Lecture 1: Global Environmental Change PDF

Lecture 1 Global Environmental Change  Today’s Lecture – Global Environmental Change 1. Origins – who we are 2. Air Pollution – burning fossil fuels produces smog 3. Land Use – deforestation and monoculture 4. Oceans – overfishing, depletion of coral- reefs 5. Ozone – CFCs pro...

Lecture 1 Global Environmental Change  Today’s Lecture – Global Environmental Change 1. Origins – who we are 2. Air Pollution – burning fossil fuels produces smog 3. Land Use – deforestation and monoculture 4. Oceans – overfishing, depletion of coral- reefs 5. Ozone – CFCs producing ozone hole 6. Climate Change – increase CO2 5. The Ozone Hole  Ozone Found in troposphere (e.g., Ozone = O3 pollution in cities) and stratosphere (natural). Tropospheric ozone is toxic. Stratospheric ozone protects us from UV radiation. O3 -> O2+O Ozone in the stratosphere is depleted by chlorofluorocarbons (CFCs). CFCs were produced as propellants in spray cans and refrigerants. more info at: https://ozonewatch.gsfc.nasa.gov/facts/SH.html  Ozone hole September 1979 September 2023 https://ozonewatch.gsfc.nasa.gov Because of peculiar meteorological conditions, ozone destruction is particularly severe over Antarctica, giving rise to an “ozone hole.” (Dobson unit = 0.01 mm of ozone at standard temperature and pressure)  Ozone Hole “healing” (area through time) large hole growth healing trend? small Dots show observations, colored lines reconstructions with different methods Since the 2000s a trend of “healing” has started to emerge However, the ozone hole will persist for decades Solomon et al., 2016, Science Earth Systems 1 Atmosphere 2 Hydrosphere 3 Lithosphere 4 Biosphere 5* Cryosphere *All part of our climate and weather systems  Example quiz We will now test iClickers https://join.iclicker.com/GQXS GQXS Information for getting started: https://coe.bruinlearn.ucla.edu/academic-tech-to ols/iclicker-cloud  Weather vs. Climate iCl WHAT IS THE DIFFERENCE? ick Tim er Read the following definitions: e! 1) atmospheric conditions that occur locally over short periods of time—from minutes to hours or days (e.g., rain, snow, clouds, winds, floods, or thunderstorms) 2) long-term (usually at least 30 years) regional or even global average of temperature, humidity, and rainfall patterns over seasons, years, or decades a) 1 represents climate and 2 represents weather b) 1 represents weather and 2 represents climate c) I am not sure  iCl Weather vs. Climate ick Tim er WHAT IS THE DIFFERENCE? e! Test your understanding: Which ones represent climate, which ones represent weather? 1) The temperature at noon was 73 F 2) The all-time record high temperature is 108 F 3) This winter was wetter than last winter 4) Yesterday, the relative humidity was 90% A B C 1) Climate 1) Weather 1) Weather 2) Weather 2) Climate 2) Climate 3) Weather 3) Weather 3) Climate 4) Climate 4) Climate 4) Weather  What is Climate change? Long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates, caused by natural or anthropogenic (human- made) processes Natural processes, which have been overwhelmed by human activities, can also contribute to climate change, including internal variability (e.g., cyclical ocean patterns like El Niño, La Niña and the Pacific Decadal Oscillation) and external forcings (e.g., volcanic activity), change in sun’s energy output Changes observed in Earth’s climate since the mid-20th century are driven by human activities, particularly fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere, raising Earth’s average surface temperature, leading to sea-level rise, melting  Global warming? Global warming is the long-term heating of Earth’s surface observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat- trapping greenhouse gas levels in Earth’s atmosphere. This term is not interchangeable with the term "climate change."  Fossil Fuels? Fossil fuels are formed from the remains of (decomposing) ancient plants and animals o Coal: material usually found in sedimentary rock deposits where rock and dead plant and animal matter are piled up in layers o Oil: found as a solid material between layers of sedimentary rock (mud + clay = shale). This material is heated in order to produce the thick oil that can be used to make gasoline o Natural gas: usually found in pockets above oil deposits. It can also be found in sedimentary rock layers that don’t contain oil. Natural gas is primarily made up of methane The burning of fossil fuels generates energy, electricity, and power 6. Climate Change  Atmospheric CO2 and the “Keeling Curve” Latest reading 418.06 ppm The reading was 397 ppm when I first taught this class on September 22, 2015! Data from Scripps CO2 Program (https://scripps.ucsd.edu/programs/keelingcurve/)  Data source: NOAA, measured at the Mauna Loa Observatory, Hawaii CLICK HERE FOR MORE! CLICK HERE FOR MORE!  This graph shows atmospheric carbon dioxide from Antarctic ice cores for the past 800,000 years, combined with the Mauna Loa data after 1958. Clearly, today’s atmospheric CO2 concentrations are unprecedented for at least the last million of years! The increase in carbon dioxide coincides with the invention of the internal combustion engine and industrialization, and corresponds to the amount of fossil fuel burned.  Consequences The increase in carbon dioxide is global and has been traced unequivocally to the burning of fossil fuels. Carbon dioxide is not a toxic gas (at atmospheric concentrations). It is critical to plant life and occurs naturally in the atmosphere. But carbon dioxide plays an important role in regulating earth’s climate. As we’ll see, it’s a “greenhouse gas” whose levels control the planet’s temperature Yielding multiple changes in the Earth system including changes to the water cycle and frequency of extreme events.  Conclusion Local effects of human natural resource exploitation have become “super-sized” by industrialization, so that they are now global. A by-product of industrialized exploitation is a global increase in CO2 -- a gas fundamental to the planet’s environmental state. Human effects are strong enough to say we’ve entered the Anthropocene, a new geologic era. Summary Humans have always affected their environment, surviving by exploiting a variety of resources. The human footprint on planet Earth increased with human population, and exploded after the industrial revolution, catalyzed by several technological innovations. All aspects of the Earth System (atmosphere, land, ocean) are affected by human activities. Today, impacts are global, and include:  Air and water pollution, resource depletion, deforestation, overfishing, loss of biodiversity, changes in the chemical composition of the atmosphere, global warming, etc. Emissions of man-made chemicals (CFCs) to the atmosphere caused a reduction of ozone (O 3) in the stratosphere, and an expansion of the ozone hole around Antarctica, with human health consequences. Following the Montreal protocol, ozone-depleting substances were banned, reducing their concentration in the atmosphere and driving ozone recovery (“healing” of the ozone hole). The success of this international treaty relied on sound scientific information and mobilization of the public opinion. CO2 is also increasing in the atmosphere, to levels that are unprecedented in human history, as shown by direct and indirect measurements. This is at the root of current climate change. Essential skills: Familiarize with the broad aspects of human impacts on the various components of the Earth System. Discuss examples of these impacts, their causes and consequences, and the scientific evidence supporting them. Read and interpret scientific graphics, such as maps and time-series (e.g., ozone and CO2 measurements in the atmosphere, ozone hole maps, etc.). Interpret statistically significant “trends”, and underlying variability (the “wiggles” in the time series).