According to the Intergovernmental Panel on Climate Change (IPCC), agriculture is a main source of negative greenhouse gases. The calculations are based on empirical facts but also, like all research, on certain perspectives or paradigms including assumptions and subjective choices of system boundaries for analysis. Greenhouse gases in relation to agriculture are often presented in diagrams showing, for example, arrows of emissions from soil, cattle, tractors, and manure storage. However, the fundament of agriculture is the photosynthesis. Carbon dioxide (CO2) is caught by crops that, in turn, produce oxygen (O-2) and at the same time binds carbon (C) in roots and shoots. One part of this C transforms into soil organic C, and that is sometimes discussed in research, the public debate, and by IPCC. But the main part transforms into harvested crops, that is, cereals like wheat (Triticum aestivum L.), and other carbohydrate products like pea (Pisum sativum L.) or oilseed. This last-mentioned photosynthesis effect is not, in the IPCC calculations, considered as a positive climate contribution from the agricultural sector. The consequence of this might be that policymakers will not understand the whole picture of agriculture in relation to climate effects; and therefore make decisions that affect food production, climate change, and biodiversity in a not optimal way from a holistic sustainability viewpoint.