GEF

Unit 2  |  Humanity’s Ecological Footprint 49 Climate change is also having negative impacts on human populations. At present, much of humanity relies on subsis- tence agriculture for survival. For example, in Sub-Saharan Africa, climate change is decreasing the ability to use rainwa- ter to irrigate. Even in developed countries, climate change is expected to have negative impacts on agriculture, making harvests less predictable and raising global food prices. While it is impossible to blame the severe damage caused to New Orleans by Hurricane Katrina in 2005 on climate change, scientists predict that severe storms like Katrina will become more frequent in coming years. In addition, climate change is allowing insect populations to spread, raising fears that insect- carried tropical diseases such as malaria will become more common around the world. Climate change is proved to have a direct cause and effect relationship with catastrophic weather events such as Superstorm Sandy in 2012. ?  DID YOU KNOW Levels of Atmospheric CO 2 have fluctuated greatly dur- ing Earth’s history, leading to dramatic changes in the climate. For instance, Earth was largely covered by ice about 650 million years ago, when atmospheric CO 2 levels were extremely low. About 50 million years ago, when CO 2 concentrations were very high, tropical vegetation was found from the equa- tor to the North and South poles.