Climate Change, Equilibrium Temperature and Climate of the Earth - Essay Example

Insert Introduction Climate change can be simply defined as a significant and lasting change in the statistical distribution of weather patterns over durations spanning from decades to millennia (change in statistical characteristics of the climate system when considered over long periods of time, regardless of cause). Consequently, variations over short periods of time (shorter than a few decades such as the El Nino) do not constitute climate change. At times, the term is used to denote climate change that results from human activity rather than the changes caused by natural processes of the earth. In this case, the term climate change has been used to mean the same as anthropogenic global warming. However, most extracts, environmental journals and literature view global warming as a mere surface temperature increase with climate change encompassing global warming along with any other thing affected by the increase in greenhouse gas levels (Friedman, 17). Generally, the equilibrium temperature and climate of the earth/ a region are dependent on the rate at which energy is insulated from the sun and the rate at which this heat is lost in space. This energy in the atmosphere is dispensed and spread across the world by winds, ocean currents and such other mechanisms thus affecting the climates of different areas of the world. Forcing mechanisms, also termed climate forcings, are those elements which determine climate. These elements/ factors include processes like differences in solar radiation, changes in greenhouse gas concentrations, variations in the earth’s orbit, mountain building and continental drift. Different parts of the earth respond differently to these climate forcings with others such as oceans and ice caps exhibiting a slower response than others which respond relatively quickly. In addition, the forcing mechanisms can either be amplified or effects diminished by what are known as climate change feedbacks (Lerner and Chiara, 377). Forcing mechanisms can either be internal (natural processes within the climate system itself like thermohaline circulation) or external (which are either natural like changes in solar output or anthropogenic such as increase in greenhouse gas emission), but whether the initial forcing mechanism is internal or external, the response of the climate system may be quick (as in the sudden cooling due to reflection of sunlight by airborne volcanic ash), slow (such as thermal expansion of warming ocean water) or a combination of both such as the slow water thermal expansion that precedes ice melting in the arctic ocean and the resulting sudden loss of albedo. Thus, while it may take centuries or even more for the forcing mechanism to fully develop, the climate system can still exhibit a quick response. Internal processes of the climate system encompasses natural alterations in the components of the earth’s climate system (these components of the earth’s climate system include lithosphere, hydrosphere (surface, rocks, soils and sediments), atmosphere, cryosphere and the biosphere) and their interactions which lead to internal climate changes. Carbon IV Oxide, which can be used as a feedback when modeling climate, is equally considered a forcing in the climate system (Lerner and Chiara, 411). Ocean Variability The ocean is a very important component of the climate system. Some of the variations that take place in it compared to those in the ethanosphere usually span longer periods, have far greater masses and posses very high thermal inertia like the ocean depths which still lag today in temperature adjustment that occurred in the Little Ice Age. By carrying out a very slow and extremely deep movement of water and long-term redistribution of heat in the world’s oceans, alterations to ocean processes such as thermohaline circulation play a critical function in redistributing heat on longer time spans. Events such as the El Nino-southern oscillation, the Pacific decadal oscillation, the North Atlantic oscillation and the Arctic oscillation which were short-term variations spanning only years to a few decades do not represent climate change but rather climate variability (Friedman, 345). Life Life influences climate via processes such as albedo, evapotranspiration, cloud formation, weathering and also plays a role in the carbon and water cycle. Instances from the past when life affected climate include Paleocene-Eocene Thermal Maximum termination by flourishing marine phytoplankton (55million years ago), 800,000 years of arctic azolla blooms which reverse global warming 49 million years ago, the expansion of grass-grazer ecosystem-driven global cooling over the past 40 million years, glaciations caused by the evolution of oxygenic photosynthesis 2.3 billion years ago and the long-term burial of the decomposition resistant detritus of vascular land plants (leading to coal formation) which caused glaciations 300 million years ago (Tanaka, 57). External Forcing Mechanisms Human Influence There are certain human activities/ influences, also termed anthropogenic factors, which impact climate. Scientists agree that climate is changing globally and that for most part, these changes which are largely irreversible, are driven mostly by human activities. The greatest concern of these anthropogenic factors remains the alarming increase in Carbon IV Oxide levels which occur as a result of man’s combustion of fossil fuels. There is also the release of particulate matter into the atmosphere in the form of aerosols and the release of Carbon IV Oxide into the atmosphere from cement manufacturing processes. Other anthropogenic factors that contribute significantly to climate change include land use, livestock farming, deforestation and ozone depletion. These human factors can work solely or in interaction with other factors to impact climate, microclimate and other measures of climate variables (Friedman, 365). Volcanic Action Volcanicity is classified as an external forcing agent, though they are technically part of the lithosphere. Volcanic activity releases gases and particles into the earth’s atmosphere with eruptions big enough to facilitate climate change. Common and occurring several times in a century, these emissions from volcanic actions into the atmosphere cause cooling by blocking incoming solar radiation to the earth surface for a considerable amount of time. Following the eruption of Mount Piantubo in 1991, global temperatures were lowered by approximately 0.5̊C (0.9̊F). This was the second largest terrestrial eruption in the 20th Century after the Novarupta eruption of 1912. The eruption of Mount Tambora in 1815 resulted in the year without a summer because of this cooling effect. Eruptions larger than the above mentioned, known as large igneous provinces, however, occur only a few times every 100 millennia and may result in global warming and mass extinctions (Tanaka, 98). Volcanoes also form part of the carbon cycle by releasing Carbon IV Oxide from the earth’s crust and mantle over long geological periods and consequently counteracting the uptake of Carbon IV Oxide by sedimentary rocks and other geological Carbon IV Oxide sinks. Studies indicate that volcanic actions however, emit 100-300 times less Carbon IV Oxide than human activities with annual volcanic emissions only equaling 3-5 days of human induced output. The annual human output is speculated to be greater than the amount of Carbon IV Oxide released by the super-eruptions such as the Indonesian Toba eruption 74,000 years ago (Lerner and Chiara, 418). Orbital Variations There are differences in seasonal distribution of the sunlight that reaches the earth surface and how it spreads on the earth surface due to the earth’s orbital position. Although there can be strong changes in the geographical and season distributions, there is normally very little change area-averaged annually average sunshine. There are basically three types of orbital variations. These include changes in the tilt angle of the earth’s axis of rotation, precession of the earth’s axis and variations in the earth’s eccentricity. These three orbital variations combined together constitute what is called the Milankovitch cycles. The Milankovitch cycles (with large effects on climate are recognizable for their relationship with the glacial and interglacial periods, the advance and retreat of the Sahara and their occurrence in statigraphic records) are noted to have driven the ice age cycles with Carbon IV Oxide preceding the temperature change with a lag of up to hundreds of years as a feedback amplified temperature change. The ocean depths have a lag time in altering temperatures and upon seawater temperature change, the solubility of Carbon IV Oxide in the oceans and other factors affecting air-sea Carbon IV Oxide exchange changed (Tanaka, 231). Solar Output The main source of energy on earth is the sun. Changes in solar intensity, both long and short-term, produce an impact on global climate. The sun is thought to have initially emitted about 70% of much power as it does today and if the atmospheric conditions today were similar to how they were back then, then liquid water would not have been available on the earth surface. Contrary to this belief, there appears to have been water in the early earth, for example in the hadean and archean periods, leading to the faint sun paradox which speculates a significantly different atmosphere with higher concentrations of greenhouse gases than today’s. The energy output of the sun increased and atmospheric composition changed (with the Great Oxygenation event/ oxygenation of the atmosphere around 2.4 billion years ago the most notable changes) over the next 4 billion years. It is predicted that over the next 5 billion years, the sun will get fainter and transform into a red giant and finally a white dwarf. These changes are predicted to have immense impacts on life on earth with the red giant phase of the earth forecasted to bring to an end any form of life on earth that will still be around (Friedman, 400). Plate Tectonics The movement of tectonic plates over decades causes reconfiguration of global lands and ocean areas while also creating new topography. This consequently influences global and local climate patterns and atmospheric ocean circulation. The patterns of ocean circulation are as a result of the geometry of the oceans which are themselves influenced by the positions of the continents. The positions of water masses (oceans and seas) are vital in regulating heat and moisture transfer across the globe and consequently in determining global climate. The formation of the Isthmus of Panama approximately 5 million years ago which halted the direct mixing of the Atlantic and Pacific Ocean waters, is a relevant example of tectonic control on ocean circulation (which greatly impacted the dynamics of the Gulf Stream and is thought to have resulted in the northern hemisphere ice cover). In addition, approximately 300-360 million years ago, that is, the Carboniferous period, the large scale storage of carbon and increased glaciations are thought to have been a result of plate tectonics. Geological information suggests a mega-monsoonal circulation at the time of the supercontinent Pangaea with climate modeling indicating that the existence of the supercontinent was favorable to the establishments of monsoons. The continent size also played a key role since a bigger supercontinent will have more area in which climate is strongly seasonal than in smaller continents or islands. The stabilizing influence of oceans on temperature causes lower yearly temperature variations in coastal areas than in inlands (Ollhoff, 450). Evidences of Climate Change Evidences of climate change are inferred from a myriad of sources that can be used to reconstruct past climates. Complete global records are available from the mid-late 19th Century while earlier periods’ climates are deduced from changes in proxies and such indicators that may reflect climate as glacial geology, vegetation, dendrochronology, ice cores, glaciers, `precipitation and sea level changes (Gillard, 312). Ice Cores A relationship between temperature and global sea changes can be demonstrated by an analysis of ice in a core drilled from an ice sheet such as the Antarctic ice sheet with air trapped in bubbles in the ice useful in giving some idea of the Carbon IV Oxide changes in the atmosphere from ancient periods before modern influences creped in. this study in atmospheric Carbon IV Oxide variations over periods of time has been valuable in comprehending the differences in the ancient and modern atmospheres (Woodward, 777). Temperature Radiosonde balloons, extensive atmospheric observations and global; satellite information have supplemented the instrumental temperature records from surface stations. Another example of temperature proxy method is the 18 O/ 16 O ratios in calcite and ice core samples that are used to deduce ocean temperatures of the past. Sea Level Changes Sea level changes over the last centuries have been estimated using the tide gauge to yield a long-term average. There is also the use of the altimeter and satellite systems to study sea level changes. Scientists, using uranium series, radiocarbon, cosmogenic nucleolides and so on have dated coral reefs near ocean surfaces, coastal sediments, marine terraces, ooids in limestone and near-shore archaeological remains to gauge sea level changes and hence climate change. In the early Pliocene, world temperatures were 1-2̊C warmer than present temperatures and sea level 15-20 meters higher than today (Ollhoff, 320). Pollen Analysis The study of contemporary and fossil palynomorphs including pollen is termed palinology. These studies are used to determine geographical distribution of plant species which often depend on climatic conditions. Pollen can survive lengthy periods after the death of the parent plant because of the presence of a resilient outer covering. Variations in the type of pollen found in different layers of bog, lakes and river sediments point to changes in plant communities in the area which in turn point to climate change. Arctic Sea Ice Loss The reduction in the extent and thickness of arctic sea ice is an indicator of rapid climate change. 1979-2000 satellite images show that arctic ice is reducing at a rate of 11.5% per decade (Woodward, 654). Vegetation Changes in climate may result in equal changes in the type, distribution and coverage of vegetation. Climate change that yields more precipitation and warmth causes an increase in plant growth and sequestration of airborne Carbon IV Oxide. Increase in warmth means early flowering and fruiting which consequently results in changes in the timing of life cycles of dependent organisms. On the other hand, plant life cycles will drag in cold climates. In addition, under certain circumstances, vegetation stress, quick plant loss and desertification may occur with larger, faster and more radical changes in climate. For example, in the Carboniferous Rainforest Collapse (CRC), 300 million years ago, rainforests that covered the equatorial region of Europe and America were devastated as many plants and animals became extinct (Ollhoff, 512). Historical and Archaeological Proof Insights into past changes in climate can be given by archaeology, oral history and historical documents. Climate changes are related to the collapse of various world civilizations and therefore recent climate changes may be determined by shifts in settlements and agricultural patterns. Dendroclimatology Dendroclimatology, the analysis and study of tree ring growth patterns to determine past climates changes, is also commonly used to prove the phenomenon of climate change where for example, thin, narrow rings are proof of low rainfall periods and less than favorable growing conditions. Wide and thick rings on the other hand point towards a fertile, well-watered growing/ planting period (Woodward, 889). Animals Changes in primary productivity with varying climates can impact marine food webs. For instance, the abundance of certain fish species has been seen to have a significant relationship with the prevailing climatic conditions. In addition, the fact that different species of beetles tend to be found under different climatic conditions, means that the remains of beetles in fresh water and land sediments may offer a route towards accurate inference of past climatic conditions and hence the climate change of an area (Gillard, 413). Works Cited Friedman, Lauri S. Climate change. Detroit: Greenhaven Press, 2009: 17, 345, 365, 400. Print. Gillard, Arthur. Climate change. Detroit: Greenhaven Press, 2011: 312, 413. Print. Lerner, Adrienne Wilmoth and Chiara Pierre. Climate change. Farmington Hills, MI: Greenhaven Press, 2009: 377, 411, 418. Print. Ollhoff, Jim. Climate change. Edina, Minn.: ABDO Pub. Company, 2011: 320, 450, 512. Print. Tanaka, Shelley. Climate change. Toronto: Groundwood Books, 2006: 57, 98, 231. Print. Woodward, John. Climate change. New York, N.Y.: DK Publishing, 2008: 654, 777, 889. Print. Read More