Climate ChangeFloods and Droughts Alyssa Corrigan
Climate Change… Climate change is when the climate is altered over time for a long time as a result of human or natural influences. There are many examples of effects of climate change such as a rise in sea level during the past century from four to eight inches, an increase in precipitation by approximately one percent, changes in the ecosystem altering the amount of snow in the north, a rise from five to ten percent in rainfall, and summers becoming increasingly dry while ice in the Artic Ocean decreases. Climate change can bring positive changes, such as its effect on extending the growing season in areas with short seasons, but when change comes quickly, living systems don’t have time to adapt.
Global Warming… Global warming is the increase of the Earth’s surface median temperature over time. Since late in the 19th century the average global surface temperature has gone up .5F and during the 20th century, surface temperatures grew by about 1F. Predictions for the next 100 years are for a 2.7-8 degree F increase, depending on how much fossil fuels are burned and forest systems are removed. An increase in greenhouse gasses is the cause of global warming. Some effects include: an increase in sea level, difficulties in agriculture, change in rainfall, and changes in the ecosystem which will cause animals and plants to have to adapt or perish.
The Effect on Floods Higher surface temperatures and changes in precipitation cause floods in some places, and droughts in others. floods. A rise in sea level (explained on next slide) and severe rain are two causes of floods. Long term changes in the hydrological cycle (the flow of water throughout Earth) due to higher temperatures (more evaporation; melting of ice, more intense rain fall) contribute to more floods. More water vapor in the atmosphere, because the atmosphere is heating up, can cause floods to happen more regularly.
Floods Continued Sea level rising will also contribute to more floods. The sea level is predicted to go up from four inches to three feet. Sea level rises when the water warms and increases in amount, or when glaciers and ice melt. As the glaciers and ice turn into water the sea level increases and floods could start to last for a longer amount of time and happen more frequently.
Examples and Predictions of Flooding There are predictions that as a result of climate change there will be a large increase in famine by 2050 of 30 million people going hungry because of less crops caused by flooding. One country that suffers from flooding because of climate change is Bangladesh. They experienced major flooding in 1998 in which two thirds of the country was underwater. There are predictions for this to become worse with more constant flooding and more of the country underwater by 2100 if it continues the same way. Many coastal cities would be affected, including Manhattan, San Francisco, New Orleans, and Miami, and cities around the world including highly populated ones like Shanghai.
The Effect on Droughts There will also be more droughts as a result of global warming and climate change. The period of time during which droughts last will also be increased. The changing in the hydrologic cycle cause changes in precipitation. Some places get wetter, other drier. When there is a build up of water vapor in the atmosphere because the atmosphere is heating up, or very sudden changes in climate, droughts happen more regularly.
Precipitation Graph This graph shows that heavy times of precipitation have been rising steadily over time but not frequent precipitation.
Examples and Predictions of Droughts Droughts, like floods, could also cause famine because they ruin crops. An example of droughts as a result of climate change are the droughts in Africa. For example at the base of Mount Kilimanjaro there is becoming a very limited water supply. Africa is also very sensitive to any temperature change, which causes droughts to come more easily. In February and March, 2005, there were droughts in Zimbabwe, Mozambique, Malawi, Zambia, and Namibia. The droughts lasted for about four to eight weeks.
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