If everyone on Earth were to suddenly die, the planet would undergo a series of changes over time as the effects of human absence, industrial processes, and environmental deterioration began to take their toll. Here’s a rough outline of what might happen in the first year after a mass extinction event:
Week 1:
- Immediate Aftermath: With humans gone, cities would quickly become disordered. Electricity in many areas may fail after a few days if power plants are not kept operational. This loss would lead to failures in refrigeration, creating risks of food spoilage and the release of ammonia and other gases from decomposing organic matter.
- Transportation: Unattended vehicles may block roads, and public transportation systems will come to a halt, creating further obstacles in urban areas.
Weeks 2-4:
- Infrastructure Deterioration: Without maintenance, buildings and structures, especially in urban environments, would begin to deteriorate. Water treatment facilities would fail, leading to contamination of drinking water sources.
- Wildlife Impact: Animals may initially thrive without human presence, but pollution from abandoned factories could start to seep into the environment.
Month 2-3:
- Nature Takes Over: Vegetation would begin to reclaim urban areas. Weeds and grasses would sprout through cracks in sidewalks, and parks would overgrow.
- Fires and Explosions: Industrial sites may begin to fail. Without supervision, hazardous materials could leak, and poorly managed chemicals might cause fires or explosions in factories, particularly in plants that produce explosives or chemicals.
Month 4-6:
- Toxin Accumulation: Many chemical plants, if left unrepaired or monitored, could leak or create hazardous spills. This would lead to an increase in environmental toxins that would harm wildlife.
- Failing Structures: Buildings would begin collapsing due to lack of upkeep. Roofs may cave in from water damage, and infrastructure such as bridges could fail.
Month 7-9:
- Ecosystem Disruption: As toxins increase and animal populations shift, ecosystems would begin to show signs of stress. Some species may flourish while others decline, leading to a shift in food chains.
- Air Quality Begins to Deteriorate: The release of pollutants and aerosols from disrupted industrial sites and natural wildfires would lead to poor air quality, impacting any surviving wildlife.
Month 10-12:
- Long-term Pollution Effects: As contaminants continue to enter ecosystems, many species would struggle to survive. Bioaccumulation of toxins could lead to mass die-offs in affected animal populations.
- Geological Changes: Although changes near the core of the Earth are a long-term process, the destabilization of land due to chemical pollution could potentially impact local geology in specific areas (e.g., subsidence).
Year 2:
- Continued Decline: By this point, many ecosystems may start to collapse due to the accumulated effects of pollution and habitat destruction. With gradual increases in radiation from chemical reactions in abandoned facilities, localized disasters may occur, leading to even further destruction.
- Global Temperature Shifts: Without human industrial activity, the climate may start to stabilize but could take decades to revert to pre-industrial levels. The initial toxicity in the atmosphere would likely create severe local environmental crises.
Long-Term Outlook:
While some ecosystems might be resilient and show signs of recovery over time, the overall trajectory would heavily depend on the extent of pollution and damage already done. With constant disruption from toxins and pollution, many areas may remain uninhabitable for long periods.
Overall, while the Earth's systems are robust and can recover from significant disturbances, the immediate aftermath of human absence would lead to a complex and challenging set of environmental dynamics—most of which would move towards degradation rather than restoration in the absence of human stewardship. Recovery could take hundreds to thousands of years in heavily degraded areas.