Topic 6: Atmosphere and Climate change (6.1 Intro Atmosphere; 6.2 (yes.) Climate Change — causes & impacts; 6.3 (yes.) Climate Change — mitigation vs. adaptation; 6.4 Stratospheric Ozone)

(6.1) How ATMOSPHERE systems work Earth?

STRUcture of Atmosphere:

(highest —> lowest)

• thermosphere

• mesosphere

• stratosphere

• troposphere (most life reactions, ozone formation + clouds)

Albedo

• albedo = Earth’s reflectivity; 30% sun reflected back, 70% absorbed by Earth

Explain “The GREENHOUSE EFFECT”

• “The GREENHOUSE Effect” = Earth’s atmosphere + gases (GHGs) trap heat (reflected off surface), some reflect back

  • **humans adding extra GHGs, increasing Greenhouse effect

—> side note: Main GHGs = water vapor + carbon dioxide + methane

Role of water vapor

• Water vapor (is most significant GHG) **usually excluded from climate models bc changes frequently tho

Role of chlorofluorocarbons (CFCs)

• Chlorofluorocarbons (CFCs) = MEGA destructive; one CFC can have rippling effect, 5,000-10,000 times more potent than CO2

aerosols

• aerosols = small solid particles suspended in atmosphere (e.g. soot, etc.)

  • come from naturals; volcanic eruptions, forest fires

  • GOOD bc COOLING—reflect radiation back to space!!

  • BAd bc cause respiratory issues, can release hydrocarbons/global warming stuff, smog formation

↳“radioactive forcing (RF)” = incoming - outgoing energy (Net)

(6.2) To what extent humans CAUSE Climate change?

A. How humans CAUSE Climate Change?

A. *NOTE, long-term climate change ALWAYS happening BUT…tipping points passed means dynamic equilibrium unable to return to stable, reaching NEW equilibriumspecifically—RATE of global warming concerning + matches 50% increase post-industrial CO2

1. accelerating carbon cycle w/ GHG emissions — HOW HUMANS INFLUENCE CARBON CYCLE??? + global warming……..

• fossil fuels (industry, cars, etc.)

• deforestation (removing forest sinks), destroying plants

• industrial agriculture; using fertilizers, livestock farming, etc. + FOOD WASTE!?

• urbanization

B. IMPACTS of Climate Change

1. Oceans, sea level

   1. sea level rise ⇒ flooding in Bangladesh, Maldives, etc. coastal communities

   2. fish migrating away

   3. ocean acidification (+25%) bc absorbing CO2 !! coral bleaching. shells dying, fish eggs sensitive, phytoplankton skeletons

   4. Polar ice caps

      1. Melting. (leads to sea level rise) + desalination

      2. positive feedback loop → trapped methane in ice released

2. Glaciers

   1. loss of freshwater (scarcity!), drought in Himalayas, Ganges, etc.

      1. hurts water supplies + changes human migration/refugees, bad for indigenous peoples (ex. Mbororo of Sahel suffering from drought in pastoral lands) +  societal inequities (poverty, etc.) + even economic hurts

3. Weather

   1. ⬆ violent + unpredictable weather, severe drought, Bigg storms, monsoon

5. Animal ecosystems & biodiversity

   1. killing plants—can’t really migrate to cooler regions

   2. extinction!! of polar bears, alpine plants, burning koalas and trees and plankton

6. Food production

   1. kill plankton, kill livestock w/ heat + drought

   2. change soil quality, dry land

How can we Model Climate CHange?

==> 5 MAIN easy climate can change…(in models)...

1. direct relationship (aka incr solar radiation, increase methane, incr pos. feedback loop)

2. buffering action = forcing increases but climate change NOT linear; ex. negative feedback loops

3. acceleration of climate to new equilibrium

4. reach tipping point! — when reaches threshold, climate SUDDEN changes

5. stuck NEW equilibrium.

(6.3) How humans FIX Climate change (—mitigation vs. adaptation)?

International Policies for Climate Change

Climate Change:

• UN Conventions (or treaties) that legally bind

  • ex. three sister “Rio Conventions” — UNFCCCC, Convention on Biodiversity, UN Convention to combat Desertification

  • GOAL—STABILIZE GHG emissions

• “Paris Agreement” (2015) = keep global average temp. rise < 1.5 ℃ from pre-industrial levels

  • CONS: NO legal “enforcement” for compliance

• Kyoto Protocol = 5% total GHG emissions reduction

  • *Doha Amendment to Kyoto Protocol; reduce GHGs by 18%.

• Intergovernmental Panel on Climate Change (IPCC)

  • consolidates/assesses existing climate research —> helps policy

  • CONS: doesn’t even do its own research, requires consenesus which is dificult, takes (too) long-term studies

Ozone:

• The Montreal Protocol (1987): regulates use + trade of CFCs, ODs (Ozone Depleting Substances)

  • PROS: part UNEP, Massive SUCCESS 197 countries, 99% phase out CFCs international coordination!!!!

  • CONS: illegal CFC trade, expensive alternatives for refridgeration/AC, HCFCs later used as alternatives

How can HUMANS FIX Climate Change — MITIGATION vs. ADAPTATION??

A. “The precautionary principle” = act NOW, in case

B. DECARBONIZATION

• switch electric, energy efficiency

• REDUCE food production; meat/dairy consumption, vegetarian diets + STOP FOOD WASTE>

• technology—carbon recapturing, farming (vertical farming, hydroponics, etc.)

C. Mitigation STRATEGIES:

• REDUCE GHG emissions;

  • change diets/agriculture (livestock)

  • fossil fuel alternatives (renewable energy)

  • carbon tax

  • STOP deforestation

• REMOVE CO₂ from atmosphere;

  • afforestation

  • rewilding, land management

  • carbon capture technology

  • geoengineering —> manual cooling……..so like injecting sulfur dioxide into the air, reflecting sun back

D. Adaptation STRATEGIES:

1. “adaptive capacity” = ability or potential of system respond successfully to climate changes (w/ tech, etc.)

1. flood-resistant infrastructure (sea walls)

1. drought-resistant crops

2. ..green infrastructure —> permeable pavement, green roofs, etc.

3. manage weather—cloud seeding, re-planting trees

4. vaccination, other legislation + policies

NAPAS

• *NAPAS = requests submitted to UNFCCC by vulnerable countries, asking help for URGENT adaptation (e.g. flooding help, building, etc.)

(6.4) Describe ozone equilibrium works + HUMAN affect OZONE?

Role of ozone

• Ozone (O3) = gas

  • Tropospheric ozone = BAD; pungent, causes ground-level ozone pollution, photochemical smog, coughing/respiratory issues

  • Stratospheric ozone = good!; deflects sun’s harmful UV rays (preventing skin cancer, photochemical smog, etc.)

Describe the ozone EQUILIBRIUM. (Chapman cycle)

• The Chapman Cycle is where ozone is created/destroyed at EQUAL rates (steady-state equilib)

  • HOW? UV radiation breaks DOWN ozone (O₃) to O₂ and O, which REFORM into O₃

What are Pros/Cons of UV radiation?

• PROS

  • most harmful (UV-C, most UV-B) absorbed by stratosphere

  • vitamin D + light

  • kills some bad bacteria, purify water/air

• CONS

  • skin cancer

  • UV damages phytoplankton, ecosystems (esp. near poles)

  • Photochemical SMOG

How do humans affect OZONE? (“The Ozone Hole)

—> “THE OZONE HOLE”: = depletion STRATOSPHERIC ozone

• CFCs + HCFCs; “ODs” = ozone depleters

  • (CHANGEs Chapman cycle — more formation than depletion)

• OTHERS!

  • coolants, aerosols, etc.; react w/ UV radiation, releasing chlorine, etc.

[==> hundred years to degrade…]