Climate Change
Climate change refers to a long-term significant change in the “average weather” of a region or the earth as a whole. Average weather includes variables like average temperature, precipitation, wind patterns and so on. The global climate changes are brought about by dynamic processes of Earth, external forces and also by human activities. In recent usage, especially in the context of environmental policy, the term “climate change” usually refers to changes in modern climate.
1. Variations within the Earth’s Climate
Though daily whether tends to be variable, its prediction in terms of average state of weather is easier and more precise. Measurable climate variables like the average temperature, amount of precipitation, days of sunlight, and other variables, can be measured at any given site and any pattern if existent can be studied and used for further predictions. However, there are also changes within the Earth’s environment affecting the climate that do not follow a pattern and are therefore not as easy to predict.
Climate Change Factors : Global climate changes reflect variations within the Earth’s atmosphere, other atmospheric changes oceans and the gradual impact of human activity. The external factors that can shape climate are often called climate forcings, which are a function of variations in solar radiation, the Earth’s orbit, and greenhouse gas concentrations.
Glaciation : Glaciers are the most sensitive indicators of climate change, advancing substantially during climate cooling and retreating during climate warming. Glaciers grow and collapse, both contributing to natural variability, resulting in amplification of external forced changes. For the last century, however, glaciers have been unable to regenerate enough ice during the winters to make up for the ice lost during the summer months. The most significant climate processes of the last several million years are the glacial and interglacial cycles of the present ice age. Though shaped by orbital variations, the internal responses involving continental ice sheets and 130 m sea-level change certainly played a key role in deciding what climate response would be observed in most regions. Other changes, including Heinrich events, Dansgaard–Oeschger events and the Younger Dryas show the potential for glacial variations to influence climate even in the absence of specific orbital changes.
Ocean Variability : Oceans play a very important role in the climatic changes, thus impacting the day-to-day climate. The interaction of the atmosphere and oceans, over decades, lead to climate fluctuations — including not only the El Niño Southern oscillation but also the Pacific decadal oscillation, the North Atlantic oscillation, and the Arctic oscillation — owe their existence at least in part to different ways that heat can be stored in the oceans and move between different reservoirs. On longer time scales ocean processes such as thermohaline circulation play a key role in redistributing heat, and can dramatically affect climate.
2. Non Climate Factors Driving Climate Change
Greenhouse gases are also important in understanding Earth’s climate history. Greenhouse effect is the global warming produced as greenhouse gases trap heat in the earth’s atmosphere leading to increased global warming and play a key role in regulating Earth’s temperature. There are several examples of rapid changes in the concentrations of greenhouse gases in the Earth’s atmosphere that do appear to correlate to strong warming, including the Paleocene–Eocene thermal maximum, the Permian–Triassic extinction event, and the end of the Varangian snowball earth event.
Plate Tectonics : The earth is a huge store of greenhouse gases. Due to plate tectonics these gases are continuously released into the atmosphere thereby contributing to the climate change. During the Carboniferous, tectonics may have triggered the large-scale storage of Carbon and increased glaciation. More recently, plate motions have been implicated in the intensification of the present ice age when, approximately 3 million years ago, the North and South American plates collided to form the Isthmus of Panama and shut off direct mixing between the Atlantic and Pacific Oceans.
Solar Variation : The energy output of the sun, which is converted to heat at the Earth’s surface, is an integral part of shaping the Earth’s climate. With time sun is becoming brighter and brighter and this slow change its affecting the Earth’s atmosphere adversely. Solar intensity variations are triggering a climate change that is causing climatic changes that can be studied only up to certain extent. Understanding issues related to all kinds of climate changes and their nature is not an easy task. Its needs time and acumen to predict the next stage of the cycle and the course of action required to deal with its ill effects for the human race.
Orbital Variations : Orbital variations are a predictable consequence of mutual interactions between Earth, its moon, and the other planets. They are an extension of the solar variations, as the slight variations in the Earth’s orbit lead to changes in the distribution and abundance of sunlight. These variations are considered the driving factors underlying the glacial and interglacial cycles of the present ice age. Subtler variations are also present, such as the repeated advance and retreat of the Sahara desert in response to orbital precession.
Volcanism : Huge eruptions, known as large igneous provinces, occur only a few times every hundred million years, but can reshape climate for millions of years and cause mass extinctions. Initially, scientists thought that by partially blocking the transmission of solar radiation to the Earth’s surface, the dust emitted into the atmosphere from large volcanic eruptions was responsible for the cooling,. However, measurements indicate that most of the dust thrown in the atmosphere returns to the Earth’s surface within six months.
3. Evidence for Climatic Change
Evidence for climatic change is taken from a variety of sources both direct and indirect. Most of the climatic changes are studied and inferred from changes in climate change indicators such as vegetation, dendrochronology, ice cores, sea level change, glacial retreat, etc.
Pollen Analysis : Palynology, the science of contemporary and fossil palynomorphs, including pollens, is used to infer the geographical distribution of plant species. Different groups of plants have pollen with distinctive shapes and surface textures, and since the outer surface of pollen is composed of a very resilient material, they resist decay. Changes in the type of pollen found in different sedimentation levels in lakes, bogs or river deltas indicate changes in plant communities; which are dependent on climate conditions.
Beetles : Remains of beetles are common in freshwater and land sediments. Different species of beetles tend to be found under different climatic conditions. Knowledge of the present climatic range of the different species, and of the age of the sediments in which remains are found, allows past climatic conditions to be inferred.
Glacial Geology : Advancing glaciers leave behind moraines and other features that often have datable material in them, recording the time when a glacier advanced and deposited a feature. Similarly, by tephrochronological techniques, the lack of glacier cover can be identified by the presence of datable soil or volcanic tephra horizons. Glaciers are considered one of the most sensitive climate indicators by the IPCC, and their recent observed variations provide a global signal of climate change.
4. Human Influences on Climate Change
Anthropogenic factors are human activities that change the environment and influence climate. In some cases the chain of causality is direct and unambiguous (e.g., by the effects of irrigation on temperature and humidity), while in others it is less clear. The biggest concern today is the increase in CO2 levels due to emissions from fossil fuel combustion, followed by aerosols emissions, and cement manufacture. Other factors like land use, ozone depletion, animal agriculture and deforestation, also affect climate.
Fossil Fuels : It is known that carbon dioxide levels are substantially higher now than at any time in the last 750,000 years. Beginning with the industrial revolution in the 1880s and accelerating ever since, the human consumption of fossil fuels has elevated CO2 levels. If current rates of emission continue, these ever increasing concentrations are projected to reach dangerous levels by the end of the 21st century.
Cement Manufacture : Cement manufacture contributes CO2 to the atmosphere when calcium carbonate is heated, producing lime and carbon dioxide, and also as a result of burning fossil fuels. The cement industry produces 5% of global man-made CO2 emissions, of which 50% is from the chemical process, and 40% from burning fuel. The amount of CO2 emitted by the cement industry is nearly 900 kg of CO2 for every 1000 kg of cement produced.
Land Use : Humanity’s largest effect on local climate is likely to have resulted from land use. Irrigation, deforestation, and agriculture fundamentally change the environment. For example, they change the amount of water going into and out of a given location. There is evidence to suggest that the climate of Greece and other Mediterranean countries was permanently changed by widespread deforestation between 700 BC and 1 AD (the wood being used for shipbuilding, construction and fuel), with the result that the modern climate in the region is significantly hotter and drier, and the species of trees that were used for shipbuilding in the ancient world can no longer be found in the area.
Livestock : According to a 2006 United Nations report, Livestock’s Long Shadow, livestock is responsible for 18% of the world’s greenhouse gas emissions as measured in CO2 equivalents. This however includes land usage change, meaning deforestation in order to create grazing land, as well as livestock natural gas emissions. In addition to CO2 emissions, livestock produces 65% of human-induced nitrous oxide (which has 296 times the global warming potential of CO2) and 37% of human-induced methane (which has 23 times the global warming potential of CO2).
These climate change facts are sufficient to tell us that mankind and their lifestyles are majorly contributing to the climate change, and it’s high time that we start thinking seriously about the issues and mal-effects of these changes that are being brought about in the climate before they pose threats to humanity as a whole.
