Present Day Climate Change PDF

lesson 7: Present Day Climate Change 1 Overview: 1. Earth’s energy balance & controls on climate - Greenhouse gasses, albedo, & feedback cycles 2. Evidence of a warming climate 3. Likely effects & implications 4. Climate change mitigation & what you can do...

lesson 7: Present Day Climate Change 1 Overview: 1. Earth’s energy balance & controls on climate - Greenhouse gasses, albedo, & feedback cycles 2. Evidence of a warming climate 3. Likely effects & implications 4. Climate change mitigation & what you can do. 2  1. Energy Balance Climate is consequence of energy balance: Sun Atmosphere Earth’s surface 3 1. Energy Balance: Albedo Albedo is the fraction of shortwave radiation reflected away from Earth. - Current albedo is ~0.3 - Ice/snow, clouds, and aerosols increase albedo. - Forests and dark soil decrease albedo. - Controls how much light is absorbed by Earth. 4 1. Energy Balance: Incoming Versus Outgoing Radiation All objects emit radiation. - Hotter = shorter wavelength, - Colder = longer wavelength. Incoming solar radiation = shortwave - Mostly passes through atmosphere & is absorbed at the surface. Earth emits longwave radiation - Atmosphere absorbs longwave radiation & it is Re-emitted in all directions. - Re-emission of longwave radiation is key factor in the greenhouse effect. 5 1. Energy Balance: Greenhouse Gasses Different gasses absorb different wavelengths of light. - Water vapor is the strongest greenhouse gas. - Other greenhouse gasses absorb longwave radiation where water doesn’t. 6 1. Energy Balance: Incoming Radiation Changes The amount of incoming solar radiation can change. - Earth’s orbit causes different seasons. - Earth’s orbit changes on 10 000 - 100 000 year timescales. Control climate on geologic - The sun has become ~30% brighter since Earth formed. time scales. (Next lecture) 7 1. Energy Balance: Key Points Energy balance depends on: - Albedo - Amount of incoming light reflected - Shortwave vs longwave absorption and re-emission - Greenhouse gasses – Different absorption spectra - Changes to incoming solar radiation Mostly just important on Geologic Timescales. 8 1a. Greenhouse Gasses: Carbon Cycle What are the sources and sinks of carbon dioxide? 9 1a. Greenhouse Gasses: Carbon Cycle - Ocean/Air Exchange Atmosphere & ocean carbon dioxide exchange: - CO2 easily exchanges with ocean/atmosphere. - Much higher solubility in water than other gasses. 10 1a. Greenhouse Gasses: Carbon Cycle - Sources Sources of Carbon Dioxide: - Cellular respiration - Decaying organic materials - Burning forests and fossil fuels - Volcanic activity 11 1a. Greenhouse Gasses: Carbon Cycle - Sinks Sinks of Carbon Dioxide: - Photosynthesis in water and on land. - Weathering of rocks (silicate minerals react with carbonic acid). - Incorporation into carbonate seashells & lithification into rock (long term storage). - Burial of organic matter (forms coal or methane; can also be long term storage). 12 1a. Greenhouse Gasses: Carbon Cycle - Sinks – Coal & Methane Thermogenic Methane and Coal: - Organic matter in anoxic conditions (such as in peat bogs), is buried deep. - Over millions of years, high pressure and temperature transform organic material to coal and methane (fossil fuels; generally long term storage) 13 1a. Greenhouse Gasses: Carbon Cycle - Sinks – Coal & Methane Biogenic Methane: - Methanogens live in anoxic conditions (also in peat bogs) & decompose organic matter to methane (near-surface environments). - Both biogenic & thermogenic methane can be stored as methane hydrates in permafrost or sea ice. Methane surrounded by water molecules as methane hydrate 14 1a. Greenhouse Gasses: Carbon Cycle – Increasing & CH4 Changes to carbon cycle that increase 𝟐 or CH4: - Burning fossil fuels (CO2) - Melting permafrost (CH4) - Deforestation (reduces photosynthesis) - More acidifies ocean & kills phytoplankton (reduces photosynthesis AND carbonate shell formation) 15 1a. Greenhouse Gasses: Carbon Cycle - + CH4 Impacts More 𝟐 and CH4 increases the greenhouse effect: - Recall that the atmosphere absorbs longwave radiation & Re-emits it in all directions. - Recall that and CH4 absorb longwave radiation where water vapor doesn’t. 16 1a. Greenhouse Gasses: Carbon Cycle - Key Points Key Points: - Carbon cycle is a balance of sources and sinks on different timescales. - Altering sources/sinks can influence atmospheric & CH4 concentration, and thus affect the climate. 17  1b. Feedback Cycles Wait… is only ~ 0.042% of the atmosphere. Does it really impact climate that much? Positive Feedback = Amplifying Negative Feedback = Stabilizing 18 1b. Feedback Cycles: Water Vapor/Temperature Feedback - Water vapor is the strongest greenhouse gas. - Warmer air can hold more water vapor. Warmer Increased Atmosphere Evaporation Positive Feedback More Atmospheric water vapor 19  1b. Feedback Cycles: Water Vapor/Temperature Feedback - More water vapor can produce more clouds. - Clouds increase albedo and block sunlight. Warmer Increased Atmosphere Evaporation Positive Feedback Colder More Atmospheric atmosphere water vapor Negative Feedback Increased More Clouds Albedo 20  1b. Feedback Cycles: CO2/Ocean Acidity More oceanic Greater Ocean Carbonic acid Acidity Positive Feedback More Carbonates Atmospheric CO2 can’t form Less Photosynthesis Less carbonate Phytoplankton sediment being die lithified into rocks The high solubility of CO2 in water is why atmospheric concentrations are so low. 21 1b. Feedback Cycles: Ocean Biological Pump Increase phytoplankton Decrease CO2 photosynthesis More ocean Cooler global nutrients Positive Feedback temperatures (P, Fe, N) Glaciation Rock dust goes grinds rock to into ocean. powder Increases in oceanic biological productivity are thought to be responsible for ~50% of CO2 drop during last glacial maximum! 22 1b. Feedback Cycles: CO2/Vegetation Feedback More More atmospheric precipitation moisture Warmer Increased Temperatures Vegetation Lower Negative Feedback Temperatures Less CO2 More photosynthesis 23 1b. Feedback Cycles: Ice/Albedo Feedback More Ice Higher Albedo Melting Ice Lower Albedo Temperature More Sunlight Temperature More Sunlight Decreases Reflected Increases Absorbed Is the Ice/Albedo feedback positive, negative, or both? Both are positive regardless of heating or cooking the 24 earth because positive or negative is determined whether the feedbacks amplify the effect 1b. Feedback Cycles: Ice/Albedo Feedback All Ice - Snowball Earth No Ice Discussed in detail next week. 25  1b. Feedback Cycles: Brief Activity Take 3 minutes - Discuss with the person beside you any additional positive or negative climate feedbacks you can think of. There are tons! - Different carbon sources and sinks are shown in the diagram. - Recall albedo from earlier, it plays into lots of feedback cycles too. 26 1b. Feedback Cycles: Rapid Climate Forcings Climate forcings externally disrupt Earth’s energy balance & cause climate change. - On geologic timescales, generally climate changes very slowly (hundreds of thousands to millions of years). Changes to solar flux is an example of a long-term climate forcing. - An intense, rapid climate forcing is necessary to perturb the climate from its dynamic equilibrium on short timescales. Must be pushed past a “tipping point”. 27 1b. Feedback Cycles: Rapid Climate Forcings – Volcano/Meteor Ejected dust can increase global albedo significantly. - Supermassive volcanic eruptions or meteor impacts eject significant dust to the atmosphere. - The dust increases albedo significantly, blocking sun and causing rapid cooling. - Huge volcanic eruptions & meteors have caused global “volcanic/impact winters” in the past. Ex: Temperature after eruption of Pinatubo. 28 1b. Feedback Cycles: Rapid Climate Forcings – Anthropogenic CO2 Humans are rapidly emitting CO2 on a very short timescale. - Carbon in fossil fuels form over millions of years and are generally long-term reservoirs. - We are releasing all the fossil fuel carbon to the atmosphere near-instantaneously on geologic timescales. - Steady atmospheric CO2 input can slowly perturb the climate system to a “tipping point”. 29 1b. Feedback Cycles: Tipping Points – Ocean Circulation A change to ocean circulation impacts global heat distribution. - Ocean circulation (thermohaline circulation) brings warmth from the equator to the poles. - Changes in ocean salinity or temperature impact the water’s density and can suddenly alter ocean circulation. - A new circulation can rapidly and significantly alter global climate. 30 1b. Feedback Cycles: Tipping Points – Methane Release Melting of permafrost or sea ice can decompose methane hydrates. - Decomposition of methane hydrates releases methane; a potent greenhouse gas. - Rapid warming can then decompose more methane clathrates, causing positive feedback & extremely rapid warming. Methane surrounded by water molecules as methane hydrate 31 1b. Feedback Cycles: Other Tipping Points Tipping points can also be reached with other feedback cycles. - Run away melting of ice – (Ice-Albedo feedback) - Ocean acidification – reducing photosynthesis & carbonate burial/lithification - Severe deforestation – reducing photosynthesis, increasing albedo 32 1b. Feedback Cycles: Key Points Key Points: - Many different positive and negative feedback cycles interact to form the climate. - A rapid climate forcing can abruptly alter part of the energy balance. - Energy balance changes can impact the intertwined feedback cycles, surpass a “tipping point”, & cause irreversible, rapid climate change. - Human release of CO2 is changing the energy balance, feedback cycles, and the overall climate. There is a fear of reaching a “tipping point.” 33  2. Evidence of Climate Change Is it really happening? Unfortunately, yes… 34 2. Evidence of Climate Change: Temperature and CO2 Increase Average global temperature and CO2 levels have continued increasing. - CO2 has increased by ~90 ppm in 60 years. - Average global temperature has risen ~1°C over the same period. - Effects of global warming are more pronounced at the poles. Temperature Change 1979-2019 35 2. Evidence of Climate Change: Sea Level rise Melting ice and increasing ocean temperatures causes sea level rise. - Increasing sea temperature causes thermal expansion of water (lower density). - Melting of the Greenland and Antarctic ice sheets, and other small glaciers increases sea level. - Since 1880, sea level has risen ~21-24 cm. 36  2. Evidence of Climate Change: Glacial Retreat Glaciers have been observed retreating globally. - Glacial retreat has been observed globally. - Vancouver Island had ~170 glaciers in 1970. Now there are five. Vancouver Island Retreat observed of the Bear Glacier (West Canada) over 5 years. The Comox Glacier, one of five remaining glaciers on Vancouver Island. 37 2. Evidence of Climate Change: Glacial Retreat Large ice sheets have also been observed shrinking. Antarctic Ice Sheet Loss/gain per year 38 2. Evidence of Climate Change: Increase in Extreme Weather Severe storms, drought, floods, etc. continue increasing globally. - Warmer atmosphere  more H2O vapour  more storms. - Warmer oceans  Ideal conditions for stronger hurricanes. November 2021 BC Severe Flooding Event 39  2. Evidence of Climate Change: Other impacts on Canada An ice road Northern Canada is especially susceptible to climate change. - Melting Permafrost damages structures (roads, pipelines, etc.) - Currently, many northern communities are only serviced by winter ice roads that melt in the summer, may require expensive year-round roads if winter becomes too short. - On Aug. 8, 2024, an arctic heat wave reached 35.9 °C above the arctic circle. 35.9°C – Aug. 8, 2024 Damaged road near Yellowknife from permafrost thaw. 40 2. Evidence of Climate Change: Key Points Key Points: - Changes to carbon dioxide levels, global temperature, sea level rise, and glacial retreat in over only a few decades indicate rapid climate change. - We can compare to geologic temperature history with the rock record (discussed next lecture). 41  3. Likely Implications What main impacts will occur? 42 3. Likely implications: Global Changes The observed impacts so far will continue worsening. - Sea level will continue rising – coastal flooding - Storms will intensity – worse storm surge, stronger winds, more rain 43  3. Likely implications: Climate changes to different regions Different locations will experience different climatic changes - Some places hotter and drier - Some places hotter and wetter - Increase in severe storms in many locations Predicted climate changes for ~2°C warming. 44 3. Likely implications: Scenarios for different global warming Increasing the level of global warming exacerbates the extremes. - Despite some variation, overall hot locations are hotter, dry locations are drier, and wet locations are wetter with increased global warming. 45  4. What can we do? Is it too late? What can we do to solve this? 46 4. What can we do? – Climate Engineering – Increase Albedo Increasing albedo reduces incoming solar flux. - Cloud seeding – Disperse small particles into the atmosphere to nucleate water. - Solar mirrors – Place large mirrors in space to reflect sun. - Reflective Aerosols – induce artificial cooling by dispersing small particulate into the high atmosphere. 47 4. What can we do? – Climate Engineering – Remove CO2 Reducing CO2 lowers the greenhouse gas effect. - Re-forestation – Plant new trees to replenish forests. - CO2 capture and storage – Remove CO2 from atmosphere, liquify it, and store it underground. - Ocean Iron Fertilization – Add iron (nutrient) to the ocean to increase phytoplankton photosynthesis and draw down CO2. 48  4. What can we do? – Renewable Energy Transition to using renewable energy sources to reduce CO2 output. - Increase renewable energy production - Hydroelectricity – Excellent if there is lots of moving water. - wind, solar – Good if these resources are present. Must be coupled with a storage method (battery) to maintain consistent energy availability. - Nuclear – traditional fission produces minimal waste, possibility of even safter nuclear fusion in the near future! - Geothermal – Great if the geothermal gradient is high. 49  4. What can we do? – Green Technology Fully electrify the world to minimize fossil fuel usage & reduce CO2 output. - Must transition industry, automotive, aviation, etc. to fully electric. - We are part way there, but issues with energy density and sufficient storage. - We will always need minor fossil fuels (coal for steel production). 50  4. What can we do? – Resource Demand Electrifying the industry is increasing demand of certain materials - Lithium for lithium-ion batteries. - Copper – highly conductive, used in nearly all electronics. - Rare Earth Elements – Pr, Nd, Sm, Dy used in strong magnets – wind & electric vehicles. - Current resource productions are well below what is required for complete energy transition. 51  4. What can we do? – Role of Earth Science & Geology Geology & Earth science are playing key roles in mitigating climate change Academia - Understanding all the factors impacting climate change. - Development of mitigation techniques (carbon capture). - Develop safe & efficient mineral extraction methods. Industry - Exploration for new critical mineral resources - Development & extraction of critical minerals - Work on new technologies like carbon capture 52  4. What can we do? – Globalized Effort A global effort to solving climate change is necessary. - 198 countries have signed the Paris agreement – commit to keep global temperature rise below 2 degrees of pre-industrial levels. - India announced to triple coal production by 2030. - Germany continued shutting down their nuclear power during Russia- Ukraine war & is burning fossil fuels again. - If all countries to not work together to solve the climate crisis, severe climate change will continue. 53  4. What can we do? – Individual Level Small changes can all help reduce CO2 production - Reducing non-essential energy consumption - Walking or cycling shorter distances - Reducing food waste - Purchase second hand, re-use items - Raise awareness  Lesson Summary Key Points: 1. Earth’s energy balance & controls on climate - Albedo, Greenhouse gasses & why they increase warming - Carbon cycle sources & sinks, feedback cycles, climate forcings, tipping points. 2. Evidence of a warming climate - Recent CO2 & temp. changes, sea level rise, extreme weather, etc. 3. Likely effects & implications - Global and regional climate changes. 4. Climate change mitigation & what you can do. - Climate engineering, green technology, globalized & individual effort - Role of geology & Earth Science 55