unit 7

• what did IPCC say in 2023?

  human activities, through emissions of greenhouse gases have caused global warming
• how much of methane comes from human activities?

  60% and is 25x more potent than carbon dioxide
• what is the energy budget?

  balance between incoming radiation from sun and outgoing radiated heat plus reflected radiation from the sun
• incoming energy from sun is in form of...

  light energy, shortwave radiation referred to as insolation

  only half of insolation reaching outer atmosphere is absorbed by earths surface, as insolation passes through atmosphere some is reflected and some is scattered back into space
• most of insolation that reaches earths surface is...

  absorbed and converted into heat energy (long wave radiation) some is reflected, heat energy radiates outwards and some is trapped by greenhouse gases warming the atmosphere
• what are the impacts of increasing atmospheric carbon?

  changes to patterns & levels of precipitation/extreme weather events and river discharge

  sea level rise and acidification of the oceans
• what is a feedback system?

  series of responses that change steady state equilibrium of a system
• what is a positive feedback cycle?

  when series of responses increases or amplifies initial change
• what is a negative feedback cycle?

  when a series of responses stops or reverse the initial change
• many scientists believe global temps will rise above...

  1.5 degrees which is irreversible changes in global carbon cycle because of positive feedback process, impossible to return to original equilibrium state
• if climatic thresholds or tipping points are reached what positive feedback loops occur?

  methane feedback

  crysophere feedback

  marine carbon feedback

  terrestrial ecosystem feedback
• since the Industrial Revolution, how much has methane increased by?

  250%
• what is the methane feedback loop?

  as global temp increases, permafrost melting is occurring at higher latitudes in Russia and Canada

  permafrost stores carbon and as temp rises, thaws and organic matter decomposes and methane released is 25x more potent than co2
• what is a tipping point?

  accelerated global warming or runaway greenhouse effect
• what is the cryosphere feedback loop?

  reflectivity is known as albedo and albedo is 80% in snow and ice so energy from sun is reflected back to space

  increased atmospheric temp increases melting of ice, reduced albedo of earths surface and increased absorption of insolation
• marine carbon feedback is?

  eustatic sea level rise at rate of 3mm per year

  temperatures are rising, ice is melting shrinking glaciers and adding water to oceans

  oceans are warming as sea water expands as temp rises
• what isn ocean acidification?

  increasing atmospheric co2, oceans absorb co2 by diffusion then surface water is more acidic as there is decreased carbonate and increase h+ ions