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Appendix!|!104!
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• As!of!August!2010,!a!new!version!of!WARM!includes!a!more!comprehensive!analysis!of!
composting!yard!and!food!waste!than!it!has!in!the!past.!First,!the!calculation!of!landfill!emissions!
from!organ ics!is!bas ed !on!a !first-order!decay!rate!to!better!measure!when!emissions!are!
generated.!Previous!versions!of!the!model!only!calculated!the!lifetime!methane!yield.!In!
addition,!landfill!gas!capt u re!s ys te ms!are!modeled!with!a!time!element,!assuming!systems!are!
phased!in!at!landfills.!With!these!two!new!elements,!the!model!is!able!to!estimate!the!amount!
of!methane!being!generated!at!a!particular!time!and!the!amount!of!methane!being!captured!at!
that!time.!This!new !ca lculatio n!m e tho do logy !mo st!affe cts!foo d!waste!and!grass.!The!emission!
factors!for!branc he s,!wh ich !deg rad e!a t!a!very!slo w !rate,!ch an ge d!ve ry!little.!The !ne w !em iss ion !
factor!takes!into!ac co un t!the !high er!so il!carb on !seq ue stratio n !cap acity!fo r!compost-improved!
soil!as!well!as!the!GHG!emissions!involved!in !co mposting!m ac h in er y!a n d !tra n sp o rta t ion .!
However,!the!updated!model!still!does!not!include!an!emission!factor!for!other!compostable!
materials,!like!non-recyclab le!pa pe r.!W AR M !also !do es!no t!inclu de !GH G !em issio ns!o r!em issio ns!
reductions!ass ocia ted !with !othe r!co-benefits!associated!with!the!use!of!compost,!such!as!water!
conservation!and!changes!in!fertilizer!use.!WARM!also!does!not!differentiate!between!the!
potential!for!varying!emissions!from!compost!sites!themselves!as!a!function!of!technology!(e.g.,!
anaerobic!vs.!aerobic!composting,!or!centralized!vs.!home!composting).!
• WARM!counts!long-term!carbon !seq ue stratio n!in!lan dfills,!while!ICL EI’s!GH G!Emissions!Analysis!
Protocol,!and!the!California!Air!Resources!Board!Local!Government!Operations!Protocol!do!not.!
• WARM!only!allows!comparison!against!a!single!disposal!option.!If!your!community!sends!waste!
to!more!than !on e!disp os al!facility!(for!exa m ple,!a!lan dfill!with!ga s!reco ve ry,!a!land fill!withou t!gas !
recovery,!and!a n!inc inera tor),!the n!m u ltiple !runs !of!the !model!are!required.!
• WARM!treats!international!production!–!both!of!virgin!and!recycled!materials!–!as!if!production!
in!other!c o u nt rie s!h a ve !th e !sa me!emission s!f ac to rs !(e m is sio n s !p er!t o n )!as !d o m e s tic !pr o du c tio n .!
Given!the!international!flow!of!products!and!recycled!feedstocks,!and!the!potential!for!
significant!regional!differences!in!emissions!based!on!regional!fuel!mixes!and!technology!
patterns,!this!is!a!potential!limitation.!This!is!particularly!acute!in!the!forest!carbon!
sequestration!element!of!WAR M !(for!paper!recycling!and!source!reduction),!which!is!based!
entirely!on!modeling!of!forest!management!practices!in!the!domestic!US.!Forest!managemen t!
practices,!and!the!associated!carbon!benefits/impacts!of!reducing!use!of!wood,!likely!vary!
widely!between!the!US!and!some!other!areas!of!the!world,!including!areas!that!would!supply!
virgin!fiber!to!foreign!mills!were!it!not!for!their!use!of!wastepaper!exported!from!the!US.!
• Currently,!WARM!is!not!intended!as!an!inventory!or!accounting!tool.!It!is!not!sufficiently!precise!
and!it!is!not!easily!connected!to!other!inventory!protocols.!As!mentioned!in!the!Inventories!
section,!conventional!"purist"!inventories!are!based!on!single!locations!and!designated!
timeframes .!Em ission !saving s!in!W AR M !w ill!likely!fall!outside!b oth !of !th ese !bo un da ries.!
• WARM!does!not!currently!break!emissions!and!emissions!reductions!into!the!years!in!which!
they!actually!occu r.!Ra the r,!WA R M !rolls!all!future !em ission s!an d!em issio ns!red u ction s!into!a!
single!number.!While!appropriate!for!com paring!program !options!against!each!other,!this!limits!
WARM’s!usefulness!in!inventories,!since!most!other!emissions!are!reported!in!the!years!in!which!
they!actually!occu r.!Org an ic!m ateria ls!(e.g.!cardb o ard ,!pap er,!lum be r)!hav e!av oide d!e m issions !
associated!with!source!reduction!and!recycling!that!is!time-sensitive.!!
• Forest!carbon!sequestration:!When!paper!is!recycled,!fewer!trees!are!cut!down.!This!carbon!
sequestration!reduces!the!net!emissions!associated!with!pap er!source!redu ction!and!
recycling.!The!red uc tion s!occ ur!ov er!decades,!since!every!year!following!the!actual!recycling!
or!source!reduction!event,!over!their!lifetime,!these!trees!absorb!carbon!as!they!continue!to!
grow.!