El surgimiento del derecho ambiental internacional ha generado importantes desafios a los mas inveterados fundamentos del derecho internacional publico. De este modo, conceptos tradicionales como la soberania de los Estados, los sujetos de derecho internacional, asi como las perspectivas mas tradicionales de la seguridad nacional estan sufriendo grandes cambios. Las necesidades de la sociedad internacional contemporanea difieren sustancialmente de aquellas generadas en los preceptos de la sociedad westfaliana, evento que explica el surgimiento de miradas alternativas que permiten la comprension de dinamicas vigentes en el derecho internacional, ejemplifi cadas en conceptos como res communis, preocupaciones comunes o simplemen te “comunes”, los cuales vienen adquiriendo una posicion privilegiada en el estudio del derecho internacional. Tales desarrollos han permitido, asimismo, el fortalecimiento de conceptos juridicos internacionales como el de las llamadas obligaciones internacionales erga omnes, las cuales constituyen una piedra angular para la explicacion de la existencia misma del derecho internacional ambiental.The emergence of international environmental law has produced important challenges to the very foundations of public international law. Traditional concepts such as state sovereignty, subjects of international law, and the early perspectives of national security are being transformed. The needs of the contemporary international society differ from the ones of the Wesphalian conception, situations which clearly explains the raise of alternative views for the understanding of the current dynamics of international law, where concepts like res communis, common concerns and simply “commons” take a privileged place in the study of international law. The foregoing has been strengthened by the international development of the so called erga ommnes obligations, label which is being used by international environmental law as the perfect explanation of its own existence. This academic article presents and studies the above mentioned concepts trying to compare what international law used to be before the emergence of international environmental law and what it is and what it should be in order to attend the developments and challenges imposed by the contemporary international society, particularly by international environmental law, a new field of the corpus juris of public international law.