translate English to French: In summer, there is also a small but significant contribution, amounting to about 15% of total emissions, from natural sources that consist primarily of lightning, forest fires, and emissions from soils.
L'été, il y a également une contribution faible, mais non négligeable (environ 15 % des émissions totales), des sources naturelles, principalement la foudre, les feux de forêt et les émissions des sols.