Source-Dreamstime
Global warming is a long-term increase in the temperature of the Earth's surface. This is the main factor in climate change. This has been proven by directly measuring temperatures, and measuring the various effects of global warming. The terms global warming and climate change are often used interchangeably.
But, more precisely, global warming is an increase in global surface temperatures, primarily caused by humans, that continues. Climate change, in addition to global warming, also includes changes in precipitation (such as rain and snow). Although global warming has also occurred in prehistoric times, the increase in temperatures since the mid-20th century is unprecedented.
Regional Trends
Global warming refers to global averages. But the intensity of warming varies from region to region. Since pre-industrial times, global average soil temperatures have risen nearly twice as fast as global average temperatures. This is due to the high heat capacity of the oceans, which lose more heat through evaporation.
Warming does not depend on where greenhouse gases are emitted. Because these gases stay in the atmosphere long enough to spread across the planet; However, black carbon deposits on snow and ice are contributing to Arctic warming.
The Northern Hemisphere and North Poles have warmed much faster than the Southern Hemisphere and South Poles. Not only is there more land in the Northern Hemisphere, but as a result of the arrangement of land around the Arctic Ocean, the sunlight reflected from the snow and ice blanket provides more heat to the ocean and land surfaces.
Arctic temperatures have already risen. Moreover, it is predicted to grow twice as much as the rest of the world in the 21st century. As the temperature difference between the Arctic and the equator decreases, ocean currents such as the Gulf Stream, which are caused by that temperature difference, weaken.
Physical Causes of Recent Climate Change
The climate system undergoes various cycles. These cycles can last for years (such as the El Niño-Southern Oscillation), decades, and even centuries. Other changes are caused by external pressures. These forces are "external" to the climate system, not external to Earth.
Examples of extrinsic stressors include changes in the composition of the atmosphere (eg concentrations of greenhouse gases), solar irradiance, volcanic eruptions, changes in the Earth's orbit around the Sun, etc.
To conclude that the changes in temperatures are due to the increase of anthropogenic greenhouse gases, it must first be concluded that internal climate variations and natural external pressures are not the cause. For this, physical and statistical computer modelling should be used to identify all potential causes and their unique imprints.
By comparing these imprints with observed patterns of climate change evolution with pressure evolution, the causes of these changes can be determined. Scientists have concluded that greenhouse gases, changes in land use, aerosols, and soot are the main causes of current climate change.
Greenhouse Gases
Greenhouse gases trap heat from the Earth into space. These gases in the atmosphere absorb and re-emit this heat in the form of infrared radiation. This warms the lower atmosphere and the surface of the earth. Before the Industrial Revolution, naturally occurring greenhouse gases in the atmosphere kept air temperatures at the surface about 33 °C (59 °F) higher than they would have been in their absence.
If there was no real atmosphere on Earth, the average temperature of Earth would be much lower than the freezing point of water. The largest contributors to the greenhouse effect are water vapour (~ 50%) and clouds (~ 25%). As the temperature increases, they also increase. Hence they are considered feedback. Gases like CO2, Ozone, and N2O are considered exothermic gases.
Change in Land Use
Human conversion of land surface to agricultural land is the main cause of land use change. 50% of the world's habitable land is devoted to agriculture, while 37% is forest. Forest land is decreasing. Land use is affected mainly by forest loss in tropical areas. This deforestation is an important factor in land use change affecting global warming. The main causes of deforestation: are beef, agricultural products like palm oil (27%), forest products (26%), short-term agriculture (24%), and forest fires (23%).
Current trends in land use are affecting global warming in various ways. While some factors contribute significantly to greenhouse gas emissions, soil carbon fixation and photosynthesis also sequester CO2. As this is more than these greenhouse gas sources, they remove a net of 600 million tonnes of CO2 per year. This accounts for 15% of total CO2 emissions.
Smaller Sources: Sun, short-lived greenhouse gases
Since the Sun is the Earth's primary energy source, changes in sunlight directly affect the climate system. Solar radiation is measured directly by satellites. Indirect measurements have been available since the early 1600s. There is no increasing trend in the energy reaching the Earth from the Sun, so it is not the cause of the current warming.[26]
Physical climate models that consider only solar output and volcanic activity are unable to explain the rapid warming observed in recent decades. Another piece of evidence that warming is not caused by the Sun is the varying temperatures in Earth's atmosphere at different levels.
According to basic physical principles, the greenhouse effect warms the lower atmosphere (troposphere) and cools the upper atmosphere (stratosphere). If solar changes are responsible for the warming, then both the troposphere and stratosphere should warm. But that didn't happen.
Ozone in the troposphere, the lower layer of the atmosphere, is also a greenhouse gas. Moreover, it is a very active gas, reacting with other greenhouse gases and aerosols.
Conclusion
Adapting to and mitigating climate change are two complementary responses to global warming. If emissions are significantly reduced, adaptation is easy. Many of the countries that are the least contributors to global greenhouse gas emissions are the most affected by climate change. This raises jurisdictional questions regarding relief and adaptations.
Written by Kundena Nikhil
.jpeg)
0 Comments