Lecture 4d – Our climate by 2100 Learning Outcomes • Be able to explain how we know climate varied in the past and have a rough idea of how different climate has been in the past • Be able to describe how our climate has been changing and why • Be able to explain how we predict future changes: – What factors are included in climate models – What are some of the major uncertainties in the models – “Representative concentration pathways” • Be able to describe what our climate might be like by 2100 Current track of carbon emissions…. Climate changes by 2100: Temperature 6 oC – global catastrophe 5 oC – Food prices double, billion refugees worldwide, mass extinctions 4 oC – Arctic Canada is new agricultural area, deserts expand 3 oC – Amazon rainforest dries out and burns 2 oC – Arctic becomes ice free in summer, coral reefs die 1 oC – droughts in US, loss of snowpack, hurricanes start to hit South Atlantic http://www.youtube.com/watch?v=7T9IjSEqT74 Climate changes by 2100: Temperature Warming will not be distributed evenly – much greater in the Arctic due to positive feedback processes From Fig SPM.8 IPCC AR5 Climate changes by 2100: Precipitation Contrast between wet and dry regions and wet and dry seasons will increase Modeling precipitation is very hard to do so we have much less certainty RCP2.6 From Fig SPM.8 IPCC AR5 RCP8.5 Climate changes by 2100: Sea level – Projected sea level rise = 45-75 cm – Further sea level rises would continue after 2100 as the oceans take a long time to warm and icesheets continue to melt From Fig SPM.9 IPCC AR5 http://sealevel.climatecentral.org/surgingseas/ Climate changes by 2100: Ocean pH From Fig SPM.6 and SPM.77 IPCC AR5 Effects of climate change on USA •Read Chapter 20 of the National Climate Assessment Report (available below this video) •Make note of the 5 key messages – how many of these relate to the cryosphere in some way? http://nca2014.globalchange.gov/report#section-1948 Lecture 4c – Modelling future climate change Learning Outcomes • Be able to explain how we know climate varied in the past and have a rough idea of how different climate has been in the past • Be able to describe how our climate has been changing and why • Be able to explain how we predict future changes: – What factors are included in climate models – What are some of the major uncertainties in the models – “Representative concentration pathways” • Be able to describe what our climate might be like by 2100 How will climate change in the future We make predictions using complex computer models for Earth’s climate system: -Land -Atmosphere -Ocean -Ice -Biosphere -Water, energy and biogeochemical cycling Climate changes by 2100: Uncertainties The biggest uncertainties in climate models are: • Response of clouds/precipitation • Potential for sudden shifts in climate state that involve ocean circulation/sea ice changes/biosphere changes • Ice sheet volume loss – will the flow of the big ice sheets change enough to significantly affect the amount of sea-level rise expected in a warming world? But… by far the biggest uncertainty going forward are human factors How will climate change in the future • Representative Concentration Pathways (RCPs) = plausible greenhouse gas trajectories for the future based on economic growth, energy sources, population growth etc. E.g. RCP2.6 = radiative forcing of +2.6 W/m2 in 2100 From van Vuuren et.al. 2011 Why has our climate been changing? How will climate change in the future From van Vuuren et.al. 2011 How will climate change in the future From van Vuuren et.al. 2011 How will climate change in the future Which of these scenarios do you personally think is more likely? a) RCP2.6 b) RCP4.5 c) RCP6 d) RCP8.5 From van Vuuren et.al. 2011 Current track of carbon emissions…. Lecture 4b – Current climate change Learning Outcomes • Be able to explain how we know climate varied in the past and have a rough idea of how different climate has been in the past • Be able to describe how our climate has been changing and why • Be able to explain how we predict future changes: – What factors are included in climate models – What are some of the major uncertainties in the models – “Representative concentration pathways” • Be able to describe what our climate might be like by 2100 Introducing… Intergovernmental Panel on Climate Change • This should always be the first place you look for information related to climate change • Latest report came out in 2013/2014 • Openly peer-reviewed by scientific community and the summaries must be approved by all participating governments (over 120 countries) http://www.ipcc.ch/ Introducing… Intergovernmental Panel on Climate Change This is not simply an earth system science issue. Where do you and your interests fit in? How has our climate been changing? Atmosphere: • Warming of 0.86 oC from 1880-2012 • Frequency of heat waves has likely increased in Europe, Asia and Australia • Likely hotter today than any other time in last 1300 years From Fig SPM.1 IPCC AR5 How has our climate been changing? Where has the greatest warming been? a) Over the oceans c) Over the land at higher latitudes b) At the Equator d) Over Antarctica From Fig SPM.1 IPCC AR5 How has our climate been changing? Oceans: a) Oceans warming • have taken up 90% of extra energy between 1971-2010 b) Increase in sea level • about 3mm per year today due to thermal expansion and melting cryosphere c) Ocean acidification • oceans have become 0.1pH units more acidic due to additional CO2 in atmosphere Figure TS.1 from AR5 WG1 How has our climate been changing? Precipitation patterns: • Wetter in wet places • Dryer in dry places • More frequent floods and droughts From Fig SPM.2 IPCC AR5 Changes are impacting ecosystems http://www.arborday.org/media/mapchanges.cfm Why has our climate been changing? Natural forcings include: solar variability, volcanic eruptions, changes in Earth’s orbit Anthropogenic forcings include: greenhouse gases, aerosols, surface changes https://www.bloomberg.com/graphics/2015-whats-warming-the-world/ Why has our climate been changing? How much extra warming is Earth experiencing due to greenhouse gases? a) 0.2 W/m2 b) 1.5 W/m2 c) 2.6 W/m2 d) 4 W/m2 Where is the carbon coming from? • Fossil fuel burning • 280Gt C to atmos since 1900 • 6-7 Gt C per year now • Deforestation • 200 GtC to atmos since 1850 • 0.5 – 2 GtC per year now Lecture 4a – Past climate change Learning Outcomes • Be able to explain how we know climate varied in the past and have a rough idea of how different climate has been in the past • Be able to describe how our climate has been changing and why • Be able to explain how we predict future changes: – What factors are included in climate models – What are some of the major uncertainties in the models – “Representative concentration pathways” • Be able to describe what our climate might be like by 2100 “The Climate System” Characterized by CHANGE Past Climate: how do we know? 1. Instrumental Record (recent, ~1800s to present) Past Climate: how do we know? 1. Instrumental Record (recent, ~1800s to present) 2. Geologic Record – fossils – landscape features (sand dunes, dry lakes/rivers, glacial valleys etc) Past Climate: how do we know? What created Yosemite valley? a) Erosion by rivers b) Erosion by wind c) Earthquakes d) Erosion by glaciers Past Climate: how do we know? 1. Instrumental Record (recent, ~1800s to present) 2. Geologic Record – fossils – landscape features (sand dunes, dry lakes/rivers, glacial valleys etc) 3. Proxy Records “records of natural events that are controlled by, and closely mimic, climate” Past Climate: Proxy Records 3. Natural “layered” records e.g. – Tree rings If you find a thicker than normal tree ring what might that indicate? a) Warmer temperatures b) Wetter conditions c) Less pollution Past Climate: Proxy Records 3. Natural “layered” records e.g. – Tree rings – Ice cores (CO2 and temperature records) Earth is presently in a cool period – dark bands show times when large ice sheets were present on continents. We are currently in an “Ice Age”. During much of Earth’s history, there is no evidence for ice – much warmer atmosphere, warmer oceans and higher sea levels. Millions of years before present History of ice on Earth Snowball Earth? Middle Cretaceous – 100 Myrs ago Around 100 million years ago: • Coral reefs grew closer to the poles • Sea level was 100 – 200 m higher than today (no ice sheets) • Global average temperatures are estimated to be 6-14oC warmer Why? 1. continent positions changed Earth’s albedo and ocean circulation 2. CO2 levels were 8-10 times greater than today (~3900 ppm) Last 50 Myrs Gradual cooling over last 50 Myrs Climate changes due to: -redistribution of continents -changes in ocean and wind currents -gradual fall in CO2 levels Figure 14.1, Skinner et al., 1999 Figure 14.17, Skinner et al., 1999 Last 2 Myrs Alternating glacial (cold) and interglacial (warm) periods every ~100,000 years or ~40,000 years Climate changes due to: – Milankovitch cycles – amplifying climate feedbacks Current interglacial – Last 10,000 yrs • Relatively very stable “interglacial” climate • Has allowed development of agriculture and civilization Past Climate Summary • World has been warmer and colder than today in Earth’s history • But… human civilization is very much “adapted” to the current, very stable climate • The RATE of climate change over the next 100 years is greatest threat likely 10 times faster than any other change in the last 65 million years Lecture 5d – Climate action so far US emissions Why have US greenhouse gas emissions begun to fall? US emissions Global emissions cuts: Paris Agreement • Aims are: a) Limiting global average temperature rise to well below 2 °C b) Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience c) Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development • Came into effect on 4th November 2016 • As of November 2017 it has been signed by all world countries and EU • Each country decides how to best cut emissions then makes a public commitment Global emissions cuts: Paris Agreement • Aims are: a) Limiting global average temperature rise to well below 2 °C b) Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience c) Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development • Came into effect on 4th November 2016 • As of this November it has been signed by all 194 countries and EU • Each country decides how to best cut emissions then makes a public commitment Global emissions cuts: Paris Agreement • Aims are: a) Limiting global average temperature rise to well below 2 °C b) Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience c) Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development • Came into effect on 4th November 2016 • As of this November it has been signed by all 194 countries and EU • Each country decides how to best cut emissions then makes a public commitment Global emissions cuts: Paris Agreement Reference 4.2ºC in 2100 Greenhouse Gas Emissions (GtonsCO2e / year) 60 No cuts 50 40 30 ▪ Other Developing ▪ China ▪ Other Developed ▪ US ▪ EU ▪ India 20 10 0 2000 2020 2040 2060 2080 2100 Global emissions cuts: Paris Agreement 3.2ºC in 2100 Greenhouse Gas Emissions (GtonsCO2e / year) 60 Current Plans 50 40 30 ▪ Other Developing ▪ China ▪ Other Developed ▪ US ▪ EU ▪ India 20 10 0 2000 2020 2040 2060 *All countries achieve their NDCs by the target year, and their midcentury strategy (MCS) if they have one. 2080 2100 Global emissions cuts: Paris Agreement 1.9ºC in 2100 Greenhouse Gas Emissions (GtonsCO2e / year) 60 Needed cuts 50 40 30 ▪ Other Developing ▪ China ▪ Other Developed ▪ US ▪ EU ▪ India 20 10 0 2000 2020 2040 2060 *US and all developed countries achieve their NDC by target year, then decrease to 80% below reference year CO2eq by 2050, and then continue rates of decline 2080 2100 New proposed US environmental policies Under new Biden administration proposed actions include: – Ensuring the US achieves a 100% clean energy economy and net-zero emissions by 2050 – Rejoin Paris Climate agreement and incorporate climate change into foreign policy and national security strategies and approach to trade – Ending subsidies for fossil fuels and ban new oil and gas permitting on public lands – Things to watch for this year: – Upcoming infrastructure bill which is likely to contain funding for green infrastructure e.g. electric vehicle charging stations, grid Biden hosting summit for 40 world leaders on April 22nd and expected to make some extra commitments 2021 Nov 1st-12th UN Climate Change Conference to review commitments made during original Paris agreement and push for further action ( will happen every 5 years) California emission targets • 80% below 1990 emissions by 2050 – Proposed policies include cap and trade, low carbon fuel and renewable energy, zero-emissions vehicles Cutting carbon emissions Topic of Discussion in Week 3. What strategies would you use to reduce our emissions and prevent climate change? Lecture 5c – CCS and geoengineering Learning Outcomes • For both “conservation” and “efficiency”: Be able to • give examples of how they could reduce carbon emissions • For “carbon-free energy”: Be able to • explain the basics of how we generate electricity • explain the advantages and disadvantages of carbon-free methods and why these might limit our ability to use them • explain the advantages of fossil fuels and suggest reasons we haven’t stopped using them • For “carbon capture and storage”: Be able to • describe briefly how it would work and what challenges it could pose • For “geoengineering”: Be able to – explain how the various methods would prevent climate change – explain major advantages and disadvantages of these methods A Framework for Climate Action: Carbon capture and storage Carbon Capture and Storage (CCS) • Capture the CO2 released by burning fossil fuels or released from manufacturing steel/cement • Store it underground in depleted oil/gas reserves • However….. to avoid 15% of global emissions we would have to capture, transport, and store a volume equivalent to 1.2 times the volume extracted by the global oil industry each year! A Framework for Climate Action: Geoengineering Geoengineering solutions Geoengineering solutions Which of these solutions would prevent ocean acidification? a) Space mirrors b) Aerosols c) Afforestation d) Covering deserts with reflective surfaces Lecture 5b – Carbon-free or carbon-neutral energy Learning Outcomes • For both “conservation” and “efficiency”: Be able to • give examples of how they could reduce carbon emissions • For “carbon-free energy”: Be able to • explain the basics of how we generate electricity • explain the advantages and disadvantages of carbon-free methods and why these might limit our ability to use them • explain the advantages of fossil fuels and suggest reasons we haven’t stopped using them • For “carbon capture and storage”: Be able to • describe briefly how it would work and what challenges it could pose • For “geoengineering”: Be able to – explain how the various methods would prevent climate change – explain major advantages and disadvantages of these methods A framework for climate action: Carbon-free energy Carbon-free energy Generating the energy we need using renewable sources rather than fossil fuels How do we generate electricity? Carbon-free energy Generating the energy we need using renewable sources rather than fossil fuels What are some of the carbon-free ways of generating electricity? Carbon-free energy: Renewables + Solar Carbon-free energy: Nuclear Happens in the center of the Sun, but not yet possible on Earth. Form of nuclear energy used on Earth. Remaining fossil fuels How much of the known fossil fuels on Earth have we already used up? a) b) c) d) Less than 25% 26% – 50% 51 – 75% 76% or more Remaining fossil fuels Estimated amount of carbon produced by fossil fuel use so far compared with amount still left (as of 2006) Carbon-free energy Generating the energy we need using renewable sources rather than fossil fuels Why haven’t we switched from fossil fuels? 1. We have lots of them and the infrastructure we need to obtain, transport, and use them! 2. On-demand power when we need it 3. High energy density and power density (gets lots of energy from little mass and little area) 4. Often cheaper but becoming less so, especially if a price is put on carbon… Lecture 5a – Conservation and efficiency Learning Outcomes • For both “conservation” and “efficiency”: Be able to • give examples of how they could reduce carbon emissions • For “carbon-free energy”: Be able to • explain the basics of how we generate electricity • explain the advantages and disadvantages of carbon-free methods and why these might limit our ability to use them • explain the advantages of fossil fuels and suggest reasons we haven’t stopped using them • For “carbon capture and storage”: Be able to • describe briefly how it would work and what challenges it could pose • For “geoengineering”: Be able to – explain how the various methods would prevent climate change – explain major advantages and disadvantages of these methods Current track of carbon emissions…. A framework for climate action: Conservation Conservation Conservation = reduced demand for goods/services that produce CO2. How could we incentivize/encourage conservation? Conservation How much food in the US is wasted each year? a) b) c) d) 2-5% 8-10% 15-20% 30-40% Conservation How could we incentivize/encourage conservation? – Make businesses more responsible for the disposal/recycling of their products. – Put a price on carbon

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