 A meta-analysis in 2014 revealed consensus that yield is expected to decrease in the second half of the century, and with greater effect in tropical than temperate regions.Writing in the journal "Nature Climate Change", Matthew Smith and Samuel Myers (2018) estimated that food crops could see a reduction of protein, iron and zinc content in common food crops of 3 to 17%.This is the projected result of food grown under the expected atmospheric carbon-dioxide levels of 2050.