Hello everyone and welcome to this week's blog post. Today, I am going to explore one of the many deplorable impacts that climate change has on our world - specifically its effect on our oceans. I will start by explaining the natural causes of climate change, before moving onto how this has been exacerbated by humans and finally conclude with the effect of climate change on our oceans.
Climate change is a real threat that endangers our world and everything living on it. While the earth's climate has changed constantly throughout history, with numerous periods of glacial advancement and retreat, scientists have concluded with over 95% probability that recent changes in temperatures are almost solely due to human activity.
Climate change naturally causes because of numerous reasons including changes in the Earth's orbit. The amount of solar radiation reaching the earth varies due to three ways in which the earth's orbit around the Sun changes. These are known as Milankovitch cycles. They include eccentricity, which describes the way how over a period of 100,000 years the orbit changes from a circle to an oval and back. As this changes the distance between the Earth and the Sun, this has a large effect on the temperature of our planet. Furthermore, the angle of tilt of the Earth also changes from 21.5° to 24.5 °. If there is less tilt, summers are cooler and winters are milder. Precession, the wobble of the earth over a period of 23,000 also affects the climate, changing the severity of the seasons.
There are also variations in energy received by the planet from the sun, which varies over time. This is due to sunspots on the surface of the sun. The amount of these sunspots varies over the years in a cycle every 11 years. A higher amount of sunspots leads to more solar energy being emitted and higher temperatures on Earth.
A further natural cause of climate change is volcanic activity. Major volcanic eruptions can cause cooler temperatures. This is because ash and gases are ejected into the stratosphere which forms a blanket, reflecting more solar radiation into space. As a result, this leads to cooler temperatures. To take an example, the eruption of Mount Pinatubo in the Philippines on 15 June 1991 released 20 million tonnes of sulfur dioxide, cooling the world's climate by 1.3°C over three years.
While it is true that global changes in temperature naturally occur, humans are vastly increasing the rate at which global temperatures are rising and glaciers are melting. Over the last 100 years, temperature increases, due to pollution through industry and deforestation, have cancelled out the cooling that has happened naturally over the last 6,000 years.
The Industrial Revolution is a great example of the impacts that humans have inflicted of the planet. In 1750AD the population of the world was 790 million and exploitation of resources was limited mostly to firewood and muscle power. As minerals were dug out of the ground the landscape did start to change but on a small local scale. During and after the Industrial Revolution humans, with a population of 7 billion have caused a dramatic increase in the rate of change to the environment due to erosion, agriculture, construction chemical evolution and radioactive waste.
Today, climate change is perhaps the biggest threat to civilisation. Just one example of this is the fact that sea levels are rising at the fastest rate in 3000 years. Indeed, entire countries such as Tuvalu could be underwater by the end of the century. Further, the threat to our wildlife is staggering, with the Living Planet Report reporting that the average size of vertebrate populations has decreased by 60% between 1970 and 2014.
Moreover, climate change also is detrimental to the health of the world. This is because, due to rising temperatures, the geographical location where the Aedes aegypti mosquito thrives has enlarged. As such, people living in these areas are more at risk of contracting malaria and Zika virus disease, as well as many other illnesses.
Climate change also leads to ocean dead zones, which can lead to the mass extinction of marine species and potentially dire consequences for hundreds of million people across the world. Due to increased temperatures in some parts of the world, the temperature of the oceans is also rising. As warm water holds less oxygen (because the water molecules have more kinetic energy, meaning they move faster and allow oxygen molecules to escape more quickly), the burning of fossil fuels actually contributes to the large scale deoxygenation of the oceans. This creates 'ocean dead zones' with no oxygen, where the majority of marine species can't survive.
Dead zones can also form due to surface run-off from agricultural areas, as excess nutrients are flushed into the ocean. These nutrients spark an algal bloom with phytoplankton (microscopic algae containing chlorophyll) gathering in the area to absorb these nutrients. However, because these phytoplankton block the sunlight from reaching the seabed, aquatic plant life dies. Zooplankton also accumulate in the area to feed on the phytoplankton. Bacteria then decompose the dead plant material and zooplankton corpses, resulting in the oxygen concentration in the waters falling drastically
After the water's oxygen level drops to below 2 milligrams per litre, it creates an uninhabitable zone for marine life. Not only does this lead to catastrophic damage to the marine ecosystem, with the death of millions of aquatic species, but this also has devastating effects on the people living near these areas. The oceans currently feed more than 500 million people across the globe and support 350 million jobs, however, the presence of these dead zones decimates fisheries, leading to job loss and food shortages across the world.
In order to reduce the number and size of dead zones, aside from taking steps to combat climate change and reduce greenhouse emissions, we must also improve farming practices in areas close to the sea, so that surface runoff is reduced and that there are fewer nutrients in the water for the algae to feed on. Furthermore, we should encourage the government to take action to reduce these dead zones since, as is evidenced by cleanup operations in the Chesapeake Bay and the Thames, these dead zones are partially reversible.
Sources:
Comments