1. MET 112 Global Climate Change - Lecture 6 Wildfire Impacts Dr. Craig Clements San Jose State University Outline  Wildfires  Aerosols

3. Del Puerto Canyon Fire California July 2006 Wildland Fire is a Complex Environmental System

4.  wildfire - an unwanted fire that requires measures of control.  prescribed fires - when a fire is used to manage land resources.   Prescribed fires can be natural fires that are allowed to burn under specified conditions or fires that are ignited by resource managers.  flame length –height above ground of flame  black line – Pre-burning of fuels adjacent to a control line before igniting a prescribed burn.  head fire - A fire spreading or set to spread with the wind.  backing fire – A fire spreading or set to spread into (against) the wind. Fire Terminology

5. Burn over caused 5 firefighter fatalities Burn over caused 5 firefighter fatalities Rate of spread=20-40 mph (10-20 m s -1 ) Rate of spread=20-40 mph (10-20 m s -1 ) Flame lengths = 90 feet Flame lengths = 90 feet Convection column of up to 18,000 feet high occurred. Convection column of up to 18,000 feet high occurred. Esperanza Fire: October 26, 2006 Fire Fighter Fatalities

6. Photo by Tim Becker Prescribed Fire- used to maintain ecosystems

7. (a) (b) (c) (d) Infra-red Video Imagery During Ignition

13. Protecting Resources

14. What do wildfires emit to the atmosphere?  Stuff like…  Ash, Soot (Aerosols)  CO 2  CO  NO and NO 2 –precursors for Ozone formation

15. Atmospheric Aerosols  Microscopic liquid/solid particles –Natural sources - examples:  Volcanoes (sulfur)  Fires, dust –Dust, sulfate particles reflect incoming sunlight: ___________________ –Smoky soot absorb incoming sunlight: ____________________ Cool atmosphere warm atmosphere

16. Aerosols (II)  Natural sources include: – Dust, sea salt and volcanic emissions  Anthropogenic sources include –Automobiles, factories and biomass burning.  Biomass burning: –Anthropogenic portion: burning of large forests for agriculture  Aerosols have ‘short’ relative lifetimes –They can ‘float’ around for a few days to a week or two.  Aerosols affect the Earth’s energy balance by – reflecting incoming energy and/or –absorbing incoming shortwave and longwave radiation.  Cooling influence is stronger

17. Aerosols (III)  There are three major types of aerosols –Sulfate aerosols –Black carbon aerosols –Organic carbon aerosols –All have been increasing in concentration over the last 150 years – the industrial revolution.

18. Sulfate Aerosols  Natural source: volcanoes  Anthropogenic sources: burning of fossil fuels  90% of sulfur aerosols are anthropogenic  Example: SO 2 (sulfur dioxide- –From coal combustion  Sulfate aerosols increasing globally  Sulfate aerosols reflect incoming solar radiation. Total effect on Earth’s energy budget Cooling

19. Black Carbon (Aerosols)  Natural source: –Natural biomass burning  Anthropogenic source –incomplete combustion from coal and diesel engines; biomass burning  Also know as - ‘Elemental Carbon’ or ‘soot’  Black carbon absorbs solar radiation –It’s black so has a low albedo.  Potentially harmful if inhaled. Total effect on Earth’s energy budget –Warming

20. Organic Carbon (Aerosols)  Natural source –Natural biomass burning  Anthropogenic source –Burning fuel –Biomass burning  Produced as a result of incomplete combustion.  These aerosols are reflective Total effect on Earth’s energy budget –Cooling

21. Aerosol Observations from NASA Satellite

26. What about around the world?

27. Indirect Effect due to aerosols (I)  Certain aerosols may enhance cloud production and character  Recall how clouds form –Water vapor condenses to liquid water –This processes requires ‘cloud condensation nuclei’ –Examples of cloud condensation nuclei  Dust, salt, smoke (all of which are natural aerosols)  So, aerosols (with both natural and anthropogenic origin) –may serve as cloud condensation nuclei.

28. Indirect Effect due to aerosols (II)  More cloud condensation nuclei – would enhance cloud production  The question then is how would clouds change –Current understanding is that This processes would increase cloud albedo  This idea of enhanced cloud formation by increases in aerosols is termed –The ‘indirect effect’ of aerosols  Understanding of these processes is currently incomplete. –But model results suggest more low clouds and thus  Total effect on Earth’s energy budget –Cooling –Radiative Forcing: negative –Cirrus cloud (high clouds) production possible, but still uncertain how important.