比較86種減低二氧化碳排放計畫，與搭乘飛機時不託運行李的減碳效果

1：何謂「Project Drawdown反轉地球暖化計畫」？

「Would you still bring your luggage on board a plane after looking at this data?」在先前主要使用了日本環境省的數據，比較了每人每日平均排放二氧化碳的減碳效果。這次則使用了「Project Drawdown反轉地球暖化計畫」的數據，針對各種減碳效果做了更多樣的比較。

在「Project Drawdown反轉地球暖化計畫」中，共集結190位研究員、專家、科學家組成了國際性團體，針對氣候變遷議題，提出了在現今技術發展之下能夠實際執行且大膽的解決方案，出版了「Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming」一書。這本著作透過領導世界的科學家及決策者們縝密的調查，提出了涵蓋2020年至2050年的解決方案，並在全世界中獲得高度評價。

「Project Drawdown」的最新數據可以在「https://drawdown.org」中看到。而我們利用了最新數據，以到日本旅行時不託運20公斤行李來減低二氧化碳排放量，這樣的減碳效果，比較書中提出的各種氣候變遷對策。我們使用的數據為Scenario 1，Scenario 1是至2100年為止將氣溫上升控制於2度的方案，另外，「Project Drawdown」將氣溫上升控制於1.5度的方案標註為Scenario 2。

Reduction in CO2 emissions（Drawdown Scenario 1 and 2）

	SOLUTION	SECTOR(S)	SCENARIO 1	SCENARIO 2
			Gigatons CO2 Equivalent Reduced / Sequestered (2020–2050)
1	Reduced Food Waste	Food, Agriculture, and Land Use / Land Sinks	88.5	102.2
2	Plant-Rich Diets	Food, Agriculture, and Land Use / Land Sinks	78.3	103.1
3	Family Planning and Education	Health and Education	68.9	68.9
4	Refrigerant Management	Industry / Buildings	57.2	57.2
5	Tropical Forest Restoration	Land Sinks	54.5	85.1
6	Onshore Wind Turbines	Electricity	47.0	143.6
7	Alternative Refrigerants	Industry / Buildings	42.7	48.8
8	Utility-Scale Solar Photovoltaics	Electricity	40.8	111.6
9	Clean Cooking	Buildings	31.4	76.3
10	Distributed Solar Photovoltaics	Electricity	26.7	64.9
11	Silvopasture	Land Sinks	26.6	42.3
12	Methane Leak Management	Other Energy	25.8	31.3
13	Peatland Protection and Rewetting	Food, Agriculture, and Land Use / Land Sinks	25.4	40.3
14	Tree Plantations (on Degraded Land)	Land Sinks	22.0	35.1
15	Temperate Forest Restoration	Land Sinks	19.4	27.9
16	Concentrated Solar Power	Electricity	18.0	21.5
17	Perennial Staple Crops	Land Sinks	16.3	32.9
18	Insulation	Electricity / Buildings	15.4	18.5
19	Regenerative Annual Cropping	Food, Agriculture, and Land Use / Land Sinks	15.1	23.2
20	Tree Intercropping	Land Sinks	15.0	24.4
21	LED Lighting	Electricity	14.5	15.7
22	Managed Grazing	Land Sinks	13.7	20.9
23	Multistrata Agroforestry	Land Sinks	13.3	23.9
24	Conservation Agriculture	Food, Agriculture, and Land Use / Land Sinks	12.8	8.1
25	Abandoned Farmland Restoration	Land Sinks	12.5	20.3
26	Recycling	Industry	10.4	11.3
27	Offshore Wind Turbines	Electricity	10.2	9.9
28	Improved Rice Production	Food, Agriculture, and Land Use / Land Sinks	9.9	14.4
29	Building Automation Systems	Electricity / Buildings	9.6	14.0
30	Public Transit	Transportation	9.4	15.4
31	Efficient Trucks	Transportation	9.2	10.8
32	Carpooling	Transportation	9.1	11.1
33	High-Performance Glass	Electricity / Buildings	8.8	11.3
34	Indigenous Peoples’ Forest Tenure	Food, Agriculture, and Land Use / Land Sinks	8.7	12.5
35	Bamboo Production	Land Sinks	7.7	19.6
36	Alternative Cement	Industry	7.7	15.6
37	Electric Cars	Transportation	7.7	9.8
38	Smart Thermostats	Electricity / Buildings	6.9	7.3
39	Efficient Ocean Shipping	Transportation	6.7	9.8
40	Waste to Energy	Electricity / Industry	6.3	5.2
41	District Heating	Electricity / Buildings	6.2	9.7
42	Geothermal Power	Electricity	6.2	9.2
43	Methane Digesters	Electricity / Industry	6.0	7.1
44	Forest Protection	Food, Agriculture, and Land Use / Land Sinks	5.6	8.8
45	Efficient Aviation	Transportation	5.3	5.8
46	Biogas for Cooking	Buildings	4.7	9.7
47	Improved Cattle Feed	Food, Agriculture, and Land Use	4.4	15.1
48	Recycled Metals	Industry	4.3	12.3
49	High-Efficiency Heat Pumps	Electricity / Buildings	4.0	9.1
50	Perennial Biomass Production	Land Sinks	4.0	7.0
51	Seafloor Protection	Food, Agriculture, and Land Use	3.8	5.1
52	Reduced Plastics	Industry	3.8	5.4
53	Solar Hot Water	Electricity / Buildings	3.4	13.7
54	Grassland Protection	Food, Agriculture, and Land Use / Land Sinks	3.4	4.3
55	Improved Manure Management	Food, Agriculture, and Land Use	3.3	6.1
56	Nuclear Power	Electricity	3.2	3.6
57	System of Rice Intensification	Food, Agriculture, and Land Use / Land Sinks	2.9	4.4
58	Walkable Cities	Transportation	2.8	3.5
59	Nutrient Management	Food, Agriculture, and Land Use	2.8	11.5
60	Bicycle Infrastructure	Transportation	2.7	4.6
61	Telepresence	Transportation	2.6	4.4
62	Biomass Power	Electricity	2.6	3.6
63	Macroalgae Protection and Restoration	Coastal and Ocean Sinks	2.6	3.8
64	Seaweed Farming	Coastal and Ocean Sinks / Coastal and Ocean Sinks	2.5	4.7
65	Recycled Paper	Industry	2.3	2.9
66	Electric Trains	Transportation	1.9	3.3
67	Small Hydropower	Electricity	1.7	3.2
68	Hybrid Cars	Transportation	1.6	4.7
69	Electric Bicycles	Transportation	1.4	1.6
70	Biochar Production	Engineered Sinks	1.4	3.0
71	Sustainable Intensification for Smallholders	Food, Agriculture, and Land Use / Land Sinks	1.4	0.7
72	Bioplastics	Industry	1.3	2.5
73	Ocean Power	Electricity	1.3	0.8
74	High-Speed Rail	Transportation	1.3	3.6
75	Coastal Wetland Protection	Food, Agriculture, and Land Use / Coastal and Ocean Sinks	1.2	1.6
76	Farm Irrigation Efficiency	Food, Agriculture, and Land Use	1.1	2.1
77	Composting	Industry	1.1	1.4
78	Improved Fisheries	Food, Agriculture, and Land Use / Coastal and Ocean Sinks	1.0	1.5
79	Low-Flow Fixtures	Electricity / Buildings	0.9	1.5
80	Coastal Wetland Restoration	Coastal and Ocean Sinks	0.8	1.0
81	Water Distribution Efficiency	Electricity	0.6	0.9
82	Green and Cool Roofs	Electricity / Buildings	0.5	1.0
83	Recycled Plastics	Industry	0.5	1.7
84	Improved Aquaculture	Food, Agriculture, and Land Use	0.5	0.8
85	Dynamic Glass	Electricity / Buildings	0.3	0.5
86	Micro Wind Turbines	Electricity	0.1	0.1
Total			1,047.0	1,638.7

Source： Project Drawdown

2：比較每人每日平均排放二氧化碳的減碳效果

「Project Drawdown」在計算每人平均二氧化碳排出量的減碳效果時，使用了2020年當時的世界人口數量（78.2億人）、經濟合作暨發展組織（OECD）會員國的人口數量（13.7億人）、高所得國家的人口數量（12.4億人），這三個數據。之所以會使用經濟合作暨發展組織（OECD）及高所得國家的人口數量來做計算，是由於考慮到全世界的二氧化碳排放量中，先進國家的二氧化碳排放量在整體裡佔更高比例，因此先進國家也有更大幅的減碳空間。順帶一提，2019年時全世界的二氧化碳排放量佔比，其中經濟合作暨發展組織（OECD）會員國佔了34％，而從高所得國家來看則是佔了35％。

在「Project Drawdown」記載的86種降低二氧化碳計畫（Scenario 1之數據）中，以每人每日平均的減碳量來計算的話，擁有最高減碳效果的做法是「減少食物浪費」，其次則為「在飲食中多攝取植物性食品」。「減少食物浪費」所提出的每日平均減碳效果為，世界人口每人平均減碳1.0公斤、經濟合作暨發展組織（OECD）會員國每人平均減碳5.9公斤，高所得國家每人平均減碳6.5公斤。

如同「看過這些數據後你還會決定攜帶行李上飛機嗎？」的分析，搭乘飛機到日本旅行時不託運20公斤行李的話，便有減低74.5公斤二氧化碳排出量的效果（全世界19國搭機訪日之單程平均值），也就是說，若比較在「Project Drawdown」中記載的數據，不託運行李擁有10倍以上的二氧化碳減碳效果。

Daily CO2 emissions reduction per capita (kg)

SOLUTION	World population	OECD poluration	High income population
Reduced 20kg luggage (One way to Japan)	74.50	74.50	74.50
Reduced Food Waste	1.03	5.90	6.51
Plant-Rich Diets	0.91	5.22	5.76
Family Planning and Education	0.80	4.59	5.07
Refrigerant Management	0.67	3.81	4.21
Tropical Forest Restoration	0.64	3.63	4.01
Onshore Wind Turbines	0.55	3.13	3.46
Alternative Refrigerants	0.50	2.85	3.14
Utility-Scale Solar Photovoltaics	0.48	2.72	3.00
Clean Cooking	0.37	2.09	2.31
Distributed Solar Photovoltaics	0.31	1.78	1.96
Silvopasture	0.31	1.77	1.96
Methane Leak Management	0.30	1.72	1.90
Peatland Protection and Rewetting	0.30	1.69	1.87
Tree Plantations (on Degraded Land)	0.26	1.47	1.62
Temperate Forest Restoration	0.23	1.29	1.43
Concentrated Solar Power	0.21	1.20	1.32
Perennial Staple Crops	0.19	1.09	1.20
Insulation	0.18	1.03	1.13
Regenerative Annual Cropping	0.18	1.01	1.11
Tree Intercropping	0.18	1.00	1.11
LED Lighting	0.17	0.96	1.06
Managed Grazing	0.16	0.91	1.01
Multistrata Agroforestry	0.15	0.88	0.98
Conservation Agriculture	0.15	0.85	0.94
Abandoned Farmland Restoration	0.15	0.83	0.92
Recycling	0.12	0.69	0.76
Offshore Wind Turbines	0.12	0.68	0.75
Improved Rice Production	0.12	0.66	0.72
Building Automation Systems	0.11	0.64	0.70
Public Transit	0.11	0.63	0.69
Efficient Trucks	0.11	0.61	0.67
Carpooling	0.11	0.60	0.67
High-Performance Glass	0.10	0.59	0.65
Indigenous Peoples’ Forest Tenure	0.10	0.58	0.64
Bamboo Production	0.09	0.51	0.57
Alternative Cement	0.09	0.51	0.57
Electric Cars	0.09	0.51	0.56
Smart Thermostats	0.08	0.46	0.51
Efficient Ocean Shipping	0.08	0.45	0.49
Waste to Energy	0.07	0.42	0.46
District Heating	0.07	0.41	0.45
Geothermal Power	0.07	0.41	0.45
Methane Digesters	0.07	0.40	0.44
Forest Protection	0.06	0.37	0.41
Efficient Aviation	0.06	0.35	0.39
Biogas for Cooking	0.05	0.31	0.34
Improved Cattle Feed	0.05	0.29	0.33
Recycled Metals	0.05	0.29	0.32
High-Efficiency Heat Pumps	0.05	0.27	0.30
Perennial Biomass Production	0.05	0.27	0.29
Seafloor Protection	0.04	0.25	0.28
Reduced Plastics	0.04	0.25	0.28
Solar Hot Water	0.04	0.23	0.25
Grassland Protection	0.04	0.22	0.25
Improved Manure Management	0.04	0.22	0.25
Nuclear Power	0.04	0.21	0.23
System of Rice Intensification	0.03	0.19	0.21
Walkable Cities	0.03	0.19	0.21
Nutrient Management	0.03	0.18	0.20
Bicycle Infrastructure	0.03	0.18	0.20
Telepresence	0.03	0.18	0.19
Biomass Power	0.03	0.17	0.19
Macroalgae Protection and Restoration	0.03	0.17	0.19
Seaweed Farming	0.03	0.17	0.18
Recycled Paper	0.03	0.15	0.17
Electric Trains	0.02	0.13	0.14
Small Hydropower	0.02	0.11	0.12
Hybrid Cars	0.02	0.11	0.12
Electric Bicycles	0.02	0.09	0.10
Biochar Production	0.02	0.09	0.10
Sustainable Intensification for Smallholders	0.02	0.09	0.10
Bioplastics	0.02	0.09	0.10
Ocean Power	0.01	0.08	0.09
High-Speed Rail	0.01	0.08	0.09
Coastal Wetland Protection	0.01	0.08	0.09
Farm Irrigation Efficiency	0.01	0.08	0.08
Composting	0.01	0.08	0.08
Improved Fisheries	0.01	0.07	0.07
Low-Flow Fixtures	0.01	0.06	0.07
Coastal Wetland Restoration	0.01	0.05	0.06
Water Distribution Efficiency	0.01	0.04	0.04
Green and Cool Roofs	0.01	0.04	0.04
Recycled Plastics	0.01	0.03	0.04
Improved Aquaculture	0.01	0.03	0.04
Dynamic Glass	0.004	0.02	0.03
Micro Wind Turbines	0.001	0.01	0.01

Source: Project Drawdown, Japan Tourism Agency, Worldometer, World Bank Data, ECTA, and our calculations

Note: Calculations based on Scenario 1 of Project Drawdown

Source: Project Drawdown, Japan Tourism Agency, Worldometer, World Bank Data, ECTA, and our calculations

Note: Per capita reduction is calculated based on the population of Scenario 1, High-income countries in Project Drawdown. “Reduced 20kg luggage” is the reduction in CO2 emissions when 20kg of luggage is not carried on board an airplane for travel to Japan (the average one-way trip from 19 countries).

3：比較每人每年平均排放二氧化碳的減碳效果

根據日本觀光廳的「訪日外國人消費動向（2019年）」報告指出，外國人平均一年訪日次數為1.8次，以全世界19國搭機訪日的飛行距離・訪日人數・平均一年訪日次數來計算的話，若在搭飛機時不託運20公斤的行李，便可以得到一年總計減低137公斤二氧化碳排放量的效果（以一年平均訪日1.8次計算）。

Annual CO2 emissions reduction per capita (kg)

	SOLUTION	World population	OECD poluration	High income population
1	Reduced Food Waste	377.2	2,152.9	2,377.3
2	Plant-Rich Diets	333.8	1,905.5	2,104.1
3	Family Planning and Education	293.7	1,676.1	1,850.8
4	Refrigerant Management	243.6	1,390.3	1,535.2
5	Tropical Forest Restoration	232.1	1,324.6	1,462.6
6	Onshore Wind Turbines	200.1	1,142.1	1,261.2
7	Alternative Refrigerants	182.1	1,039.5	1,147.8
8	Utility-Scale Solar Photovoltaics	174.0	993.3	1,096.8
	Reduced 20kg luggage (1.8 round-trip to Japan)	136.6
9	Clean Cooking	133.7	763.4	842.9
10	Distributed Solar Photovoltaics	113.6	648.3	715.9
11	Silvopasture	113.3	646.6	714.0
12	Methane Leak Management	110.1	628.4	693.9
13	Peatland Protection and Rewetting	108.3	617.9	682.3
14	Tree Plantations (on Degraded Land)	93.9	536.2	592.0
15	Temperate Forest Restoration	82.8	472.4	521.7
16	Concentrated Solar Power	76.7	437.9	483.5
17	Perennial Staple Crops	69.6	397.5	438.9
18	Insulation	65.6	374.1	413.1
19	Regenerative Annual Cropping	64.4	367.8	406.2
20	Tree Intercropping	64.1	365.6	403.7
21	LED Lighting	61.6	351.5	388.2
22	Managed Grazing	58.5	333.8	368.5
23	Multistrata Agroforestry	56.5	322.6	356.2
24	Conservation Agriculture	54.6	311.6	344.1
25	Abandoned Farmland Restoration	53.2	303.6	335.2
26	Recycling	44.2	252.0	278.3
27	Offshore Wind Turbines	43.6	248.6	274.5
28	Improved Rice Production	42.0	239.6	264.6
29	Building Automation Systems	40.7	232.3	256.5
30	Public Transit	40.1	229.2	253.0
31	Efficient Trucks	39.0	222.6	245.8
32	Carpooling	38.6	220.4	243.4
33	High-Performance Glass	37.6	214.6	236.9
34	Indigenous Peoples’ Forest Tenure	37.0	211.4	233.4
35	Bamboo Production	32.8	187.3	206.8
36	Alternative Cement	32.8	187.3	206.8
37	Electric Cars	32.6	186.3	205.8
38	Smart Thermostats	29.5	168.1	185.6
39	Efficient Ocean Shipping	28.6	163.5	180.5
40	Waste to Energy	26.7	152.5	168.4
41	District Heating	26.3	150.3	166.0
42	Geothermal Power	26.2	149.6	165.2
43	Methane Digesters	25.7	146.4	161.7
	Reduced 20kg luggage (1.8 round-trip to Japan)		136.6
44	Forest Protection	23.7	135.0	149.1
45	Efficient Aviation	22.5	128.7	142.1
	Reduced 20kg luggage (1.8 round-trip to Japan)			136.6
46	Biogas for Cooking	19.8	113.1	124.9
47	Improved Cattle Feed	18.8	107.5	118.7
48	Recycled Metals	18.4	104.8	115.8
49	High-Efficiency Heat Pumps	17.2	98.3	108.5
50	Perennial Biomass Production	17.0	97.3	107.4
51	Seafloor Protection	16.2	92.4	102.1
52	Reduced Plastics	16.0	91.5	101.0
53	Solar Hot Water	14.5	83.0	91.6
54	Grassland Protection	14.3	81.5	90.0
55	Improved Manure Management	14.2	81.3	89.7
56	Nuclear Power	13.5	77.1	85.2
57	System of Rice Intensification	12.4	70.5	77.9
58	Walkable Cities	12.1	68.8	76.0
59	Nutrient Management	11.8	67.4	74.4
60	Bicycle Infrastructure	11.6	66.4	73.3
61	Telepresence	11.3	64.2	70.9
62	Biomass Power	11.2	63.7	70.4
63	Macroalgae Protection and Restoration	11.1	63.5	70.1
64	Seaweed Farming	10.7	60.8	67.2
65	Recycled Paper	9.7	55.5	61.2
66	Electric Trains	8.1	46.5	51.3
67	Small Hydropower	7.0	40.1	44.3
68	Hybrid Cars	6.9	39.2	43.2
69	Electric Bicycles	5.9	33.8	37.3
70	Biochar Production	5.8	33.1	36.5
71	Sustainable Intensification for Smallholders	5.8	33.1	36.5
72	Bioplastics	5.7	32.4	35.7
73	Ocean Power	5.4	30.9	34.1
74	High-Speed Rail	5.4	30.7	33.8
75	Coastal Wetland Protection	5.1	29.2	32.2
76	Farm Irrigation Efficiency	4.8	27.5	30.4
77	Composting	4.8	27.5	30.4
78	Improved Fisheries	4.3	24.6	27.1
79	Low-Flow Fixtures	4.0	22.6	25.0
80	Coastal Wetland Restoration	3.2	18.5	20.4
81	Water Distribution Efficiency	2.6	14.8	16.4
82	Green and Cool Roofs	2.3	12.9	14.2
83	Recycled Plastics	2.2	12.6	14.0
84	Improved Aquaculture	2.1	12.2	13.4
85	Dynamic Glass	1.4	8.3	9.1
86	Micro Wind Turbines	0.4	2.2	2.4

Source: Project Drawdown, Japan Tourism Agency, Worldometer, World Bank Data, ECTA, and our calculations

Note: Calculations based on Scenario 1 of Project Drawdown

Note: CO2 emissions reductions per capita are calculated based on Scenario 1 of Project Drawdown and the world population. “Reduced 20kg luggage” is the CO2 emissions reduction effect of stopping loading 20kg of luggage on airplanes when traveling to Japan (one-way average from 19 countries).

若將減碳137公斤的效果，與「Project Drawdown」所提出的86種降低二氧化碳排放量計畫相比，在世界人口平均減碳效果中排名第9名，經濟合作暨發展組織（OECD）會員國中的減碳效果中排行第44名，高所得國家的減碳效果中則排行第46名，這在全世界科學家嚴選出來的「反轉地球暖化100招」中算是非常靠前的排名，我想這證明了只要在搭乘飛機時減量行李，便能夠達成非常大的減碳效果。

「Project Drawdown」在解決方案中，提出了從現在起至2050年為止能夠實踐的減碳方法，因此有些方法在目前技術上尚未發開完成，而搭乘飛機時減量行李則是此刻就可以立即實踐的方式。搭飛機時不攜帶行李，更可以省去旅行前準備行李、旅途中搬運行李、旅遊後清洗及整理衣物所需花費的時間及精力，並且讓高齡者及身心障礙人士、親子旅行等較不方便移動的族群，能更輕易地出遊，進而解決旅行落差的問題。立即來體驗看看這種為我們、為地球帶來多種好處，不攜帶行李的新型態旅行吧！