Changing Climate #13

Definition: Nuisance flooding refers to temporary flooding that creates inconveniences but does not pose severe hazards. Examples include local road closures, backed-up storm water systems, and damage to roadways.
Examples of Affected Cities:
- Boston, MA: Projected sea level rise of 1 to 2 m (3.3 to 6.6 ft) by 2100.
- Annapolis, MD and Charleston, SC: Experience 30 or more days of nuisance flooding annually.
- Wilmington, NC: Recorded over 80 days of nuisance flooding in 2015.
Visual Data: Graphs illustrate days of nuisance flooding in various cities including Norfolk, VA, and Atlantic City, NJ.

Global Average: The sea level has risen 23 cm (9 in) since 1880, with certain areas experiencing rises up to 20 cm (7.9 in).
Causes: Sea level rise results from factors such as melting glaciers, thermal expansion of seawater, local land subsidence, and loss of natural coastal wetlands.
Consequences: The increase in sea level affects coastal infrastructure, previously built above extreme high-tide lines now becoming subject to flooding.

Extreme High Tides: With sea levels rising, extreme high tides are now frequently reaching coastal developments, leading to increased flooding risks.
Geographical Impact: The East Coast and Gulf Coast regions of the U.S. are particularly at risk due to their flatter coastal topology and larger recent increases in sea level compared to the West Coast.

Weather vs. Climate:
- Weather: Refers to the state of the atmosphere at any given moment, changing from minutes to weeks.
- Climate: The long-term average of weather, defined over a period of about 30 years, encompassing average conditions and frequency of extreme weather events.

Definition: Refers to the long-term alterations in temperature, precipitation, and other environmental elements exerted by both natural and anthropogenic factors.
Global Average Temperature Changes:
- Lower atmosphere warming: 0.99° C (1.78° F) since 1880.
- Sea surface temperature increase: 0.56° C (1°F).

Climate Forcing: External factors that influence the climate system independently, such as the sun's intensity and volcanic eruptions.
Positive Feedback: Drives changes that destabilize the climate system, exemplified by the ice-albedo feedback; loss of ice leads to lower reflectivity, increased absorption of solar energy, and further warming.
Negative Feedback: Stabilizes the climate; for example, increased plant growth due to elevated CO2 levels leads to more carbon being absorbed.

Ice-Albedo Feedback: With more ice, energy is reflected leading to lower temperatures. Less ice means absorbed energy which increases temperatures.
Wildfire-Carbon Feedback: Higher temperatures lead to more wildfires, releasing CO2 and exacerbating warming.
Permafrost-Carbon Feedback: Thawing permafrost releases methane (CH4) and CO2, contributing to climate change.

Geologic Timeframe: Current climate systems span over the last 10,000 years against the backdrop of the Earth’s 4.6 billion-year history.
Pleistocene Epoch: Spanning from 2.58 million years to around 11,700 years ago, characterized by approximately 26 glaciations.
Milankovitch Cycles: Orbital variations that affect climate:
- Eccentricity: Variations in Earth’s orbit shape and its influence on solar distance over a 100,000-year cycle.
- Obliquity: Changes in the axis tilt and its impact on seasonal climate over approximately 41,000 years.
- Precession: The wobble of Earth’s axis over a 24,000-year cycle.

Climate Anomalies: Deviations from expected climate patterns can be caused by solar irradiance changes or volcanic activity.
Sunspots: Cycles of sunspot activity can influence solar output, leading to slight variations in climate.
Volcanic Eruptions: Significant eruptions like Mount Pinatubo can inject aerosols into the stratosphere, leading to temporary cooling periods.

Impact of Freshwater Influx: Freshwater from melting ice can disrupt ocean currents, affecting climate stability.
Historical Context: Events like the Younger Dryas (12,900 - 11,600 years ago) signify the consequences of disrupted oceanic circulation patterns.

Sources of Paleoclimatology: Methods to study past climates include:
- Tree Rings: Provide annual records.
- Ice Cores: Contain air bubbles for ancient atmospheric composition.
- Marine and Lake Sediments: Offer information extending back millions of years with varying degrees of resolution.

Long-Term Carbon Cycle: Involves carbon storage in the lithosphere over millions of years versus short-term cycles occurring within decades.
Anthropogenic Influence: Human activities such as fossil fuel combustion and deforestation have dramatically increased carbon emissions, contributing to climate change.

Keeling Curve: A record of atmospheric CO2 concentration measured at Mauna Loa, showing levels have risen to 408 ppm with an annual increase of roughly 2.5 ppm.
Extreme Temperature Records: Notable high temperatures from different global locations indicate increasing overheating, with records set in recent years.

IPCC Reports: The Intergovernmental Panel on Climate Change regularly assesses climate change and makes projections for future scenarios, highlighting the need for significant emission reductions to avert catastrophic warming.
RCP Scenarios: Representative Concentration Pathways (RCP) 2.6 and 8.5 provide contrasting future warmth scenarios based on current emission trends.

Global Agreements: The Paris Agreement seeks to limit warming to 2°C (3.2°F) above pre-industrial levels through international cooperation.
Carbon Budget: Estimates indicate 1 trillion tons of carbon emissions as a limit to meet targets, with already significant emissions reducing this budget dramatically.
Reduction Strategies: Efforts to reduce carbon footprints include enhancing energy efficiency and transitioning to renewable energy sources.

Lifestyle Changes: Reducing waste, minimizing car usage, improving home energy efficiency, and engaging politically can contribute significantly to lowering individual carbon footprints.

Exploration of Technological Solutions: While geoengineering presents potential pathways to mitigate climate change, it also carries risks and uncertainties.