Recalculating the global warming impact of italian livestock methane emissions with new metrics

Figures & data

Figure 1. Estimated twenty-year cumulative CO₂ equivalents (ECO₂e) and twenty-year cumulative CO₂ warming equivalents (ECO₂we), calculated applying the global warming potential (GWP) and the global warming potential star (GWP*), respectively, on twenty-year methane emissions. Starting emission was 1 kt of CH₄/year. (Adapted from Cady (2020), with recalculated values).

Figure 2. Livestock methane (CH₄) emissions in kilotons (kt) from 1990 to 2020 (Romano et al. 2021) from International Panel on Climate Change (IPCC)’s emission category ‘enteric fermentation’ and ‘manure management systems’ (IPCC 2019).

Figure 3. Methane (CH₄) climate impact of Italian livestock for dairy cattle, non-dairy cattle and buffalo, from 2010 to 2020. Annual (left panel) and cumulative (rigth panel) methane emissions estimated as CO₂ equivalents (ECO₂e; blue solid lines) using the global warming potential (GWP), and as CO₂ warming equivalents (ECO₂we; orange dotted lines), calculated by global warming potential star (GWP*).

Figure 4. Methane (CH₄) climate impact of Italian livestock for sheep and goat, from 2010 to 2020. Annual (left panel) and cumulative (rigth panel) methane emissions estimated as CO₂ equivalents (ECO₂e; blue solid lines) using the global warming potential (GWP), and as CO₂ warming equivalents (ECO₂we; orange dotted lines), calculated by global warming potential star (GWP*).

Figure 5. Methane (CH₄) climate impact of Italian livestock for swine, horses, and mules and asses, from 2010 to 2020. Annual (left panel) and cumulative (rigth panel) methane emissions estimated as CO₂ equivalents (ECO₂e; blue solid lines) using the global warming potential (GWP), and as CO₂ warming equivalents (ECO₂we; orange dotted lines), calculated by global warming potential star (GWP*).

Figure 6. Methane (CH₄) climate impact of Italian livestock for poultry and rabbits, from 2010 to 2020. Annual (left panel) and cumulative (rigth panel) methane emissions estimated as CO₂ equivalents (ECO₂e; blue solid lines) using the global warming potential (GWP), and as CO₂ warming equivalents (ECO₂we; orange dotted lines), calculated by global warming potential star (GWP*).

Figure 7. Total methane (CH₄) climate impact of Italian livestock (dairy cattle, non-dairy cattle, buffalo, sheep, goat, swine, horses, mule and asses, poultry, rabbits) from 2010 to 2020. Annual (left panel) and cumulative (rigth panel) methane emissions estimated as CO₂ equivalents (ECO₂e; blue solid lines) using the global warming potential (GWP), and as CO₂ warming equivalents (ECO₂we; orange dotted lines), calculated by global warming potential star (GWP*).

Table 1. Total methane (CH₄) emissions of Italian livestock (dairy cattle, non-dairy cattle, buffalo, sheep, goat, swine, horses, mule and asses, poultry, and rabbits) from 1991 to 2020 (Romano et al. 2021) and methane climate impact from 2010 to 2020 calculated with global warming potential (GWP) and global warming potential star (GWP*) metrics.

Species	CH4 1991 (kt)	CH4 2020 (kt)	Total variation (%)	Annual average variation (%)	(SD)^a	Cumulative GWP 2010–2020 (kt CO2e)^b	Cumulative GWP* 2010–2020 (kt CO2we)^c
Dairy cattle	325.2	259.1	−20.3	−0.7	3.1	74159	−28610
Non-dairy cattle	325.5	252.8	−22.3	−0.8	2.7	66437	−53786
Buffalo	7.8	36.9	372.2	5.9	10.0	9933	27073
Sheep	63.3	54.4	−14.1	−0.4	4.9	15427	−17763
Goats	6.5	5.5	−15.5	−0.3	7.9	1427	−1962
Swine	81.6	82.9	1.6	0.1	1.8	23530	12266
Horses	6.2	7.3	17.3	0.6	3.7	2100	2356
Mules and Asses	0.7	0.8	8.8	0.7	9.0	205	431
Poultry	1.5	1.0	−32.7	−1.3	4.4	369	−306
Rabbits	2.5	1.7	−30.7	−1.2	4.4	653	−310
Total Livestock	820.9	702.4	−14.4	−0.5	1.7	194240	−60610

^aSD: standard deviation of Annual average variation; ^bGWP: global warming potential; CO₂e: CO₂ equivalents; ^cGWP*: global warming potential star; CO₂we: CO₂ warming equivalents.

Table 2. Nitrous oxide (N₂O) GWP of Italian livestock (dairy cattle, non-dairy cattle, buffalo, sheep, goat, swine, horses, mule and asses, poultry, and rabbits) from 2010 to 2020 (Romano et al. 2021) and methane (CH₄) + N₂O climate impact from 2010 to 2020 calculated with global warming potential (GWP) and global warming potential star (GWP*) metrics.

Species	N2O GWP 2010–2020	GWP(N2O) + GWP(CH4)	GWP(N2O) + GWP*(CH4)
Dairy cattle	3022	77182	−25587
Non-dairy cattle	3639	70076	−50147
Buffalo	505	10438	27578
Sheep	243	15670	−17519
Goats	33	1460	−1929
Swine	2123	25653	14389
Horses	158	2258	2514
Mules and Asses	28	233	459
Poultry	1785	2154	1480
Rabbits	314	966	4
Total Livestock	11851	206091	−48759

Table 3. Time series of Italian livestock from 1991 to 2020 (head × 1000) (Romano et al. 2021).

Year	(head × 1000)
	Dairy cattle	Non-dairy cattle	Sheep	Swine	Buffalo	Goats	Horses	Mules and Asses	Poultry	Rabbits
1991	2340	5582	8397	8549	83	1261	314	66	173061	15877
1992	2146	5426	8461	8244	103	1355	316	57	172684	16399
1993	2119	5322	8670	8348	101	1409	323	49	173261	16531
1994	2012	5157	9964	8023	108	1658	324	43	178659	16905
1995	2080	5189	10668	8061	148	1373	315	38	184202	17111
1996	2080	5094	10943	8171	172	1419	312	34	183045	17434
1997	2078	5095	10894	8293	161	1351	313	30	186815	17610
1998	2116	5013	10894	8323	186	1331	290	34	198800	17705
1999	2126	5036	11017	8414	200	1397	288	33	196573	18021
2000	2065	4988	11089	8307	192	1375	280	33	176722	17874
2001	2078	4661	8311	8766	194	1025	285	33	195541	18495
2002	1911	4599	8138	9166	185	988	278	29	186367	18853
2003	1913	4591	7951	9157	222	961	283	29	180182	18867
2004	1838	4466	8106	8972	210	978	278	29	178914	19655
2005	1842	4410	7954	9200	205	946	278	30	174667	20504
2006	1821	4296	8227	9281	231	955	287	31	173679	20238
2007	1839	4444	8237	9273	294	920	316	35	179222	20965
2008	1831	4348	8175	9252	307	957	332	36	183588	19515
2009	1878	4224	8013	9157	344	961	344	41	181314	17690
2010	1746	4086	7900	9321	365	983	373	46	175912	17957
2011	1755	4143	7943	9351	354	960	373	51	174787	17549
2012	1857	3886	7016	8662	349	892	396	60	174648	17465
2013	1862	3985	7182	8562	403	976	394	63	176919	16549
2014	1831	3925	7166	8676	369	937	391	67	175564	16436
2015	1826	3955	7149	8675	374	962	385	71	177392	15761
2016	1822	4108	7285	8478	385	1026	388	74	178690	15207
2017	1791	4158	7215	8571	401	992	368	72	178635	14001
2018	1693	4230	7179	8492	401	986	368	72	175022	12090
2019	1643	4332	7001	8510	402	1059	368	72	175520	10874
2020	1638	4355	7034	8543	407	1066	368	72	178907	11010

Figure 8. Trend of the dairy cattle consistency (number of head × 1000, dark green line) and cow’s milk yield (tons × 1000, yellow line) in Italy from 2002 to 2020. (Romano et al. 2021; ISTAT 2021).

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Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.