Disadvantages of Global Warming

Ocean circulation disrupted, disrupting and having unknown effects on world climate.
Higher sea level leading to flooding of low-lying lands and deaths and disease from flood and evacuation.
Deserts get drier leaving to increased desertification.
Changes to agricultural production that can lead to food shortages.
Water shortages in already water-scarce areas.
Starvation, malnutrition, and increased deaths due to food and crop shortages.
More extreme weather and an increased frequency of severe and catastrophic storms.
Increased disease in humans and animals.
Increased deaths from heat waves.
Extinction of additional species of animals and plants.
Loss of animal and plant habitats.
Increased emigration of those from poorer or low-lying countries to wealthier or higher countries seeking better (or non-deadly) conditions.
Additional use of energy resources for cooling needs.
Increased air pollution.
Increased allergy and asthma rates due to earlier blooming of plants.
Melt of permafrost leads to destruction of structures, landslides, and avalanches.
Permanent loss of glaciers and ice sheets.
Cultural or heritage sites destroyed faster due to increased extremes.
Increased acidity of rainfall.
Earlier drying of forests leading to increased forest fires in size and intensity.
Increased cost of insurance as insurers pay out more claims resulting from increasingly large disasters.