ENVIRON 102 Lecture Notes - Lecture 16: Solar Radiation Management, Carbon Dioxide Removal, Carbon-12
4 May 2018
School
Department
Course
Professor
Climate Change
4.09.15 Lecture Notes
I. The earth’s climate is changing; overall, warming
A. Evidence
B. Methodology
Discussion
Geoengineering: application of geosciences, where mechanics, mathematics, physics, chemistry,
and geology are used to understand and shape our interaction with the earth
o Solar radiation management (SRM): controlling sunlight before it reaches the planet
o Carbon dioxide removal (CDR) and sequestration: artificial trees, ocean fertilization
Risks and unknowns to geoengineering
Trying to reverse climate change hasnt worked for 20 years
Recently carbon emissions have been leveling off
IPCC
Represents a consensus of climate scientists of what theyre certain about and what theyre
uncertain about
The IPCC has 3 working groups and a task force:
o Working Group I assesses the scientific aspects of the climate system and climate change
o Working Group II assesses the vulnerability of socioeconomic and natural systems to
climate change, negative and positive consequences of climate change, and options for
adapting to it
o Working Group III assesses options for limiting greenhouse gas emissions and otherwise
mitigating climate change
o The Task Force on National Greenhouse Gas Inventories is responsible for the IPCC
National Greenhouse Gas Inventories Programme
5th Assessment finalized in 2014
Temperatures are rising
Retreating/shrinking glaciers such as Qori Kalis
Melting of permafrost
Northwest passage recently came into existence
Historical carbon dioxide measurements
Where does the CO2 come from?
o From fossil fuels? But how do you know? What about other sources such as deforestation?
o Carbon -12 and -14 ratios
▪ Carbon-14 is a radioactive isotope of carbon-12
• Formed by radiation from the Sun reacting with nitrogen in the atmosphere,
then carbon-14 decays to nitrogen with half-life of about 6000 years
▪ Burning carbon dioxide without carbon-14, then the ratio is not in equilibrium and
the amount of carbon-12 will be higher in proportion
• Because fossil fuels have a high concentration of carbon-12 because most of
the carbon-14 have decayed from the long amount of time in the earth
o Ice cores: taking carbon dioxide concentrations from the bubbles in the ice to understand
levels of carbon dioxide
o Cores of sediment
▪ Which organisms were alive a few hundred/thousand years ago?
▪ Based on what was alive, we can see where was warmer/colder
Mauna Loa, Hawaii – Keeling curve – measurements of carbon emission done by scientist
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o Why is the curve jagged?
o Majority of landmass is north of equator where the trees are pulling carbon out of
atmosphere in the spring and summer
Industrial Revolution has caused a dramatic rise in carbon dioxide
II. Human role
Factors affecting the earths climate
What contributes to earths climate change?
o Radiation from Sun (may vary)
o Earths surface oceans, land, snow/ice which is variable because of the reflectivity of the
surface
o Atmospheres reflectivity and ability to insulate
Global convection processes
Atmospheric and oceanic convection cycles move heat around
Atmospheric components
Atmospheric gases that absorb the Earths infrared radiation are greenhouse gases
o Total greenhouse effect ~ 33C (mostly water)
Major gaseous components are not greenhouse gases (do not insulate) such as nitrogen, oxygen
Methane, water vapor, carbon dioxide are greenhouse gases
Analogous to Venus and Mercury
Stratosphere: with limited convection the stratosphere acts like a cap, trapping warm gases in the
troposphere
Troposphere:
Climate players
Carbon dioxide = primary anthropogenic greenhouse gas due to amount
Relative heat trapping ability
o Carbon dioxide = 1
o Methane = 12
o Nitrous oxide = 100+
o HFC-23 = 10-100
Aerosols can:
o Warm by absorbing solar radiation (soot because its black and it absorbs heat well)
o Cool by reflecting solar radiation (sulfates are reflective of solar radiation)
o Have complex effects (clouds reflect incoming radiation shortwave radiation, but also
outgoing longwave radiation)
o Overall, generally, cooling effect
o Note usually short half-life and regional effects
Water vapor plays a large role, but is not directly affected at a global level by human activity
Relative contributions
Climate forcing refers to external factors that affect climate
Radiative forcing is usually quantified as the rate of energy change per unit area of the globe as
measured at the top of the atmosphere, and is expressed in units of Watts per square metre.
Feedback and uncertainties
DISCUSSION
o Glaciers receding, but also creates more land and ocean to absorb heat (positive feedback)
o More land for tree growth
o Plants grow better with increased carbon dioxide
o Climate change = fucks up seasons = plants are like WTF???
POWERPOINT
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
4. 09. 15 lecture notes: the earth"s climate is changing; overall, warming. Geoengineering: application of geosciences, where mechanics, mathematics, physics, chemistry, and geology are used to understand and shape our interaction with the earth. Risks and unknowns to geoengineering: solar radiation management (srm): controlling sunlight before it reaches the planet, carbon dioxide removal (cdr) and sequestration: artificial trees, ocean fertilization. Recently carbon emissions have been leveling off. Trying to reverse climate change hasn(cid:495)t worked for 20 years. Represents a consensus of climate scientists of what they(cid:495)re certain about and what they(cid:495)re. Industrial revolution has caused a dramatic rise in carbon dioxide. What contributes to earth(cid:495)s climate change: radiation from sun (may vary) Global convection processes: earth(cid:495)s surface (cid:523)oceans, land, snow/ice(cid:524) which is variable because of the reflectivity of the, atmosphere(cid:495)s reflectivity and ability to insulate surface. Atmospheric and oceanic convection cycles move heat around. Atmospheric gases that absorb the earth(cid:495)s infrared radiation are greenhouse gases: total greenhouse effect ~ 33c (mostly water)
