Climate Change Essay Example | Topics and Well Written Essays - 1000 words

Climate Change - Essay Example Describe three key findings of the AR4 report that are mentioned in the Introduction Section. Key findings include: 1. An increase in global average air and ocean temperatures, widespread melting of snow and ice and rising global sea levels 11 out of last 12 years from 1995-2006 rank among the 12 hottest years on record Global sea level rise of 1.8mm from 1961-2003 Polar ice caps shrinking – Artic sea ice extent shrank 2.7% per decade Changes in precipitation – decline in Mediterranean, Sahel, southern Africa and increase in eastern part of North and South America, North Europe 2. Natural systems are being affecting by regional climate change, particularly temperature increase Glacial runoff increase glacial lake sizes Hydrological effects – increase runoff, earlier spring peak discharge, warming of lakes/rivers, which effects thermal structure and water quality 3. Effects of regional climate change in natural and human environment are emerging, although many are difficult to discern due to adoption and non climatic drivers Agricultural changes – planting crops earlier on in the year Increase in climatic health hazards, e.g. European 2003 heat wave killed 15,000 people in France What is the difference between natural and anthropogenic drivers of climate change? Provide an example of each. Natural changes refer to climatic alterations in the Earth’s atmosphere that aren’t affected by humans. Astronomical Effects Terrestrial Effects Orbital variability of the Earth Global geometry of continent/ocean distribution Solar storms and flares Ocean tide cycles Sunspot cycles Periodic ocean circulation changes, e.g. El Nino These processes control the amount of suns radiation reaching specific latitudinal zones on Earth Volcanic eruptions Anthropogenic drivers have also been highlighted as contributing to climate change and accelerating the warming of the Earth’s atmosphere. Examples include increased CO? (280ppm from pre industrial levels to 379pmm by 2005), burning of fossil fuels, deforestation, CFC’s and aerosols and from agriculture, e.g. cows releasing significant amounts of methane. What is a greenhouse gas (GHG), and how have their levels changed in the atmosphere changed since 1970? A GHG is a gas in the Earth’s atmosphere that contributes to the greenhouse effect through absorbing and emitting radiation causing climate change. They include CO?, methane, nitrous oxide and halocarbons. Changes in the atmospheric concentrations of greenhouse gases and aerosols, land cover and solar radiation alter the energy balances of climatic systems. There has been a 70% increase in global GHG emissions due to human activities between 1970-2004. CO? annual emissions have increased by 80% from 21 to 38 gigatonnes. CO? also represents 77% of total anthropogenic GHG emissions. Describe the SRES scenarios. What are they, and why do we have more than one of them? SRES refers to the scenarios descr ibed in the IPCC Special Report on Emission Scenarios. The SRES project an increase of baseline global GHG emissions by a range of 9.7 to 36.7 GtCO? – eq (25% to 90%) between 2000-2030. The SRES scenarios are grouped into 4 scenario families (A1, A2, B1, B2). They explore alternative development pathways, covering a wide range of demographic,