Final answer:
The United Nations is focusing on climate change as a global concern, which indicates its importance. Climate change can cause an increase in diseases, and scientists do collaborate, although international agencies can help facilitate cooperation.
Step-by-step explanation:
The fact that the United Nations is focusing on climate change indicates that it is a global concern. The United Nations is an international organization that addresses various global issues, including conflicts, but climate change has become a pressing issue due to its impact on the environment and people's lives. Climate change can indeed cause an increase in diseases as it disrupts ecosystems and contributes to extreme weather events that may lead to the spread of infectious diseases. Scientists often collaborate and work together regardless of whether an international agency orders them to. However, international agencies can facilitate global cooperation and provide a platform for scientists to share their research and findings.