If a General Artificial Intelligence (AGI) were to unexpectedly emerge in a world unprepared for its existence, the implications could be profound and varied, encompassing technological transformations to unprecedented ethical and security challenges. Here are some of the possible consequences:

1. Impact on the economy and employment: AGI could automate almost any job, from manual tasks to complex intellectual occupations, leading to a radical transformation of the labor market. This could result in an unprecedented unemployment rate and increase economic inequality.

2. Security and ethical challenges: An AGI capable of autonomous action could make decisions without human supervision, posing significant risks if its objectives are not aligned with human values. Security issues range from intentional misuse to the possibility of the AGI acting in unexpected and potentially dangerous ways.

3. Regulatory and governance issues: The sudden appearance of an AGI would leave governments and international organizations struggling to establish appropriate regulations to control its development and use. The lack of preparation could lead to an uncontrolled race for the development of AGI without adequate ethical considerations.

4. Social and cultural impact: AGI could radically transform many aspects of daily life, from how we interact with technology to how we conceive of intelligence and consciousness. Adapting to these changes could be a significant challenge for society.

5. Potential benefits vs. existential risks: While an AGI could offer solutions to some of humanity's most challenging problems, such as curing diseases, solving the climate crisis, and optimizing food production, there is also the risk that it could act in ways that might threaten humanity's existence.

In conclusion, although the development of an AGI has the potential to bring significant benefits, its unexpected emergence in an unprepared world presents substantial risks that require careful consideration and planning. The need for international regulations, the preparation of social and economic infrastructures, and the development of strategies to ensure value alignment between AGI and humanity are urgent imperatives to mitigate associated risks.