Local and social facets of planetary boundaries: right to nutrients

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Pas and p esen biophysical edundancy o coun ies as a bu e o changes in ood supply Ma ianela Fade , Ma ia C is ina Rulli, Joel Ca e al. Local and social ace s o plane a y bounda ies: igh o nu ien s View he able o con en s o his issue, o go o he jou nal homepage o mo e 2015 En i on. Res. Le . 10 104013 (h p://iopscience.iop.o g/1748-9326/10/10/104013) Home Sea ch Collec ions Jou nals Abou Con ac us My IOPscience En i on. Res. Le . 10 (2015)104013 doi:10.1088/1748-9326/10/10/104013 LETTER Local and social ace s o plane a y bounda ies: igh o nu ien s Helena Kahiluo o 1 , Miia Kuisma 2 , Anna Kuokkanen 3 , Mi ja Mikkilä 3 and Lassi Linnanen 3 1 Na u al Resou ces Ins i u e Finland (Luke), Jokiniemenkuja 1, FI-01370 Van aa, Finland 2 Na u al Resou ces Ins i u e Finland (Luke), Lönn o inka u 5, FI-50100 Mikkeli, Finland 3 Lappeen an a Uni e si y o Technology, PO Box 20, FI-53851 Lappeen an a, Finland E-mail: helena.kahiluo o@luke.fi Keywo ds: global equi y, locali y, his o y, bo om-up assessmen , ipping poin , social plane a y bounda y, ea h sys em go e nance Supplemen a y ma e ial o his a icle is a ailable online Abs ac An h opogenic nu ien flows exceed he plane a y bounda ies. The bounda ies and he cu en excesses a y spa ially. Such a ia ions ha e bo h an ecological and a social ace . We explo ed he spa ial a ia ion using a bo om-up app oach. The local c i ical bounda ies we e de e mined h ough he cu en o accumula ed flow o he p eceding fi e yea s be o e he plane a y bounda y c i e ia we e me . Finland and E hiopia se ed as cases wi h con as ing ecology and weal h. The a ia ion in excess depends on his o ical global inequi ies in he access o nu ien s. Globally, he accumula ed use pe capi a is 2300 kg eac i e ni ogen (N )and 200 kg phospho us (P). Fo Finland, he accumula ed use pe capi a is 3400 kg N and 690 kg P, whe eas o E hiopia, i is 26 kg N and 12 kg P. The c i ical N bounda y in Finland is cu en ly exceeded by 40 kg cap −1 a −1 and he accumula ed excess is 65 kg cap −1 a −1 , while he global cu en excess is 24 kg cap −1 a −1 and he e is space in E hiopia o inc ease e en he accumula ed flow. The c i ical P bounda y is exceeded in Finland and (al hough less so)in E hiopia, bu o con a y easons: (1) he excessi e pas inflow o he ag i ood sys em in Finland and (2) he excessi e ou flow om he ag i ood sys em igge ed by defici s in inflow and was e managemen in E hiopia. The c i ical bounda ies se by Finnish ma ine sys ems a e lowe and hose se by eshwa e s a e highe han he plane a y bounda ies downscaled pe capi a. The shi o dominance o in e nal loading in wa e cou ses ep esen s a ipping poin . We conclude ha ood secu i y wi hin he sa e bounda ies equi es global edis ibu ion o nu ien s in esidues, soils and sedimen s and o igh s o use nu ien s. Bo om-up assessmen s e eal local dynamics ha shed new ligh on he ele an bounda y c i e ia and on es ima es and emedies. 1. In oduc ion Resea ch sugges s ha an h opogenic nu ien flows ha e ansg essed he uppe ole able limi s o he Ea h sys em (Rocks öm e al 2009, Ca pen e and Benne 2011, S e en e al 2015a). Beyond such ‘plane a y bounda ies’unp edic able changes ha a e di ficul o e e se a e p obable. The sa e bounda ies a y acco ding o he cha ac e is ics o local ecosys- ems. The excess in nu ien flows a ies acco ding o local c i ical bounda ies and, in addi ion, acco ding o local socio-economic ea u es ha a ec nu ien use. De e mining such spa ial a ia ions wi h hei ecologi- cal and social ace s can ad ance he unde s anding o he dynamics unde pinning he plane a y bounda ies and hei ansg ession, as well as o equi y issues (S e en e al 2015b)when alloca ing he necessa y educ ion in he flows and ailo ing he emedies o e u n o he sa e space. Plane a y bounda ies can be ansg essed by bo - om-up o cing h ough cumula i e change o by eme - gen op-down o cing h ough a sys emic change (Tu ne e al 1990,Ba noskye al 2012).Rega ding nu ien s, bo h o hese wo modes o o cing occu . Ni ogen-con aining (N)g eenhouse gas emissions and N con ibu ion o acidifica ion ep esen global o cing, while N and phospho us (P)flows o coas al and esh- wa e sys ems cons i u e local o cing. In addi ion, he human dimension o ansg essing he bounda ies h ough he excess use o nu ien s a ies a ound he OPEN ACCESS RECEIVED 4 No embe 2014 REVISED 8 Augus 2015 ACCEPTED FOR PUBLICATION 10 Augus 2015 PUBLISHED 16 Oc obe 2015 Con en om his wo k may be used unde he e ms o he C ea i e Commons A ibu ion 3.0 licence. Any u he dis ibu ion o his wo k mus main ain a ibu ion o he au ho (s)and he i le o he wo k, jou nal ci a ion and DOI. © 2015 IOP Publishing L d globe, mainly acco ding o a o dabili y, illus a ing he spa ial inequi y. I espec i eo he oleo global o cing, plane a y bounda ies a e ansg essed by local ac ions and he gaps (i.e., he excess use o nu ien s),mus be b idged locally. In ligh o he in e egional linkages o spa ial equi y, global ac ions may also be equi ed. Humani y’s ood supply depends on N and P, he wo elemen s mos limi ing o ag icul u e. In addi ion, 74% o he con e sion o a mosphe ic N 2 o eac i e N (N )and 80% o P flows o wa e sys ems se e ag i ood sys ems (Kahiluo o e al 2014a). The global spa ial a ia- ion in c op yield is p ima ily nu ien and wa e -limi ed (Muelle e al 2012).The a ia ioninnu ien use ela- i e o c op up ake is ma ked: 32% o he N su plus and 40% o he P su plus occu on 10% o he global field a ea (Foley e al 2011). The his o ical weal h- ela ed a - ia ion in nu ien use is eflec ed in he cu en local ese es in field soils, wa e sys ems and esidues. These ese es essen ially influence cu en c op yields and he equi emen o e ilize applica ion o main ain ag i- cul u al p oduc i i y. The u bulence in global ood p i- ces in ecen yea s has agg a a ed ood insecu i y mos hea ily in he coun ies elying on ood impo s and especially among he u al poo (Comp on e al 2010, FAO 2011,Headey2011), emphasizing he impo ance o esou ce dis ibu ion o ood p oduc ion. P io assessmen s o plane a y bounda ies exclu- ded he dimension o spa ial and empo al social-eco- logical a ia ion. In his s udy, we quan i y he spa ial a ia ion o c i ical nu ien bounda ies and he dis- ance om he bounda y, i.e., excess in nu ien flows o capaci y o inc ease hose flows, aking in o accoun he his o ical nu ien accumula ion. Then we assess he a ia ion in he p opo ions o ag i ood sys ems o he eac i e nu ien flows. We downscale he pla- ne a y nu ien bounda ies h ough e en pe capi a dis ibu ion and compa e hem o he locally de e - mined c i ical nu ien bounda ies o Finland wi h a agile ecology, and o he socio-ecologically con as - ing E hiopia. We posed he ollowing ques ions: 1. How can plane a y nu ien bounda ies be made spa ially explici a he na ional scale? 2. How much do c i ical nu ien bounda ies, excesses and p opo ions o ag i ood sys ems a y in space? 3. A e he ecological o socio-economic and cu en o his o ical spa ial a ia ions mo e decisi e o he excess? 2. Me hods 4 2.1. S eps in he assessmen The plane a y nu ien bounda ies p oposed by Rocks öm e al (2009), he P bounda y o eshwa e sys ems p oposed by Ca pen e and Benne (2011), and he N bounda y eassessed by de V ies e al (2013), e ised by S e en e al (2015a,b)and complemen ed by Kahiluo o e al (2014a)we e applied in he socio-ecologically con as ing local cases o Finland and E hiopia. Fi s , he p oposed plane a y nu ien bounda ies we e downscaled h ough an equal dis ibu ion wi hin he global popula ion ( able 1). The ea e , he sa e bounda ies we e locally de e mined o Finland o compa ison, based on he cha ac e is ics o he local ma ine (N, P)and eshwa e (P)ecosys ems (see sec ion 2.2). Rega ding E hiopia, he downscaled plane a y bounda ies we e used due o lack o his o ical ecological da a. To indica e he socio-economic spa ial a ia ion, he cu en and accumula ed (1900–2010)use o N and P, and P flow o wa e sys ems, we e es ima ed globally and o Finland and E hiopia (see sec ion 2.3). The excess was de e mined as he di e ence be ween he cu en o he accumu- la ed flows and he c i ical bounda y. Finally, he p opo ion o he ag i ood sys ems o he local eac i e nu ien flows was assessed. Fo he s eps in he assessmen , see also able 1. 2.2. Plane a y nu ien bounda ies: owa ds a bo om-up app oach P e iously, he plane a y N bounda y including bo h he clima ic and wa e sys em isks, was se a 20 M N a −1 (de V ies e al 2013, S e en e al 2015a, b). Fo P in oceans, he p oposed bounda y c i e ion was o a oid an ex ensi e anoxia in he nea -bo om laye s o he nex 1000 yea s (Rocks öm e al 2009). Fo P in eshwa e s, 24 mg P m −3 o wa e , which ep esen s he meso-eu ophic in e ace, i.e., a ypical a ge o limi he eu ophica ion o lakes and ese - oi s, and o P flow om e es ial ecosys ems o eshwa e sys ems, 1.2 M a −1 (Ca pen e and Ben- ne 2011)was p oposed. In his s udy, he p oposed plane a y bounda ies we e downscaled o he local case h ough an equal dis ibu ion wi hin he global popula ion o 7.0 billion in 2010 (UN 2011). When a emp ing a bo om-up app oach by locally de e mining a c i ical N bounda y, he local con e sion o he a mosphe ic N 2 o N in Finland was es ima ed. This a emp is in line wi h he s a emen o S e en e al (2015a):‘The plane a y bounda y (PB) a- mewo k is no designed o be ‘downscaled’o ‘dis- agg ega ed’ o smalle le els, such as na ions o local communi ies.’In he assessmen o he cu en N con e sion, syn he ic e ilize use in ag icul u e and o es y (153 k a −1 )(G ön oos and Nikande 2002, MMM 2008, Me la 2012, Tike 2013), o he use o Habe -Bosch N (36 k a −1 )(Galloway e al 2004, 2003, 2008), cul i a ion-induced biological N 2 fixa ion (C- BNF, 9 k a −1 )(An ikainen e al 2005, Sipiläinen e al 2012)and ossil ene gy use (42 k a −1 )(S a is ics Fin- land, 2013, 2014a,b; Minis y o Employmen and he 4 Re e ences ci ed in his sec ion a ailable in supplemen a y ma e ial. 2 En i on. Res. Le . 10 (2015)104013 H Kahiluo o e al Economy 2012)we e aken in o accoun (see Kahi- luo o e al 2014a). The mean alues o 2006–2010 we e used o all da a unless o he wise s a ed. Rega d- ing he accumula ed local N con e sion o Finland, he global bounda y downscaled o he Finnish popu- la ion (16 k a −1 )was adop ed as ou p oposed c i ical N bounda y. The N use accumula ed a e he accu- mula ed bounda y was ansg essed es ima ed (N con e sion o he global bounda y downscaled, 1900–2010, 16 000 k ). When assessing he necessa y annual educ ion o he accumula ed excess, i was assumed ha he excess would be educed du ing as many yea s as i needed o e ol e. The ecology o he Bal ic Sea was hypo hesized o se an addi ional bounda y o ha by he N con e - sion because ‘i has been deba ed whe he N o P is he mos limi ing nu ien in he Bal ic Sea’(HELCOM 2009). Reduc ions in bo h P and N a e equi ed, and he p ima y p oduc ion o he sp ing pe iod is N lim- i ed in he open basins, excep o in he Bo hnian Bay and Bo hnian Sea. The decade o he apid expansion o hypoxia in he Bal ic Sea was iden ified (Sa chuk Table 1. Spa ial a ia ion in nu ien flows, c i ical nu ien bounda ies and excess globally and locally (Finland and E hiopia). Nu ien s: ni ogen (N)(N 2 con e sion o eac i e N (N )) and phospho us (P)flow o wa e sys ems. Flow Bounda y Excess kg cap −1 kg cap −1 a −1 kg cap −1 kg cap −1 a −1 kg cap −1 kg cap −1 a −1 Global N Downscaled a 27 2.9 24 P Downscaled Oceansa 1.5 1.6 -0.1 Downscaled F eshwa e sb 1.3–4.6 0.2 1.1–4.4 Finland N Cu en Con e sionc 43 2.9 40 Cu en Bal ic Sead 43 8.4 34 Cu en Lakese No limi ing Accumula ed Con e sion 1900–2010 3,400 68 g No known 2.9 g >3400 65 g P Cu en Bal ic Seah 0.7 0.2 0.5 Cu en Lakesi 0.7 0.7 0.01 Accumula ed Bal ic Sea 1900–2010 j 44 1.3 g 0.2 0.004 g 44 1.3 g Accumula ed Lakes 1900–2010 k 39 1.5 g 4.9 0.1 g 34 1.4 g E hiopia N Cu en Con e sionc 1.7 2.9 -1.2 Accumula ed Con e sion 1900–2010 l 26 2.8 g 51 2.9 g –25 -0.1 g P Cu en F eshwa e sm 0.2 0.2 0.1 Accumula ed F eshwa e s 1900-2010 l 5.5 0.6 g 3.1 0.2 g 2.4 0.4 g a The plane a y bounda ies o N (de V ies e al 2013, S e en e al 2015a,b)and o P Rocks öm e al (2009)equally di ided o he global popula ion in 2010; o he cu en flow es ima e see Kahiluo o e al (2014a). b The plane a y bounda y es ima e o Ca pen e and Benne (2011)equally di ided o he global popula ion in 2010; o he cu en flow es ima e see Kahiluo o e al (2014a). c The downscaled plane a y bounda y see a . The local cu en a e age flow 2006–2010. d The local bounda y based on he ca ying capaci y o he Bal ic Sea and on he local a e age flow 1926–1930. The local cu en flow see c . e P limi ing ac o o eu ophica ion. The bounda y o accumula ed use: he global downscaled bounda y; he local flow exceeded ha al eady be o e 1900. The flow accumula ed 1900–2010. g Assuming ha he excess will be deple ed du ing as many yea s as i needed o e ol e. h The local bounda y based on he ca ying capaci y o he Bal ic Sea, equally di ided o he popula ion o he Bal ic Sea d ainage in 2010, and on he local a e age flow o wa e sys ems 1926–1930. The local cu en a e age flow o wa e sys ems 2006–2010. i The local bounda y based on he ca ying capaci y o local lakes and on he local a e age flow o wa e sys ems 1956–1960. The local cu en flow see h . j The bounda y o accumula ed use: he flow o wa e sys ems accumula ed (since 1900)when exceeding he local bounda y (in he end o 1930s). The flow accumula ed 1940–2010. k The bounda y o accumula ed use: he flow o wa e sys ems accumula ed (since 1900)when exceeding he local bounda y (1960). The flow accumula ed 1961–2010. l The bounda y o accumula ed use: he global downscaled bounda y.The flow accumula ed 1993–2010. m The downscaled plane a y bounda y see b . The local cu en a e age flow o wa e sys ems 2006–2010. 3 En i on. Res. Le . 10 (2015)104013 H Kahiluo o e al e al 2008; Ca s ensen e al 2014), indica ing he ans- g ession o he ca ying capaci y. The mean con e - sion o N 2 o N pe capi a in Finland o he p eceding fi e-yea pe iod (1926–1930, 47 k a −1 )was es ima ed as he c i ical N bounda y se by he Bal ic Sea. Addi- ionally, he c i ical N bounda y was assessed in ana- logy wi h he assessmen o he c i ical P bounda y, i.e., based on he mean N flow in he Bal ic Sea ca ch- men du ing ha pe iod (331 k a −1 )(HELCOM 2011, Gus a sson e al 2012, Bal ic S e n, 2013). The excess was es ima ed as he di e ence be ween ou p oposed c i ical bounda y and he cu en flow in Finland (73 k a −1 )(Biodi e si y/SYKE, 2014). Rega ding a c i ical P bounda y o he Bal ic Sea, he same bounda y c i e ion o ex ensi e hypoxia as o N was used. P is he limi ing ac o o oxic sum- me blooms o cyanobac e ia in he Bal ic Sea bo h cu en ly and, o an e en g ea e ex en , p e iously (Vah e a e al 2007, Sa chuk e al 2008, Conley 2012). Cyanobac e ia con ibu e ‘ emendous quan i ies’o N o he ecosys em, making i especially impo an o educe P loads. The P flows in he Bal ic Sea ca chmen we e es ima ed o he p eceding fi e yea s’pe iod o he apid expansion o hypoxia (1926–1930, 18 k a −1 ) (HELCOM 2011, Gus a sson e al 2012, Bal ic S e n, 2013) o define a c i ical P bounda y o he Bal ic Sea. The excess was es ima ed based on he cu en P flow in Finland (4,1 k a −1 )(Biodi e si y/SYKE, 2014). The expanding hypoxia has he e been empo ally ela ed o Pflows and no o soil P s ocks o e ilize inpu s, as S e en e al (2015a)sugges o local/ egional scales because P flows a e di ec ly ela ed o he isk o eu o- phica ion and a e compa able wi h N bounda y and ac oss spa ial (e.g., globe . Finland . E hiopia)and empo al (1960s . cu en )scales; by con as , he ela i e significance o he soil nu ien s ocks and e - ilize inpu a ies among hose scales (see Ca pen e and Benne 2011, S e en e al 2015a). The Finnish P flow o 1900–1954 was based on he ag icul u al flow in e pola ed elying on he e ilize P use in 1900–1954 and on he a io o P flow and e ilize P use in 1956–1960. The e ilize P use in 1900–1910 was assumed o be equal o ha es ima ed o 1910 (An ikainen e al 2008). Fo he accumula ed P flow, ou p oposed local c i ical bounda y o he Bal ic Sea was de e mined based on he accumula ed annual P flow o 1900–1939 (0.02 k a –1 ), i.e., un il he local P bounda y was ansg essed. The P flow accumula ed a e he accumula ed bounda y was ansg essed was es ima ed (1940–2010, 250 k ) Rega ding he Finnish lakes, o de e mine a c i ical P bounda y, he same bounda y c i e ion o ex ensi e hypoxia was used as o he Bal ic Sea and N (Rocks öm e al 2009). Eu ophica ion o Finnish lakes has since he 1960s been conside ed la gely P-limi ed. While he h esholds be ween he mul i- s abili y s ages o shallow lakes a e mul iple (Sche e and an Nes 2007), he uppe ole able limi o P flows was de e mined based on he c i e ion o expanding hypoxia (Rocks öm e al 2009)and/o ab up eu ophica ion and hen empo ally ela ed o he P flow in o he eshwa e sys em. The decade o apid eu ophica ion and expansion o hypoxia was iden ified based on (1)biological changes in he sedi- men s o obse ed lakes (Räsänen e al 1992, Me - iläinen and Hamina 1993, Kauppila e al 2002, Kauppila and Valpola 2003, Kauppila 2005, Heikkinen and Väisänen 2007, Koi unen 2008, Kihlman and Kauppila 2010, Kauppila unpublished)and (2) he de elopmen o he concen a ion o o al o bioa ail- able P (Mi ikka and Ekholm 2003, Räike e al 2003, Ekholm and Mi ikka 2006). The mean P flow o a p e- ceding fi e yea pe iod (1956–1960, 4.0 k a −1 ), o igi- na ing om sca e ed sou ces (ag icul u e 1.1 k a −1 , u al dwellings 0.5 k a −1 , o es y 0.03 k a −1 )and poin sou ces (indus y 0.6 k a −1 , municipali ies 1.8 k a −1 , and fish a ming, u a ming and pea p o- duc ion 0.0 k a −1 )was hen es ima ed (Biodi e si y/ SYKE 2014). The P flow om ag icul u e in 1955–2010 was es ima ed elying on he ag icul u al soil P s a us in 1955–2000 (Män ylah i 2002)and 2005–2009 (Uusi alo e al 2014)and on he es ima es o he flow a ailable o 1995–2010 (Biodi e si y/ SYKE 2014). The P load om field soils o he wa e - cou ses linea ly depends on soil ex ac able P (Ekholm e al 1999), and mo e han 90% o he ag icul u al load o igina es in field soils (Rekolainen e al 1995). The es ima es o P flow om popula ion cen es o 1971–2010 and om sca e ed dwellings o 1995–2010 (Biodi e si y/SYKE 2014)we e ex a- pola ed o 1955–1970 and 1955–1994, espec i ely, based on he deg ee o u baniza ion (S a is ics Finland 1997). The es ima es o P flow om indus y o 1972–2010 and om o es y o 1995–2010 (Biodi- e si y/SYKE 2014)we e ex apola ed o 1955–1971 and 1955–1994, espec i ely, based on he g ow h a e o he o es indus y (Kahiluo o 1986). The P flow om o he poin sou ces was assumed ze o be o e he fi s o ficial es ima ion in 1976 (0.025 k a −1 ; Biodi- e si y/SYKE 2014). Fo he accumula ed P flow, a local c i ical bounda y was de e mined based on he accumula ed annual P flow o 1900–1960 o he eshwa e s (0.4 k a –1 ), i.e., un il he local P bounda y was ansg essed. The P flow accumula ed a e he accumula ed bounda y was ansg essed was es i- ma ed (1961–2010, 220 k ). Fo E hiopia, he plane a y N bounda y (de V ies e al 2013, S e en e al 2015a,b)and he plane a y P bounda y o eshwa e s (Ca pen e and Ben- ne 2011)we e ansla ed o he pe capi a alloca ion by di iding he global bounda y wi h he cu en wo ld popula ion (2.9 kg N , and 0.2 kg P cap −1 a −1 ). The cu en N con e sion in E hiopia (133 k a −1 ) was es ima ed, including he syn he ic e ilize use (91 k a −1 )(FAO 2013), o he use o Habe -Bosch N (0.2 k a −1 )(Galloway e al 2003, 2004, 2008), he C-BNF (37 k a −1 )and he ossil ene gy use (4.7 k a −1 ). The C-BNF in E hiopia was assessed 4 En i on. Res. Le . 10 (2015)104013 H Kahiluo o e al assuming he global a io o C-BNF and he syn he ic e ilize use. The con e sion o N 2 o N in ossil ene gy use in E hiopia (Wo ld Bank 2014c)was asses- sed assuming he a io o N c ea ion pe ossil ene gy use in Finland. The cu en P flow o wa e sys ems in E hiopia (21 k a −1 )was assessed based on he sca ce a ailable da a on he P flow om ag icul u e (17 k a −1 )(Haileslassie e al 2005, 2007)and om sewage o u ban households (3.4 k a −1 )(Nyenje e al 2010, Wo ld Bank 2014a). Fo E hiopia, he mino accumula ed N con e sion (1800 k )was es ima ed o 1993–2010. The accumula ed P flow in E hiopia (460 k )was es ima ed conside ing he empo al (1993–2010)de elopmen o he a able land a ea (FAO 2015)and u ban popula ion (Wo ld Bank 2014a). Conclusions ega ding he p ecise es ima es wa an cau ion. 2.3. Spa ial a ia ion in nu ien use: he socio- economic ace In e ms o he G oss Domes ic P oduc (GDP, pu chasing powe pa i y)in in e na ional dolla s (In $)pe capi a, Finland is anked 24 h (36 000 In $)and E hiopia 172nd (1 240 In $)among he 182 coun ies epo ed (Wo ld Bank, 2014b). The accumula ed N and P use o 1900–2010 globally and o Finland and o 1993–2010 o E hiopia we e es ima ed (including he cu en use, see sec ion 2.2). Da a sou ces o hese es ima es included he con- e sion o N 2 o N in he Habe -Bosch p ocess o syn he ic N e ilize s, o he N chemicals (Galloway e al, 2003, 2004, 2008), C-BNF (Vi ousek e al 1997, Galloway e al 2003, 2008, An ikainen e al 2008, Sipi- läinen e al 2012)and he ossil ene gy use (N emis- sions)(S a is ics Finland 2013, 2014a, b, Galloway e al 2003, 2004, 2008, An ikainen 2007, Vi ousek e al 1997, Minis y o T ade and Indus y 1977, Wo ld Bank 2014c). Global syn he ic e ilize use was egis- e ed a 5–10 yea in e als o he pe iod 1900–1960 (Smil 2004, Smil 2000)and annually o he pe iod 1961–2010 (FAO 2013). Syn he ic e ilize use in Fin- land in 1910–1950 (An ikainen e al 2008), 1961–1993 (FAO 2013)and 1994–2010 (FAO 2013, Tike 2013, Me la 2012, MMM 2008, G ön oos and Nikande 2002)was conside ed. The es ima e o he e ilize nu ien use in E hiopia elied on he da a ha ep e- sen he pe iod 1993–2010 (FAO 2013). Rega ding P use, he es ima es o syn he ic P e i- lize use we e complemen ed by es ima es on he use o syn he ic P eed (Smil 2000; Pou iainen 2002, Lin- de holm e al 2012)and de e gen s (O and Rechbe - ge 2012, Smil 2000). The p opo ion o N con e sion in he local ag i- ood sys em consis ed o he syn he ic e ilize use, C-BNF and ossil ene gy use. The es ima e o ossil ene gy use in he Finnish ag i ood sys em was based on he GDP sha e o ag icul u e (2.8%)and oodp o- cessing indus y (7.1%)(Vii aha ju e al 2014),in E hiopia based on he GDP sha e o ag icul u e (47%)(Wo ld Bank 2015). The con ibu ion o he Finnish ag i ood sys em o he P flow o wa e sys- ems was es ima ed elying on he flows om ag i- cul u e, fish a ming, municipali ies, sca e ed dwellings and indus ies apa om he pulp and pape indus ies (Biodi e si y/SYKE, 2014).The po ion o he ag i ood sys em om P flows om municipali ies, sca e ed dwellings and indus ies was es ima ed based on he de e mined (see abo e) p opo ion o syn he ic P use in he ag i ood sys- em (89%). Figu e 1. Spa ial a ia ion in access o nu ien s. Accumula ed ni ogen (N )and phospho us (P)use (kg cap −1 )and he cu en a e age (2006–2010) ood supply (kcal cap −1 d −1 )(FAO 2014)globally and in Finland and E hiopia. 5 En i on. Res. Le . 10 (2015)104013 H Kahiluo o e al 3. Resul s 3.1. Plane a y nu ien bounda ies: owa ds a bo om-up app oach The ecology o he Bal ic Sea did no se an N bounda y based on he a oidance o a la ge-scale ocean hypoxic e en addi ional o ha based on he con e sion o N 2 o N ( able 1). I only he N flow o he Bal ic Sea was conside ed (excluding con e sion o a mosphe ic N 2 ), aflow o 13 kg, bounda y o 3.7 kg and excess o 9.4 kg N cap −1 a −1 was es ima ed. Consequen ly, he downscaled PB o N is also he p oposed c i ical N bounda y o Finland. Rega ding P, applying he global bounda y c i e ion o en imes he p e- indus ial flow would allow a u he inc ease in P flow o he sea ( able 1). Howe e , he P flow pe capi a ole a ed by he local ma ine ecology is below he global a e age. Expanded hypoxia has been eco ded since he 1930s in he Bal ic Sea, and he cu en Finnish flow o he sea clea ly exceeds ou p oposed c i ical bounda y. Fo he local lake sys em, he uppe ole able P bounda y was es ima ed o be ansg essed in he mid-1960s. In con as wi h he global s a e, he local P flow o lakes has cu en ly e u ned o wi hin he sa e bounda ies, bu he accumula ed flows exceed he co esponding sa e bounda y by 15 old. 3.2. Spa ial a ia ion in nu ien use: he socio- economic ace The highe excess in he local N flow in Finland compa ed wi h he global flow, ela i e o he sa e bounda y, is due o he di e ence in nu ien use, while he bounda y pe capi a is equal ( able 1).In 2010, he nu ien use in Finland was 41 kg N wi h 2.9 kg P, wi h he N use being one- hi d highe han bu he P use sligh ly lowe han he global a e age pe capi a. The nu ien use in E hiopia in 2010 was 2.1 kg N and 1.0 kg P capi a −1 . Fe ilize use ep e- sen s 64% o he o al N use and 74% o he o al P use o Finland and 69% and 21% o E hiopia, espec- i ely. The excess cumula ed ac oss he las cen u y e eals he en i e global spa ial dispa i y. The cumu- la ed (1900–2010)N and P uses pe capi a a e 2300 kg N and 200 kg P globally, 3400 kg N and 690 kg P o Finland, and 26 kg N and 12 kg P o E hiopia (figu e 1). While he pe capi a use o P in Finland has exceeded he global a e age since he beginning o he cen u y, peaking in 1973, he local use o N has only exceeded he global a e age since he beginning o he 1950s, peaking in 1974. I he global his o ical nu ien equi y pe capi a we e induced, and he excess in he nu ien use we e educed a he same pace as i accumula ed in Finland (1900–2010 o N and 1961–2010 o P), no u he N con e sion o i gin P flow o wa e sys ems would be possible globally o in Finland, con a y o E hiopia ( able 1). The Finnish ag i ood sys em was esponsible o 69% o he local N con e sion and o 81% o he local P flow o wa e sys ems, while he co esponding p opo ions o he E hiopian ag i ood sys em we e 98% o N con e sion and 83% o P flow o wa e sys ems. 4. Discussion 4.1. Plane a y nu ien bounda ies: owa ds a bo om-up app oach Nu ien flows ac as d i e s o o he human-induced shi s in he Ea h sys em, making i di ficul o assess he c i ical h esholds. The ‘fi s guess’on he quan i- a i e plane a y N bounda y by Rocks öm e al (2009) has been e ised by de V ies e al (2013), Kahiluo o e al (2014a)and S e en e al (2015a). The global N use al eady had exceeded he bounda y e ised by S e en e al 2015a (20 M a −1 )in 1909 and he Finnish use had al eady exceeded he downscaled plane a y N bounda y 16 k a −1 be o e he beginning o he 20 h cen u y (31 k a −1 in 1900). In E hiopia, howe e , e en he accumula ed N use may be inc eased wi hin he p oposed bounda y. N con e sion a he han eu o- phica ion as he bounda y c i e ion was suppo ed by he local si ua ion in Finland whe e N is no a limi ing ac o o eu ophica ion ei he in he local eshwa e o in he ma ine sys em (Sa chuk e al 2008). In e nal P loading and consequen N emo al igge ed by he la ges anoxic seafloo in he wo ld (Ca s ensen e al 2014)p omo es N-fixing cyanobac e ia (Vah e a e al 2007), main aining he P limi a ion. The bu e ing capaci y p o ided by he o iginally oligo ophic, shallow lakes wi h a egula ice co e (Sche e and an Nes 2007)which ep esen 10% o he spa sely popula ed Finnish a ea, ole a es g ea e pe capi a P flows han he global a e age. The pas shi o dominance o in e nal loading bo h in he local ma ine sys em and in ag icul u al lakes has made eu ophica ion p ac ically i e e sible (Ekholm e al 1997, Räike e al 2003, Ekholm and Mi ikka 2006, Vah e a e al 2007, Sa chuk e al 2008, A o ii a e al 2014). This si ua ion is eflec ed in he c i ical bounda ies o P flow o he local lake sys em de e mined he e: while he cu en flow al eady is wi hin he bounda ies, he accumula ed flow by a exceeds hem. A shi o dominance o in e nal loading ep esen s a po en ial ipping poin in he wo ld’s eshwa e sys ems and es ua ies, agg a a ed by cli- ma e change (Meie e al 2012). This obse a ion se es one goal o bo om-up assessmen s o plane a y bounda ies also e e ed o by S e en e al (2015b): ‘We emphasize ha ou subglobal-le el ocus is based on he necessi y o conside his le el o unde s and he unc ioning o he Ea h Sys em as a whole.’ 4.2. Spa ial a ia ion in nu ien use: he socio- economic ace The his o ical access o nu ien s— he c i ical esou ce o ood p oduc ion—illus a es he social 6 En i on. Res. Le . 10 (2015)104013 H Kahiluo o e al ace o plane a y nu ien bounda ies. Es ima es show ha 80% o he wo ld’s expo s o he i gin, economically exploi able P ese es o igina ed in 2011 in No h A ica (de Ridde e al 2013)whe e li le e ilize P is used because o a o dabili y issues. The excess in nu ien use is high in weal hy indus ialized coun ies such as Finland; howe e , he di e ences be ween he weal hies and poo es na ions a e declin- ing, and he e o e, he inequi y is mos eflec ed in he accumula ed ese es. In Finland he o iginally low field soil P con en inc eased by a ac o o 2.2 om 1960 o 1995 (Män ylah i 2002)wi h li le change he ea e (Aakkula and Leppänen 2014). In many o he poo es egions o he wo ld such as in sub- Saha an A ica, he use ne e eally began and small P ese es and low o ganic ma e con en wi h N and P s ocks occu in a able soils (Johns on 1986, San- chez 2002)deg aded by exploi a ion. Whe eas he i gin P ese es we e a eason o wa s in he pas (Bu ne 2005), he ecyclable ese es a e a mo e impo an asse o ealloca e as he wo ld e u ns o he c i ical bounda ies. When conside ing he accumula ed use, he e is no longe any space wi hin he c i ical bounda ies globally and in he weal hy No h o exploi i gin nu ien s. E en in he Sou h, such as in E hiopia, whe e he cu en annual con e sion a e o N can be nea ly doubled, he e is only a li le space o inc ease he accumula ed annual con e sion a e o N . The ‘ze o ole ance’ o N con e sion poses a highe chal- lenge due o he una oidable gaseous losses han o he P flow. The N losses can be educed, e.g., by epla- cing ossil ene gy wi h he anae obic diges ion o ag i- ood esidues o wi h o he enewable esou ces no compe ing o , o emi ing, nu ien s such as sola and wind powe . The nu ien esidues and ese es a e mos e ficien ly used whe e he need o a esponse o ood secu i y is highes and he local nu ien flow is leas abo e he ole able limi , as in E hiopia. 4.3. Limi s o he local ood supply The pe spec i e o he plane a y bounda ies empha- sizes he o e all ecological ole o ag i ood sys ems ela i e o he dominan Finnish iew o da e, which was based only on he ag icul u al nu ien flows o wa e s. The local sha e o he nu ien flows ha occu wi hin he ag i ood sys em (see sec ion 3.2)is a hi d highe han he local sha e o he nu ien load o wa e s ha o igina e in ag icul u e ( o N 47%, P 57%) (SYKE 2014). This di e ence is due fi s o he en i e ‘ag i ood sys em’and no only p ima y p oduc ion (‘ag icul u e’)and, second, o gaseous emissions, no only leaching o wa e sys ems, being included in he plane a y nu ien bounda y pe spec i e. P and N use, was e and emissions in a ious pa s o he ag i ood sys em such as in consump ion, ading, ood and eed p ocessing and fish a ming, in addi ion o ag icul u e, a e included. The N con e sion also co e s gaseous emissions om e ilize s and manu e and om ene gy use in e ilize manu ac u e, anspo a ion, p ocessing and ading, as well as loading o wa e sys ems. Only h ough such shi s in pe spec i es he majo o e all ole o ood o e u ning o he ‘sa e space o humani y’e en in pu ely ecological e ms (Ga ne 2011)becomes e iden , and he selec ion o means o e u n o he bounda ies while simul a- neously enhancing ood secu i y becomes b oade . Inno a ions a e necessa y o ulfil his ask, and he po en ial ood secu i y wi hin he c i ical bounda ies is no ye known. The la ge sha e o he nu ien s flowing h ough ag i ood sys ems emphasizes he need o ans o ma- ions in hose sys ems o educe he nu ien excess and secu e he local access o ood globally. In sub- Saha an A ica such as in E hiopia, he icious cycle o nu ien deple ion and insu ficien eplenishmen o N, P, po assium, sulphu and ca bon d i es he u he decline o soil o ganic ma e (Ki kby e al 2013, Kahi- luo o e al 2014b)and hus nu ien losses h ough e osion (Haileslassie e al 2005)and ca bon and N emissions, as well as leads o low p oduc i i y, limi ed nu ien flows in he ag i ood sys ems and ood inse- cu i y. Consequen ly, he c i ical P bounda y appea s o be exceeded in Finland and E hiopia o he ollow- ing con a y easons: (1)excessi e pas inflow o he ag i ood sys em in Finland, and (2)excessi e ou flow om he ag i ood sys em igge ed by defici s in he inflow and in sewage managemen in E hiopia, con- ibu ed o by imp ope managemen in bo h cases. While imp ope managemen in Finland implies ine - ficien ecycling o nu ien s due o manu e con- cen a ion, low u iliza ion o o he ag i ood esidues and excessi e e ilize use (Kahiluo o e al 2011),i implies o e exploi a ion o ag icul u al land in E hio- pia wi h insu ficien nu ien inpu s and low ecycling o esidues ha se e as odde and u he as ene gy sou ce (Rimhanen and Kahiluo o 2014). Equi y in he access o nu ien s is necessa y o inc ease he global e ficiency in nu ien use o ood. The added alue o nu ien use o c op yield and comba ing hunge may be many imes g ea e and he loads o wa e s smalle in a eas wi h a low his o ical access o nu ien esou ces. Equi y in he access o nu ien s is also a s ep owa ds access o ood despi e global p ice ola ili y, conflic s, and poo local in a- s uc u e and go e nance. The his o ical spa ial a ia- ion in wel a e limi s he p esen ag icul u al p oduc ion and consump ion wi hin he sa e bound- a ies mo e han he local ecosys em o he cu en spa- ial inequi y. The pas inequi y in access o esou ces mani es s in he nu ien ese es a ailable in soil and sedimen s and, mo e impo an ly, in he inequi y in nu i ion e iden in he social and human capaci ies oday. The unde -nu i ion o child en leads o he i e e sibly diminished physical de elopmen o he body and b ains (s un ing), educing he cogni i e 7 En i on. Res. Le . 10 (2015)104013 H Kahiluo o e al capaci ies; s un ed women being mo e likely o gi e bi h o s un ed child en (UNICEF 2014). 4.4. B idging he gap The cu en and p ojec ed u u e ailu e in e e sing he local nu ien cycles h ough educing P flow only (Ekholm and Mi ikka 2006, Ja is e al 2013, Aakkula and Leppänen 2014, Hayga h e al 2014)shows ha o a ansi ion o a low-nu ien socie y, majo echnological, social and ins i u ional inno a ions a e s ill o come. This is highligh ed by he scena io ha i nu ien inpu s a e educed o he le el ha exis ed mo e han 100 yea s ago, he Bal ic Sea would no be eco e ed e en a e 130 yea s (Sa chuk and Wul 2009). Recycling he ese es in soils (Sa a i e al 2012), in wa e biomass (Kahiluo o e al 2011)and in ag icul u al lake and ma ine sedimen s may help o es o e he ecology o wa e sys ems and he p oduc- i i y o he deg aded soils in he global Sou h, i i is based on a fi m ecological unde s anding. To mee he shown equi emen o educe nu ien use in he global No h, many means in a ious pa s o he ag i ood sys ems, such as die a y shi s and was e p e en ion, a e equi ed in addi ion o ecycling (Kahiluo o e al 2014a). Fo example, he exchange o nu ien quo a (NEFCO 2008)o a combina ion o axes (Goulde and Schein 2013)and subsidies, spa ially di e en ia ed in he global scale, may igge , finance, and complemen he ading o nu ien ese es and he igh s o use nu ien s. The plane is a social-ecological sys em. The majo complemen o he PB amewo k equi ed o se e as a sus ainabili y a ge is he social dimension o global equi y, igh ly coupled wi h he bounda ies o he key biophysical p ocesses (Rocks öm e al 2009; S e en and S a o d Smi h 2013, S e en e al 2015a,b). The ipping poin o he pi o al social bounda y, equi y in he access o nu ien s and hus o ood, equi es bo - om-up conside a ions a lowe hie a chical le els han he plane a y scale. This c i ical bounda y has been epea edly ansg essed in he pas and is cu - en ly locally ansg essed, highligh ing he impe a i e o he local social-ecological con ex when assessing and comba ing hese ansg essions. 5. Conclusions The unequal pas dis ibu ion o nu ien flows hinde s cu en equal access o nu ien s and ood. The ealloca ion o he ecyclable ese es is a p e- condi ion o achie ing ood secu i y. Spa ial a ia ion in c i ical nu ien bounda ies and, pa icula ly, in pas nu ien use highligh s he necessi y o moni o ing he cumula i e ansg ession o he bounda ies and o a wo ld-wide financing amewo k o enable he edis- ibu ion o nu ien s. Bo om-up assessmen s e eal local sys em dynamics ha u he elucida e he ele an bounda y c i e ia, es ima es and emedies. Spa ial equi y in nu ien flows implies a c i ical ac o o global equi y and human igh s, namely, he igh o ood. Acknowledgmen s The wo k was pa o he T ansi ion Towa ds Sus ain- able Nu ien Economy (NUTS)p ojec o he G een G ow h P og am o Tekes— he Finnish Funding Agency o Technology and Inno a ion. We app eci- a e he use ul discussions wi h Tommi Kauppila and Pe i Ekholm on he ecological his o y o he Finnish eshwa e sys ems. 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