Hello,

The peanut plant is a C3 plant. There are thousands of different types of plants, but only three different ways in which they can under go photosynthesis, or taking carbon dioxide from the air, water from their roots and sunlight and transforming it into sugar and oxygen.These different types are C3, C4 and CAM. 
C3 plants are the most common and the most efficient at photosynthesis in cool, wet climates. They keep their stomata open during the day.
By making use of photosynthesis the plant can fixate nitrogen.

The most imporant source of Biological Nitrogen Fixation is the symbiotic interaction between soil bacteriia and legume plants, including many crops that are important to humans. The NH3 resulting from fixation can be transported into plant tissue and incoporated into amino acids, which are then made into plant proteins. Peanut plants contain high levels of protein and are among the most important agricultural sources of protein in the world. Peanuts are able to interact symbiotically with soil bacteria that fix nitrogen.
The picture shows the nitrogen cycle. It tells how nitrogen fixate and what is needed for that.

Not only can peanut plants fixate nitrogen, but they are also indeterminate in both vegetative and reproductive development. This means that the plant in producing new leaves and stems at the same time that it is flowering, pegging and developing pods. Consequently, developing pods compete with vegetative components for carbohydrates and nutrients.

However, all the process will be more difficult with flobal warming. Researches found out that that global warming could dramatically reduce peanut production in places where temperatures are already high. In the USA, the themperature can already be really high right now.
If the temperature rises, the peanut production will start moving northward towards more temperate regions. However, if the temperature is too high for the peanut plant, the yield dropps by about 6% per degree of increase.
More CO2 in the air will not be benificial for the production; the crop will grow big and green, but will not produce seeds at all.
Not only the temperature and CO2 will be a problem, but also rain. Peanut plants are rain-fed, if global warming also leads to drought in these areas, yield could be even lower.