Thứ Hai, 26 tháng 7, 2021

The Causes of Climate Change!

The Causes of Climate Change

Since the 1950s, scientists have noticed a global warming trend. They say that this warming trend is due to the human expansion of the greenhouse effect. The greenhouse effect happens when the atmosphere traps the Earth's heat.

Some gases in the atmosphere stop heat from escaping. A portion of these gases remain in the atmosphere. They do not respond to changes in temperature. Scientists say these gases are "forcing" climate change.

Other gases, such as water vapor, respond to changes in temperature. Scientists call these "feedbacks."

Greenhouse Gases

Gases that contribute to the greenhouse effect include:

  • Water vapor. Water vapor is the most common greenhouse gas. It also acts as a feedback to the climate. Water vapor increases as the Earth's atmosphere warms. It also increases the possibility of clouds and rain. These are some of the most important feedback mechanisms to the greenhouse effect.
  • Carbon dioxide (CO2). CO2 is a minor but important part of the atmosphere. Carbon dioxide is released through natural processes and human activities. Examples of natural processes are breathing and volcano eruptions. Examples of human activities are deforestation, land-use changes, and burning fossil fuels. Humans have increased atmospheric CO2 concentration by 47% since the Industrial Revolution began. This is the most important "forcing" of climate change.
  • Methane. Methane is a hydrocarbon gas. Like CO2, it is produced both through natural sources and human activities. Landfill waste is an example of a human source of methane. Agriculture is another human source of methane. For example, rice farming produces significant amounts of methane. Domestic livestock, such as cows and sheep, are also significant sources of methane. Methane is a far more active greenhouse gas than carbon dioxide. But, there is also much less of it in the atmosphere.
  • Nitrous oxide. Nitrous oxide is a powerful greenhouse gas. It comes from soil cultivation practices in farming, such as commercial and organic fertilizers. Burning fossil fuels and biomass also produce large amounts of nitrous oxide.
  • Chlorofluorocarbons (CFCs). CFCs are synthetic compounds. This means they are not natural at all. They are completely manmade and very powerful. CFCs are so powerful that they can destroy the ozone layer.

Human Activities

Human activities are changing the Earth's natural greenhouse. Humans burn fossil fuels like coal and oil. These are a major source of carbon dioxide (CO2) in the atmosphere. The process of burning coal and oil combines carbon with oxygen in the air to make CO2.

Deforestation has increased concentrations of greenhouse gases. Deforestation is the clearing of land for agriculture, industry, and other human activities. This has less of an impact than fossil fuels, but the amount of deforestation is increasing.

The Consequences of Climate Change

The consequences of climate change are difficult to predict. But some effects seem likely:

  • The Earth will become warmer.
    • Some regions will become wetter. Warmer conditions will lead to more evaporation and rain around the world. 
    • Some regions will become drier. Warmer conditions will lead to more droughts. 
  • The ocean will become warmer.
    • Glaciers and ice sheets will melt.
    • Warm ocean water will expand.
    • Sea levels will rise.
  • Crop yields will be affected. "Crop yields" are the number of grains, fruits, and vegetables that farmers can grow.
    • If it gets too hot, crop yields may be smaller.
    • Droughts, floods, and extreme temperatures can cause crop losses.
    • Crop losses can threaten farmers' livelihoods and the food security of communities worldwide.
    • Warmer temperatures, wetter climates, and increased CO2 levels increase weeds, pests, and fungi. These can also reduce crop yields.
    • Rising CO2 can increase plant growth but it can also reduce nutritional value. More CO2 will reduce the amount of protein and essential minerals in most plant species.
  • There will be new patterns of pests and diseases. This affects plants, animals, and humans. It poses new risks for food security, food safety, and human health.

The Role of Human Activity

The Intergovernmental Panel on Climate Change is a group of 1,300 scientists. They say that is very likely that recent human activities have warmed our planet. In fact, they say the possibility is more than 95 percent. In the past 150 years, human activities have raised C02 levels from 280 to 414 parts per million.

The Role of Solar Activity

The Sun drives our climate system. We call energy from the sun "solar activity".

You might have heard that changes in solar activity are causing the climate to change.

In fact, studies show that changes in solar activity have changed the climate in the past.

For example, the Earth experienced a Little Ice Age between 1650 and 1850. Some seas froze and glaciers advanced. This was likely caused by a decrease in solar activity and an increase in volcanic activity.

But changes in solar activity cannot explain the current global warming trend.

Since 1750, the average amount of energy coming from the Sun has not changed much at all. It has remained constant or only increased

Only the Earth's surface and lower atmosphere are warming. The upper atmosphere is cooling. That's because greenhouse gases are trapping heat in the lower atmosphere. Increased solar activity would create warmer temperatures in all layers of the atmosphere.

Climate models that include changes in solar activity can’t reproduce the current warming trend without including a rise in greenhouse gases

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