If atmospheric CO2 concentrations increase two fold or more, how will plants be affected, disregarding any changes in the climate ?
1. All plants will experience increase in photosynthesis
2. C3 plants will have faster growth, C4 plants will be minimally affected
3. C4 plants will have faster growth, C3 plants will be minimally affected
4. Plants growth will not affected because atmospheric CO2 concentrations are never limiting for plant growth