(M2) 14a - Climate Change Flashcards
Definitions: climate change vs. global warming; today’s climate change
Climate Change: long-term variations of the average weather conditions experienced in a particular region.
- Ex. Edmonton has milder winters than 30 yrs
- External forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use
- Changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer
Today’s Climate Change: a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere
Global Warming: increase over time in the average temperature across the entire planet.
- Ex. The planet as a whole is on average 1 degree warmer than it was in 1880
6 main drivers of climate change today
- Aerosols
- tiny solid particles in the atmosphere - Natural fluctuations in solar output
- Clouds
- contribute to holding the radiation and also alter the amount of sun that reaches the surface - Ozone
- retains heat - GHG and large aerosols
- Surface albedo changes
- reflectiveness of light/radiation
- helps keep temp cooler and not heat up the surface too much
4 events that can cause climatic shifts
- Variations in solar output
- The amount of solar radiation we receive from the sun varies on daily, yearly, decadal, centennial, and millennial basis
- Changes in Total Solar Irradiance (TSI) are caused mostly by changes in activity of sunspots (more sunspots = increased TSI) - Variations in Earth’s orbit
- Orbit around the Sun is eccentric (it changes over time)
- Greater eccentricity = more elliptical
- The obliquity (tilt of the Earth) changes as well; high angle = more extreme seasons; low angle = less extreme seasons
- Precession: changes in the orientation of the Earth’s axis. Can alter the position of the Earth with respect to perihelion and aphelion; which hemisphere is facing the Sun at each point - Volcanic and meteorite events
- Volcanic eruption = more ashes in atmosphere = preventing some sun irradiance to reach surface = cooling effect - Anthropogenic GHG emissions
Natural phenomena/events that can and have caused climate changes over longer periods of time (Milankovitch cycles, solar output)
Milankovitch Cycles: regular cycling of the eccentricity, obliquity, and precession of Earth’s orbit drives glacial and interglacial periods.
- Orbit around the Sun is eccentric (it changes over time)
- Greater eccentricity = more elliptical
- The obliquity (tilt of the Earth) changes as well; high angle = more extreme seasons; low angle = less extreme seasons
- Precession: changes in the orientation of the Earth’s axis. Can alter the position of the Earth with respect to perihelion and aphelion; which hemisphere is facing the Sun at each point
Solar Output
- The amount of solar radiation we receive from the sun varies on daily, yearly, decadal, centennial, and millennial basis
- Changes in Total Solar Irradiance (TSI) are caused mostly by changes in activity of sunspots (more sunspots = increased TSI)
Natural phenomena/events that can and have caused climate changes over short and long period of times (volcanoes, meteorites)
Volcanic Eruptions
- Produce: sulfuric gas (sulfate aerosols) and volcanic ash (itty bitty particles of rock and glass); these two compounds can cause cooling
- Volcanoes can cause warming as well: water vapor and CO2 (both GHG and aid heat retention)
Meteorites
- Meteorite strikes can have similar effects as volcanic events, concerning climate
- Create dust upon impact; dust can sometimes block solar radiation for months at a time
- Also create shock waves that can disrupt ecosystem structure
- Ex. Chicxulub Crater
Focus on anthropogenic causes of climate change
- Greenhouse gas emissions (CO2)
“We are in a distinctly different climate system, where the main drivers of climate change are no longer Milankovitch’s orbital cycles, but rather, massive and rapid anthropogenic GHG emissions.”
The Greenhouse Effect
= the process through which heat is trapped near Earth’s surface by substances known as GHG
- Some solar radiation is reflected by the Earth and the atmosphere; most radiation is absorbed by the Earth’s surface and warms it.
- Some of the infrared radiation passes through the atmosphere. Some is absorbed and re-emitted in all directions by GHG molecules. The effect of this is to warm the Earth’s surface and the lower atmosphere.
- Infrared radiation is emitted by the Earth’s surface.
All About CO2
- Most abundant GHG
- It lasts hundreds of yrs in the atmosphere
- The Keeling Curve: measuring directly the amount of CO2 in the atmosphere; increase has been a lot.
Focus on anthropogenic causes of climate change
- Where the emissions are coming from (countries and sectors)
Majority coming from countries experiencing intense industrialization phase.
- 31% China
- 13% USA
- 7% India
- 5% Russia
By Sector
- 25% Electricity and heat production
- 24% Agriculture, Forestry and Other Land Use (AFOLU)
- 21% Industry
- 14% Transport
- 9.6% Other energy
- 6.4% Buildings
Canadian Emissions by Sector
- oil & gas > transport > buildings > electricity > heavy industry > agriculture > waste & other
Focus on anthropogenic causes of climate change
- Concept of total and per capita carbon footprint
Carbon Footprint
- Amount of CO2 generated by an individual, organization, country, or any other entity over a given period
- China has the largest national carbon footprint; the US has one of the largest per capita carbon footprints
Main feedback loops in the context of climate change
- Positive vs. negative feedback loops
- Examples
Feedback Loops: Self-reinforcing processes that can either amplify or dampen the effects of climate change. They can have significant and sometimes unpredictable effects on global temperatures and environmental conditions
Positive (= amplifying)
- Reduced albedo
- Carbon Cycle
- More water vapor in the atmosphere
- Melting of permafrost
- Deforestation
Negative (= dampening)
- Increased albedo
- Clouds
- Biological uptake of CO2
- Ocean heat uptake
- Ocean C sequestration
CRYOSPHERE
Land surface warming
= decreasing spring snowpack = early spring peak flow
= glacial shrinkage = changes in river discharge patterns and increased runoff in glacial fed-rivers
= permafrost degradation = increased runoff in glacial-fed rivers and changes in locations of thermokarst lakes and increased coastal erosion = impacts on livelihoods of indigenous peoples
Ocean surface and atmospheric warming; Wind and ocean circulation changes
= sea ice recession, earlier breakup
= increased coastal erosion and effect on non-migratory marine animals
= impacts on livelihoods of indigenous peoples
OCEAN
Ocean surface warming
= range shifts of fish and macroalgae = changes in fishery yields
Ocean surface warming
= increased thermal stratification
= range shifts of fish and macroalgae = impact on large non-fish species
Ocean surface warming
= increased thermal stratification
= expansion of hypoxic zones
= regional changes in species abundance
= impacts on large non-fish species and changes in fishery yields
Ocean surface warming
= increased coral mortality and bleaching AND increased primary production at high latitudes = regional changes in species abundance
= impacts on large non-fish species and changes in fishery yields
Ocean and atmosphere circulation changes
= arctic sea ice retreat
= changes in species richness
FORESTS
Atmospheric warming
= upward shift in treelines
= upward shift in fauna
Atmospheric warming
= increase in insect pests
= increased tree mortality
Precipitation changes
= increased soil moisture drought
= decreased tree density
