Sustainability and Planetary Boundaries

• Sustainable development meets today's needs without compromising future generations, balancing environment and development.

Anthropocene Definition

• The Anthropocene is the epoch of human-dominated ecosystems on a global scale.
• It started around the beginning of the industrial revolution.

Planetary Boundaries

• Climate change
• Ozone depletion
• Freshwater use
• Biodiversity loss
• Chemical pollution
• Ocean acidification
• Nitrogen and phosphorus cycles
• Land use change
• Aerosols

Exceeded Planetary Boundaries

• Climate change
• Biodiversity loss
• Nitrogen and phosphorus cycles

Planetary Boundaries Importance

• Planetary boundaries define the safe operating space for humanity using thresholds for biophysical Earth systems.

Tightly Coupled Boundaries

• Exceeding one boundary reduces the resilience of others, making further transgressions more likely.

US Energy Sources

• Fossil fuels account for 80% of energy.
• Renewables make up 11%.
• Nuclear energy comprises 9%.

Energy System Scale and Complexity

• Shifting from fossil fuels to other dominant sources is a slow process.
• Transitioning away from fossil and increasing renewables is lengthy.
• Infrastructure and path dependence create complexity lasting for years.
• Replacing 2 billion MWH of coal electricity requires around 57 million hectares of wind turbines.

COVID-19 Impact

• Lockdowns initially lowered energy demands and CO2 emissions.
• Energy demands and CO2 emissions quickly rebounded.

Atmospheric CO2

• Not all emitted CO2 remains in the atmosphere, some is absorbed.
• 33% is absorbed by vegetation, and 25% by oceans.
• 45% of emitted CO2 accumulates when emission rates exceed absorption capacity.

Bathtub Model

• The Earth's atmosphere is like a bathtub, where anthropogenic and natural sources are the faucet for GHGs.
• Vegetation and oceans act as a drain to remove GHGs.
• Too many GHGs cause the climate to rise.

Charles Keeling

• Charles Keeling developed an accurate technique for measuring CO2 in 1958.
• He discovered increasing CO2 in the atmosphere at the Scripps Institution of Oceanography.

Keeling Curve

• The Keeling curve measures CO2.

Weather vs. Climate

• Weather is daily atmospheric conditions.
• Climate is the average weather over months/years.

Observed Climate Changes

• Earlier first leaf out
• Retreating glaciers
• Warmer winters
• Less snow and more rain
• Overall more rain
• Greater extremes
• Warming and acidifying ocean (25% more acidic)
• Increase in storm surge/flooding risk
• Increasing SLR
• More nuisance flooding

Mitigation

• Mitigation involves reducing human contributions to the greenhouse effect by adjusting sources and sinks.
• Sources refer to GHG emission sources that contribute to warming.
• Sinks increase CO2 uptake through land use change and forestry.
• Greater mitigation lessens future warming severity and impacts.

ACUPCC

• The American College and University Presidents' Climate Commitment (ACUPCC) is the main instrument for higher emissions reduction.
• It requires development of CAP, emissions inventory, reporting, actions to reduce GHG, and plan for climate neutrality.

Climate Momentum

• Climate momentum is why adaptation is important.
• About 20% of emissions remain in the atmosphere for thousands of years.

Paris Agreement

• The Paris Agreement is the most recent effort originating from the 1997 Kyoto Protocol.
• It covers GHG emissions from 195 countries from 2020.
• The agreements goal is to reduce carbon output to limit global warming to "well below 2 degrees C".
• Limitations include voluntary and conditional reductions.
• Strengths include its global approach which drives innovation.

NDCs and Paris Goals

• Current NDCs promise carbon output reduction to keep global warming "to well below 2 degrees C".

Carbon Neutral vs. Climate Neutral

• Climate neutrality means compensating for every ton of GHG emitted.
• Carbon neutrality refers only to CO2 emissions.

Stabilization Wedges

• A wedge is a strategy to reduce carbon emissions that grows from 0 to 1.0 GtC/yr over 50 years.
• It commercialize a solution to the CO2 problem:

Adaptation

• Adaptations adjust natural or human systems in response to actual or expected climatic changes.
• Reduce harm or increase beneficial opportunities.
• Structural and non-structural adaptations protect ecosystems, biodiversity, and natural resources.
• Other measures enable, support, and incentivize adaptation.

Non-Stationarity

• Stationarity assumes future climate will be like the past.
• Adaptation is not straightforward, changes are uncertain, and subject to surprise due to non-stationarity.

Freshwater Availability

• About 2.5% of water is freshwater suitable for human consumption.
• Less than 1% is readily accessible.

Water Withdrawals & Conservation

• The biggest water withdrawals are for thermos cooling in the US and agriculture worldwide..

Virtual Water

• Virtual water is the water needed to produce food, products, or energy.

Water Stress

• Water stress involves quality, environment, access, and quantity.
• Scarcity focuses only on physical water availability.
• Stressed areas worsen with climate change.

Ecosystem and Diversity

• Ecosystems are living organisms interacting with their surroundings.
• Biodiversity is the variability among living organisms within and between species in ecosystems.
• Regulating benefits: habitat creation, pollination, air quality regulation, etc.
• Material benefits: energy, food, medicine.
• Non-material benefits: learning, experiences

Ecosystem Health & Biodiversity

• Nature's benefits for people are declining, impacting quality of life and well-being.
• Natural ecosystems have declines, and species extinctions have been high and accelerating.
• Land/sea use change and exploitation drive over half the impact.
• Over half of GDP depends on nature, so biodiversity loss is a huge risk.

Safe Drinking Water Act

• Loss of pressure/concerns about contamination drive boil-water advisory.
• It has reduced waterborne disease but millions drink water that doesn't meet standards.
• It has shifted from treatment alone to also preventing pollution and regulating distribution system qualities.

Cyanotoxins

• Cyanotoxins are toxic substances produced by cyanobacteria (blue-green algae).
• They are not directly regulated by SDWA or the federal government in the US.

Subsidence & Aquifer Compaction

• Subsidence is graduall sinking of land.
• Aquifer compaction occurs when water is removed from unconsolidated aquifers which causes settling in the aquifer.
• Some subsidence is non-recoverable and areas with high water stress often have slow GW recharge.

Water Allocation

• US states determine how much water can be used for a particular use.
• They issue permits or rights to use that quantity of water for a given period.
• Prior appropriation is first in time, first in right.
• Riparian water users can use the water if they own the land next to the water.

Flood Risk Assessments

• First Street maps every flood risk area, where FEMA doesn't.
• FEMA prioritizes high populations or high-risk areas.
• First street updates risk maps whereas some FEMA maps are over 15 years old.

Building in Floodplains

• Building in floodplains increases flood risks.
• Building takes up storage that was available.
• Now when the same size storm event hits, the flood level (depth) and flood extent increase to make up for that lost storage.

Houston Flooding

• Increased impervious cover over 20 years since last FEMA map revisions; also doesn't account for climate change or existing problems with SW management.

Low-Income Flood Exposure

• Low-income families are disproportionately exposed to and impacted by floods.
• Poor families tend to live in flood-prone areas and close to industrial sites.
• Often cannot afford flood insurance and so don't get FEMA recovery funds.
• Have less capacity to prepare and to withstand the event.

Dam Risks

• Hazard creep comes from more people living in flood plains below than when initially built.
• High hazard dams risk at least one loss of life if they fail.
• Non-stationarity, creeping hazards, lack of maintenance/inspection, changiung climate adds risk.
• Most common failures are overtopping, foundation defects, erosion from seepage around pipes.
• To improve dam safety, increase funding for repairs, better risk assessment, and incorporate climate change analysis.

Clean Water Act

• The Clean Water Act's objective is restoring and maintaining the nation's water.
• Goals were to eliminate pollution discharge into navigable waters by 1985 and protect uses by 1983.
• These goals have not been achieved.
• It has been fairly effective at reducing point sources of pollution with National Pollutant Discharge Elimination System (NPDES).
• Limitations include it not effective for cleaning up NPS.

Ecological Deficit

• Ecological deficit occurs when the footprint of a population exceeds the biocapacity of the area.