Climate change is the long term increase in the Earth’s average surface temperature and the large scale changes in global, regional, and local weather patterns that result from that increase, caused by a significant increase in the greenhouse gases produced by the use of fossil fuels.
- Climate is the average weather in a place over many years.
- The weather can change in just a few hours whereas climate takes millions of years to change.
- Planet earth has witnessed many variations in climate since the beginning.
Since the 1960s, the levels of carbon dioxide in the atmosphere have risen from less than 320 parts per million to more than 420 parts per million. While that may seem like a small shift, it’s enough to make a huge difference.
Carbon dioxide works a bit like the glass of a greenhouse. Greenhouses let light pass through them, but trap some of the heat. That’s why it can get even hotter inside your car than it is outside. Carbon dioxide and other greenhouse gases trap some of the sun’s heat on earth. That’s obviously good to a certain extent. We couldn’t live on a planet that didn’t trap any heat. But trapping too much can be a problem.
There are natural sources of carbon dioxide people breathing, plants and animals decomposing, and even some geological events but only the last few hundred years of burning fossil fuels, like oil, coal, and natural gas, account for the present rise in carbon dioxide. Other greenhouse gases, like methane, nitrous oxide, hydrofluorocarbons, also trap heat.
Climate Change
Evidence of Climate Change
- Sea level rise
- Global temperature rise
- Warming oceans
- Shrinking ice sheets
- Declining Arctic sea ice
- Glacial retreat
- Extreme natural events
- Ocean acidification
- Decreased snow cover
How will climate change affect us ?
Climate change is a threat to mankind. The earth’s average surface temperature has increased by 0.3-0.6 0C since the end of the 19th century. Such increase in temperature may seem to be minimal to us but they can lead to a disaster as highlighted below.
Agriculture
The increasing population has resulted in increased demand for food. This results in pressure on natural resources. Climate change will affect agricultural yield directly because of alterations in temperature and rainfall, and indirectly through changes in soil quality, pests, and diseases. It is said that the yield of cereals is expected to decline in India. Extreme weather conditions such as high temperature, heavy rainfall, floods, droughts, etc. will also affect crop production.
Weather
A warmer climate will change rainfall patterns, lead to increased droughts and floods, cause melting of glaciers and polar ice sheets, and result in increased sea- level rise. An increase in the number of cyclones and hurricanes over the last few years has been attributed to changes in temperature.
Sea level rise
One of the outcome of climate change is the rising sea level. The heating of oceans, and melting of glaciers and polar ice sheets, is predicted to raise the average sea level by about half a metre over the next century. Sea-level rise could have a number of physical impacts on coastal areas, including loss of land due to inundation and erosion, increased flooding, and salt-water intrusion. These could adversely affect coastal agriculture, drinking water resources, fisheries, human settlements, and health.
Health
Global warming will directly affect human health by increasing cases of heat-related mortality, dehydration, spread of infectious diseases, malnutrition, and damage to public health infrastructure.
Forests and wildlife
Plants and animals in the natural environment are very sensitive to changes in climate. If the rate of climate change continues to increase, extinction of various species of plants and animals could happen.
Astronomical causes
The astronomical causes are the variations in solar output related to sunspot activities.
Sunspots are dark and cooler patches on the sun which rise and fall in a recurring manner.
When the number of sunspots increases, cooler and wetter weather and greater storminess occur.
These modify the amount of insolation received from the sun, which in turn, might have a bearing on the climate.
Milankovitch oscillations, which infer cycles in the variations in the earth’s orbital characteristics around the sun, the wobbling of the earth and the changes in the earth’s axial tilt. All these alter the amount of insolation received from the sun, which in turn, might have a bearing on the climate.
The rate of emissions has been steadily increasing over time, and computer models of the earth’s climate system (including both natural and human causes) are unable to simulate recent warming unless they include anthropogenic emissions of greenhouse gases.
Land based human activities, such as forest clearing and unsustainable agricultural practices, are not only increasing GHG emissions from these sources, but are also reducing the earth’s natural ability to absorb GHGs. The evidence that current global warming is due to human activities associated with industrialization and modern agriculture is overwhelming.
When fossil fuels burn, they release greenhouse gases mostly carbon dioxide (CO2). This CO2 acts like a blanket, trapping extra energy in the atmosphere near the Earth’s surface. This causes the planet to heat up.
Since the start of the Industrial Revolution when humans started burning large amounts of fossil fuels the amount of CO2 in the atmosphere has risen by more than 50%, far above levels seen in the Earth’s recent history.
The CO2 released from burning fossil fuels has a distinctive chemical fingerprint. This matches the type of CO2 increasingly found in the atmosphere.
What effects of climate change have already been seen ?
more frequent and intense extreme weather, such as heatwaves and heavy rainfall
rapid melting of glaciers and ice sheets, contributing to sea-level rise
the shrinking of Arctic sea-ice
warmer oceans, which can fuel more intense storms and harm sea life
These changes are already having serious consequences for people and economies around the world.
Global warming of 1°C or 1.5°C represents an average across the planet many places will warm faster, and see far greater temperature increases. For example, the Arctic is warming 2-3 times faster than any other place on Earth. The effects of global heating are far-reaching, including rising sea levels, glacier retreat, changes in the timing of seasonal events (plants flowering, migration patterns), and a rise in the frequency and severity of extreme weather events. These categories of impacts have direct and indirect consequences on people and wildlife. Direct consequences include displacement of people and communities due to sea level rise and extreme weather events, whereas indirect consequences may include disruptions to economic development, food production, escalation in water crises, and increased public health risks.
The impacts of climate change will not be evenly felt around the world people living in the poorest countries and in geographically vulnerable regions will be first and most significantly impacted. This is because communities living in poverty are more likely to be exposed to environmental hazards, are often more dependent on natural resource-based livelihoods such as agriculture, and have fewer resources to cope with climate impacts.
Each fractional degree of warming also results in outsized impacts on biodiversity and species extinction, and disturbances in natural ecosystems.
Even if carbon emissions in the atmosphere can be absorbed and stabilized over a long period of time, many of the impacts on wildlife, land, water, and people will be irreversible once they occur, which makes halting the release of greenhouse gas emissions, and limiting global warming as much as possible, the first priority.
Temperature on Earth depends on energy from the sun. It is determined by the difference between the energy that comes in (input) and energy that is reflected back (output).
The amount of radiation we receive from the sun keeps changing. Factors like slight variations in the earth’s orbit, solar cycles and changes in the fraction of radiation reflected by clouds affect input solar radiation.
Increase in the temperature of surface air increases the concentration of greenhouse gases in the atmosphere, which in turn amplifies changes in the surface temperature of Earth. Higher concentration of greenhouses gases trap more radiation which is reflected by the Earth’s surface. This is how a positive feedback loop works.
However, human activity is causing a lot more greenhouse gases and as a result, the earth’s temperature is increasing by too much. Here are just a few examples of how humans contribute to their increase:
Pollution – Fossil fuels such as coal, gas and oil are used to make electricity and run cars. These fossil fuels are burnt in power stations and as a result, carbon dioxide is released into the air. Carbon dioxide is a greenhouse gas, and it’s very harmful to the environment.
Deforestation – Huge areas of trees are being cut down for different reasons, such as using wood for fuel, building houses or factories. This contributes to global warming as there are fewer trees left to absorb carbon dioxide in the air.
Agriculture and Farming – We need food to survive, so farming is very important for us. However, animals such as cows, sheep, pigs and chickens release a greenhouse gas called methane, which is very harmful to the environment. To feed these animals, farmers use fertilizers and pesticides to help plants grow well. These cause even more greenhouse gases to be released.
Water Vapour – Most water vapour ends up in the atmosphere in a natural way for example, when water evaporates from the oceans and seas. However, human activities such as power plant cooling and flying can contribute to the creation of this greenhouse gas as well.