The predicted effects of global warming are various and many, both for humans and the environment.
These effects include:
- The polar ice caps could melt and sea levels rise. If the sea level were to rise in excess of 4 metres almost every coastal city in the world would be severely affected, with the potential for major impacts on worldwide trade and economy. Presently, the IPCC predicts sea level rise of less than 1 metre through 2100, but they also warn that global warming during that time may lead to irreversible changes in the Earth's glacial system and ultimately melt enough ice to raise sea level many metres over the next millennia. It is estimated that around 200 million people could be affected by sea level rise, especially in China, Thailand, Indonesia, Bangladesh, Egypt and the Philippines and this would cause population displacement.
- Some areas could become more humid or wetter. Places such as North Africa would become drier as they would experience more drought, while areas like the British Isles could experience a climate similar to that of the Mediterranean.
- There could be more landslides, avalanches, flooding and stronger hurricanes. While the relationship between hurricanes and global warming is still being debated, scientists increasingly seem to make the case that two phenomena are linked.
- Increasing global temperature means that ecosystems may change; some species may be forced out of their habitats (possibly to extinction) because of changing conditions, while others may flourish.
Global Glacial Mass - Balance in the last 40 years, reported to the World Glacier Monitoring Service. Note the increased negative trend beginning in the late 1980s.
- Global warming has led to glacier retreat around the world. Oerlemans (2005) showed a net decline in 142 of the 144 mountain glaciers with records from 1900 to 1980. Since 1980 global glacier retreat has increased significantly. Similarly,
Dyurgerov and Meier (2005) averaged glacier data across large-scale regions (e.g. Europe) and found that every region had a net decline from 1960 to 2002, though a few local regions (e.g. Scandinavia) have shown increases. Upwards of 90% of glaciers reported to the World Glacier Monitoring Service have retreated since 1995 .
- The incidence of infectious diseases such as cholera and malaria could change and this would lead to more pressure on medical services as patterns of the disease changed.