The first international Earth summit, also known as the United Nations Conference on Environment and Development (UNCED), was held in Rio de Janeiro, Brazil, from June 3 to 14, 1992. This conference was a significant milestone in addressing global environmental issues and promoting sustainable development.

**Background of the Earth Summit:**
The idea of the Earth Summit was proposed by Gro Harlem Brundtland, the former Prime Minister of Norway, in her report "Our Common Future" (also known as the Brundtland Report) in 1987. The report emphasized the need to achieve sustainable development to meet the needs of the present generation without compromising the ability of future generations to meet their own needs.

**Objectives of the Earth Summit:**
1. To address pressing environmental and developmental challenges.
2. To promote sustainable development globally.
3. To strengthen international cooperation in the field of environment and development.

**Key Themes and Outcomes:**
The Earth Summit focused on several key themes, including climate change, biodiversity, deforestation, desertification, and sustainable development. The conference attracted participation from 172 governments, along with numerous NGOs, scientists, and other stakeholders.

The major outcomes of the Earth Summit were:

1. **Adoption of Agenda 21:** Governments agreed to adopt Agenda 21, a comprehensive plan of action to achieve sustainable development in the 21st century. It covered a wide range of issues, such as poverty alleviation, sustainable agriculture, waste management, and conservation of natural resources.

2. **Convention on Biological Diversity (CBD):** The CBD was signed during the conference. It aimed to conserve biodiversity, ensure the sustainable use of its components, and promote the fair and equitable sharing of benefits derived from genetic resources.

3. **Framework Convention on Climate Change (UNFCCC):** The UNFCCC was adopted, which aimed to stabilize greenhouse gas concentrations in the atmosphere to prevent dangerous human interference with the climate system.

4. **Declaration on Environment and Development:** The Rio Declaration was endorsed, which outlined 27 principles to guide sustainable development, including the precautionary principle, the right to development, and the polluter pays principle.

5. **Establishment of the Commission on Sustainable Development (CSD):** The CSD was created to oversee the implementation of Agenda 21 and monitor progress on sustainable development.

**Conclusion:**
The first international Earth summit held in Rio de Janeiro, Brazil, in 1992 was a groundbreaking event that set the stage for global environmental governance and sustainable development. It resulted in the adoption of key agreements, such as Agenda 21, the CBD, and the UNFCCC, which continue to shape international efforts to address environmental challenges today.