EVIDENCE FOR CLIMATE CHANGE, IS CURRENT CHANGE HUMAN INDUCED?
Firstly by examining a number of sources climatologists are able to create proxy data therefore giving us insight as to what climatic conditions were, before modern measuring devices were created. This is called palaeoclimate reconstruction. Sources of proxy data include: ice cores in which isotope analysis, physical characteristics as well as trace elements and microparticle concentrations is examined; geological sources include sediments, either marine (inorganic or organic) or terrestrial (aeolian, glacial, preglacial, lacustrine) sediments are determined. Another geological source includes sedimentary rocks, when examining rocks climate is determined by facies, microfossil or fossil, mineral and isotope geochemistry analysis. Biological indicators include tree rings, pollen species and insects; we also look at historical records, for example meteorological, parameteorological and phenological records.
With isotope analysis of ice cores the O18 concentrations determine if polar conditions were warmer or colder as O18H2 freezes in colder polar regions as water ice, therefore having a much lower concentration than in warmer conditions. These findings indicate that we are experiencing higher temperature than in the past hundred years. We also look at the fact that glaciers are drastically retreating causing a rise in sea-level, sea ice shelves are breaking off(Larsen-B ice shelf for example) causing a reduction in ocean salinity, permafrost is melting causing the appearance of potholes and the draining of many lakes as their frozen bases melt away. We also look at the fact that sea temperatures are rising.
We also look at the emission rate of greenhouse gases which has increased drastically over the past 200 years. Greenhouse gases, you could say, play the most important role in climate change as it has a direct influence on temperature. An increase in greenhouse gases then increases global air temperatures due to the greenhouse effect. Examples of greenhouse gases include Carbon dioxide, water vapour, Nitrous dioxide and Methane.
Whether these increases in gases is cause global warming is debated among scientists but anthropogenic influence in global warming is inevitable as proven by records showing an exponential increase in these gases after the industrial revolution.
Reviewed by:Angela Campher
University of the Western Cape