Climate Change and Its Effects

Flashcards covering key vocabulary and concepts related to climate change and its impacts, based on the lecture notes.

Greenhouse Gas Effect

The process by which certain gases in the atmosphere trap heat from the sun, maintaining the Earth's temperature and permitting life.

Climate vs. Weather

Climate refers to long-term patterns of weather in an area, while weather denotes short-term atmospheric conditions.

Albedo

The reflectivity of a surface; higher albedo means more sunlight is reflected, which can lead to cooling.

Hadley Cells

Large-scale wind patterns characterized by rising warm air at the equator which cools and descends at around 30 degrees latitude, influencing trade winds.

Photosynthesis

The process by which plants convert carbon dioxide from the atmosphere into organic compounds using sunlight, reducing atmospheric CO2 levels.

Ocean Acidification

The decrease in pH levels in the ocean due to absorption of excess atmospheric CO2, which can harm marine life.

El Niño

A climate pattern characterized by warmer-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean, affecting global weather patterns.

Fast Carbon Cycle

The rapid cycling of carbon through living organisms via photosynthesis and respiration, occurring on a timescale of years.

Slow Carbon Cycle

The long-term carbon cycle involving geological processes such as rock weathering and the formation of fossil fuels, occurring over millions of years.

Thermal Haline Circulation

A global pattern of oceanic circulation driven by temperature and salinity differences, influencing climate and weather.

Pleistocene Mega Faunal extinctions

• Large scale extinctions (4%of big mammals species) at the end of the last “Ice Age”

• Potential causes: hunting by spreading humans, climate change

• Extinctions were spatially and temporally heterogeneous

• Lack of global synchrony makes it an unideal marker

Dawn of agriculture

 Dramatic change in species composition
 Evidence: increased fossil pollen from domestic plants
 Not an ideal boundary because of:
multiple independent, asynchronous origins
secondary markers (e.g. ceramics) not consistently associated with agriculture

Columbian exchange

 Cross-Atlantic exchange of human-associated species (crops, farm animals, diseases)
Potatoes, corn, tobacco, cocoa: New to Old World
Sugar cane, wheat, horse, smallpox: Old to New world
 Pollen from crops widespread
 Potential good marker – global, time constrained, secondary

Industrial Revolution

 Rise of capitalism
Land ownership = greater agricultural productivity
 Technological innovation
Greater productivity → more food access
Improved medicine → rapid human population growth
Rise of factories → urbanization
Rapid increase in fossil fuel use → rise in atmospheric CO2
Industrialization: spatial and temporal asynchrony

The Great Acceleration

Major expansion in human population
Medical advances
Green revolution in agriculture = better nutrition
Major changes in biogeochemical cycles
Industrialized farming = widespread use of N and P fertilizers
Large increase in fossil fuel use = increased atmospheric CO2
Novel products
Nuclear testing (visible in sediments)
Plastics, concrete, pure Aluminium

Summary

▪ Major shifts during human history in energy use and organization may mark the start of a new geological time, the Anthropocene.
▪ Human society has modified many elements of the Earth’s critical systems.
▪ Changes of such magnitude have only rarely occurred in the Earth’s history.
▪ Environmental change drivers are highly interconnected.
▪ Tipping points, where systems shift into different states, pose a considerable risk to humanity’s future.

The Start of the Anthropocene coincides with major shifts in energy use and organization

• Two energy transitions:
  • Agriculture
  • Fossil fuel use and industrialization

• Two organizational transitions:
  • Globalization and the trans-Atlantic interchange
  • The Great Acceleration

3.Decay & homogenization of biodiversity

• Humans have raised extinction rates to levels only comparable to the five mass extinctions. Is this the 6th mass extinction?
• Extinction rate is 100-1000 times the background rate.
▪ Yearly Loss of 11,000 – 58,000 species
▪ Widespread decreases in insect biomass (20-75%)
• Mixing of biota across oceans is unprecedented (e.g. 20% of plant species are exotic in many regions).

1.Major changes in biogeochemical cycles

• Atmospheric CO2 increased from 280 ppm in 1800 to 413 ppm today, mostly due to burning of fossil fuel. Causes warming.
• Ocean pH is more acidic due to CO2 uptake, with a decrease of 0.1 units or 26%. Affects marine organisms.
• Nitrogen cycling is highly affected by industrial processes and fertilizers. Causes eutrophication in aquatic environments

2.Exploitation of energy and resources

• About 97% of large mammal biomass is human (30%) or domestic animals (67%).
• Humans appropriate ~38% of Global Net Primary Productivity.
• Humans use 50% of available fresh water (70% of this for agriculture). Only 37% of rivers globally (2% in the US!) are unimpeded by dams.