…The earth is never overburdened. The heaviest mountains and oceans on the face of the earth hold more living entities than there are human beings, and they are not overburdened. If a census were taken of all the living beings on the surface of the earth, certainly it would be found that the number of humans is not even five percent of the total number of living beings.
…The material creation is meant for fulfilling the desire of the Lord, and His desire is that the conditioned souls who are unfit to enter into the kingdom of God have a chance to improve their conditions for entering. The entire process of cosmic arrangement is intended just to give a chance to the conditioned souls to enter the kingdom of God, and there is an adequate arrangement for their maintenance by the nature of the Lord…
Srimad Bhagavatam
By His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
Third Canto, Chapter 3, Text 14
kiyān bhuvo ’yaṁ kṣapitoru-bhāro
yad droṇa-bhīṣmārjuna-bhīma-mūlaiḥ
ṣṭādaśākṣauhiṇiko mad-aṁśair
āste balaṁ durviṣahaṁ yadūnām
kiyān—what is this; bhuvaḥ—of the earth; ayam—this; kṣapita—abated; uru—very great; bhāraḥ—burden; yat—which; droṇa—Droṇa; bhīṣma—Bhīṣma; arjuna—Arjuna; bhīma—Bhīma; mūlaiḥ—with the help; aṣṭādaśa—eighteen; akṣauhiṇikaḥ—phalanxes of military strength (vide Bhāg. 1.16.34); mat-aṁśaiḥ—with My descendants; āste—are still there; balam—great strength; durviṣaham—unbearable; yadūnām—of the Yadu dynasty.
[After the end of the Battle of Kurukṣetra, the Lord said:] The abatement of the earth’s great burden, eighteen akṣauhiṇīs, has now been effected with the help of Droṇa, Bhīṣma, Arjuna and Bhīma. But what is this? There is still the great strength of the Yadu dynasty, born of Myself, which may be a more unbearable burden.
Purport
It is a wrong theory that due to an increase in population the world becomes overburdened and therefore there are wars and other annihilating processes. The earth is never overburdened. The heaviest mountains and oceans on the face of the earth hold more living entities than there are human beings, and they are not overburdened. If a census were taken of all the living beings on the surface of the earth, certainly it would be found that the number of humans is not even five percent of the total number of living beings. If the birthrate of human beings is increasing, then the birthrate of other living beings is increasing proportionately. The birthrate of lower animals—beasts, aquatics, birds, etc.—is far greater than that of human beings. There is an adequate arrangement for food for all the living beings all over the earth by the order of the Supreme Lord, and He can arrange more and more if there is actually a disproportionate increase of living beings.