Examing Tree Rings, Fire-Scars, and History to Predict Future Fires

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In this video by The YEARS Project, leading ecologist Tom Swetnam sheds light on future fires by looking into the past. Swetnam uses dendrochronology, the use of tree rings to reconstruct and evaluate variations in past and present environments, to study the natural and cultural disturbances of forest ecosystems.

Tree rings are like time capsules. Each ring tells the story of a year in the tree’s life.

“Very small, narrow ring –drought year.
Big fat, thick ring –wet year.”

–Tom Swetnam

Tom examines tree rings along with scars in fire-scarred trees to learn how fires have responded to climate changes in the past. Once Tom knows how climate affected trees in the past, he can then extrapolate how the environment will affect future fires.

“We began to see these really large high-severity fires beginning in the ’70s and ’80s–fires that were like more than 10,000, more than 20,000 acres. Then suddenly, in the late ’80s, we started seeing fires routinely in that size range. And then, since the droughts of 2000, 100,000-acre fires, 400,000-acre fires. Just last year, 500,000-acre fire.”

–Tom Swetnam

Swetnam discovered the following:
•Fires in the American West are now six times more destructive than they were just forty years ago
•Fire season is now nearly four months longer than it used to be.
•Some of today’s fires burn so hotly that they destroy the soil, preventing trees from growing back for thousands of years.

“The smoking gun is basically there. It’s getting hotter, getting dryer, and the fires are going right up along with that.”

–Tom Swetnam

Trees store vast amounts of carbon. When trees burn, the stored carbon releases into the atmosphere and further warms the climate. The warmer the climate, the higher the chance for monster fires.

“This is outside of the norm. To burn every living tree for five miles around. This is catastrophic. We’re starting to see fire behaving in ways that nobody has ever seen before. From our knowledge, with tree ring records and old historic photographs and old pioneer accounts, in these landscapes there’s just no evidence of huge fires burning big holes like that in these places anytime.”

“I really doubt that this place is coming back to forest for many, many, many lifetimes. So, if this continues for the next 20, 30, 50 years, probably could lose 50 percent of our forests.”

“And when we know that we have been the cause of this or at least a large part of the cause of this, then the responsibility, the feeling of responsibility, is even greater to do something.”

–Tom Swetnam

Eco-Labels vs. Greenwashing, Q&A With EarthTalk

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There are so many eco-labels out there these days. How can I tell which ones are valid and not just “greenwashing”? 
– Penny Rasmussen, Calumet, MN                            

With countless products now available labeled as “eco-friendly,” “safe for the environment” or “organic,” it’s hard to know which ones are actually good for the planet. Many are legitimate, but lots of others feature deceptive or unsubstantiated claims. And even the legitimate labels vary a lot in meaning. Truly valid ecolabels are awarded by independent third parties, not the companies who sell products on which they’re featured. These days many companies are placing misleading claims and nonsense labels on their products to create the illusion of environmental friendliness, a practice known as “greenwashing.”

Third parties, on the other hand, require that products meet certain specific criteria before granting the right to display their eco-label. When we know they are trustworthy, eco-labels can serve as a potent means for altering consumer behavior in a way that benefits the environment.

There are some common eco-labels that we can vouch for given decades of trustworthy certifications. The U.S. government’s ENERGY STAR label identifies products, devices, and appliances that meet stringent energy efficiency standards. If you buy an ENERGY STAR certified dishwasher, you know you’re saving energy (and money) versus other models that don’t qualify.

Another trustworthy eco-label seen often on coffee, fruits, tea, paper or furniture is “Rainforest Alliance Certified,” a designation for foods and building materials sustainably sourced from tropical rainforests. The non-profit Rainforest Alliance runs this program in part by vetting producers throughout the tropics.

These Rainforest Alliance Certified coffee plants are grown under natural shade created by native tree species on this Guatemalan coffee farm. Credit: Charlie Watson, FlickrCC.
These Rainforest Alliance Certified coffee plants are grown under natural shade created by native tree species on this Guatemalan coffee farm. Credit: Charlie Watson, FlickrCC.

If you like to know the products you buy are sourced sustainably by workers who were not exploited and were paid a living wage, look for the “Fair Trade Certified” label. Almost a million workers across 45 different countries currently benefit from the sourcing or production of Fair Trade items.

Meanwhile, the “Certified Organic” label signifies that food contains at least 95 percent organic ingredients. Plant-based foods bearing this label have not been treated with petroleum-based fertilizers or conventional pesticides, and have not been genetically modified. You can rest assured that any “Certified Organic” animal products you consume have not been treated with antibiotics or growth hormones and were fed organic feed and allowed access to the outdoors. And any products labeled “Made with Organic Ingredients” contain at least 70 percent organic ingredients.

Some other trustworthy labels include LEED, GreenSeal, FSC-Certified, Salmon-Safe, WaterSense and Non-GMO Project Verified. If the label in question isn’t mentioned above, it might be worth investigating. Sharing what you know about eco-labels, whether by word-of-mouth or via social networks, is a fantastic way of helping the environment. As awareness grows, those you have enlightened will be able to exert an ever-greater positive force upon the market.

CONTACTS: ENERGY STAR; Rainforest Alliance; Fair Trade Certified; USDA Certified Organic; LEED; Green Seal; Forest Stewardship Council; Salmon-Safe; WaterSense; Non-GMO Project Verified.

EarthTalk® is produced by Roddy Scheer & Doug Moss for the 501(c)3 nonprofit EarthTalk. Send questions to: question@earthtalk.org.

Perovskite-Based Solar, Q&A With EarthTalk

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What is perovskite-based solar all about, and how does it differ from silicon-based solar?                                             
–Mary W., Baltimore, MD

No doubt, solar power has been growing rapidly, with a 28-fold increase since 2009. This expansion has been driven mainly by a massive reduction in the cost per kilowatt of solar-generated electricity. In many regions, it’s more economical to set up solar arrays than it is to create new coal or natural gas plant. But how much further can we really take solar given that we’re already maxing out the efficiency of our panels and many regions of the world are still too dark to take advantage of them accordingly?

Perovskites: Researchers at the University of Oxford in the UK are experimenting with perovskites as the semiconductor in these small tin solar cells that could someday be on your rooftop supplying your home with free electricity. Credit: University of Oxford Press Office FlickrCC.
Researchers at the University of Oxford in the UK are experimenting with perovskites as the semiconductor in these small tin solar cells that could someday be on your rooftop supplying your home with free electricity. Credit: University of Oxford Press Office FlickrCC.

One answer might be perovskites. This calcium titanium oxide crystal found in the Earth’s mantle can be used instead of silicon as a semiconductor driving the capture and transmission of energy from solar rays to electricity. There are many different types of perovskites, but they all share the same general molecular structure. Recently, materials scientists have been working on ways to harness their unique electrical and photovoltaic properties to boost the efficiency of solar collection. They see this as an imperative, given that our current crop of silicon-based panels top out at only 20 percent efficiency in ideal conditions, and that’s after decades of research and development to optimize them.

In 2009 when research in perovskite-based solar was just beginning, panels made with the crystal showed efficiencies of around four percent. By 2018, researchers boosted this number to 24 percent. No other type of solar technology has seen an efficiency jump of this magnitude in such a short amount of time.

Several other properties add to the appeal of perovskite-based solar cells. They are relatively easy and cheap to produce and are suitable for use in applications that silicon-based panels aren’t. Perhaps most important, they can generate electricity using wavelengths of light that most of our current commercially available panels can’t harness. Researchers envision a future where perovskite panels are actually fused into a layer on top of traditional silicon panels. In this tandem application, perovskite panels would capture part of the incoming light while the rest shines through for the silicon panels below.

Despite the promise of perovskites, there are still many hurdles to overcome before they can become a viable large-scale option. One is lifespan: Silicon-based panels last between 25 and 30 years, while perovskite versions created in the lab only last a year at most. Another issue is scalability. The high efficiencies in perovskite cells that scientists have observed have only been achieved on very small (“postage stamp” sized) panels. On larger perovskite panels, the efficiencies have been much lower. The final big obstacle for perovskite researchers to overcome is toxicity. At the moment, high-efficiency perovskite cells can only be made using relatively toxic compounds, such as lead. While less toxic versions exist, they are also less efficient.

Daunting though these challenges may be, many bright minds are working to solve them. While solar power’s future is by no means certain, it is looking increasingly like this powerful little crystal will play a major role in bringing sun-derived energy into the mainstream market.

CONTACTS: Worldwide Renewable Energy Forecast 2019; Rise in Perovskite Research 2011-2015.

EarthTalk® is produced by Roddy Scheer & Doug Moss for the 501(c)3 nonprofit EarthTalk. Send questions to: question@earthtalk.org.