8 - Agricultura
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A agricultura representa 22% das emissões de gases com efeito de estufa no mundo (2019)[1].A agricultura utiliza muito poucos combustíveis fósseis, e as suas emissões de CO2 estão essencialmente ligadas à Desflorestação[2]. A Agricultura é responsável por 80% da Desflorestação[3]. De facto, são necessárias grandes superfícies para cultivar, especialmente para alimentar o gado[4].A estabilização do clima há 10 000 anos, no início do Neolítico, permitiu às civilizações sedentarizarem-se e desenvolverem a agricultura[5]. A Agricultura permitiu alimentar uma população cada vez maior. Mas a agricultura moderna coloca muitos problemas ambientais: perda de habitats e substâncias nocivas para a biodiversidade (desflorestação e pesticidas), eutrofização dos meios aquáticos (fertilizantes), emissões de gases com efeito de estufa (ruminação (metano) e fertilizantes (óxido nitroso)). Esta carta também agrupa as atividades relacionadas com a aquacultura (produção animal ou vegetal em meio aquático).
AR6 WG3 TS.3 p17 (p65) // AR6 WG3 Figure TS.6 p18 (p66) ↩︎
AR6 WG3 TS.3 p17 (p65) // AR6 WG3 Figure TS.6 p18 (p66) ↩︎
Segundo OECD : 81% : https://www.oecd.org/env/indicators-modelling-outlooks/monitoring-land-cover-change.htm p6 ↩︎
https://www.science.org/doi/10.1126/science.aaq0216 ↩︎
AR6 WG2 Cross-Chapter Box PALEO // p165 (p152) // https://www.science.org/doi/10.1126/sciadv.adh2458 ↩︎
1Cause
accounts for 25% of GHGs if we include induced deforestation.
2Consequences
Deforestation is due for 80% to agriculture. It can be considered as a human activity or as a consequence of agriculture of both.
The pictures in the background of card 9 should put you on the track!
5Other possible consequences
Spraying crops does result in aerosols and air pollution, but not to the same extent as incomplete combustion from power plants.
It doesn't matter if this link is not made, but it is true that agriculture can improve storage capacity through photosynthesis. This is the 0.4% principle (if we increased the soil's capacity to sequester carbon by even 0,4%, we would have a significant impact on CO2).
Here, we are thinking mainly of pesticides (especially Roundup or neonicotinoids). No link with the climate, but an interesting relation to make.
Agriculture does not use much fossil fuel, just enough to keep tractors running. Its carbon emissions are high, bu mainly because of methane and nitrous oxide.
Agriculture does not emit much CO2 except from deforestation. Its carbon emissions mainly come from othe GHGs.
2Wrong causes
It would be more logical to link to agricultural yields.
Yes, the yield decline does affect agriculture, but the agriculture card is here to stand for one of the causes of GHG emissions.