Warming Disclaimer: This is not an official document. But the sources I used in this document are official sources and are accurate and the links to these sources I used will be put at the end of this document.
Index What is Global Warming? Sea Level Rise Ocean Currents Jetstreams Polar Vortex Temperature How Will NZ be affected? Information used
What is Global Warming? Global Warming is caused by greenhouse gases such as CO2 (carbon dioxide) entering our atmosphere and trapping the heat in our atmosphere. Global Warming will cause our temperature to rise and our ice to melt but it is not just our temperature and our ice caps that will be effected it will effect other parts that also make up our weather such as jetstreams, ocean currents and the polar vortex.
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Sea Level Rise
Our seas are rising due to the ice melting in not just Antarctica but in Greenland as well. Glaciers are also being affected by global warming. The ice in Antarctica and Greenland does melt in the warmer months but in the colder months its replenished. But due to the global temperature rising our ice caps and glaciers are melting at an accelerated rate. Sea level rise is a threat to costal life across the globe. The consequences of the sea level rising will be the intensity of storm surges will increase so will flooding and the damage to costal areas. In many cases in some countries most of the population lives on the coast and sea level rise will affect a lot of people. It will also affect wildlife. The rise in sea levels will cause many people to be displaced and they will need to find safer homes. Sea level rise will also cause the groundwater to become salty and the soil will also be contaminated. The Map above is showing what countries will be affected the most.
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Ocean Currents
The ocean currents around the world help carry warm and cold air across the globe. This causes some parts of the world to be warmer or colder than others. The warm water from the equator is less dense so it rises to the surface and then is pushed to the poles by the wind. Once it reaches the poles it becomes much colder and denser which causes it to sink to the deeper parts of the ocean. It is then pushed back to the equator where it becomes warmer again and the cycle continues. But since the ice is melting it will cause the cycle to change due to freshwater entering the ocean. Freshwater causes the density of the sea water to be lowered which means it will sink more slowly. Without the force to drive it downward the whole global system will change and it will affect our global temperature and our weather. In 2018 scientists discovered that the major ocean current in the Atlantic Ocean had slowed down by 15% some studies have also predicted that it could worsen to more than 30% by 2100. These significant changes to the ocean currents and the atmosphere could cause the winters in Europe to be much colder. The South Atlantic could be warmer and could disrupt monsoon cycles in Asia and South America due to the ocean currents influencing the temperature, rainfall and the wind.
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Jetstreams Our planet has four jet streams two polar jet streams near the south and north poles and two sub-tropical jet streams which are closer to the equator. The jet streams are formed in the troposphere when warm air and cold air mixes. The Sun also doesn’t heat the earth evenly which means places near the equator are much hotter than others while places near the poles are much colder than others. When hot air meets cold air the hot air rises and the cold air sinks to replace the hot air this creates an air current. On average a jetstream moves at 110 miles per hour but if there is a dramatic change in temperature the jetstream will move at 250 miles per hour or higher. The faster winds usually happen in the polar jet streams during winter. The fast moving winds in a jet stream help move weather systems across the globe affecting temperature and rainfall. But if a weather system is further away from the jetstream it might stay in one place this is how weather events such as heatwaves and floods are created.
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Polar Vortex
The polar vortex is a large area of low pressure and cold air around the poles. When the polar vortex is stable it remains closer to the North Pole due to the strong polar jetstream that stops the cold air from moving to the continents below it. This polar jetstream is sustained by the temperature difference between the warmer regions and the polar region and the rotation of the Earth. When the temperature difference is large the strong winds keep the polar vortex stable. But if the temperature difference is small the jetstream is much weaker causing the polar vortex to become unstable and it breaks off. A low pressure system creates winds such as cyclones or the polar vortex. A high pressure system pushes air away into the low pressure system to create balance. Due to climate change the behaviour of the polar vortex has become more extreme as the temperature difference between the warmer regions and the polar region has been reduced and will continue being reduced. This will cause the polar jetstream to be much weaker and unstable and more cold air will be bought south. Climate change will further weaken the polar jetstream causing our weather to be more extreme.
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Temperature
Temperature will be one of the first immediate effects of climate change. Temperature increase at different speeds around the world with the temperature increase being more significant over land while in the ocean its warming more slowly. The most warming is happening in the Arctic in the winter seasons while in the warmer regions near the equator its happening in the warmer seasons. Many countries will experience heat waves and extremely hot temperatures such as Central and Eastern North America, Central and Southern Europe, the Mediterranean, Northern Africa, the Middle East, Western and Central Asia and Southern Africa. Many Arctic land regions will see the cold extremes warm by 5.5 degrees Celsius. Many countries will also be getting more droughts such as the Mediterranean, Southern Europe, Northern Africa, Middle East, Southern Africa, South America and Australia. Many countries will also have to deal with extreme flooding such as Western Canada, Eastern Canada, Greenland, Iceland, Northern Europe, Northern Asia, Southeast Asia, and Eastern North America. Temperature will also affect our ocean currents, sea level, jetstreams and our polar vortex.
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Here
In New Zealand most of our weather is influenced by a Southern Hemisphere mid latitude jetstream. A jetstream is a narrow band of very strong winds that stretch from the surface of the Earth to the troposphere which is the lowest layer of the Earths atmosphere at about 18km in height. These jet streams are created by the difference in temperature in the atmosphere by the cold polar air and the warm tropical air and the Earths rotation. This jetstream gives us our westerlies which encircle the Southern Ocean. This jetstream doesn’t stay near New Zealand all the time it travels across the globe. But in winter this jetstream is directly above New Zealand but sometimes it moves south. Climate change is having a significant effect on our jetstream. New Zealand air temperatures have increased by 1 degree in the past 100 years just like the rest of the globe. But within the the tropics the air temperature is increasing 80% faster than the surface. At the same time the man made ozone depletion has helped cool the air in Antarctica. This increasing temperature difference between the tropics and the south pole is causing a significant effect on our jetstream and is changing the properties of the atmosphere forcing the jetstream to mover further south towards the south pole. These effects will depend on the seasons. In summer and autumn the jetstream will shift further south causing the westerlies to be weaker and the conditions will be drier and calmer especially in the north island. In winter and spring the jetstream will be stronger which will cause the westerlies to be much stronger and there will be more rain on the west coasts of both islands and there will be less rain on the east coasts. Due to the increasing strength of our jetstream bigger waves will be impacting our coastlines.
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Sources that were used What is Global Warming- https://www.nrdc.org/stories/globalwarming-101#:~:text=A%3A%20Global%20warming%20 occurs%20when,bounced%20off%20the%20earth’s%20 surface.&text=That’s%20what’s%20known%20as%20the%20 greenhouse%20effect. Sea Level Rise- https://www.nationalgeographic.org/encyclopedia/ sea-level-rise/ Ocean Currents- https://chinadialogueocean.net/15101-how-doesclimate-change-affect-the-ocean/#:~:text=Ocean%20currents%20 are%20vulnerable%20to,drag%20surface%20water%20with%20 them. Jetstreams- https://scijinks.gov/jet-stream/ Polar Vortex- https://climatechange.ucdavis.edu/climate-changedefinitions/what-is-the-polar-vortex/ Temperature- https://climate.nasa.gov/news/2865/a-degree-ofconcern-why-global-temperatures-matter/ How Will NZ be affected- https://www.mfe.govt.nz/climate-change/ likely-impacts-of-climate-change/likely-climate-change-impacts-nz https://www.newshub.co.nz/home/new-zealand/2020/01/alarmingnew-map-shows-the-devastation-rising-sea-levels-could-cause-innew-zealand.html