Tgp ehi Khoa hgc va Cdng nghe Bien; Tap 14, Sd 1; 2014: 18-24 ISSN: 1859-3097 http://www.vjs.ac.vn/mdex.php/jmst
KET QUA BJJdC DAU DANH GlA T A C D O N G CUA BIEN DOI KHI HAU DOI V(3l NGHE CA BIEN VIET NAM B A N G P H U ' O N G P H A P
HAM SAN XUAT
Nguyen Ngoc Thanh^ Nguyen Viet Thanh^', Dir Van Toan', Ngo Tho Hiing^
Dai hgc Tai Nguyen va Mdi trudng Ha Ngi, Viet Nam t r u d n g Dai hgc Kinh tg-Dai hgc Qude gia Ha Ngi, Vigt Nam
Tdng eye Bien va Hai Dao Vigt Nam, Vigt Nam
"Cdng Ty Cd PhSn DSu Tu Va Phat Trign Hda Phong E&C, Viet Nam E-mail; [email protected]
Ngay nhan bai: 16-12-2013
T6M TAT: Nghien cihi nay ddnh gid tdc ddng cua biin ddi khi hau ddi v&i khai thac thuy sdn Viet Nam Hdm sdn xudt dugc su dung trong nghien euu di mo hinh hda tdc dgng cia biin ddi khi hgu doi v&i sdn lugng khai nhdm ddnh gid tdc dgng cua biin ddi khi hau ddi v&i nghi cd biinVi^t Nam. DH lieu theo ehudi th&i gian tir 1976 din 2010 cua sdn lu(mg khai thac, cu&ng luc khai thac.
lao dgng nghe cd. lugng mua trung binh nhiet do trung binh. s6 lugng bao hang ndm dd du^c thu thgp va phan tich Kit qud nghien euu ban ddu cho thdy lugng mua trung binh hdng nam khu vuc ven biin co tdc ddng tieu cue din sdn lugng khai thac hdi sdn cua Viet Nam. Tuy vgy anh hu&ng ctia vi4c tdng lugng mua ddi v&i sdn lugng khai thac hdi sdn Id tuang ddi nhd so v&i cdc yiu td khac dugc nghien citu nhu cu&ng luc khai thac vd lao dgng nghi cd.
Tu khda: Biin ddi khi hdu, nghi cd biin Viet Nam, hdm sdn xudt.
GIOI THIEU
Cae nghien euu khoa hoc da chi ra rang bien doi khi hau la mdt mdi de dga nghiem tigng tren pham vi toan eau va ddi hdi tat ea cac nudc phai cung nhau hanh dgng dg phdng ngira va ngan chan cac tac dgng tieu cue do bien doi khi hau gay ra. Theo ket qua nghign ctiu ciia Stern [12], ngu eae nudc khdng cd hanh dgng de ddi phd vdi bien ddi khi hau thi thigt hgi do bien ddi khi hau gay ra ude tinh vao khoang 5-20% GDP toan cau mdi nam, trong khi dd chi phi dg giam khi thai gay higu ting nha kinh nham ngan ehgn tae dgng tieu cue cua bien ddikhi hgu ehi vao khoang 1% GDP toan cau mdi nam. Kgt qua nghien euu ciia Yusuf va Francisco [15] cho thay^ Viet Nam la mgt trong nhirng nudc rSt dl bi tdn thuong bdi tac dgng eua bien ddi khi hau tiong khu vi;c
Ddng Nam A. Vigt Nam dting thu 6 trong bang xep hgng toan eSu ehi sd nii ro do bign ddi khi hau (CRI) giai doan 1991-2010 [9]. Viet Nam eung dung thu 23 trong bang xdp hang toan cau ehi sd tdn thuong do bign ddi khi hgu gay ra trong 30 nam tdi [11], Theo eae kich ban ve bign doi khi hau eho Vigt Nam [4], dgn cudi thg ky 21, khi hgu tren tat ea cac vung cua Vi^t Nam se ed nhieu thay ddi, tdng lugng mua nam va lugng mua mua mua tang trong khi lugng mua mua khd Igi giam. Ngoai ra, mue nudc bign se dang len khoang 75 cm so vdi trung binh thdi ky 1980 - 1999. Tuy chua cd danh gia thiet hgi do bien ddi khi hgu gay ra, nhung thift hgi do cac hi?n tugng thdi tiet bat thuong nhu bao, lu va trieu cudng gay ra la dang ke ddi vdl Vi?t Nam hang nam. Theo kdt qua nghien ctiu ciia Le Trudng Giang [8], ti-ong khoang thdi gian tii 1994 den 2003, thigt hai tiimg binh do
Kgt qua budc dau danh gia tac dgng ..
thien tai gay ra ddi vdi_ Vigt Nam yao khoang gan 250 trigu ddla mdi nam, chigm khoang 0,8% GDP trung bmh tiong cung khoang thdi gian nay.
Thuy san la nganh kinh te quan trgng trong ngn kinh tg Vigt Nam, theo thdng kg [14], gia tii xuat khau thiiy san da tang gap ba lan trong 10 nam qua va da dat hon 6,1 tiddia nam 2011.
Tuy nhien, thuy san lai la nganh chiu nhieu anh hudng tu cac hign tugng thdi tigt bat thudng.
Chi tinh rieng con bao Linda nam 1997 da lam chim va hu hgi gkn 2.000 tau thuygn khai thac thuy san, gay thigt hai khoang 136.000 heeta dign tieh nuoi trong thuy san va han 34.000 tan thuy hai san [3]. Ngoai ra, vdi hang trieu lao dgng tryc tigp va gian tiep tham gia hogt dgng san xult thuy san, chu ygu sdng d khu vue ven bien, nganh thuy san Vigt Nam rit dg bi tdn thuong bdi cac tai bign thidn nhien va nude biin dang do bign ddi khi hgu gay ra. Do vay, vigc nghien euu tac dgng ciia bign doi khi hgu ddi vol thuy san la het sue can thigt nham xac djnh cae yeu to va mue dg tac ddng eiia bien ddi khi hgu vdi thuy san dg lam eo sd xay dung cac bien phap ting phd phu hgp.
Nghign etiu nay danh gia tac dgng eua bign ddi khi hau ddi vdi khai thac thiiy san Vigt Nam. Ham san xult duoc sii dung trong nghign cihi dg md hinh hda tac dgng ciia bign ddi khi hau ddi vdi san lugng khai thac thuy san nham danh gia tac dgng eua bien doi khi hau ddi vdi khai thac thuy san eua Viet Nam. Cau true nghien ctiu nay dugc trinh bay nhu sau: phan tiep theo md ta phuong phap sii dung ham san xuat trong nghien ctiu tae dgng ciia bign ddi khi hgu. Phan ke tigp md ta dfl lieu va cuoi cung la phan ket qua va thao luSn.
PHU'ONG PHAP NGHIEN CUtJ Md hinh ham san suat
Phuang phap tigp can thay ddi nang suat (change-in-productivity approach - CP^ edn dugc ggi la phuong phap ham san xuat (the production-function method), tiep can tac dgng len san xult (effect on production approach), hay dinh gia mdi trudng nhu la mgt diu vao (valuating environment as an input) tim each khai thac moi quan hg gi&a eae thugc tinh mdi trudng va mtic san lugng cua mgt boat ddng
kinh te [5]. Gia djnh eo ban ia, khi mgt thugc tmh mdi trudng dugc dua vao ham san xuat cua mgt doanh nghiep, tae ddng kinh te do thay ddi mdi trudng cd the dugc do bang each xem xet higu qua san xuat va xae dinh gia tri eua tae ddng theo gia thi trudng dau ra cua san phim.
Day la phuang phap lugng gia gian tiep, khdng dya vao dudng cau (nhu phuong phap chi phi du lieh hay gia hudng thu), vi vgy sd tign ude tinh nen dugc hieu ia mgt chi thi (khdng phai gia trj thyc su) do tae ddng ciia thay ddi mdi trudng tdi phuc Igi cudi eiing. Phuang phap tiep can ham san xuat da duge su dung rgng rai, dae bigt la de danh gia nhung tae dgng cua su thay ddi chat lugng mdi trudng (vi du nhu mua axit, d nhiem nude) vao ndng nghiep [I] va thuy san [10]. Vi dy khac ve ung dung bao gdm phan tich tae ddng eua ddng chay [2] va xae dinh gia tri Igi ich bao ve cua vung dat ngap nudc ven bign ehdng Igi thigt hgi do bao gay ra [7], Theo Barbier, phuong phap ham san xuat phii hgp dg ap dung eho cac nudc dang phat tiien bdi vi suj)hu thudc true tigp cua nhigu he thongs san xuat d cae nudc nay ddi vdi tai nguyen thign nhien va eae chtie nang sinh thai.
Mdt each khai quat, phuong phap tiep can ham san xuat bao gdm mgt quy trlnh hai budc. Budc diu tien la xac djnh cac tae dgng vgt ly eua su thay ddi mdi trudng Ign boat ddng san xuat.
Budc thu hai la lugng gia nhung tac ddng nay dua tren diu ra ciia boat ddng san xuat. Ro rang, d giai doan dau tien, hgp tac la can thigt giira eae nha khoa hgc tir nhien, kinh te va cac nha nghien euu khac, dg xac dinh ban ehat eiia cac mdi lign hg giua cac ygu td mdi trudng va hoat dgng san xuat [7, 10]. Ggi Y la dau ra ciia hoat ddng san xuat, ENV la bien mdi trudng quan tam, X,... X^ ta cac bien diu vao khac ciia hogt dgng san xuat, ham san xuat eua mgt doanh nghiep hay mdt nganh san xuat ed the duac md ta blng edng thuc (I):
Y = f(X,... Xk,ENV) (1) Neu 5Y/5ENV khae khdng, bign mdi trudng thg hign qua ENV (vi dy nhu tang hoac giam nhigt do, lugng mua) vdi dieu kien cac yeu td khae khdng ddi,se lam giam/tang mue san lugng. Nhin chung, khi san lugng dau ra Y la mdt hang hda thi trudng, va gia ca cd the quan sat duge va khdng bi anh hudng bdi cac
Nguyen Ngoc Thanh, Nguyen Vigt Thanh,...
yeu to lign quan ngoai thi trudng, mue gia nay vao (X,... Xk) cln thiet de duy tri san lugng dau cd the dugc su dung dg ude tinh gia tri cCia mgt ra d mgt mue dg nhat dinh. Trong nghien ciiu Sir thay doi do tac dgng cua eae yeu to mdi
trudng (qua bien ENV). Ngoai ra, gia trj nay cung ed the duge ude tinh blng each xem xet nhiing thay ddi cua thi trudng cae yeu to dau
nay md hinh ham san xuSt vdi cac bien dau vao tiuyen thong dugc sit dyng trong nghe ca [6, 11] dual dang logarit dugc md ta trong phuong timh (2):
fn(lO =J?o +T,%Mn(xd+-L%ui-i^jCq (2) Trong dd CCj - la cac bign lign quan dgn
bien ddi khi hgu.
Md hinh ham san xuat cd dang (3) sau:
ln(catcht) = jSo + A 7* + fizln(capacitryc) + fistnilabaurt) + p^RaiUt, -H ^^Temp^
+ P^typhoouc 4- Sc (3)
Catcht = san lugng khai thac (tan) nam t.
Capacityi - cudng lye khai thac cua dgi tau (1.000 CV) nam theo thdi gian nam t.
Labour, = sd lugng ngudi tham gia khai thac hai san nam theo thdi gian nam t.
Rain, = lugng mua tmng binh nam t (mm).
Temp,= nhigt dg mat bign tnmg binh nam t (°C).
Hurricane, = so lugng con bao bien nam t (sue gid mgnh hon 100 km/h).
T = xu hudng thdi gian.
P,,j = cac hg so thue nghigm.
Du li^u
Dfl ligu su; dung cho md hinh duge thu thgp tii eae n ^ o n thong kg cua Bg Ndng nghigp va Phat tiien Ndng thdn, Bg Tai nguygn va Mdi tmdng va Tong cue Thong ke [4, 12, 13]. Du lieu theo ehudi thdi gian tu 1976 den 2010 cua san lugng khai thae, cudng lye khai thae, lao dgng nghe ea, lugng mua tmng binh, nhigt dg tmng binh, sd lugng bao hang nam da dugc thu thap va phan tfch. Cac du lieu nay dugc md ta tiong bang 1.
Bang 1. Md ta dii ligu su dyng trong nghien euu (1976-2010) U&u thu thSp GiA trj trung
binh
B$ l$ch
chu^n Gid tri nh6
nhit Gid trj 16^
nh4t Sdn lif^ng
(tSn) Lao Qtfng (ngudi) Cuitmg l^c (CV) Lu^ng mua (mm) Nhiet (50("C) Bao (ccn bao)
1.073 771 665.872 2,082.611
1.793,79 25,72
1.41
626.058 566031 1 883 244
246 0,34 1,37
377.192 190 399 453.871 1.311.33
25,23 0
2.420.800 1.767,000 6.123.000 2 288,60 26,67
5 KET QUA VA THAO L U ^
Bang 2 md ta ket qua tinh toan ban diu md hinh him san xuat ddi vdi nghe ca cua Vi$t
Nam vdi du lieu theo ehudi thdi gian tir 1976 den 2010.
Ket qua budc dau danh gia tac dgng . Bang 2. iTdc lugng ham san xult cho nghe ea Vigt Nam vdi dii ligu tu 1976-2010
Ky hi^u Cdc bi^n [f&c luyng (d6 l^ch chuJIn) H $ s 6
Xu hirdng th&i gian (T) Cu&ng li/c (capacity) Lao dOng (labour) Lirgrng m i / a (rain) Nhi$l dO (temperature) S6 li/grng bSo (hurricane) R^
F Statistic DW statistic
9,39" (1,58) 0,009 (0,005) 0.23 (0,14) 0,31-(0,13) -0,00022* (0,0000698) -0,1056(0,064) -0,0016(0,0011) 0,97 216 1.31
Bienph^ thuQC Id ln(Catch), n=34. *p<O.OJ.
Kiem dinh Durbin-Watson (DW) dg xem xet hign tugng tu tuong quan bae mgt cua md hinh vdi mtic y nghTa 5% (n^34, k'=6) eho thly gia tii thdng kg (d) nlm trong khoang gidi hgn eao(l,89)va thap (1,08), thugc mien khdng ket lugn. Tuy nhien, kiem dinh thay thg (the
Durbin's altemative test - durbinalt) va kigm dinh ty tuong quan bae eao hon (Breusch- Godfrey) eho thly khdng ed hign tugng ty tuang quan trong md hinh da ude lugng vdi mtic y nghTa 5% (cac ket qua kiem dinh duge tiinh bay tai hinh 1 va bang 3).
Hinh 1. Bleu dd ket qua kiem dinh ty tuong quan cua md hinh ude lugng Bang 3. Trinh bay cac kigm dinh ddi vdi md hinh da ude lugng
GhichO Durbin's alternative test -
durbinalt Breusch-GodTrey test Ramsey RESET test Breusch-Pagan
Gid trj quan 3,22 3.75 2,18
sdt Gid trj xdc s u i t 0,073 0,053 0,116
KhOng bdc bo gii thuyet Ho: "I<h6ng c6 t\r ti/ong quan"
Khflng bdc b6 gid thuydt HQ: "Ithflng cfl ti,rti/o'ngquan"
Khflng bSc bo gi3 thuydt HQ: "mfl hinh cfl dgng hdm diing"
Khflng bdc bo gii thuyet Ho: "mO hinh khflng cfl phifong sai sai s6 thay d6i"
Nguyin Ngoc Thanh, Nguyen Viet Tlianh,, Tu kgt qua phan tich djnh lugng, sy phy thugc eua san lugng khai thae dpi vdi bign dau vao va bign lien quan den bien ddi khi hau
dugc chung tdi tim dugc edng thuc tinh toan ra cho nghe ca viing bien Vigt Nam:
XnCcatch) = 9,38 -H 0,09 T + 0,23ln(capacUy') + 0,00022flai7t + 0A056Temp
— 0,0016typhoo7i
Kgt qua ude lugng budc dau cho thly neu lao ddng khai thac thiiy san tang 1% thi san lugng khai thac se tang 0,31%. Kgt qua cung cho thly ngu lugng mua tmng binh hang nam khu vyc ven bien tang len 100 mm (0,1 m) thi san lugng khai thae se giam khoang 2,2%. Ket qua nay phii hgp vdi thue te vi tang lugng mua ed thg giam eudng lue khai thac va pha buy co sd ha ting nghg ca ven bign. Tuy vay anh hudng eiia vigc tang lugng mua ddi vdi san lugng khai thac la tucmg ddi nhd. Nhu mong dgi, tang nhigt dg tmng binh va sd lugng can bao Idn hang nam cd thg anh hudng tieu cue dgn san lugng khai thae. Md hinh eho thay xu the thdi gian gia tang ddi vdi san lugng khai thac nhung cln cd nhieu dfl ligu thdng kg ehi tiet va lien tue hon.
De cd nhflng nhgn djnh ehinh xac hon vg tae ddng eua bien ddi khi hau ddi vdi khai thac thuy san, du ligu nhigt dg mgt bign va mgt sd bign chinh saeh can dugc thu thap va dua vao md hinh. LTdc lugng tac dgng ciia bien ddi khi hgu ddi vdi nghg ca d cac khu vyc khac nhau (khu vyc mien Blc, Tnmg Bg va Nam Bg) eung ean duge nghien ciru. Ngoai ra, vigc qui dinh eae md hinh khac nhau, lua ehgn md hinh phii hgp cho mdi viing va lugng gia tac dgng eiia bign ddi khi hau ddi vdi nghe ea d cae khu vyc khac nhau theo cac kich ban bien ddi khi hau eung cln dugc nghien etiu sau hon.
K E T L U ^
Nghign ctiu nay sii dyng ham san xult de danh gia tae dgng eiia bien ddi khi hgu ddi vdi khai thac thuy san Vigt Nam. Cac bign_san lugng khai thac, cudng lue khai thac, lao dgng nghe ca, lugng mua tnmg binh, nhi?t dg tmng binh, sd lugng bao hang nam da dugc thu thap va phan tich. Ket qua ude lugng budc dau cho thly neu lao dgng khai thac thuy san tang 1%
thi san lugng khai thac se tang 0,31%. Ket qua
cung eho thly neu lugng mua tmng binh hang nam khu vue ven bidn tang len 100 mm (0,1 m) thi san lugng khai thac se giam khoang 2,2%.
Ngoai ra, viec tang nhigt dg trung binh va so lugng con bao Idn hang nam eung cd the dnh hudng tieu eye den san lugng khai thac va xu the thai gian cd the gia tang ddi vdl san lugng khai thae. Tuy v^y eae tac ddng nay khdng cd y nghTa ve mgt thdng kg vi vgy can cd thgm dQ lieu thong ke de phan tieh va kiem djnh trudc khi cd eae ket luan chinh xac ban.
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Nguygn Nggc Thanh, Nguyen Viet Thanh,...
PREMILINARY ESTIMATION RESULTS OF IMPACT OF CLIMATE CHANGE ON MARINE FISHERIES IN VIETNAM
BY USING PRODUCTION FUNCTION
Nguyen Ngoc Thanh', Nguyen Viet Thanh^ Du Van Toao^, Ngo Tho Hung'' 'Hanoi University of Natural Resources and Environment, Vietnam
^VNU University of Economics and Business, Vietnam Vietnam Administiation of Sea and Islands, Vietnam ''Hoa Phong E &C Investment and Development JSC, Vietnam
ABSTRACT: This paper presents an premilinary estimation of climate change impacts on marine fishery in Vietnam An augmented production function is used in the present study to model the effects of climate change on fishery outputs, in order to determine the impact of climate change on marine fisheries m Vietnam. The data by time series of catch, fishing effort, labour, average temperatiire and annual number of typhoons from 1976 to 2010 have been collected and analyzed.
The preliminary results show that the annual average rainfall in coastal areas has negatively effected fo Vietnam's catching production. However, the impacts of increasing rainfall on catching production are relatively smaller than those of other examined factors such as fleet capacity and labour.
Keywords: Climate change, marine fishery in Vietnam, production function
