Transcript PP - snc2p_u4l6_climate_change_factors

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."
Forcings
Solar 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.
Watch An Inconvenient Truth
You Tube Link to What can be done