Week 1.docx

Climate Change Mitigation Week 1 What is Climate Change? “Refers to long term shifts in temperatures and weather patterns” Two types of climate change: e.g. Natural Plate tectonics The Sun The Earth’s orbit Unforced variability Greenhouse gases e.g. Human activities Burning of fossil fuels (coal...

Climate Change Mitigation Week 1 What is Climate Change? “Refers to long term shifts in temperatures and weather patterns” Two types of climate change: e.g. Natural Plate tectonics The Sun The Earth’s orbit Unforced variability Greenhouse gases e.g. Human activities Burning of fossil fuels (coal, oil, gas) Tectonic Motion Continents are moving gradually from plate tectonics Continent location determines formation of ice sheets and ocean circulation Ice sheets can significantly affect the global climate because: Ice reflects sunlight, increases planetary albedo which increases the reflection of solar radiation back to space This cools down the planet e.g. Drake Passage Took place 30 million years ago when Antarctic Peninsular parted from southernmost tip of S America – creating Drake Passage Winds and water flowed around Antarctica because of this passage reducing transport of warm water and air from the tropics Dramatic cooling of the Antarctica took place – created the Antarctic ice sheet The Sun The sun’s energy balance is changing – incoming solar radiation is the same but outgoing terrestrial radiation is decreasing (because GHG’s are increasing) Overall this means internal energy is increasing Incoming = outgoing + change of internal energy The rate of fusion is increasing because of more hydrogen and helium is being produced This helium builds up and increases the density of the Sun’s core Earth’s Orbit Solar constant is determined by the distance between the earth and sun Earth’s orbit is shaped as an ellipse with varying eccentricity over time (ratio of the length of the ellipse to the width) Snowball earth – a deep freeze that took place 715 mya and lasted 120 mya Average temperature at the equator was -20 degrees Most life was wiped out but it allowed the firs animals to evolve and dramatic flourishing of life – Cambrian explosion Greenhouse gases They trap the sun’s heat and temperatures Planet needs a cooling mechanism in order to make it habitable but too many gases is harmful Earth is 1.1 degrees warmer than the late 1800s Between 2011-2020 earth was warmest on record Main emitters – energy, industry, transport, buildings and agriculture Global temperature increases with increases in carbon dioxide emissions Impacts of Climate Change Climate change can affect: Health Ability to grow food Housing Work The most vulnerable people to climate impacts live in small island nations, in developing countries or are poor Factors that control emissions: Technology: The energy intensity – a measure of how much energy it takes to generate a dollar of GDP (J/$) The carbon intensity – a measure of how much GHG is emitted to generate a joule of Energy (CO2/$). Population: Emissions are proportional to population (as population doubles so does GDP which increases GHG) Affluence: how rich each person is (as people get richer, their consumption increases) The wealth effect leads to enormous disparities in emission per person (numbers from 2017) USA 16.2 tonnes of carbon dioxide per person – a rich family in a rich country China 6.9 tonnes of carbon dioxide per person – a low/medium class family in a rich country Nigeria 0.6 tonnes of carbon dioxide per person – poor family in a farm in Sub Saharan Africa Amount of GHG released by a society is determined by total amount of GDP consumed by a society There were drops in GHG seen during recession and during COVID pandemic Impact = Population x Affluence (consumption per person) x Technology (Impact/consumption) Responses to Climate Change Adaptation Responding to the negative impacts of climate change. If climate change causes sea-level rise, an adaptive response to this impact would be to build seawalls or relocate communities away from the encroaching sea. Mitigation Policies that avoid climate change in the first place, thereby preventing impacts such as sea-level rise from occurring. This is accomplished by reducing emissions of greenhouse gases, usually through policies that encourage the transition from fossil fuels to energy sources that do not emit greenhouse gases. Geoengineering The active manipulation of the climate system. Under this approach, people would continue adding greenhouse gases to the atmosphere, but we would intentionally change some other aspect of the climate in order to cancel the warming effects of the greenhouse gases. For example, increasing the albedo of the Earth Solar Energy: Photovoltaic energy Direct conversion of light into electric power (no fluids). Solar panels located on houses or buildings (and on satellites and the Space Station). Certain materials such as silicon generate electricity when exposed to light. Solar thermal energy Uses mirrors to concentrate sunlight on a working fluid heating it to several hundred degrees Celsius.  This hot fluid is then used to boil water and drive a turbine, which in turn drives a generator that produces electricity. Pros Renewable Solar energy can reduce your home’s electricity bill Homes with solar panels installed may improve home value Solar panels have low maintenance costs Solar energy can generate electricity in any climate. Cons Intermittency The area required to generate solar energy. The high initial costs of installing panels Solar energy storage is expensive Solar doesn’t work for every roof type Wind energy: Windmills or wind turbines – a wind turbine can generate as much as 10 MW of power every year. Offshore and onshore. Putting upwind turbines does not preclude using the land simultaneously for other activities (agriculture). Pros Clean energy source Renewable energy source Space efficient Cheap energy Cons Intermittent Environmental impact Noise pollution Aesthetics Limited locations Biomass energy: The process of growing crops and then burning them to yield energy. They are a promising technology but they need to be carefully constructed so they don’t emit any carbon Pros Renewable Reliable Abundant Waste reduction Carbon-neutral Cons Expensive Requires space Greenhouse gas emissions Environmental impact Hydroelectricity energy: Generated when water running through a dam spins turbines and generates electricity. Source for 16% of the world’s electricity. Many of the world’s big rivers are already dammed, and new dams often cause local environmental problems Opposition from those individuals living in the area. Pros Minimal pollution Clean energy source Relatively low operations and maintenance costs. The technology is reliable and proven over time Renewable - rainfall renews the water in the reservoir, so the fuel is almost always there Cons High investment costs Hydrology dependent (precipitation) Wildlife • Loss or modification of fish habitat • Fish entrainment or passage restriction Changes in reservoir and stream water quality Displacement of local populations Conflicts between countries. Nuclear energy: The energy in the nucleus, or core, of an atom. One of the most contentious options for reducing GHG emissions. Nuclear reactors generate 16% of the world electricity. Uranium fuel. How does nuclear power work? Heat, Steam, Turbines generate electricity, Nuclear energy Cons Reactor safety Meltdown of a reactor at Chernobyl 1986. Explosion of a reactor in Fukushima Japan in 2011 after a tsunami damaged the plant. Power plants are attractive targets to terrorists. Nuclear waste Geological Disposal Facilities (GDF) to dispose of nuclear waste in many countries. Proliferation Nuclear weapons – conflicts. The nuclear power plants are relatively cheap to run, they are extraordinary expensive to build Total energy supply (TES) by source – UK 1990-2021 Less depending on oil, coal and natural gas. Increasing in wind and solar energy. Limited investment in the hydro power. Around 25% of our projected electricity demand in 2050 will be from nuclear power. Carbon capture and sequestration (CCS): The process by which fossil fuels are burned in a way that the carbon dioxide generated is not vented to the atmosphere. Rather the carbon dioxide is captured and placed in long term storage. Combination with coal combustion. CCS may be the only way to both burn this coal and avoid climate change. Carbon dioxide removal: The attempt to modify the carbon cycle in order to remove carbon dioxide from the atmosphere much faster than natural processes. Planting trees. Adding iron to the ocean To remove carbon dioxide from the air chemically. Attractive because it would stabilise the climate (temperature, ocean acidifications and precipitation). Cons The scale required of required carbon dioxide removal is enormous. Humans are adding 40 billion tonnes of carbon dioxide to the atmosphere every year). Some approaches to removing carbon dioxide from the atmosphere like adding iron to the oceans could be risky. Uncertainty about the carbon cycle in the oceans (we know that there are too many details which we don’t know. Unforeseen and serious impacts on ocean ecosystems. Solar radiation management: A way of increasing the Earth’s albedo Increasing the aerosol in the atmosphere Inject SO2 into the atmosphere. SO2 reacts with water vapour to form sulphate aerosols which reflects the sunlight back to space, thereby increasing the albedo of the Earth and leading to cooling. It is the same mechanism by which volcanic eruptions cool the planet. Increasing the reflectivity of the low clouds. To increase cloud- condensation-nuclei (CCN) into the clouds. Seeds that cloud droplets form around. Pros High confidence, the physics supporting these suggestions is robust. Once implemented, temperatures will react immediately Cheaper than building a nuclear reactor. Cons Solar radiation management may create other problems. When started, it is difficult to stop. The life-time of aerosol in the atmosphere is a few weeks to a few years Political problems. Overall solar radiation management is appealing but risky!!!