Facts on how human activities cause global warming

When people talk about climate change today, they often tend to mean man-made or anthropogenic climate change, which refers to the global rise of the earth’s temperature as a result of human activities.



More than 97% of scientists all over the world agree that climate change is man-made.



In this era of social media, fake news and misinformation, some social media users have claimed that the concept of man-made climate change is a myth. One recently posed : “Man-made climate change is a myth. If it was real investors would not invest in property development in areas that will be 10 feet under the sea I believe the nonsense is. Also, banks wouldn’t give mortgages. No home insurance. Show climate change in any home insurance.”



This claim is false, as science has proven that  greenhouse gases in the atmosphere, released due to human activities, are responsible for trapping  heat and slowing down the rate at which heat is lost to space.



These greenhouse gases, as detailed by NASA, include carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. Carbon dioxide, for example, is released into the atmosphere  through natural processes and human activities such as burning fossil fuels and deforestation. Methane,  which can also be released by both natural and human caused processes, has more than doubled in the atmosphere since pre industrial times.



For nitrous oxide, its release stems from commercial and organic fertiliser production and use, burning fossil fuels and vegetation.



“Over the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide . This increase happens because the coal or oil burning process combines carbon with oxygen in the air to make carbon dioxide. To a lesser extent, clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases,” says NASA.



NASA details that even though the sun may have played a part in past climate changes, the recent one being witnessed is contributed to by a factor separate from the sun.



“Since 1750, the average amount of energy from the Sun either remained constant or increased slightly. If a more active Sun caused the warming, scientists would expect warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere and a warming at the surface and lower parts of the atmosphere. That’s because greenhouse gases are slowing heat loss from the lower atmosphere,” states NASA.



“Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases.”



The Intergovernmental Panel on Climate change states that the increase of greenhouse gases in the atmosphere over the industrial era is “the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere, and biosphere.”



The same sentiments are echoed by the United States Environmental Protection Agency(EPA), which explains that human activities currently release over 30 billion tons of carbon dioxide into the atmosphere every year.



“Atmospheric carbon dioxide concentrations have increased by more than 40% since pre-industrial times, from approximately 280 parts per million (ppm) in the 18th century to 414 ppm in 2020.Human activities increased methane concentrations during most of the 20th century to more than 2.5 times the pre-industrial level, from approximately 722 parts per billion (ppb) in the 18th century to 1,867 ppb in 2019,”says EPA.



“Nitrous oxide concentrations have risen approximately 20% since the start of the Industrial Revolution, with a relatively rapid increase toward the end of the 20th century. Nitrous oxide concentrations have increased from a pre-industrial level of 270 ppb to 332 ppb in 2019,”adds EPA.



The UN Climate Action details that as a result of man-made climate change, the earth is now experiencing hotter temperatures, more severe storms, increased drought, warmer ocean which leads to rising sea levels, inadequate food and extinction of species, health risks and displacement of communities.



“As greenhouse gas concentrations rise, so does the global surface temperature. The last decade, 2011-2020, is the warmest on record. Since the 1980s, each decade has been warmer than the previous one. Nearly all land areas are seeing more hot days and heat waves. Higher temperatures increase heat-related illnesses and make working outdoors more difficult. Wildfires start more easily and spread more rapidly when conditions are hotter,” says the UN.



“Destructive storms have become more intense and more frequent in many regions. As temperatures rise, more moisture evaporates, which exacerbates extreme rainfall and flooding, causing more destructive storms. The frequency and extent of tropical storms is also affected by the warming ocean. Cyclones, hurricanes, and typhoons feed on warm waters at the ocean surface. Such storms often destroy homes and communities, causing deaths and huge economic losses,” it adds.



The UN also details that climate change is to be bland for making water scarce, including in regions that were already struggling with water availability. As a result, it leads to Increased drought, which is known to create conditions that encourage insect and disease infestation in certain crops.



Droughts also lead to Low crop yields which can result in rising food prices and shortages, potentially causing malnutrition. Besides, droughts negatively impact livestock health by causing malnutrition, diseases and even death.



“The ocean soaks up most of the heat from global warming. The rate at which the ocean is warming strongly increased over the past two decades, across all depths of the ocean. As the ocean warms, its volume increases since water expands as it gets warmer. Melting ice sheets also cause sea levels to rise, threatening coastal and island communities. In addition, the ocean absorbs carbon dioxide, making the ocean more acidic, which endangers marine life and coral reefs,” says the UN Climate Action.



“Climate change poses risks to the survival of species on land and in the ocean. Exacerbated by climate change, the world is losing species at a rate 1,000 times greater than at any other time in recorded human history. One million species are at risk of becoming extinct within the next few decades (because of)  Forest fires, extreme weather, and invasive pests and diseases,” adds the UN.



Besides leading to shortage of food, climate change is responsible for harming human health through  expanding diseases, overwhelming health care systems, air pollution, extreme weather events, forced displacement, hunger and poor nutrition. Because of weather related events, around 23.1 million people are displaced each year , with around 13 million people dying.



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