Black Carbon and Methane Effects on
Climate, the Arctic, and Health
Mark Z. Jacobson
Atmosphere/Energy Program
Dept. of Civil & Environmental
Engineering
Stanford University
California Air Resources Board
Sacramento, California, May 24, 2012
Impacts of Fossil+Biofuel Soot and Methane
Soot (black carbon plus organic matter and other chemicals) 1. Direct health Impacts (~1.5 million deaths/yr worldwide) 2. Second-leading cause of global warming 3. Greatest climate impacts over Arctic and other snow/ice 4. Short-lived (weeks) so its control is the fastest method of
reducing temperatures and Arctic ice loss expected in 20-30 y
Impacts of Fossil+Biofuel Soot and Methane
Methane 1. Third-leading cause of global warming
2. Greatest climate impacts over Arctic and other snow/ice
3. Moderate (8-12 y) lifetime so its control will slow loss of Arctic
4. Produces ozone globally; natural gas leaks a major source
Impacts of Soot on Climate
Impacts on clear sky Soot absorbs solar radiation. Absorption increases with coating Impacts on clouds Soot increases number, reduces size of cloud drops (indirect effects) Soot in clouds heats clouds (cloud absorption effects) Stabilizes air, reducing water/heat transfer from ground to cloud Impacts on surfaces Soot deposits to snow/sea ice, reducing their albedos Its warming evaporates surface water, increasing warming more
Arctic Sea Ice 1979-2011
nsidc.org/arcticseaicenews
Lowest years 2011 2005 2006 2007 2009
1979-2000 mean 15.6 m sq km
Burnoff of Clouds Over Asia By BC, BrC
NASA/ORBIMAGE
7
Black Carbon Emission
Black Carbon in the Air in the Clear Sky
c) Modeled UIM BC (g/m2) (1.6x10-4)
0
0.0005
0.001
0.0015
0.002
0.0025
-180 -90 0 90 180
-90
0
90
Black Carbon in Clouds
a) In-cloud/precip BC (g/m2) (4.1x10-6)
0
2· 10-5
4· 10-5
6· 10-5
-180 -90 0 90 180
-90
0
90
Black Carbon in Snow and Sea Ice
a) BC in snow and sea ice from dry dep + precip (mg/l) (0.0025)
0
0.05
0.1
0.15
0.2
-180 -90 0 90 180
-90
0
90
Brown Carbon in the Clear Sky
e) Modeled UIM tar balls (g/m2) (0.00035)
0
0.001
0.002
0.003
0.004
-180 -90 0 90 180
-90
0
90
o.iii) PM2.5
deaths/yr w-w/o FSBSG (+1.5 million)
0
50000
100000
-180 -90 0 90 180
-90
0
90
Annual Deaths Due to Fossil-Fuel plus Biofuel Soot
Annual deaths due to biofuel soot: 1.5 million/yr Annual deaths due to fossil-fuel soot: 200,000/yr
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
2000 2020 2040 2060 2080 2100
Cum
ula
tiv
e D
air
tem
per
ature
up
on
elim
inat
ing
em
issi
on a
nd a
mb
ient
Year
Fossil-fuel soot +biofuel soot & gases
Fossil-fuel soot
CO2-50 yr
Methane
CO2-30 yr
100-yr Temperature Changes Due to Eliminating
Fossil-Fuel and Biofuel Soot, CH4, CO2 Emissions
Controlling fossil-fuel plus biofuel soot and gases may be fastest method of slowing global warming and preventing loss of Arctic sea ice. www.stanford.edu/group/efmh/jacobson/controlfossilfuel.html
-2
-1
0
1
2
Tem
per
atu
re C
han
ge
Sin
ce 1
75
0 (
oC
)
Green-housegases
Fossil-fuel
+ biofuelsoot
particles
Urbanheat
island
Coolingparticles
Netobserved
globalwarming
Contributors to Global Warming
Jacobson (2010, JGR 115, D14209)
Greenhouse gas footprint of shale gas compared with other fossil fuels
(20-year integrated global warming potential for methane)
Howarth & Ingraffea, Nature, 15 September 2011
Summary
Soot (containing black and organic carbon) and methane are the second- and third-leading causes of global warming, respectively. Soot kills ~1.5 million people/yr worldwide. Methane increases ozone, which has global health impacts. Temperature increases due to both also enhance air pollution. Controlling soot and methane may be the only methods of preventing loss of the Arctic sea ice and a tipping point to more rapid global warming. www.stanford.edu/group/efmh/jacobson/Articles/VIII/controlfossilfuel.html www.stanford.edu/group/efmh/jacobson/Articles/VII/CloudAbsorption.html
