroy soil life. Get your soil biology right, and you don’t need to spread manure, rotate crops or till soil. (At this point, even the organic farmers at the Oxford conference winced.)

Theory into practice

Ingham has spent the past 40 years putting her knowledge into practice and training farmers, growers and gardeners to become soil doctors. She has achieved impressive results. Pasture grasses, for example, have increased rooting depth and protein content has gone up from 5%-25%.

But to understand why her followers achieve the results they do requires a basic primer in the evolutionary relationship between plants and soil life.

Nature’s elegant solution

Plants use sunlight to make sugars; they then send most of these to their roots as exudates (substances that ooze out from plant tissue) – or, as Ingham puts it, they deliver ‘cakes and cookies’ to the soil for aerobic bacteria and fungi to feed on, encouraging them to amass around the roots and prosper.

These ‘good guys’ have three important functions: they form a protective army to fight off the ‘bad guys’ (anaerobic micro-organisms responsible for disease); they contain the necessary enzymes and acids to break down and transform inorganic nutrients in soil particles into organic nutrients suitable for plants; and they play a critical role in the formation of soils’ structure, which is necessary for water retention, preventing the leaching of nutrients.

Why, then, do you need an armoury of chemicals when nature has already provided a ready-made solution?

Why life needs death and death creates life

At this stage, the nutrients that plants need are still locked up in the microorganisms, and are only released when the latter die. To enable this, nature has evolved predators – creatures that eat other creatures for their food – to create food chains and thus ensure constant nutrient recycling.

In this case, the predators are protozoa, which eat bacteria, nematodes and micro-arthropods, which eat fungi. These predators then excrete the excess nutrients – now bio-available – into the surrounding soil, creating a constantly replenishing supply of food around the plant roots, where they are needed. Clever, isn’t it?

We can see why predators are necessary for plant life, and why we are better working with the fundamental rules of nature than against them. As Ingham has pointed out, Mother Nature doesn’t need human beings, but we need Mother Nature. It’s a one-way street. This is why we have to go back to soil biology to reform agriculture from the ground up. As she says, it’s the only way forward if human beings are to remain on this planet.

Compost: the key to sustaining life

The evolution of plant life is intimately bound up with the soil biology prevalent during its development. The types and ratios, for example, of bacteria, fungi and other microorganisms determine what crops will flourish, and enable evolutionary succession to take place.

It follows that what grows where is a good indicator of your soil biology; and it provides clues to where the imbalances might be in the soil, which are preventing you from growing the best crops you can. Again, the simple, quick and easy way to fix this is to ‘inoculate’ the soil with the correct compost.

This is why compost is the nearest farming gets to a cure-all: it holds the key to sustaining life. It’s cheap and easy, and as soils become self-sustaining, the problems go away and crops are more productive – they become stronger, healthier and more nutritionally dense. No wonder, then, that Ingham is not popular in conventional agriculture or the chemical industry.

It’s more than a gut feeling

As Ingham’s lecture illustrates, the vital connection between healthy soils, plants, animals, people and planet is not mere rhetoric but an evolutionary truth. Patrick Holden, Chief Executive of the SFT, has also noted that the parallels between soil and human health are too obvious to ignore. Just as the ‘good guys’ in the soil promote and protect soil health, so the beneficial microbial flora in our gut (our microbiome) are essential for promoting and protecting our digestive health, and boosting our immune system.

But guess what? Antibiotics, antibacterials and antifungals impact negatively on our microbiome. One can only wonder, then, what a lifetime of food additives, junk food, pesticide residues, degraded food produced from chemical farming and even GM ingredients do to our internal ‘soil life’?

This is why the quality of the food we eat, and how we produce it, is so vital. And it is why we need to take Ingham and other whistleblowers seriously when they warn us that the quality of our soil affects the quality of our food and its fundamental ability to nourish us.

Any sufficiently advanced technology is indistinguishable from magic.
– Arthur C. Clarke

“Magic” is how humans have customarily described the soil’s natural cycles of decay and growth. Without a scientific understanding, our ancestors relied on observation and traditional practices to grow crops.

Modern chemical agriculture has been only marginally better at understanding the soil. Unable to control the natural cycles, it bypasses them with synthetic fertilizers and pesticides. Despite the outward successes of modern agriculture, its heavy-handed approach brings with it pollution, soil degradation and other ills.

In contrast, organic methods like permaculture have attempted to work with natural cycles. Despite the many insights and successful practices that have emerged, a rigorous scientific model is still lacking. Permaculture and its brethren are accused of being belief systems rather than science. It’s hard to make progress without having a common understanding of how things work.

Recently, however, soil ecology has developed to the point where we can open the lid on the black box of underground processes. We can begin to understand how micro-organisms maintain the structure and fertility of the soil. We learn that symbiotic relationships between plants and micro-organisms are not the exception but the rule.

It is no longer just compost-lovers who are excited about soil. The respected journal Science devoted an issue to ” Soils: the Final Frontier” (June 11, 2004), saying:

“In many ways the ground beneath our feet is as alien as a distant planet. The processes occurring in the top few centimenters of Earth’s surface are the basis of all life on dry land but the opacity of soil has severely limited our understanding of how it functions…. However, perspectives are beginning to change… Interest in soil is booming, spurred in part by technical advances of the past decade.”

Waiting for Dr. Ingham

It’s a chilly winter day at the San Mateo Garden Center in Northern California. Several dozen of us are drinking tea and coffee, waiting to hear soil microbiologist Dr. Elaine Ingham talk on the soil food web. We’re drawn by the promise that by understanding soil ecology, we can grow healthier plants without relying on pesticides and synthetic fertilizers. And in the long run, we’re told, it will be cheaper and easier.

Actually most of us don’t have to be convinced — we’re a cross-section of greenies from the San Francisco Peninsula: landscape designers, horticulture teachers, nursery owners, Master Gardeners, Master Composters and permaculture activists. We know Ingham’s reputation and are here to listen to the master.

At last Dr. Ingham steps to the front and we’re off. For the next two days we are inundated with dense, high intensity information that’s very different from the usual. It’s like having your head unscrewed.

She’s the kind of professor you wish you had in college. She loves her subject and invites you to share it with her.

Much of the talk around organics is vague — but not with Dr. Ingham at the helm. Ask a question or raise an objection, and she’ll come back with a detailed response, complete with references in the scientific literature. As we say in Master Gardeners: “science-based gardening advice.”

Ingham has been researching soil microbiology for over 25 years, having received her PhD in 1981. She taught at Oregon State University (Corvallis) from 1986 to 2001. She left academia to devote herself to Soil Foodweb, Inc, the consulting and testing service she started in 1996. She has published over 50 articles in refereed journals.

Years spent peering through a microscope have given her a perspective that is … different. As one aside, she remarked that humans, if viewed from outer space, would bear a remarkable resemblance to rod-shaped bacteria. As with many good biologists, she has an affection and respect for the organisms she studies.

She also has a gift for the apt metaphor that makes a technical concept come alive:

• Pests and disease are “garbage collectors” that take away stressed plants growing in the wrong habitats.
• When adding water to compost, follow the “Goldilocks Principle” (not too little, not too much – just the right amount).

After several days of lectures, I had taken over 100 pages of notes and was in danger of getting lost in the details. How to summarize Ingham’s message? One attempt:

Life on earth is sustained by a complex underground ecological system – the soil food web.

Through ignorance, we’ve disrupted the food web, in particular with ill-advised farming and gardening methods.

We can return the food web to health by restoring the soil biology.

The picture of the soil food web that Ingham presents seems to be widely accepted. Rarely however are the ideas synthesized into a coherent whole. No wonder. The concepts come from many different fields — microbiology, ecology, soil science and agronomy. Specialists absorbed in their own fields often find it difficult to see the big picture.

Beyond the big picture, Ingham does differ from other scientists. She has a higher level of passion than one expects in academia. Also, some of her specific methods and recommendations are different than the usual. For example, she and her associates developed methods of assessing soil health by making direct counts of organisms under a microscope. Among the public, she is probably best known for advocating the use of aerobic compost tea.

The rest of this article gives highlights from Ingham’s presentations, then discusses the implications of the vision. To learn more, see the list of resources at the end of this article. Especially recommended is the Soil Biology Primer, which Ingham co-authored.

Soil food web

Learning about the soil food web is like entering an alternate reality. We see the results of the microbial world in decomposition, in foods (wine and cheese, for example) and in diseases. However this world operates with numbers and at a scale that is disturbingly alien. One handful of good garden soil can contain more organisms than the number of human beings who have ever lived: 1 trillion bacteria (10 to the 12th), 10,000 protozoa, 10,000 nematodes and 25 km of fungi, according to Young and Crawford in Science magaziney.

As far as alien-ness, let’s not even talk about bacterial sex!

I had known the numbers were high and thought that the picture was hopelessly complex. What I learned, though, is that the organisms in the soil belong to a manageable number of functional groups. These can be studied and we can make generalizations about them. Ingham’s colleague, Andrew Moldenke, says:

“All soils everywhere are comprised of the same basic critter groups. What’s different about a desert, the tundra, a rainforest or a cornfield are numbers (relative densities of critters).”

The concept that ties the different groups together is the soil food web.

Energy and nutrients are passed as one group of organisms feeds on another.

At the bottom level of the food web is the decaying organic matter in the soil that ultimately came from plants. Roots are a source of nourishment for some organisms.

Feeding on the organic matter are bacteria, fungi, root-feeding nematodes (microscopic round worms) and other organisms.

Feeding on them are the first-level predators such as protozoa (one-celled organisms like amoebae), some species of nematodes and arthropods (“bugs” with jointed legs like mites and insects).

Above them are higher level predators such as those pictured.

Even in this highly simplified diagram, you can see the multiple interconnections characteristic of a food web.

Bacteria and fungi – decomposers and mutualists

The stars of the underground are the bacteria and the fungi.

Bacteria are small bundles of protein with a high percentage of nitrogen. They’re “like power plants,” according to Andrew Moldenke. If the nutrients they need are “at the precise site of the bacterium, then bacterial metabolic rate is unequaled. But everything has to be present, just like the coal and oil at a power plant.”

In contrast, Moldenke describes fungi as being “like railroad systems. They are immensely long systems of threadlike hyphae that can mobilize carbon from one region, nitrogen from another region…”

Before learning about soil ecology, I had thought that bacteria and fungi were bit players. Some caused plant diseases, I knew, but the rest seemed innocuous and uninteresting. Several things Ingham said made me realize how wrong I was.

• Bacteria and fungi evolved one billion years before plants, according to Ingham.
  — Since plants developed in a world already inhabited by bacteria and fungi, wouldn’t they evolve to take advantage of those micro-organisms?
• About 80% of plants have fungi associated with their roots (mycorrhizal fungi). The figure is from Science).
  — Something about the plant-fungi relationship must be extremely important for it to be so widespread.
• Plants can release through their roots as much as 20% of their photosynthetic production. (Figure from Science; Ingham quotes higher figures.)
  — Why would plants make this substantial investment, unless they were getting something vital from the bacteria and fungi attracted by these foods?

Among the services that bacteria and fungi provide for plants:

• Building soil structure. Bacteria glue together small aggregates (clumps of soil); fungi glue them into larger aggregates.
• Storing nutrients and releasing them in forms plants can use. A “microbial sponge” Moldenke calls the phenomenon. One way micro-organisms do this is by incorporating nitrogen and other nutrients in their own bodies – a much less leachable form than if the nutrients were in their inorganic forms
• Protecting plants against diseases and pests. Beneficial bacteria and fungi out-compete pathogens and occupy potential sites of infection on the plant.

One of the most intriguing portion of the soil is the “rhizosphere” — the soil around the plant roots. It’s a zone of intense activity, with bacteria and fungi attracted by the sugars, carbohydrates and proteins exuded by plant roots.

As usual, Ingham has striking images to describe the process. Noting that the exudates contain the same basic ingredients as used for baking (sugar, carbohydrates (flour) and protein (eggs)), she calls them “cakes and cookies.” No wonder they’re attractive.

The bacteria and fungi attracted to the roots are “the white knights fighting off the bad guys.”

Symbiotic Fungus: Wheels within wheels… life within life. Feeder root of a plant containing the nutrient-absorbing parts (dark blue) of a symbiotic fungus. Vesicular-arbuscular mycorrhizae (“VAM”) fungi like this one colonize the root systems of most plants, providing nutrients and water to the plants, as well as protection against parasitic nematodes and root rot fungi.

Fungal vs bacterial soils

Moving back from the microscopic view, the distinction between fungi and bacteria has practical consequences for farmers and gardeners. Different plant communities have different ratios of fungi to bacteria.

Bacteria dominate in early succession communities such as bare earth, weeds and vegetable. For flowers and most row crops, fungi and bacteria are in equal balance. Late succession communities such as shrubs and trees are dominated by fungi.

Knowing the bacteria/fungal ratio for the crop you’re raising, you can employ different practices to encourage one or the other. Tilling or digging, for example, favors bacteria over fungi. (Most farmland is bacteria dominated.) Ingham suggests applying compost that is right for the plants you are growing, such as fungal-dominated compost around fruit trees (very fungal around conifers) and bacterial for grass. To build soil, she says, encourage fungi.

Predators, engineers, taxicabs and shredders

The larger organisms play a variety of roles in the soil food web.

Many are predators who keep prey populations in balance.

Some of the large organisms, especially earthworms, are “engineers”, improving the architecture of the soil by creating air passages and hallways with their burrowing.

Micro-arthropods are “taxi cabs” for the less mobile smaller organisms such as bacteria, helping them spread throughout the soil and onto the leaf surfaces. In this way, they bring bacteria to where the nutrients are.

Andrew Moldenke points out that some arthropods shred dead plant parts, so that the nutrients become accessible to bacteria.

Beneficial nematode: Many species of nematodes (microcopic roundworms) in the soil are beneficial. This is an example of a nematode that feeds on bacteria. By eating the nitrogen-rich bacteria and then excreting excess nitrogen, the nematode returns nitrogen to the soil in a form which plants can use. Other species of nematode feed on fungi, on plant roots, or on other nematodes.

Restoring the soil food web

Unfortunately, scientific knowledge of the soil food web has only come in recent decades. We haven’t appreciated what the soil food web can do for us, and Ingham says that many of our common practices degrade it:

• Compacting the soil.
• Tilling, turning and digging.
• Pollution.
• Pesticides.
• Synthetic fertilizers.

The degraded food web invites pests, disease and nutrient problems. In a vicious cycle, we attack the problems with chemical solutions which further degrade the food web.

The solution, according to Dr. Ingham, is to restore and enhance the soil biology. In her words:

“Over the last 50-60 years, the attitude has been to get rid of the bad guys through pesticides, not understanding that if you destroy the bad guys, you also get rid of the good guys. When we nuke soils and destroy life, what comes back are the bad guys.

“Put your workforce back into place. They don’t need holidays. Just make sure they’re in your soil and feed them. …. Our job is to make sure there is a diversity of micro-organisms, so plants can choose which organisms they need.”

Monitoring the soil life

The first step in restoring the soil biology is being able to diagnose it. Since we can’t look at the soil food web directly, we must rely on indirect methods. Some have suggested nematodes and springtails as indicators of soil health.

Ingham advocates a “direct count” method, in which individual organisms in a sample are counted under a microscope. Following a protocol, a trained technician counts the number of different classes of organisms (bacteria, fungi and protozoa, for example). The result is a report on the organisms estimated to be in the sample. The numbers indicate possible problems in the soil. For example, a high number of ciliates (a group of protozoa) suggests anaerobic conditions – harmful to plant life.

Other researchers have used plate counts. A soil sample is placed in a growth medium like agar, typically in a Petri dish. The number of bacterial or fungal colonies that grow from a soil sample are then counted.

Ingham maintains that this method grossly underestimates the number and variety of soil organisms. She says that the method was designed to detect and grow human disease organisms such as E. coli. In contrast, soil organisms need different conditions than the laboratory setting and growth media can provide. Only about .01 percent of soil organisms can be detected with traditional plate counts, she estimates.

Compost

Restoring soil biology requires a source of micro-organisms, and compost is ideal for that purpose. The compost should have a huge species diversity. Not just bacteria but fungi, protozoa, nematodes and microarthropods, as well as organic matter for them to feed on. The compost should be made locally, so that its soil biology is similar to the soil on which it is applied.

To people already involved with compost, Ingham’s discussion on compost-making should be familiar, if more rigorous than the usual. Most of her information comes from an Austrian family, the Luebkes, who developed the Controlled Microbial Composting (CMC) method. CMC is a thermal (hot) method, which involves frequent turning and close monitoring.

You can control the fungi-to-bacteria ratio of the compost by the raw materials you start with, and by your methods. Frequent turning, for example favors bacteria, since every time you turn a compost pile you “slice and dice” the fungal hyphae.

Fungal Strands in Compost: Not all the life in the soil food web is microscopic. Some fungi can be seen with the naked eye, as can earthworms and arthropods (such as insects, spiders and centipedes).

One thing you learn quickly about compost from Ingham: Aerobic GOOD! Anaerobic BAD!

Anaerobic bacteria – those that thrive at low levels of oxygen – are on her list of “bad guys.” Some are pathogens. The foul-smelling compounds produced under anaerobic conditions are bad for plants. Bad compost has foul odors like:

• rotten eggs (hydrogen sulfide)
• sour milk (butyric acid)
• decaying flesh (putrescine acid)
• vomit (valeric acid)
• ammonia
• vinegar (acetic acid)

Just reading the list of smells is motivation enough to keep a pile from going anaerobic.

In addition to thermal compost, Ingham’s presentation covers static (cold) compost and worm compost, which she recommends highly.

Compost tea

A keystone of Dr. Ingham’s approach is compost tea (CT), made by soaking compost in water. It’s a convenient way to the apply organisms that have grown in compost. The effect is similar to solid compost, but it’s easier to transport, and it’s the only way to apply compost organisms to leaves (foliar application).

One disadvantage is that compost teas lack the solid organic matter contained in regular compost. Without this food for the micro-organisms, the effects of compost tea do not last as long (5 years of biology vs 5 months, says Ingham).

Compost teas are not a recent invention. Ingham says they have been used in traditional agriculture since before the Roman Empire. With the chemical era, compost tea was dropped, probably because the results were variable.

Many different kinds of compost tea exist, including leachates, manure teas, anaerobic teas and passive aerobic teas. What Ingham studies and recommends is one particular variety: actively aerated compost tea (AACT). Conditions are kept aerobic by agitating the liquid or with a bubbler.

Actively aerated teas brewed from good compost make for results that can be duplicated, she says. Traditional teas, made without aeration, have variable results. And if compost tea goes anaerobic, you’ve lost most of the aerobic micro-organisms. On the other hand, she said she was interested in studying anaerobic teas and their possible benefits.

Machines for brewing compost tea in various sizes are available from manufacturers. “Caveat emptor,” (Buyer beware) Ingham says. She encourages people to read reviews and ask for data from the manufacturers. You can also make your own brewing apparatus. Ingham wrote an article explaining how for Kitchen Gardener magazine.

Some of the hints proferred by Ingham for good tea:

• Good compost.
• Good (potable) water without chlorine or chloramine.
• Good brewing machine, easy to clean.
• Appropriate temperatures
• Appropriate food for desired organisms
• Brewing times variable (about 24 hours)
• Prompt application.

To encourage bactera, add bacterial foods like sugars. For more fungi, add fungal foods like humic acid, corn meal, oatmeal and fish hydrates.

One question that puzzled me was how micro-organisms stay on plant leaves after a foliar application of compost tea. Dr. Ingham replied that bacteria quickly make slimey glue to stick to surfaces,” so they aren’t washed away.

Brewing Compost Tea: Permaculturalist Alane Weber in the middle of a compost tea brew cycle. She’s checking the smell (“Very important!” she says) and the flow in and around the mesh bags holding the compost. The brewer is a 100-gallon model from KIS, and is located at Lyngso Garden Materials, Redwood City, California. (Photo: Rick Weber / Botanical Art )

Perspective on the soil food web

( Note: this last part of the article reflects my own point of view rather than Dr. Ingham’s.)

Is compost tea the answer?

The part of Ingham’s approach that has aroused the most enthusiasm has been compost tea. It promises all the benefits a healthy food web can bring — resistance to pests and disease, better yields, more vigorous plant growth, etc. Many compost tea users seem to be happy with the results.

On the other hand, skeptics point to the paucity of scientific validation and are dubious of claims that compost tea is a cure-all. Some are suspicious of the commercialization of the process.

Dr. Ingham wisely points out the limitations of compost tea:

Compost tea is not a “silver bullet” for the problems in your yard. Other practices, such as organic fertilizing, soil amending, mulching, aeration, etc., are also important to build and sustain a healthy garden. The soil, environmental and prior chemical condition of your yard all play a role in its overall health.

So far, most of the evidence for the effectiveness of compost tea is anecdotal, she says. She doesn’t have replicated scientific studies, adding that such studies require money and resources. However, she does point to scientific studies which confirm the underlying concepts of the food web.

Determining the effects of compost tea may be complicated by the many variables in the process:

• Many preparations have been called compost tea, and the brewing process has many variables. Dr. Ingham has provided details on what she means by compost tea.
• The biology (micro-organisms)in the compost tea is wildly variable. Adding sugars or fungal food will change the nature of fungi:bacteria ratio. If compost is non-local, the resulting tea may not contain organisms adapted to the environment.
• Nature of the plant problem and the environment. For example. soils with few micro-organisms would seem to respond more dramatically to compost tea than those soils with a thriving food web.

A second difficulty is that the effects of compost tea are probably indirect rather than direct. For example, a pesticide or antibiotic tends to have a direct action on the target, perhaps by disrupting a key biological process. In contrast, a compost tea might provide resistance to disease by adding organisms that would occupy potential infection sites.

It seems rather early in the study of compost tea to make categorical pronouncements. We should remember that many organic methods that are now accepted, such as compost and non-chemical pest controls, were derided when first introduced.

With our new understandings of soil ecology, the opportunities for investigation are wide open – not only for compost tea, but for other organic and traditional practices.

Chemical and environmental models of agriculture

The soil food web gives a firmer scientific foundation for the ecological view of agriculture. The table below highlights the differences between the conventional or chemical model and the ecological model.

Many ecological ideas have been incorporated into conventional gardening and agriculture. For example Integrated Pest Management (IPM) has become part of many Ag extension programs. (see the the IPM website and the manual Pests of the Garden and Small Farm from University of Californa).

One can imagine a combination of the two models, in which environmental thinking prevailed but chemical solutions might be used on a temporary basis for intractible problems. Dr. Ingham, while fiercely opposed to the overuse of chemicals, admits that in a few cases they may be necessary as a first step in restoring some farmlands.

End of the chemical era?

A shift to a more ecological agriculture may happen sooner than we think. And the reasons may be economic and political rather than environmental.

Modern agriculture developed during the 20th century, a period of cheap energy. Oil and natural gas have been abundant, and our current food system uses both freely. Estimates are that it takes 10 or more calories of fossil fuels to grow one calorie of food. Food writer Michael Pollan says that the American diet with its emphasis on corn and corn products is really an oil diet:

“Corn is the SUV of plants. Growing it the way we do requires it to guzzle fuel in the form of fertilizer, about a quarter to a third of a gallon of petroleum for each bushel.”
(Interview from the UC Berkeley News Service)

The basis of modern agriculture is nitrogen fertilizer manufactured by the energy-intensive Haber process. Since its invention in the early 1900s, the Haber process has helped avert famines as world population rose from 2 billion to 6.6 billion. Making this fertilizer requires 1% of the world’s energy supply, estimates Science magazine. (Natural gas is the usual feedstock for fertilizers; petroleum is the feedstock for many pesticides.)

Arguments aside about its successes and shortcomings, modern agriculture needs cheap fuels. Without them, it is in trouble.

Are we facing energy shortages? An increasing number of people think so. The followers of Peak Oil believe we will soon reach the peak of oil production, after which supplies will shrink and prices will go up and up. David Holmgren and others in permaculture are talking about “energy descent” – preparing for a low-energy future. Even members of the U.S. elite are worried about disruptions to the oil supply; their number includes ex-Fed Director Alan Greenspan and ex-CIA heads James Schlesinger and James Woolsey.

Supply distruptions can happen whether or not oil production has reached its peak. When the Soviet Union disintegrated in 1989, Cuba lost its source of cheap oil and other imports required for to maintain its conventional, chemical-based agriculture. It got through the crisis by turning to organic methods and restructuring its large-scale farms.

In an era in which oil, natural gas and energy in general will probably become more and more expensive, it would seem prudent to develop an agriculture that is not so dependent on them. Soils, plants, microbes and water are everywhere. The processes of ecological agriculture may be tricky (for example, the turning and monitoring of compost), but they are do-able, and they don’t require imports from far-off countries.

What to do?

Assuming the scientists are right and the soil ecology picture is correct, what next?

As a start, let’s make soil ecology a part of the culture. If people don’t know about the soil food web, they won’t value it. Are there any visionaries who can see this as a subject for science fiction or children’s books? It will take imagination, since ciliates and springtails don’t have the cuddle factor of baby mammals. The BBC had an example of what is possible, in their wild radio segment “Soil Safari” available on the Web.

Some good basic texts would be helpful. The subject cries out for photos, figures and diagrams to make the concepts vivid. The Soil Biology Primer is a good example of what can be done. Generalizations should be linked to supporting studies, so we can sort out myth from science.

A knowledge of micro-organisms and the environment will be increasingly important in public debates. Although this article has only discussed gardening and agriculture, soil ecology plays a part in global warming (a healthy soil sequesters more carbon); in trawling and disturbance of the ocean floor; in invasive organisms and restoration ecology. A few popular science books on soil ecology have been published (see List of Resources), but there is room for many more.

As I researched this article, I kept hoping to see more work by agriculture extension programs and researchers. They have the resources to do the research and education we need. Perhaps we’ll see them adopt soil ecology as a cause, as they previously took up Integrated Pest Management.

For permaculturalists and organic gardeners, the news about soil ecology should be gratifying. Many of our practices have a scientific basis and are good for the soil food web. The way is now open for more research and experimentation.

Learning more

An article, a set of CDs or even a weekend seminar can do no more than scratch the surface of soil ecology. However excellent resources are available online and in print.

A good place to start is the Soil Biology Primer, an inexpensive ($15) 48-page booklet with clear explanations and vivid photographs. Elaine Ingham is one of the co-authors. You can read the book online, but the printed version is much easier to follow (and the pictures are better!).

Dr. Ingham makes much information available free on the website of her organization, Soil Foodweb, Inc.: http://www.soilfoodweb.com/. A good entry point is “The Soil Foodweb Approach”. The website also has details on CDs, classes and other services.

Most gardening books don’t cover soil ecology well. Either they skip over it completely, or speak in vague mystical terms. Exceptions include chapters in the permaculture-oriented Edible Forest Gardens by Dave Jacke with Eric Toensmeier; and Gaia’s Garden by Toby Hemenway.

A book to look for is Teaming with Microbes: A Gardener’s Guide to the Soil Food Web by Jeff Lowenfels, due out August 15, 2006.

Two popular science books give background on soil microbiology and the environment: Under Ground: How Creatures of Mud and Dirt Shape Our World by Yvonne Baskin and Tales From the Underground: A Natural History of Subterranean Life by David W. Wolfe.

To get deeper into the science, see Soils: the Final Frontier a special issue of Science magazine (June 11, 2004). More science references are available from Elaine Ingham’s website ( SFI: Recent academic and popular information sources). Several scientific journals and textbooks are devoted to soil ecology.

Soil food web in brief

• Soil food web is important for plant growth:
  • Builds soil structure.
  • Stores nutrients and releases them in forms plants can use.
  • Protects plants against diseases and pests.
  • Can tie up salts and harmful chemicals.
  • Provides resilience and adaptation to changing conditions.
• Some bacteria and fungi form mutualistic associations with plant roots. Both plants and micro-organisms benefit.
  • Plant roots exude proteins, sugars and carbohydrates (“cakes and cookies”) which attract beneficial micro-organisms.
  • Nitrogen-fixing bacteria inhabit the roots of leguminous plants.
  • About 80% of world’s plants have symbiotic relationships with fungi (mycorrhizae).
• Compost tea is a convenient way to apply compost.
  • Actively aerated compost tea (AACT) is what Ingham studies and recommends.
  • Other compost teas and liquid amendments exist (some anaerobic).
  • Process
    • Good compost.
    • Good (potable) water without chlorine or chloramine.
    • Good brewing machine, easy to clean. Ask manufacturer for data.
    • Appropriate temperatures
    • Appropriate food for desired organisms
    • Brewing times variable (about 24 hours)
    • Prompt application.

Resources – Short list for print version

Many online resources are listed in the web version of this document.

Resources – Extended List for Web Version

Dr. Elaine Ingham and Soil Foodweb, Inc. (SFI)

For gardeners & farmers

• Jeff Lowenfels, long-time gardener and gardening columnist.
• Edible Forest Gardens by Dave Jacke; with Eric Toensmeier. Chelsea Green. 2005. Monumental two-volume work. Chapter 5 in volume 1 covers “Structures of the Underground Economy” and describes Elaine Ingham’s soil food web concepts (pages 216-234).
• Gaia’s Garden: A Guide to Home-Scale Permaculture by Toby Hemenway. Chelsea Green. 2001. Chapter 4 is devoted to “Bringing the Soil to Life.” Chelsea Green. 2001.
• University of California at Santa Cruz,” Center for Agroecology & Sustainable Food Systems
• Steve Diver of ATTRA – National Sustainable Agriculture Information Service

Soil ecology

Soil ecology (researchers)

Compost tea

Compost tea – industry & research

Bart Anderson has been a reporter, high school teacher and technical writer. He now gardens and writes on sustainability and energy issues. He is co-editor of Energy Bulletin (http://energybulletin.net). Bart has no connection with any business or group involved in compost tea. He has made worm compost and backyard compost for his own use for years, but has not tried compost tea.

• Organic Teas from Composts and Manures (Organic Farming Research Association. Richard Merrill, Cabrillo College, Calif.) -PDF. Has extensive list of articles in the literature about Compost Tea.
• Notes on Compost Teas (includes extensive list of information sources) / PDF version – Steve Diver of ATTRA – National Sustainable Agriculture Information Service
• Commercial experiences: Time for (compost) tea in the northwest (also posted here)
• FAQs about Compost Tea International Compost Tea Council
• Compost Tea – an Industry Overview PDF (Brian Rosa, North Carolina Division of Pollution Prevention and Environmental Assistance (DPPEA), NC Dept of Environment and Natural Resources
• Compost Tea Task Force Report (National Organic Standards Board, USDA)
• An Update on Compost Tea: Benefits, Risks, Regulation by Eric Sideman, Maine Organic Farmers and Gardners Association
• Evaluating the Benefits of Compost Teas to the Small Market Grower (Greenbook 2003, Energy and Sustainable Agriculture Program, Minnesota Dept. of Agriculture)
• Compost Tea to Suppress Plant Disease (Vern Grubinger, University of Vermont extension)
• Dr. Linda Chalker-Scott (WSU) (compost tea skeptic): 1 | 2 | 3

Editorial Notes: The article originally appeared in the Fall 2006 Permaculture Activist. UPDATE (Oct 27, 2008): Added Creative Commons logo.

The 1972 book Limits to Growth, which predicted our civilisation would probably collapse some time this century, has been criticised as doomsday fantasy since it was published. Back in 2002, self-styled environmental expert Bjorn Lomborg consigned it to the “dustbin of history”.

It doesn’t belong there. Research from the University of Melbourne has found the book’s forecasts are accurate, 40 years on. If we continue to track in line with the book’s scenario, expect the early stages of global collapse to start appearing soon.

Limits to Growth was commissioned by a think tank called the Club of Rome. Researchers working out of the Massachusetts Institute of Technology, including husband-and-wife team Donella and Dennis Meadows, built a computer model to track the world’s economy and environment. Called World3, this computer model was cutting edge.

The task was very ambitious. The team tracked industrialisation, population, food, use of resources, and pollution. They modelled data up to 1970, then developed a range of scenarios out to 2100, depending on whether humanity took serious action on environmental and resource issues. If that didn’t happen, the model predicted “overshoot and collapse” – in the economy, environment and population – before 2070. This was called the “business-as-usual” scenario.

The book’s central point, much criticised since, is that “the earth is finite” and the quest for unlimited growth in population, material goods etc would eventually lead to a crash.

So were they right? We decided to check in with those scenarios after 40 years. Dr Graham Turner gathered data from the UN (its department of economic and social affairs, Unesco, the food and agriculture organisation, and the UN statistics yearbook). He also checked in with the US national oceanic and atmospheric administration, the BP statistical review, and elsewhere. That data was plotted alongside the Limits to Growth scenarios.

The results show that the world is tracking pretty closely to the Limits to Growth “business-as-usual” scenario. The data doesn’t match up with other scenarios.

These graphs show real-world data (first from the MIT work, then from our research), plotted in a solid line. The dotted line shows the Limits to Growth “business-as-usual” scenario out to 2100. Up to 2010, the data is strikingly similar to the book’s forecasts.

As the MIT researchers explained in 1972, under the scenario, growing population and demands for material wealth would lead to more industrial output and pollution. The graphs show this is indeed happening. Resources are being used up at a rapid rate, pollution is rising, industrial output and food per capita is rising. The population is rising quickly.

So far, Limits to Growth checks out with reality. So what happens next?

According to the book, to feed the continued growth in industrial output there must be ever-increasing use of resources. But resources become more expensive to obtain as they are used up. As more and more capital goes towards resource extraction, industrial output per capita starts to fall – in the book, from about 2015.

As pollution mounts and industrial input into agriculture falls, food production per capita falls. Health and education services are cut back, and that combines to bring about a rise in the death rate from about 2020. Global population begins to fall from about 2030, by about half a billion people per decade. Living conditions fall to levels similar to the early 1900s.

It’s essentially resource constraints that bring about global collapse in the book. However, Limits to Growth does factor in the fallout from increasing pollution, including climate change. The book warned carbon dioxide emissions would have a “climatological effect” via “warming the atmosphere”.

As the graphs show, the University of Melbourne research has not found proof of collapse as of 2010 (although growth has already stalled in some areas). But in Limits to Growth those effects only start to bite around 2015-2030.

The first stages of decline may already have started. The Global Financial Crisis of 2007-08 and ongoing economic malaise may be a harbinger of the fallout from resource constraints. The pursuit of material wealth contributed to unsustainable levels of debt, with suddenly higher prices for food and oil contributing to defaults – and the GFC.

The issue of peak oil is critical. Many independent researchers conclude that “easy” conventional oil production has already peaked. Even the conservative International Energy Agency has warned about peak oil.

Peak oil could be the catalyst for global collapse. Some see new fossil fuel sources like shale oil, tar sands and coal seam gas as saviours, but the issue is how fast these resources can be extracted, for how long, and at what cost. If they soak up too much capital to extract the fallout would be widespread.

Our research does not indicate that collapse of the world economy, environment and population is a certainty. Nor do we claim the future will unfold exactly as the MIT researchers predicted back in 1972. Wars could break out; so could genuine global environmental leadership. Either could dramatically affect the trajectory.

But our findings should sound an alarm bell. It seems unlikely that the quest for ever-increasing growth can continue unchecked to 2100 without causing serious negative effects – and those effects might come sooner than we think.

It may be too late to convince the world’s politicians and wealthy elites to chart a different course. So to the rest of us, maybe it’s time to think about how we protect ourselves as we head into an uncertain future.

As Limits to Growth concluded in 1972:

If the present growth trends in world population, industrialisation, pollution, food production, and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next one hundred years. The most probable result will be a rather sudden and uncontrollable decline in both population and industrial capacity.

So far, there’s little to indicate they got that wrong.

A remarkable study has calculated that there are about 3 trillion trees on the planet today but this represents just 45 per cent of the total number of trees that had existed before the rise of humans.

Using a combination of satellite images, data from forestry researchers on the ground and supercomputer number-crunching, scientists have for the first time been able to accurately estimate the quantity of trees growing on all continents except Antarctica.

Previous guesses at the global number of trees were in the range of 400 billion, or about 61 trees for every person on Earth. However, the latest, more accurate study, based on 400,000 estimates of tree densities around the world, puts the total at 3.04 trillion, or roughly 422 trees per person.

However, although the actual number of trees may be about eight times higher than previously thought, the scientists warned that we are cutting them down at the rate of about 15 billion a year, with the highest losses in the tropics where some of the oldest and biggest trees live.

The scientists calculate that there are 1.39 trillion trees growing in tropical and sub-tropical forests, about 0.61 trillion in temperate regions such as the US and Europe and 0.74 trillion in the boreal forests in the higher, more northerly latitudes of Canada and Siberia.

Mapping trees globally will help us to understand the critical role they play as part of Earth’s life-support system, explained Thomas Crowther of Yale University in New Haven, Connecticut, the lead author of the study published in the journal Nature.

“Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to comprehend their global extent and distribution,” Dr Crowther said.

“They store huge amounts of carbon, are essential for the cycling of nutrients, for water and air quality, and for countless human services. Yet you ask people to estimate, within an order of magnitude, how many trees there are and they don’t know where to begin,” he said.

“I don’t know what I would have guessed, but I was certainly surprised to find that we were talking about trillions,” he added.

The researchers collated data on tree densities using satellite images as well as information from field scientists around the world and were able to make assessments on how tree numbers were affected by factors such as climate, topography, soil and human impacts.

“The diverse array of data available today allowed us to build predictive models to estimate the number of trees at regional levels,” said Henry Glick of Yale, one of the study’s co-authors.

The greatest tree density was found in the cold, boreal forests of Russia, Scandinavia and North America, but this was because the trees here tend to be younger and more stunted than those that grow in the tropical rainforests.

The largest forests, however, are those that grow in tropical regions, such as the Amazon, which are home to about 43 per cent of the world’s trees – boreal regions account for 24 per cent and temperate forests are home to 22 per cent.

The collaborative effort, which was the result of work by nearly 40 researchers from 15 countries, documented the effects of deforestation and changes in land-use – such as the conversion of pristine forest to agricultural land – on tree cover over many years.

They found that as the human population increased, then the number of trees fell, which is what happened in Europe over the past few thousand years as a result of human development.

“We’ve nearly halved the number of trees on the planet, and we’ve seen the impacts on climate and human health as a result. This study highlights how much more effort is needed if we are to restore healthy forests worldwide,” Dr Crowther said.

Simon Lewis, a researcher in global change science at University College London, said the study is the first to come up with an accurate, global estimate for the number of living trees, but he emphasised that this is not the only important part of an ecosystem.

“A plantation forest of many small trees all of the same type isn’t better than a patch of pristine Amazon rainforest with fewer very large trees of all different species,” Dr Lewis said.

“Similarly, measuring carbon storage in forests required different techniques than counting trees, as most carbon in a forest is held in a small number of large trees, not the many small trees,” he said.

“However, global overviews do allow us to see important new aspects of Earth, as the study shows that humans have removed 46 per cent of Earth’s trees, an important statistic showing the heavy influence of human activity on all ecosystems,” he added.

A new report from Citibank found that acting on climate change by investing in low-carbon energy would save the world $1.8 trillion through 2040, as compared to a business-as-usual scenario. In addition, not acting will cost an additional $44 trillion by 2060 from the “negative effects” of climate change.

The report, titled Energy Darwinism, looked at the predicted cost of energy over the coming decades, the costs of developing low carbon energy sources, and the implications of global energy choices.

“What we’re trying to do is to take an objective view at the economics of this situation and actually look at what the costs of not acting are, if the scientists are right,” Jason Channell, Global Head of Alternative Energy and Cleantech Research at Citi, told CNBC. “There is a cost to not doing this, and although there is a cost to acting, what we’re trying to do is to actually weigh up the different costs here.”

The report includes analysis of the cost of stranded assets – the idea that in order to prevent 2ºC of warming, a third of the world’s oil reserves, half of its gas reserves, and more than 80 percent of its coal reserves need to stay in the ground.

“Overall, we find that the incremental costs of action are limited (and indeed ultimately lead to savings), offer reasonable returns on investment, and should not have too detrimental an effect on global growth,” the report’s authors write. In fact, they found that the necessary investment, such as adding renewable energy sources and improving efficiency, might actually boost the global economy.

“We believe that that solution does exist,” the report states. “The incremental costs of following a low carbon path are in context limited and seem affordable, the ‘return’ on that investment is acceptable and moreover the likely avoided liabilities are enormous. Given that all things being equal cleaner air has to be preferable to pollution, a very strong ‘Why would you not?’ argument begins to develop.”

Indeed, Citibank is not the first organization to call attention to the fact that inaction on climate change comes with a big price tag.

The Obama administration has repeatedly recognized this. A report released earlier this summer by the White House’s Council of Economic Advisers found that the longer the United States waits, the more expensive mitigation will be. In his first speech as the director of the U.S. Office of Management and Budget, Shaun Donovan emphasized the budgetary importance of climate action.

“From where I sit, climate action is a must do; climate inaction is a can’t do; and climate denial scores – and I don’t mean scoring points on the board,” Donovan said. “I mean that it scores in the budget. Climate denial will cost us billions of dollars.”

Climate change has been tied to increased severe weather, such as droughts and floods. This extreme weather can be extremely expensive. Superstorm Sandy, for instance, caused $65 billion in damage.

It’s a common trope that environmental action – whether it’s reducing carbon, protecting water, or curbing smog – costs too much.

The Environmental Protection Agency’s Clean Power Plan, finalized earlier this month, is one example of the false debate between economic benefits and addressing climate change. The EPA estimated that the plan to reduce carbon emissions from power plants by 32 percent will result in $25 to 45 billion in climate and health benefits by 2030.

But several republicans said that the plan would be an economic disaster. “We’ll all be left to suffer while the President scrambles to carve out a legacy for himself, leaving a ruined economy in his wake,” said John Tidwell, director of the Oklahoma chapter of Americans for Prosperity, a Koch-funded action group. Even presidential contenders got in on the action, with Sen. Ted Cruz (R-TX), saying the plan “will cause Americans’ electricity costs to skyrocket at a time when we can least afford it.”

The Citi report was released in advance of December’s meeting of the United Nations Climate Conference on Climate Change in Paris. The conference is “the first real opportunity to reach a legally binding agreement to tackle emissions,” according to the report.