Global_Warming

Global Warming Global Warming climate changes are mostly natural variations world climate - naturally variable have humans begun to change the climate' Timescales: is it change or variability' Is it natural for earth to change' spatial scale: local, regional, or global Greenhouse Effect: The Process: not ozone hole it is a natural effect. short-wave radiation from the sun warms the earth little is absorbed by the atmosphere the heated earth emits longwave radiation but gases in atmosphere absorb longwave radiation therefore the Earth is warmed. the warming is a natural feature ~ 20C but if we add more gases we will cause more warming. Carbon dioxide is a natural gas. Normal, cyclical nature of the gas. El Nino effect strongly influences the CO2 levels. increasing levels of CO2 since 1958: 0.5% per year - increase. predicted to be 450 PPM by year 2050. Human contribution to CO2 production is due to burning of fossil fuels. part of the carbon cycle occurs naturally and is naturally variable. however it is not the only or the most powerful greenhouse gas. Methane (CH4) levels are low compared to CO2 but 3X more effective. pre-industrial levels of methane: 650 PPB 1990: 1650 PPB increasing by 1% per year. Sources of Methane: natural wetlands, rice paddies. warming, co2, natural, gases, year, levels, regions, radiation, ppb, per, methane, human, fossil, earth, change, burning, tropical, sources, plant, naturally, increasing, increase, impacts, greenhouse, global, gas, fuels, environmental, effect, deforestation, cfcs, years, trees, since, should