Approximately seventy percent of carbon-dioxide absorbed by the blood will be transported to the lungs:

Carbon dioxide is transported in three ways:Dissolved in plasma ($7\%$).As carbamino-haemoglobin ($20-25\%$).As bicarbonate ions ($70\%$): ${\text{CO}}_2$ enters RBCs, reacts with water to form carbonic acid (catalyzed by carbonic anhydrase), which then dissociates into ${\text{H}}^{+}$ and ${\text{HCO}}_3^{-}$.