Global warming is the long-term heating of the earth’s climate system observed since the pre-industrial period. It is the gradual heating of the earth’s surface, oceans, and atmosphere, which is caused by human activities, primarily the burning of fossil fuels that emit carbon dioxide, methane, and other greenhouse gases into the atmosphere. In the U.S., it is estimated that 40% of carbon dioxide emissions stem from electricity production (power plants), and 33% of emissions come from the transportation of people and goods. Farming, deforestation, industries, fertilizers, oil drilling, natural gas drilling, and permafrost also cause global warming. Global warming occurs when carbon dioxide and other air pollutants collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the Earth’s surface. Responding to climate change will be one of the biggest challenges we face this century.
The change in the global surface temperature between 1850 and the end of the 21st century is likely to exceed 1.5 C. The World Meteorological Organization says that if the current warming trend continues, temperatures could rise 3-5 C by the end of this century. Temperature rises of 2 C had long been regarded as the gateway to dangerous warming. More recently, scientists and policymakers have argued that limiting temperature rises to 1.5 C is safer. The UN is leading a political effort to stabilize greenhouse gas emissions. China emits more carbon dioxide than any other country. It is followed by the US and the European Union Member States. But even if we now cut greenhouse-gas emissions drastically, scientists say the effect will continue. Large bodies of water and ice can take hundreds of years to respond to changes in temperature and it will take decades to remove carbon dioxide from the atmosphere.
According to the World Meteorological Organization, the world is about one degree Celsius warmer than before widespread industrialization. Across the globe, the average sea level increased by 3.6 mm per year between 2005 to 2015. However, melting ice is now said to be the main reason for rising sea levels. Most glaciers in temperate regions of the world are retreating. The Greenland ice sheet has experienced record melting in recent years. The effects of changing climate can also be seen in vegetation and land animals. These include earlier flowering and fruiting times for plants and changes in the territories of animals. The greenhouse gas with the greatest impact on warming is water vapor. But it remains in the atmosphere for only a few days. Carbon dioxide, however, persists for much longer. It would take hundreds of years for a return to pre-industrial levels and only so much can be soaked up by natural reservoirs such as the oceans. Since the industrial revolution began in about 1750, carbon dioxide levels have risen more than 30%. The concentration of carbon dioxide in the atmosphere is higher than at any time in at least 800,000 years. Other greenhouse gases such as methane and nitrous oxide are also released through human activities but they are less abundant than carbon dioxide.
There are natural fluctuations in the climate but scientists say temperatures are now rising faster than at other times. Solar energy radiation back to space from the Earth’s surface is absorbed by greenhouse gases and re-emitted in all directions. This heats both the lower atmosphere and the surface of the planet. Without this effect, the earth would be about 30 C colder and hostile to life.
Global warming could cause freshwater shortage dramatically, alter our ability to produce food, and increase the number of deaths from floods, storms, and heatwaves. This is because climate change is expected to increase the frequency of extreme weather. As the world warms, more water evaporates, leading to more moisture in the air. Many areas will experience more intense rainfall and in some places snowfall. The risk of drought in inland areas during hot summers will increase. More flooding is expected from storms and rising sea levels. Plant and animal extinctions are expected as habitats change faster than species can adapt. The health of millions of people could be threatened by an increase in malaria, water-borne diseases, and malnutrition. As more carbon dioxide is released into the atmosphere, uptake of the gas by the oceans increases, causing the water to become more acidic. Global warming will cause further changes that are likely to create further heating. This includes the release of large quantities of methane as permafrost-frozen soil found mainly at high latitudes melts.
Global warming can be reduced by adopting the following precautions: 1. Invest in energy-efficient appliances and use LED bulbs. Power your home with renewable energy. Improve insulation in your home to reduce heating. 2. Use less electricity and unplug appliances. Turn off lights when not in use. Reduce the use of air conditioning and refrigerants. 3. Don’t waste water, take shower instead of a tub bath. 4. Grow your own food and buy locally grown food. 5. Walk and use a bike and use a car less. Use public transport or carpool to go to work. 6. Use biofuels. 7. Get involved in public education and activism. 8. Try to lead a simple and healthy life.
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