how has the atmosphere changed over time
- volcanoes erupted and produced N2 (nitrogen), CO2, H20, and small amounts of NH3 (ammonia) and CH4 (methane)
- oceans formed because water vapour condensed
- CO2 in earlier atmosphere dissolved in water, carbonates precipitated producing sediments, reduces CO2 in atmosphere
what was the gas that wasn’t present in the atmosphere 4.6 billion years ago
-oxygen as photosynthesis occurred later on
how did levels of oxygen increase? (2 ways)
- ALGAE AND PLANTS, produced oxygen through photosynthesis
- (oxygen in atmosphere), plants revolves to gradually produce more oxygen which made animals evolve
how did levels of CO2 decrease? (2 ways)
- formation of sedimentary rocks and fossil fuels, remains are out of biological matter which is formed over billion of years-> these remains fall to bottom of oceans, so over millions of years, layers of sediment settled on top of them and huge pressures turned them into coal, oil, gas and sedimentary rocks (these rocks contain CO2 from the matter)
- algae and plants, reduce photosynthesis by absorbing it
proportions of gases in today’s atmosphere
N2- 80%
O2- 20%
CO2, argon, H2O, less than 1%
what is the greenhouse effect?
-radiation from sun enters earth’s atmosphere and reflects off earth. some of the radiation is re-radiated back by atmosphere to earth, warming up global temp
what are the greenhouse gases
CO2, water vapour, CH4
what are the effects of climate change
- rising sea levels
- extreme weather events (severe storms)
- change in amount and distribution of rainfall
- wildlife species may go extinct
what is incomplete and complete combustion
- less/ no O2, causes carbon monoxide and soot
- lots of O2, causes CO2
