Tag: climate change

What the world needs now to fight climate change: More swamps

(The Conversation) “Drain the swamp” has long meant getting rid of something distasteful. Actually, the world needs more swamps – and bogs, fens, marshes and other types of wetlands.

These are some of the most diverse and productive ecosystems on Earth. They also are underrated but irreplaceable tools for slowing the pace of climate change and protecting our communities from storms and flooding.

Scientists widely recognize that wetlands are extremely efficient at pulling carbon dioxide out of the atmosphere and converting it into living plants and carbon-rich soil. As part of a transdisciplinary team of nine wetland and climate scientists, we published a paper earlier this year that documents the multiple climate benefits provided by all types of wetlands, and their need for protection.

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Saltwater wetland, Waquoit Bay Estuarine Research Reserve, Mass. Ariana Sutton-Grier, CC BY-ND

A vanishing resource

For centuries human societies have viewed wetlands as wastelands to be “reclaimed” for higher uses. China began large-scale alteration of rivers and wetlands in 486 B.C. when it started constructing the Grand Canal, still the longest canal in the world. The Dutch drained wetlands on a large scale beginning about 1,000 years ago, but more recently have restored many of them. As a surveyor and land developer, George Washington led failed efforts to drain the Great Dismal Swamp on the border between Virginia and North Carolina.

Today many modern cities around the world are built on filled wetlands. Large-scale drainage continues, particularly in parts of Asia. Based on available data, total cumulative loss of natural wetlands is estimated to be 54 to 57 percent – an astounding transformation of our natural endowment.

Vast stores of carbon have accumulated in wetlands, in some cases over thousands of years. This has reduced atmospheric levels of carbon dioxide and methane – two key greenhouse gases that are changing Earth’s climate. If ecosystems, particularly forests and wetlands, did not remove atmospheric carbon, concentrations of carbon dioxide from human activities would increase by 28 percent more each year.

Wetland soil core taken from Todd Gulch Fen at 10,000 feet in the Colorado Rockies. The dark, carbon-rich core is about 3 feet long. Living plants at its top provide thermal insulation, keeping the soil cold enough that decomposition by microbes is very slow. William Moomaw, Tufts University, CC BY-ND

From carbon sinks to carbon sources

Wetlands continuously remove and store atmospheric carbon. Plants take it out of the atmosphere and convert it into plant tissue, and ultimately into soil when they die and decompose. At the same time, microbes in wetland soils release greenhouse gases into the atmosphere as they consume organic matter.

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Natural wetlands typically absorb more carbon than they release. But as the climate warms wetland soils, microbial metabolism increases, releasing additional greenhouse gases. In addition, draining or disturbing wetlands can release soil carbon very rapidly.

For these reasons, it is essential to protect natural, undisturbed wetlands. Wetland soil carbon, accumulated over millennia and now being released to the atmosphere at an accelerating pace, cannot be regained within the next few decades, which are a critical window for addressing climate change. In some types of wetlands, it can take decades to millennia to develop soil conditions that support net carbon accumulation. Other types, such as new saltwater wetlands, can rapidly start accumulating carbon.

Arctic permafrost, which is wetland soil that remains frozen for two consecutive years, stores nearly twice as much carbon as the current amount in the atmosphere. Because it is frozen, microbes cannot consume it. But today, permafrost is thawing rapidly, and Arctic regions that removed large amounts of carbon from the atmosphere as recently as 40 years ago are now releasing significant quantities of greenhouse gases. If current trends continue, thawing permafrost will release as much carbon by 2100 as all U.S. sources, including power plants, industry and transportation.

Kuujjuarapik is a region underlain by permafrost in Northern Canada. Nigel Roulet, McGill University., CC BY-ND

Climate services from wetlands

In addition to capturing greenhouse gases, wetlands make ecosystems and human communities more resilient in the face of climate change. For example, they store flood waters from increasingly intense rainstorms. Freshwater wetlands provide water during droughts and help cool surrounding areas when temperatures are elevated.

Salt marshes and mangrove forests protect coasts from hurricanes and storms. Coastal wetlands can even grow in height as sea level rises, protecting communities further inland.

Saltwater mangrove forest along the coast of the Biosphere Reserve in Sian Ka’an, Mexico. Ariana Sutton-Grier, CC BY-ND

But wetlands have received little attention from climate scientists and policymakers. Moreover, many wetland managers do not fully understand or integrate climate considerations into their work.

The most important international treaty for the protection of wetlands is the Ramsar Convention, which does not include provisions to conserve wetlands as a climate change strategy. While some national and subnational governments effectively protect wetlands, few do this within the context of climate change.

Forests rate their own section (Article 5) in the Paris climate agreement that calls for protecting and restoring tropical forests in developing countries. A United Nations process called Reducing Emissions from Deforestation and Degraded Forests, or REDD+ promises funding for developing countries to protect existing forests, avoid deforestation and restore degraded forests. While this covers forested wetlands and mangroves, it was not until 2016 that a voluntary provision for reporting emissions from wetlands was introduced into the U.N. climate accounting system, and only a small number of governments have taken advantage of it.

Models for wetland protection

Although global climate agreements have been slow to protect wetland carbon, promising steps are starting to occur at lower levels.

Ontario, Canada has passed legislation that is among the most protective of undeveloped lands by any government. Some of the province’s most northern peatlands, which contain minerals and potential hydroelectric resources, are underlain by permafrost that could release greenhouse gases if disturbed. The Ontario Far North Act specifically states that more than 50 percent of the land north of 51 degrees latitude is to be protected from development, and the remainder can only be developed if the cultural, ecological (diversity and carbon sequestration) and social values are not degraded.

Also in Canada, a recent study reports large increases in carbon storage from a project that restored tidal flooding to a saltmarsh near Aulac, New Brunswick, on Canada’s Bay of Fundy. The marsh had been drained by a dike for 300 years, causing loss of soil and carbon. But just six years after the dike was breached, rates of carbon accumulation in the restored marsh averaged more than five times the rate reported for a nearby mature marsh.

In our view, instead of draining swamps and weakening protections, governments at all levels should take action immediately to conserve and restore wetlands as a climate strategy. Protecting the climate and avoiding climate-associated damage from storms, flooding and droughtis a much higher use for wetlands than altering them for short-term economic gains.

Wildfire Smoke and Health: 5 Questions Answered

(The Conversation) Editor’s note: The federal government has declared a public health emergency in Northern California due to wildfires burning across 10 counties. One major threat is smoke, which is causing unhealthy air levels across a wide area, including San Francisco. Atmospheric chemist Richard Peltier explains why smoke from wildfires is hazardous and what kinds of protection are effective.

What substances in wildfire smoke are most dangerous to human health? What kinds of impacts can they have?

Wood smoke contains a mixture of microscopic droplets and particles and invisible gases that spread downwind from the fire source. Surprisingly, relatively few studies have investigated the types of exposures we are now seeing in California. Most studies focus on very controlled laboratory experiments, or forest firefighters who are working on controlled burning, or exposures people in developing nations experience when they use primitive cookstoves. None of these accurately reflects conditions that Californians are experiencing now.

Wood smoke is a very complicated mixture of material in the air, and much of it is known to affect human health. It comes from lots of different fuel sources, including mature trees, dried leaves, forest litter and, unfortunately, local homes. The emissions vary depending on what material is burning and whether it is smoldering or in flames.

For the most part, wildfire smoke is a mixture of carbon monoxide, volatile organic carbon and particles that include alkaline ash, black carbon and organic carbon, which usually contains polyaromatic hydrocarbon, a known cancer-causing agent.

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Smoke from wildfires in Northern California, Oregon, Washington, Idaho and Montana blankets much of the Pacific Northwest on Sept. 5, 2017. NASA

Is a brief exposure, say for a few hours, dangerous, or is smoke mainly a concern if it lingers for days? How does distance from the fire affect risk?

We don’t fully know how the size and length of the dose affect risks, but the longer you are exposed to pollutants from wood smoke, the higher the risk of developing smoke-related illnesses. Short-term exposures to intense smoke can lead to lung and cardiovascular problems in some people, especially if they are already susceptible to these diseases. Longer-term exposure over a few days or weeks increases the risk and the chance of health impacts as your cumulative dose increases.

Smoke tends to become more diluted with distance from the source, but there really isn’t any way to estimate a safe distance where the pollutants are so diluted that they pose no risk. Eventually rainfall will clean all of this pollution from the atmosphere, but that can take days or even weeks. In the meantime, these pollutants can travel thousands of miles. That means air pollution from wildfires may threaten people who are far downwind.

Image of a plume of high-altitude smoke from a forest fire near Alaska, observed in northern Quebec, Canada, more than 2,000 miles away. Richard Peltier, CC BY-ND

How do the worst pollution levels from the wildfires in California compare to bad air days in a megacity like Beijing or Mumbai?

The concentrations of pollution in communities downwind of these fires are on par with what we see in rapidly growing cities such as Mumbai and Beijing. But there is an important difference. In California these pollutants affect a relatively small geographic area, and the affected areas can rapidly shift with changing weather patterns. In locations like Mumbai and Beijing, high concentrations are sustained across the entire region for days or even weeks. Everyone in the community has to endure them, and there is no practical escape. For now, though, Californians are experiencing what it’s like to live in a developing country without strong air pollution controls.

How should people in smoky areas protect themselves? Are there remedies they should avoid?

The most effective way to protect yourself is by staying with friends or family who live far away from the smoke. People who can’t leave the area should close windows and doors, and apply weather sealing if they detect smoke leaking in. Even masking tape can be reasonably effective. But most houses leak outside air indoors, so this strategy isn’t foolproof.

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Portable high-efficiency filter devices – often marketed as HEPA – can remove indoor air pollution, but often are too small to be effective for an entire house. They are best used in individual rooms where people spend a great deal of time, such as a bedroom. And they can be very expensive.

N95 mask. Max-Leonhard von Schaper, CC BY

Products marketed as air fresheners that use odorants, such as scented candles or oil vaporizers that plug into an outlet, do nothing to improve air quality. They can actually make it worse. Similarly, products that “clean” the air using ozone can release ozone into your home, which is very hazardous.

Personal face mask respirators can also be effective, but not the cheap paper or cloth masks that many people in developing countries commonly use. The best choice is an N95-certified respirator, which is designed to protect workers from hazardous exposures on the job.

These masks are made of special fabric that is designed to catch particles before they can be inhaled. Paper masks are meant to protect you from contact with large droplets from someone who might be ill. N95 respirators block particles from entering your mouth and nose. They can be a little uncomfortable to wear, especially for long periods, but are pretty effective, and many retailers sell them.

What else do scientists want to know about wildfire smoke?

We have a pretty good understanding of the pollutants that wildfires emit and how they change over time, but we don’t have a firm grasp of how different health effects arise, who is most susceptible or what the long-term effects may be. It is not easy to predict where and when wildfires will occur, which makes it hard for scientists to evaluate individuals who have been exposed to smoke. Controlled laboratory studies give us some clues about what happens in the human body, but these exposures often are quite different from what happens in the real world.

The California fires are affecting thousands of people, and it is good to see that firefighters are starting to contain them. But there will be more wildfires, so we need to learn more about how smoke exposure affects people long after the fires end.