New insights on wildfire smoke could improve climate change models

Aug 27, 2013 by Marcia Goodrich
Field emission scanning electron microscope images of different categories of soot particles identified by scientists Claudio Mazzoleni and Swarup China. Each has different optical properties, and only 4 percent are uncoated, bare soot. Credit: Swarup China image

(Phys.org) —Where there's wildfire, there's smoke—a lot of it. And those vast, carbon-laden clouds released by burning biomass can play a significant role in climate change.

However, not much is known about the different types of particles in wildfire smoke and how they affect climate. Now two Michigan Technological University researchers have uncovered some of their secrets. In particular, they studied an important component of smoke that has so far been absent from most models of .

A team including Claudio Mazzoleni, an associate professor of physics, PhD student Swarup China and Michigan Tech physics alumnus Kyle Gorkowski of the Los Alamos National Laboratory, along with other LANL scientists, looked at two types of particles captured during the 2011 Las Conchas fire in New Mexico: soot, not unlike that found in ; and , tiny round blobs that are abundant in biomass smoke and composed largely of carbon and oxygen. Tar balls made up 80 percent of the particles from the Las Conchas fire, but they have not yet been integrated into most climate-change models.

China and Mazzoleni observed the soot and tar balls using a at low voltage, which enhanced the contrast between the different particles.

Tar balls, they discovered, come in two main types in the : "dark" and "bright." The dark tar balls are more oxidized, and the two types likely absorb and differently.

Soot particles are even more diverse. China and Mazzoleni identified four categories of soot, from bare to heavily coated, each with different optical properties.

Field emission scanning electron microscopy image of tar balls with an aggregation of soot particles from the Las Conchas fire. Credit: Swarup China image

The team also heated tar balls and soot in a special chamber, which baked off their coatings and provided additional insights into their composition and properties.

Determining what effects these particles have on climate goes beyond understanding how much heat they might retain. For example, water vapor condenses more readily on oxidized particles, so they can play a role in cloud formation.

So, do tar balls warm or cool the Earth? "We don't have an answer to that," Mazzoleni said. "The particles might be warming in and of themselves, but if they don't let solar radiation come down through the atmosphere, they could cool the surface. They may have strong effects, but at this point, it's not wise to say what. However, our study does provide modelers new insights on the smoke particle properties, and accounting for these properties in models might provide an answer to that question."

"The big thing we learned is that we should not forget about tar balls in climate models," China said, "especially since those models are predicting more and more wildfires."

Explore further: Wildfires may contribute more to global warming than previously predicted

More information: "Morphology and Mixing State of Individual Freshly Emitted Wildfire Carbonaceous Particles," Nature Communications www.nature.com/ncomms/2013/130704/ncomms3122/full/ncomms3122.html

Related Stories

Climate change and wildfire: Synthesis of recent findings

May 21, 2013

Concerns continue to grow about the effects of climate change on fire. Wildfires are expected to increase 50 percent across the United States under a changing climate, over 100 percent in areas of the West by 2050 as projected ...

Half of inhaled diesel soot gets stuck in the lungs: study

Jun 27, 2012

The exhaust from diesel-fuelled vehicles, wood fires and coal-driven power stations contains small particles of soot that flow out into the atmosphere. The soot is a scourge for the climate but also for human health. Now ...

Recommended for you

Image: Grand Canyon geology lessons on view

5 hours ago

The Grand Canyon in northern Arizona is a favorite for astronauts shooting photos from the International Space Station, as well as one of the best-known tourist attractions in the world. The steep walls of ...

First radar vision for Copernicus

5 hours ago

Launched on 3 April, ESA's Sentinel-1A satellite has already delivered its first radar images of Earth. They offer a tantalising glimpse of the kind of operational imagery that this new mission will provide ...

User comments : 0

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.