Climate Change – Causes and Impacts 7.2

Applications and Skills Discuss the feedback mechanisms that would be associated with a change in mean global temperature Evaluate contrasting viewpoints on the issue of climate change

Climate and Weather Weather is daily result of changes of temperature, pressure, and precipitation in our atmosphere. Climate is the average weather pattern over many years for for loaction on Earth. Climate change is long-term change and has always happened

Factors that Affect Climate Change Can be natural or anthropogenically influenced Fluctuations in solar insolation affect temperature Changing proportions of gases in the atmosphere released by organisms For climate change to occur on a global scale, inputs and outputs have to change Heat input increases or heat output decreases or both i

Tipping Point GHG’s reduce heat loss from the atmosphere More GHG’s = less heat lost The system changes in a dynamic equilibrium which may stabilize or reach a new equilibrium if a tipping point is passed

Greenhouse Gases and the Greenhouse Effect Things to consider when reading about climate change: Role of ozone and CFC’s Role of water vapor Whether figures refer to total GHG effects or the enhanced (anthropogenic) greenhouse effect

Global Warming Potential: GWP, relative measure of how much heat a known mass of a GHG traps over a number of years compare to the same mass of carbon dioxide.

https://www.youtube.com/watch?v=ZzCA60WnoMk https://www.youtube.com/watch?v=VYMjSule0Bw https://www.youtube.com/watch?v=EtW2rrLHs08

Feedback Mechanisms Associated with Climate Change Oceans - absorb CO2 from the atmosphere as they warm up, they release CO2 back into the atmosphere and absorb less phytoplankton (producers) photosynthesize faster in warm water Positive feedback mechanism: more atmospheric CO2 → warmer temperatures → less CO2 absorbed & more released by oceans → more atmospheric CO2 Negative feedback mechanism: warmer oceans → faster photosynthesis by phytoplankton → more CO2 absorbed for photosynthesis → lower atmospheric CO2 → lower temperatures, slowing global warming

Feedback Mechanisms Associated with Climate Change Clouds - different cloud types interact with heat differently: daytime clouds cool the area under them nighttime clouds trap heat and act as an insulating layer high thin cirrus clouds trap heat low thick cumulus and cumulonimbus clouds have a cooling effect Negative feedback: higher temperature→ more evaporation → more clouds → clouds block & reflect incoming solar radiation → lower temperatures Positive feedback: higher temperatures → more evaporation → more clouds → more heat trapped → high temperatures

Feedback Mechanisms Associated with Climate Change Pollution - positive feedback: aerosols → more clouds formed → trap heat → warmer temperatures → more evaporation → more clouds → more heat trapped positive feedback: black soot (particulates) falls on ice → dark color absorbs more heat → ice melts faster → more dark water/ground exposed → warmer temperatures → more melting negative feedback: aerosols → more clouds → reflect more heat → lowers temperatures

Feedback Mechanisms Associated with Climate Change Polar Ice - positive feedback: ice melts → exposes more dark water → warmer water melts more ice → exposes more water → more melting → repeats