Forest fires will increase as the climate warms up

Because the climate warms in the coming decades, atmospheric scientists at Harvard's School of Engineering and Applied Science (SEAS) and colleagues say that the frequency of forest fires will increase in many areas. The increase in the number of these fires also adversely affects air quality due to the more occurrence of smoke.

The study, led by SEAS's Jennifer Logan, was published on June 18 in the Journal of Geophysical Research. In their study, Logan and colleagues calculated the consequences of climate change on forest fires and future air quality in the western United States. Previous studies have explored the link between climate change and the strength of fires in the West and elsewhere.Harvard's research is a first-class effort to determine the impact of future wildfires on the air quality we breathe.

Logan said: 'Warmer temperatures can dry lower bushes, leading to more serious fires when fire breaks out due to lightning or human activity. Because smoke and other elements from fire have a very bad effect on air quality, an increase in forest fires can have a big impact on human health. '

Using a series of models, scientists predict that the geographic area affected by forest fires in the western United States may increase by 50% mainly due to rising temperatures. The largest increase of burnt areas (75-175%) belongs to the Pacific Northwest forest area and the Rocky Mountains.In addition, because wildfires are more widespread in the western United States, an important type of smoke element, organic aerosol carbon will increase by an average of about 40% in the first half of this century.

To carry out the study, the team looked at the observed records of fires and meteorology for 25 years to identify the most suitable meteorological factors for predicting a burnt area for each. ecosystem in the western United States. To see how these meteorological factors change in the future, they run a global climate model until 2055 under the A1B situation for greenhouse gas emissions. This situation, one of several cases established by the Intergovernmental Panel on Climate Change, describes the world in the future with rapid economic development and the exploitation of energy balance from fossil fuels. and other fuels. This situation leads to moderate warming of the Earth's surface temperature, about 3 degrees Fahrenheit (1.6 degrees Celsius) until 2050.

This chart shows the percentage of burnt areas increased due to forest fires, from the present to 2050, by the model of Spracken et al.(2009) calculations.This model uses a moderate increase in greenhouse gas emissions and leads to a global temperature rise of 1.6 degrees Celsius (3 degrees F) by 2050. Warmer temperatures can dry out the bushes. low, resulting in more serious fires in the future.(Photo: Loretta Mickley, Harvard School of Engineering and Applications)

Logan explains: 'By hypothesizing that the similar relationship between meteorology and burnt areas will continue in the future, we can anticipate the activity of forest fires and emissions since 2000. by 2050 '.

The final step is to use an atmospheric chemical model to understand the effect of changing forest fire activity on air quality. This model, combined with the prediction of burnt areas, shows emissions, smoke and other particles released from future fires.Therefore, air quality will also decrease and lead to a more smoky sky and adversely affect people with lung and cardiovascular diseases such as asthma and chronic bronchitis.

The authors hope this study will help policy makers set standards for 'climate punishment' in connection with efforts to reduce air pollution across the United States. In addition, the study emphasizes the need for a thorough fire control plan.

The team's next plan is to focus on future wildfires and air quality in densely populated areas in California and Southwestern United States.

Logan's collaborators in this study include researcher Loretta Mickley and former postdoctoral researcher Dominick Spracklen (currently at University of Leeds) of SEAS, Rynda Hudman, and Rosemarie Yevich; Michael D. Flannigan, Canadian Forest Protection Agency; and Anthony. L. Westerling, University of California, Merced. The authors appreciate the support of the National Environmental Research Center of the US Environmental Protection Agency, and the funding of the National Aeronautics and Space Administration.

Refer:
1. Impacts of climate change from 2000 to 2050 on wildfire activity and carbonaceous aerosol concentrations in the western United States. Journal of Geophysical Research, (in press)
2. Spracklen, DV, LJ Mickley, JA Logan, RC Hudman, R. Yevich, MD Flannigan, and AL Westerling.Climate change implications from 2000 to 2050 wildfire activity and carbonaceous aerosols in the United States.J. Geophys.Res., 2009;DOI: 10.1029 / 2008JD010966