climate change factors lesson 6. climate change factors climate forcings –the initial drivers of a...
TRANSCRIPT
Climate Change Factors
Lesson 6
Climate Change Factors
• Climate Forcings – The initial drivers of a climate shift
Climate feedbacks
• The processes that change as a result of a change in forcing, and cause additional climate change. – A feedback that increases an initial
warming is called a "positive feedback." A feedback that reduces an initial warming is a "negative feedback."
ForcingsSolar Irradiance.
• The sun has a 11-year irradiance cycle that produces about 0.1% variation in output. Solar irradiance has been measured by satellite daily since the late 1970s, and this known solar cycle is incorporated into climate models.
Aerosols, dust, smoke, and soot.
• These can be produced by natural sources and human activity. They can also have very different effects on climate.
• Sulphate aerosols, which result from burning coal, biomass, and volcanic eruptions, tend to cool the Earth.
• Greenhouse gases such as CFC’s cause the Earth to become warmer.
Feedbacks
Clouds.
• Clouds have an enormous impact on Earth's climate,
• They reflect one third of the total amount of sunlight that hits the Earth's atmosphere back into space.
Clouds
• As the atmosphere warms, cloud patterns may change, altering the amount of sunlight absorbed by the Earth. Because clouds are such powerful climate actors, even small changes in average cloud amounts, locations, and type could speed warming, slow it, or even reverse it.
Carbon cycle
• Currently, natural processes remove about half of each year's human carbon dioxide emissions from the atmosphere, although this varies a bit year to year. Carbon is absorbed by land plant life.
• There is also some evidence that the ability of the Earth’s ability to continue absorbing carbon may decline as the world warms, leading to faster accumulation in the atmosphere..
Melting Ice
• "ice-albedo feedback." As the atmosphere warms, sea ice will melt. Ice is highly reflective, while the underlying ocean surface is far less reflective. The darker ocean will absorb more heat, getting warmer and making the Earth warmer overall.
