The United States, over the years since its founding, has faced many threats and encounters from other nations and is still targeted every day. However not all threats that the United States faces is from people. One main threat we choose to ignore or push to the side is the threat from nature itself. Earth’s climate is changing. Temperatures are fluctuating, seasons are shifting, and somehow this seems to be overlooked. Some of the major threats affecting the United States are flooding, sea level rising, and storms.
http://www.climateactionprogramme.org/news/world_bank_climate_change_could_increase_number_in_poverty_by_100m_by_2030
Flooding is caused by heavy rains, strong winds in coastal areas, dam breaking, or even ice melting in the ocean. In the United States flooding was mainly caused by heavy rain storms. These heavy rain storms caused drainage systems to back up so the water cannot be transported fast enough. The excess rain water can cause banks and rivers to overflow to cause flooding. Also known as a floodplain, when water upstream is more than usual will flow downstream to valley areas and flood the land. Strong winds have also caused flooding in the United States. This has occurred mostly in the southern coastal areas such as Florida, Texas, and California. This wind that moves the ocean water to the land causes coastal flooding. Two of the main reasons for sea level rising is the melting of ice glaciers in the ocean and thermal expansion cause by warming of the ocean. In the U.S. flooding has affected many people that live in the coastal areas. Hurricane Harvey and Irma were great examples of these flooding occurrences. These hurricanes produced winds heavy and fast enough to push ocean water over and destroy wave boundaries. According to businessinsider.com hurricane Harvey was a category 4 storm and Irma was a category 5. These storms caused over 4 feet in flooding water in southeast Texas and Louisiana. In addition to ocean waves reaching homes on the coast rainfall continued and added over 4 feet of rain over Houston.
Along with flooding, sea level rising has been affecting southern parts of the U.S. before the 20th century sea levels along U.S. coastal areas have risen 1.7 mm per year. However nature is never predictable or steady. So currently the average sea level rise is 3.2 mm per year. That’s 32mm per decade! According to most research sea levels continue to rise with no intention of receding. So it is possible that even before the years the rate could increase. The more sea level rising the easier it is for storms to move ocean water onto the land causing more flooding.
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The United States over the years has seen many more extreme weather events and temperatures fluctuating no matter what season it is. This is all due to climate change and global warming. Annual average temperature over the United States has increased by 1.8°F from 1901 to 2016. This number is expected to rise about 2.5°F over the next few decades. This will result in more frequent and intense extreme weather events. Changes in the characteristics of extreme events are particularly important for human safety, infrastructure, agriculture, water quality and quantity, and natural ecosystems. There are 7 events that the United States is expected to face based on this warming trend and some may become the new normal. The first is coastal flooding. Global sea level rise has already affected the United States and the daily tidal flooding is accelerating in more than 25 Atlantic and Gulf Coast cities. Sea level rise is expected to be higher than the global average in some parts of the United States, especially on the East and Gulf coasts of the United States. This is due to changes in Earth’s gravitational field from melting land ice, changes in ocean circulation, and local subsidence. The second is larger precipitation events. We’ve seen heavy rainfall and snowfall increasing in intensity and frequency across the United States and the globe. There’s been evidence of this in the Northeast and Midwest and these trends are expected to continue. The third is heat waves. Heat waves have become more frequent in the United States since the 1960s, whereas extreme cold temperatures and cold waves have become less frequent. Recent record-setting warm years are projected to become common in the near future for the United States as annual average temperatures continue to rise. The fourth is forest fires. The incidence of large forest fires in the western United States and Alaska has increased since the early 1980s and is projected to further increase in those regions as the climate warms. The frequency of large wildfires is influenced by a complex combination of natural and human factors. The fifth is droughts. Annual trends toward earlier spring snow-melt and reduced snowpack are already affecting water resources in the western United States. These trends are expected to continue. Recent droughts and associated heat waves have reached record intensity in some U.S. regions. The sixth is hurricanes. Just last year, as mentioned in this post, we’ve seen many destructive and high impact hurricanes. Warmer waters contribute to stronger hurricanes. For Atlantic and eastern North Pacific hurricanes, increases are projected in precipitation rates and intensity. The frequency of the most intense of these storms is projected to increase in the Atlantic and western North Pacific and in the eastern North Pacific. The seventh event is atmospheric rivers. These narrow streams of moisture account for 30%–40% of the typical snowpack and annual precipitation on the U.S. West Coast. They are also associated with severe flooding events when they shed their moisture. The frequency and severity of landfalling atmospheric rivers will increase because rising temperatures increase evaporation, resulting in higher atmospheric water vapor concentrations.
These 7 events can be reduced if we can limit the amount of greenhouse gases (eg. carbon dioxide) emitted globally. Without significant cuts to emissions, annual average global temperatures will almost certainly rise beyond 2°C by the end of the century.