FIRE: Scientists Confirm That Nighttime Wildfire Activity Is Increasing

dWeb.News Article from Daniel Webster dWeb.News

Fig. 9 shows the heat emitted by wildfires at night compared to the day. The MODIS (black) time series spans 2003-2020 and the VIIRS (red) time series spans 2012-2020. The horizontal dotted line at 28% indicates the CONUS-wide value detected by MODIS from 2003-2020.

In a study of wildfires in the conterminous United States from 2003 to 2020 researchers found that while fire activity increased during the day in the 18-year period, it increased even more at night.

Heat sensing data from satellites showed significant increasing trends in nighttime wildfire fire activity, with a +54%, +42% and +21% increase in the annual nighttime sum of Fire Radiative Power (FRP), annual nighttime active fire pixel counts, and annual mean nighttime per-pixel values of FRP, respectively, in the latter half of the study period. Activity during the day increased also, with rates of +36%, +31%, and +7% respectively.

Analysis of coincident 1000-hour fuel moistures indicated that as fuels dried out, satellites detected increasingly larger and more intense wildfires with higher probabilities of nighttime persistence.

The information above is from the study “Large wildfire driven increases in nighttime fire activity observed across CONUS from 2003-2020,” by Patrick H. Freeborn, W. Matt Jolly, Mark A. Cochrane, and Gareth Roberts.

The reason wildfires typically exhibit less activity at night is due to diurnal changes in weather. Nighttime brings lower temperatures, lower relative humidity, decreased winds, and higher fuel moistures for light fuels.

However, a warmer climate and occasional long-term droughts can cause nighttime high temperatures and lower humidity. Drought can reduce the fuel moisture in dead and live vegetation. These changes can lead to fuels remaining at night for substantial and continuous fire spread. This is causing wildfires to burn with more intensity, spread more quickly, and have more resistance to control 24 hours a day.

About 15 to 20 years ago firefighters could usually count on wildfire activity slowing significantly at night as long as the wind was not extreme. Night shift crews were able to make significant progress in constructing firelines near fires. These days, fuel and weather conditions that allow direct attack by ground personnel at night or day have become less common in recent years. The size of fires is increasing. Megafires that blacken 100,000 acres are no longer rare.

So now what?

As fires show increasing resistance to control we need to ramp up our fuel treatments, including prescribed fires, by a factor of 10. If carefully planned, managed and monitored using all the available predictive tools, less than complete suppression of selected fires can be achieved when a season-ending weather condition is approaching.

We also need to realize that we will never be able to prevent all wildfires from burning into populated areas, so property owners must realize they have to live with fire, using FireWise principles. Here are six things that need to be done to protect fire-prone communities.

And, community destruction during extreme wildfires is a home ignition problem. Here is an excerpt from the article written by Jack Cohen and Dave Strohmaier:

Uncontrollable extreme wildfires are inevitable; however, by reducing home ignition potential within the Home Ignition Zone we can create ignition resistant homes and communities. Community wildfire risk should not be viewed as a wildfire prevention problem but a home ignition problem. It is against established wisdom to protect communities from wildfires by reducing their home ignition potential.

We also have to realize that the fire suppression manpower staffing model that was created 50 years ago is obsolete. Federal agencies are required to increase the number of Interagency Hotshot Crews as well as engine crews. Crews need to be managed so that personnel can have some downtime at home even during peak fire season. They can’t be away from home 90 percent of the time and expect to have a decent work/life balance. One National Forest will begin a pilot program in 2022 increasing the sizes of Hotshot and Engine crews to 30 and 10 people, respectively. This pilot program will increase work/life balance, and improve the availability of resources.

The reforms in the just-passed infrastructure bill to improve the pay and working conditions of firefighters must be implemented immediately. These improvements should not be slowed down, as is the practice of Federal agencies too often.

Technology should be used to improve firefighting safety and efficiency. Firefighters down to the crew supervisor level should have access to real time data about the location of the fire and other firefighting resources 24 hours a day. Communication capabilities must be strong and bomb-proof.

On the afternoon of November 16, 2021 we initiated a 24-hour online poll on Twitter, asking for firefighters’ observations about nighttime wildfire activity.

Question for experienced wildland firefighters.

In the last 7 years on large wildfires, have you seen typical fire activity at night, more nighttime fire activity, or less nighttime fire activity, compared to 8 to 20 years ago?

— Wildfire Today (@wildfiretoday) November 16, 2021

Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire. View all posts by Bill Gabbert

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