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NASA Chat: As the World Burns, NASA's Global View of Fires
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a forest fire

On an average day in August, NASA's MODIS satellite instrument typically detects some 10,000 actively burning fires around the world.(Credit: NASA)

More Information
› A Look Back at a Decade of Fires
› NASA's Visual Tour of Earth's Fires

This year, the American Southwest experienced a historic fire season that has produced some of the most extensive fires on record in Texas and Arizona. However, you may be surprised to learn that fires are relatively rare in North America in comparison to the rest of the world. In fact, satellite observations show that North American fires have produced only about 2 percent of the world’s burned area over the last decade.

Want to learn more about fires and how they affect the environment, climate change, and the air we breathe? On Wednesday, October 26 from 1 to 2 p.m. EDT, chat expert Dr. Amber Soja, a Senior Research Scientist at the National Institute of Aerospace and resident in the Climate Science and Chemistry and Dynamics Branches at NASA's Langley Research Center, will answer your questions.

More About the Chat Expert: Dr. Amber Soja

Dr. Soja's research focuses on the connections between fire regimes, the biosphere, atmosphere and climate systems. She has led and been a team member on many research campaigns and believes in the value of using satellite and field data in combination to explore the dynamic science questions that reveal the relationships between weather, fire, ecosystems and climate. Amber is a native of the Tidewater in Virginia and received her Ph.D. in Environmental Sciences from the University of Virginia.

To see regional views of fires over the last decade, visit: (Asia/Europe) (Africa) (Australia) (South America) (North America)


NASA Chat: As the World Burns, NASA's Global View of Fires
Expert: Dr. Amber Soja
Wednesday, October 26, 2011

Please note:
Dr. Soja was speaking through moderator Jennifer_LaPan who was transcribing for her during this chat. This transcript has been edited to reflect that. Where the transcript now reads Dr. Amber Soja, the chat -- as originally shared -- read Jennifer_LaPan.

In this transcript:
Questions are green.
Answers are dark gray.
Moderator posts are red.

micky: which are fire months in california?
Dr. Amber Soja: California isn't my state of expertise, but fires burn in California all year. Small agricultural and rangeland fires would burn more often in the late fall, winter, and spring. The big wildfire season in California will be in the Northern Hemisphere summer, most strongly from May through September/October.

Bob_Allen: Hi folks. Just wanted to let you know that Jennifer is transcribing and typing for Dr. Soja.

After the Chat...
Additional comments from Dr. Soja

In retrospect, I don't think I completely addressed a couple of the questions asked, so I would like to add an additional comment.

Biomass burning has both flaming and smoldering phases of combustion that are typically occurring at the same time. Fires that are dominated by flaming combustion, like grassland fires, are more efficient (cleaner burning). Fires that are dominated by smoldering combustion, like forest and even more so peatland fires, are less efficient, generating more of the gases and particulates that are harmful to our health.

When Randy Cofer was sampling smoke, he intentionally targeted the white and black colored smoke and did NOT find the distinct differences he expected. However, he did find distinct and statistical significant differences between the types of fuels that were burned, i.e. grasslands versus forests.

I would like to clarify one more statement, where I think I stated "If you can see smoke... then unhealthy". Actually if your neighborhood smells like a wood-burning stove and the neighborhood seems hazy in the distance, that is likely unhealthy air; the point is that you don't actually need to see smoke for it to be unhealthy.

micky: do you any stats of which part of world is most affected by fire?
Dr. Amber Soja: Affected how? South America is strongly affected by clearing the forest and burning. In Boreal forest, under the influence of climate change, fires are increasing and becoming more intense, altering ecosystems. This isn't happening in some distant future -- this is happening now.
Dr. Amber Soja: Africa and Australia have huge fire seasons every year.

KLB: Are fires happening more frequently around the world? If so, is climate change affecting that trend?
Dr. Amber Soja: Yes, in Boreal and Arctic regions. The jury is still out in temperate regions, under the control of climate change. In the tropics, fires are increasing because of humankind and forest clearing.

luca: hi
Dr. Amber Soja: Hello!!! Thanks for joining us.

rg: There have been a lot of fires in the great dismal swamp lately. Is there expected to be a lull for the next couple of years?
Dr. Amber Soja: The last big fire season in the Great Dismal Swamp was in 2008. There is more old forest to burn, but we hope not.
Dr. Amber Soja: The Great Dismal Swamp is introducing some endangered species in the old growth forest, so we hope not.

Bob_Allen: Just a reminder for our new guests, Jennifer is transcribing and typing on behalf of Dr. Soja.

Zalles: Can you recommend some readings that would be understandable to non-scienitists such as high school students about projected fire occurences in different regions of the US due to global warming?
Dr. Amber Soja: This is one resource - There are also really good, short movies here -- and search for "forecasting air quality," "the climate change connection," and "good fire bad fire."

Bob_Allen: Direct link to video --

rg: What caused the big fire season in 2008, weather conditions, old tree growth, or a combination of those? ALso is either expected to peak in the next couple of years?
Dr. Amber Soja: We can't currently forecast a year or two years away any more than we can forecast the weather for next year. But, climate warming is expected to produce dryer and warmer years, which results in increased fires.

AlanGould: What are your thoughts about the disastrous fires in Texas this past summer?
Dr. Amber Soja: I saw what you saw on CNN, and I have family there. It was awful for people and for animals. The weather conditions were perfect for this kind of disastrous long-term fire.

Bob_Allen: Thanks for the great questions! Keep 'em coming. mfiddler, we're working on a response to your question now.

mfiddler: What are the major current questions regarding emissions from fires? Is there some fraction of the gaseous emissions that are "missing" (should be there by simple mass balance, but have not yet been attributed to specific compounds)?
Dr. Amber Soja: Major unknowns are depth of burning over the large-scale, and we don't do a good job of capturing small fires. Missing? We understand hundreds of gases and aerosol emissions. If you are talking about air quality, then we haven't established complete health related connections. Smoke from fire isn't healthy to breathe. It first affects at-risk populations (old, young, asthma), and then affects healthy populations. It increases cases of bronchitis, respiratory illness, heart disease, causes decreased lung function, and at times causes death. If we know where smoke is going, we can give air quality warnings so that people can alter their behavior, such as not exercising outside, keeping children indoors, and filtering air.

AlanGould: Is there any relation between what causes fires and what caused the big dust storms we saw in Arizona this past summer (the Haboob) and in Texas just a couple of weeks ago?
Dr. Amber Soja: Climate and weather precipitate large fires, and I would imagine the conditions that drive dust storms, but I am not an expert on dust.

Dr. Amber Soja: Relative to a previous comment, climate change does not necessarily result in gloom and doom, but we should be aware and mindful.

Bob_Allen: We're halfway home, gang! If you've got any 'burning' questions (sorry), better ask 'em now.

mfiddler: What do you mean by "depth of burning"?
Dr. Amber Soja: How deep in the soil a fire burns. The Great Dismal Swamp fires in 2008 burned over five feet into the peatlands. Indonesian fires have been reported to burn over 15 feet into the peatlands. In a grassland fire, there would be limited burning into the soil organic matter.

Lee: Hello
Dr. Amber Soja: Welcome.

Bob_Allen: Please help us keep the good Dr. Soja busy for the full hour -- if you've got any questions at all (...about fires), feel free to ask away.

Dr. Amber Soja: This is fun answering questions about a subject I love. Anymore questions?

AVFireNews: Does the color of smoke have any indication on the quality of air? For example, is light grey smoke not as dangerous as dark grey or black smoke from wildfires?
Dr. Amber Soja: If you can see it, it's likely dangerous. Randy Cofer used NASA aircraft to analyze smoke samples his entire career, and he said that he was surprised that he didn't see more distinct differences between the smoke colors.

susan_kelly: Do you have annual global fire events in GIS format for students to observe trends?
Dr. Amber Soja: Yes. NASA has great global data in GIS. Link is coming in one second.

Bob_Allen: Here's the link --

AVFireNews: Interesting. Thank you for the answer.
Dr. Amber Soja: You are so very welcome. Thanks for joining us today.

Bob_Allen: How does studying fires help us to understand more about climate?
Dr. Amber Soja: Fire feeds back to the climate system in numerous ways. Weather and climate drive the amount and severity of fires, and fires feed back to the climate system by altering the reflectivity of the landscape, changing patterns of precipitation, and they produce greenhouse gases and aerosols, which are small organic particles. It's predicted that with climate change, fires will increase (in terms of area burned and severity), which will alter ecosystems. There is already evidence of fire-induced change in Boreal and Arctic ecosystems. This is not something that is going to happen in the distant future -- this is happening right now.

AlanGould: Are there "good fires" (beneficial) and "bad fires" and if so, what makes for a good fire, and what makes a fire bad ?
Dr. Amber Soja: Fires are a completely natural process, and ecosystems need fire – they are not all bad! But there are more fires now, and they are more severe. The fires are burning deeper and changing ecosystems. In the Tyvan Republic in Siberia, the Relic Pine Forest, which has been there since the last ice age, is disappearing. It is turning from forest to steppe, and it's not because fire area burned has increased – it is because the intensity of fires have increased. Fires are burning deeper, down to mineral soil, and the forest isn't capable of recovering. With climate change, patterns of fire and area burned and fire severity are predicted to increase. Also, ecosystems are predicted to move northward and up in altitude. Fire is a catalyst for ecosystem change, and it is forcing ecosystems to move more quickly toward a new equilibrium with the climate.

AlanGould: Will this chat be available as archive?
Dr. Amber Soja: We expect to post a transcript of the chat by the end of the week.

Bob_Allen: Reminder -- Jennifer = Dr. Soja. Jennifer is handling the transcribing and typing today.

guest: Do forest fire attribute to deforestation? Or do the trees grow back relatively quickly?
Dr. Amber Soja: In the tropics, forests evolved over millenia. Their diversity is extremely high. We have not quatified all the species that exist in the tropics. We are making species extinct that we never knew existed. These forests will not recover; they are secondary forests now. In other regions, there is normal succession and most forests will recover.

Lee: Will this forum only tackle large fires specifically?
Dr. Amber Soja: No. What do you have? We just mentioned small and agricultural fires.

Bob_Allen: How did you get interested in studying fires?
Dr. Amber Soja: I was interested in the subject of climate change and I wanted to understand if it was happening and what was happening from a scientific perspective. My advisor, Hank Shugart, said that if I was interested in studying carbon and feedbacks to the climate system, I should look where most of the land-based carbon is stored - in Boreal forest, most of which is stored in Siberia, Russia. One of the driving forces of carbon cycling is fire. Because I'm interested in large-scale changes, I need to use satellite data to study the connections that exist between ecosystems, fire, and climate.

Bob_Allen: Just a couple of minutes left! This is your (last) chance!

Bob_Allen: What do you hope to see as the next development in satellite technology for this field?
Dr. Amber Soja: I would love to see an instrument designed specifically to look at fire. We have the knowledge and technology to design this kind of instrument, but until it is important to more people to study fires, then we will find other ways to get as much information as we are able.
Lee: If taken per country or maybe globally, do small fires (such as burning of garbage) have as large an effect on the environment as other kinds of fire? I live in a small country and the quality of air has diminished.
Dr. Amber Soja: If you're living downwind of fires or in a city that has burning, small fires severely affect your health. Air quality is very bad in Africa during the burning seasons.

Bob_Allen: 4 questions in the queue!? You were saving the best for last! We're doing everything we can to get to them all.

mfiddler: Do you know if there is a published break-down on fire types (natural, cooking fires, land clearing, etc.)?
Dr. Amber Soja: In the United States, we have a National Emissions Inventory which is freely available, search through the EPA.

Bob_Allen: Good news! We've been extended to 2:15 thanks to your enthusiasm. Thanks!

KLB: Are controlled agricultural fires a bad thing for the climate? Should there be more regulation on them?
Dr. Amber Soja: In the U.S., we have right to farm laws that prevent regulation of fires on farmlands. That is changing in some states like Washington because of outcry from the public. No agricultural fires are strongly related to climate, BUT they can get out of control. In 2009, early season fires in Russia from agricultural burning led to smoke in the Arctic that could strongly feedback to climate change, more quickly melting the ice and snow, which affects the reflectivity of the solar radiation, again affecting climate.

Bob_Allen: I know I sound like a broken record, but Dr. Soja is responding through "Jennifer_LaPan" today. Jennifer's doing the transcribing and typing. We all owe her lunch!

mcarhartt: Thanks for the info on cooking fires. I do volunteer demos on solar cooking, and discussions of health and environmental hazards of cooking fires are big issues world wide--connecting to climate change as well.
Dr. Amber Soja: Thanks! I think it's a really good point -- good call.

Bob_Allen: Are there characteristics of fires that satellites are unable to detect that must be collected in person?
Dr. Amber Soja: It is more difficult to capture smoldering and peatland fires, as well as small agricultural and rangeland fires from space. However we can do fieldwork to determine how much carbon was burned and how deeply into the ground the fire burned. We can also use multiple satellite platforms to get a better view of fires because sometimes one satellite isn't enough.

Bob_Allen: Does studying fires help prevent them from happening in the future?
Dr. Amber Soja: With more information, we could better manage when and where some fires burn.

Bob_Allen: We're coming up on 2:15. Thanks for your participation in today's NASA Chat. Any last questions?

Bob_Allen: mfiddler / Lee / AVFireNews / Alan Gould -- Dr. Soja says, "You're welcome. Thanks for joining us."

mcarhartt: Do we need to use the word "burning" in our discussions of global awareness, since we might not make
Dr. Amber Soja: Is there more to this question? And this NASA Chat is As the World Burns, NASA's Global View of Fires, not global awareness.

Bob_Allen: Thanks everyone. Chat will be shutting down shortly.

mcarhartt: Might burning be a more inclusive word for students than fire, since we don't often see the fires that we create through burning coal, for example. Burning fuel( for our cars) is the term that connects our consumption to the forests...
Dr. Amber Soja: Burning is a great word -- thanks!
Dr. Amber Soja: Your point about connecting it to the forest fuel is a really good point.

Dr. Amber Soja: Thanks for joining us today. We've had some terrific questions, and a big thanks to Dr. Amber Soja for sitting down with us. We'll have a transcript up in a few days. For more chats, please keep an eye on Have a great afternoon.