Climate Action (6)

An introduction to climate change

Lesson 1: Global warming from 1880 to 2021

  • Warming trends in both land and sea temperatures are observed in several independent datasets including the GISS Global Surface Temperature (GISTEM) [1] and the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) [2,3].

Lesson 2: What is causing climate change?
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Human activities since the industrial revolution are the primary cause of the observed rapid and unprecedented climate change. Burning fossil fuels is a prominent example of such activities: it increases the concentration of carbon dioxide ( CO2) in the atmosphere. The increased CO2 concentration then causes temperatures to rise via the Greenhouse effect. In the next few lessons (lessons 3-6), we will explain how burning fossil fuels causes the temperature to rise.

Lesson 3: Burning fossil fuels releases CO2 into the atmosphere
ClimateChangeCause

Fossil fuels, which we primarily depend on for our energy needs, were formed over millions of years by the compression of plant and animal materials [1,2]. Examples of fossil fuels include coal, petroleum (crude oil or oil), and natural gas. They are composed of mostly the same elements–carbon–but are in different states: solid, liquid, and gas, respectively. Carbon accounts for 60–90 percent of the mass of fuels, so CO2, among other products [3], is produced and released into the atmosphere during combustion. For example, gasoline–a product of petroleum–is a commonly used fuel in cars. Burning 6.3 pounds (1 gallon in volume) of gasoline produces 20 pounds of carbon dioxide. Given that the average American drives 12,000 miles per year, if an average car uses 30 miles per gallon, the person would generate ~ 8,000 pounds of CO2.

 

  1. 1. Fossil fuels for kids: https://climatekids.nasa.gov/carbon/ (accessed April 20, 2022)
  2. 2. Fossil fuels for older kids: Energy Conservation and Environmental Protection(lesson 4a)–a course at Penn State, https://www.e-education.psu.edu/egee102/node/1950 (accessed April 20, 2022)
  3. 3. Apart from CO2, burning fossil fuels produces another greenhouse gas: nitrous oxide (N2O) https://www.epa.gov/3ghgemissions/overview-greenhouse-gases#nitrous-oxide as well as particulate matter that contributes to air pollution.
Lesson 4: What is the greenhouse effect?
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The Greenhouse effect stems from the interaction between the sun, the Earth, and Earth’s atmosphere. Some gas molecules in the atmosphere absorb the radiation from the Sun and subsequently trap heat in the atmosphere [1-6]. They include carbon dioxide (CO2), methane, water vapor, nitrous oxide, and fluorinated gases. Among these greenhouse gases, water vapor is the most abundant greenhouse gas and is responsible for about half of the greenhouse effect [7, 8]. It contributes to the greenhouse effect via different mechanisms; here we highly the two most important ones. First, it is part of a positive feedback loop triggered by the increase of any other greenhouse gases including CO2  (see the 4th diagram in [7]):  an initial increase in air temperature caused by other greenhouse gases causes more water vapor to enter the atmosphere. Then increased air temperature and water vapor concentration continue to boost each other. Second, water vapor participates in a negative feedback effect in the form of clouds [5]. Clouds can warm the atmosphere through the greenhouse effect,  but can also reflect solar radiation and cool the Earth [6]. The composition and makeup of the clouds determine which effect happens [6].

 

Without the greenhouse effect, the Earth’s temperature would be -18 degrees C (0 degrees F) [5]. Therefore, the natural greenhouse effect is crucial for life on Earth. Nowadays, however, the increased anthropic greenhouse emissions (including burning fossil fuels, agriculture, and other land use) have significantly disturbed this balance.

 

  1. 1. MIT K12 Videos https://youtu.be/Rt6gLt6G5Kc
  2. 2. CO2 experiment by Iain Steward https://youtu.be/SeYfl45X1wo
  3. 3. Svante Arrhenius was the first to predict that changes in atmospheric CO2 levels affect the surface temperature https://www.tandfonline.com/doi/abs/10.1080/14786449608620846 (accessed April 20, 2022)
  4. 4. Syukuro Manabe refined Arrhenius’s idea and included more feedback mechanisms in the model. https://www.nobelprize.org/prizes/physics/2021/press-release/ (accessed April 20, 2022)
  5. 5. American Chemical Society. ACS Climate Science Toolkit. What Is the Greenhouse Effect? https://www.acs.org/content/acs/en/climatescience/climatesciencenarratives/what-is-the-greenhouse-effect.html
  6. 6. Intergovernmental Panel on Climate Change (IPCC). IPCC Fourth Assessment Report: Climate Change 2007. FAQ 1.3 What is the Greenhouse Effect? https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-3.html
  7. 7. Steamy Relationships (NASA) (accessed August 04, 2022) https://climate.nasa.gov/ask-nasa-climate/3143/steamy-relationships-how-atmospheric-water-vapor-supercharges-earths-greenhouse-effect/#:~:text=Water%20vapor%20is%20Earth's%20most,gases%20keep%20our%20planet%20livable.
  8. 8. Humidity paradox (Carbon brief) (accessed August 04, 2022) https://www.carbonbrief.org/guest-post-investigating-climate-changes-humidity-paradox/
Lesson 5: What are some common greenhouse gasses?
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Greenhouse gases come from burning fossil fuels, biomass, biological waste, and chemical reactions--cement production as an example--that produce carbon dioxide, CO2 [4], including natural gas that is mostly methane CH4 [4]. Methane is a greenhouse gas as well. Also, nitrous oxide, N2O [4] can be produced from agriculture, land use, industrial processes, combusting hydrogen [2,3], and combustion of ammonia [3]. Finally, man-made fluorinated gases (F-gases) are greenhouse gases as well [4].

The effect of a greenhouse gas depends on both the amount of energy the gas can absorb and its lifetime in the atmosphere. The Global Warming Potential (GWP) is a figure developed to compare the global warming impacts of different gases: it is a measure of how much energy the emissions of 1 ton of a gas will absorb over a given period of time, relative to the emissions of 1 ton of carbon dioxide (CO2). Gases with a higher GWP absorb more energy, per pound emitted, than gases with a lower GWP, and thus contribute more to warming Earth [5]. Carbon dioxide, CO2, has a GWP of 1 over 100 years and a lifetime of thousands of years. Methane, CH4, has a GWP in the range of 27-30 over 100 years and a lifetime of about a decade. Nitrous oxide, N2O, has a GWP of 273 times over 100 years and a lifetime of more than 100 years. F-gases can have GWPs in the thousands to tens of thousands and lifetimes in the range of 750-50,000.

1. U.S. Energy Information Administration. Where greenhouse gasses come from. EIA. URL: https://www.eia.gov/energyexplained/energy-and-the-environment/where-greenhouse-gases-come-from.php

2. Glarborg, Peter, Miller, James A., Rusic, Branko, Klippenstein, Stephen J. Modeling Nitrogen Chemistry in Combustion. URL: https://www.osti.gov/pages/servlets/purl/1460995

3. Hayhurst, A. N., & Lawrence, A. D. (1992). Emissions of nitrous oxide from combustion sources. Progress in Energy and Combustion Science, 18(6), 529–552. https://doi.org/10.1016/0360-1285(92)90038-3

4. U.S. Environmental Protection Agency. Overview of Greenhouse Gases. EPA. URL: https://www.epa.gov/ghgemissions/overview-greenhouse-gases
5. U.S. Environmental Protection Agency. Understanding Global Warming Potentials. EPA. URL: https://www.epa.gov/ghgemissions/understanding-global-warming-potentials

Lesson 6: Temperature is rising rapidly as a result of increased CO2 level
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Earth's climate has changed throughout history. Over the last 800,000 years, there have been seven cycles of glacial advance and retreat. Carbon dioxide plays a key role in driving both cooling during the onset of ice ages and warming at their end [1,2].  However, the current warming trend is of particular significance because human activities are the primary driver of those changes. The comparison of atmospheric samples contained in ancient ice cores and more recent direct measurements shows that atmospheric carbon dioxide has increased dramatically since the Industrial Revolution [3,4]. It is estimated that human contributions to the carbon cycle are more than 100 times those from all the volcanoes in the world combined [5] and have increased the concentration in the atmosphere by over 40%: from 290 parts per million (ppm) in preindustrial times to 410 ppm today.

  1. 1. How the rise and fall of CO2 levels influenced the ice ages https://www.carbonbrief.org/explainer-how-the-rise-and-fall-of-co2-levels-influenced-the-ice-ages (accessed May 04, 2022)
  2. 2. When will the next ice age happen? (TED education) https://youtu.be/I4EZCy14te0 (accessed July 22, 2022)
  3. 3. Lüthi, D., Le Floch, M., Bereiter, B. et al. High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 453, 379–382 (2008).
  4. 4. ice core facility:  https://icecores.org/about-ice-cores (accessed April 20, 2022)
  5. 5. volcanoes v. human activities https://climate.nasa.gov/faq/42/what-do-volcanoes-have-to-do-with-climate-change/
Lesson 7: Will climate change affect you?
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Due to the nature of our interactions with climate and other ecosystems, the impacts of climate change can be cascading. The rise in temperature directly causes many physical changes, including the sea level rise and glacial retreat [1, 2]. Such changes affect human society and other ecosystems directly and through biochemical processes. In lessons 8-10, we describe how climate change impacts the ocean and cryosphere, and land.  We will see that climate change’s impact on human society is twofold. First, it directly increases the risks to people by increasing the frequency and intensity of disasters, such as droughts, hurricanes, and heatwaves [3]. Over the past 30 years, heat is the leading cause of weather-related deaths in the US [4]. Second, due to the interactions between climate, ecosystems and human society, climate change’s impacts on glaciers and the marine ecosystem are threatening our water and food supply.

  1. 1. Climate Change: How do we know? https://climate.nasa.gov/evidence/ (accessed April 20, 2022)
  2. 2. How do we know the climate is changing? https://climatekids.nasa.gov/climate-change-evidence/ (accessed April 27, 2022)
  3. 3. Billon-Dollar Weather and Climate disasters (NOAA) https://www.ncei.noaa.gov/access/monitoring/billions/overview (accessed May 10, 2022)
  4. 4. Too hot to handle (NASA) https://climate.nasa.gov/ask-nasa-climate/3151/too-hot-to-handle-how-climate-change-may-make-some-places-too-hot-to-live/#:~:text=Wet%2Dbulb%20temperatures%20are%20on,begun%20to%20exceed%20this%20limit.&text=Since%202005%2C%20wet%2Dbulb%20temperature,Pakistan%20and%20the%20Persian%20Gulf (accessed Aug 04, 2022)
Lesson 8: Ocean and cryosphere have been ‘taking the heat’
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Ocean, cryosphere (including polar regions, glaciers, and permafrost), and climate interact in complex ways through physical, biochemical, and ecological feedback (cf. Chapter 1 of Ref. [1]). The ocean has been acting like a sink for heat and CO2, moderating some of the terrestrial effects of climate change for decades. This had led to severe physical and biochemical changes, such as the retreat of the cryosphere, more frequent marine heatwaves and hurricanes, sea-level rise, and ocean acidification. Many of these physical and biochemical changes then affect the marine ecosystems [2] and eventually the human society via the water and food cycles. The continuing anthropogenic climate change can lead to many abrupt and irreversible changes (Table 6.1 in Ref. [1]). Among the events with high to very high projected likelihood or confidence level, ocean acidification and deoxygenation at depth and the retreat of the Greenland ice sheet are irreversible for millennia.

  1. 1. IPCC special report on Ocean and cryosphere, 2019: https://www.ipcc.ch/srocc/; presentation: https://www.ipcc.ch/srocc/resources/presentation/
  2. 2. Deutsch, C., Penn, J.L., Avoiding ocean mass extinction from climate warming, Science, 376, 524-526, doi: 10.1126/science.abe9039
Lesson 9: How does land affect climate?
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Land plays an important role in the weather and climate system. On the one hand, Agriculture, Forestry and Other Land Use (AFOLU) is a significant net source of greenhouse gases, producing about 23% of anthropogenic emissions of carbon dioxide, methane, and nitrous oxide. On the other hand, land conditions also directly affect the climate. For example, dry soil conditions strengthen summer heatwaves through reduced evapotranspiration and increased heat. Combined with urbanization, climate change will exacerbate warming in cities and their surroundings (urban heat island), especially during heatwaves.

Lesson 10: Climate change is resulting in more frequent and more intense disasters
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In a special report on climate change and land (Ref. [1]), IPCC assessed the impact of climate change on land and the subsequent impact on human society and ecosystems. They found with high confidence that climate change is exacerbating the rate and magnitude of ongoing land degradation processes and introducing new degradation patterns. It is affecting food security through increasing temperatures, changing precipitation patterns, and greater frequency of disasters or extreme weather and climate events. Such events include floods, droughts, wildfires, winter storms, tropical cyclones, etc. In the US, there have been 323 extreme events since 1980, costing around $2.2 trillion [2]. Around the world, the number of climate disasters tripled in the last 30 years 20 million people were forced to move out of their homes [3].

Are these extreme events caused by anthropogenic climate change? Scientists have developed robust methods to attribute extreme events based on climate models [4-6]. The comparison between observation and model-based simulation allows us to understand whether climate change has changed the probability of occurrence of an extreme event like the one just experienced. Extreme event attribution has been an emerging area in the science of detection and attribution. Webpage [7] summarizes a number of studies on extreme weather and climate events around the world on an interactive map.

 

  1. 1. IPCC special report on climate change and land, 2019 https://www.ipcc.ch/srccl/ presentation https://www.ipcc.ch/srccl/explainers-and-presentations/
  2. 2. Billon-Dollar Weather and Climate disasters (NOAA) https://www.ncei.noaa.gov/access/monitoring/billions/overview (accessed May 10, 2022)
  3. 3. Step up climate change adaptation or face serious human and economic damage (UN) https://www.unep.org/news-and-stories/press-release/step-climate-change-adaptation-or-face-serious-human-and-economic (accessed May 11, 2022)
  4. 4. Stott, P., 2016: How climate change affects extreme weather events. Science, 352, 1517–1518, doi:10.1126/science.aaf7271.
  5. 5. Hulme, M. Attributing Weather Extremes to ‘Climate Change’: A Review. Progress in Physical Geography: Earth and Environment, vol. 38, no. 4, Aug. 2014, pp. 499–511, doi:10.1177/0309133314538644.
  6. 6. Easterling, D. R., K. E. Kunkel, M. F. Wehner, and L. Sun, 2016: Detection and attribution of climate extremes in the observed record. Weather and Climate Extremes, 11, 17–27, doi:10.1016/j.wace.2016.01.001.
  7. 7. Attributing extreme weather to climate change https://www.carbonbrief.org/mapped-how-climate-change-affects-extreme-weather-around-the-world (accessed May 11, 2022)
Lesson 11: What actions can we take?
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The rapid climate change is driven by the surge of greenhouse gases produced by human activities (lessons 1-6), such as burning fossil fuels. To treat this cause, we must reduce greenhouse gas emissions and/or remove them from the atmosphere. Such action is known as mitigation. The ultimate mitigation goal is to achieve net-zero: cutting greenhouse gas emissions as close to zero as possible, with any remaining emissions re-absorbed from the atmosphere, by oceans and forests for instance [1]. While mitigation is the only solution in the long term, climate change (1.2oC warming compared to the preindustrial level) is already impacting human society and ecosystems (lessons 7-11). Therefore, we must also adapt to the climate change in the pipeline, which includes recovering from and forecasting extreme events, protecting people from sea-level rise, etc  [2, 3]. In the following lessons, we will discuss what mitigation and adaptation actions we can take as a society: what can the governments do? what can each individual do?

  1. 1. Net Zero Coalition (UN) (accessed June 20, 2022) https://www.un.org/en/climatechange/net-zero-coalition
  2. 2. Climate adaptation fast facts (UN) (accessed June 20, 2022) https://www.un.org/sites/un2.un.org/files/2021/07/fastfacts-adaptation.pdf
  3. 3. Climate adaptation (UN) (accessed July 31, 2022)  https://www.un.org/en/climatechange/climate-adaptation
Lesson 12: Why is net-zero important?
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Currently, the global temperature is about 1.2oC higher than the preindustrial level. It will rise to up to ~3oC  if we continue emitting greenhouse gases into the atmosphere at the current rate (figure SPM.3 of Ref. [1]). In order to preserve a livable planet, we must slow down or stop the warming trend. At the 2015 United Nations Climate Change Conference (COP 21), the Paris Agreement was adopted: 196 Parties agreed to take action and limit warming to 2oC and preferably 1.5oC [2]. This entails reducing carbon emissions by 45% by 2030 and reaching net-zero by 2050. More recently at COP26 (Glasgow, 2020), the countries submitted their plans for climate action known as nationally determined contributions (NDCs) [3,4].

 

  1. 1. Impacts, Adaptation, and Vulnerability (Summary for Policymakers) https://report.ipcc.ch/ar6wg2/pdf/IPCC_AR6_WGII_SummaryForPolicymakers.pdf
  2. 2. The Paris Agreement (UN) (accessed June 20, 2022) https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement
  3. 3. COP26: update to NDCs (UN) (accessed June 20, 2022) https://unfccc.int/news/cop26-update-to-the-ndc-synthesis-report
  4. 4. All about the NDCs (UN) (accessed June 20, 2022)

https://www.un.org/en/climatechange/all-about-ndcs

Lesson 13: What can we do to achieve net-zero?
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We must rapidly reduce the use of fossil fuels and replace them with renewable energy sources [1]. Examples of renewable technologies include geothermal, hydropower, wind, and solar [2-6].  In the US, renewable energy generates about 20% of electricity. In 2022, solar and wind are expected to add more than 60% of the utility-scale generating capacity to the U.S. power grid [7]. Apart from phasing out fossil fuels and reducing emissions, another strategy is removing carbon so that the atmospheric CO2 concentration no longer increases. This entails enhancing natural carbon sinks–forests and oceans–as well as developing new technologies [8,9].

  1. 1. Most fossil-fuel reserves must remain untapped to hit 1.5 C warming goal (accessed August 08, 2022) https://www.nature.com/articles/d41586-021-02444-3#ref-CR1
  2. 2. Types of renewable energy (DOE) (accessed June 20, 2022) https://www.energy.gov/eere/renewable-energy#:~:text=Renewable%20energy%20is%20energy%20produced,heating%20and%20cooling%2C%20and%20transportatio
  3. 3. How do solar panels work (TED) (accessed June 20, 2022) https://www.youtube.com/watch?v=xKxrkht7CpY
  4. 4. How do wind turbines work (TED) (accessed June 20, 2022) https://www.youtube.com/watch?v=xy9nj94xvKA
  5. 5. How much land does it take to power the world? (TED) (accessed June 20, 2022) https://www.youtube.com/watch?v=DW0jTe80kmM
  6. 6. Building the world’s largest (and most controversial) power plant (TED) (accessed June 20, 2022) https://www.youtube.com/watch?v=dcZ0BXJYlUA
  7. 7. Solar power in 2022 (EIA) (accessed June 20, 2022) https://www.eia.gov/todayinenergy/detail.php?id=50818
  8. 8. What to know about 5 big plans for US carbon removal (WRI) https://www.wri.org/insights/us-carbon-removal
  9. 9. Direct air capture (Climeworks) https://climeworks.com/
Lesson 14: What is adaptation?
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Beyond doing everything we can to cut emissions and slow the pace of global warming, we must adapt to climate consequences so we can protect ourselves and our communities [1]. Here we describe two adaptation methods against flood and sea-level rise. The first is Netherlands’ Delta Works: it is the Netherlands’ largest flood protection system, consisting of 13 dams, storm surge barriers, and sluices [2, 3]. The photon in the slides shows the Maeslant barrier (Maeslantkering in Dutch), a storm surge barrier on the Nieuwe Waterweg, in South Holland. It automatically closes when Rotterdam (especially the Port of Rotterdam) is threatened by floods. Another approach to a similar problem is restoring mangrove forests as shown in the right figure. Unlike Delta Works, this is the  Ecosystem-based Adaptation (EbA) [4]. Restoring floodplains and mangroves not only reduces the impacts of flooding, droughts, and sea level rise but also provides a habitat for animals and plants and is thus crucial to the local food supplies [5, 6].

1. Climate adaptation (UN) (accessed July 31, 2022)  https://www.un.org/en/climatechange/climate-adaptation

  1. 2. Why isn’t the Netherlands underwater? (TED) (accessed July 11, 2022) https://www.youtube.com/watch?v=25LW_PG2ZuI
  2. 3. Watersnood Museum (accesed July 31, 2022) https://watersnoodmuseum.nl/en/knowledgecentre/delta-works/
  3. 4. What is ecosystem-based adaptation (UNEP) (accessed July 31, 2022) https://www.youtube.com/watch?v=fhDuqvRk6LY
  4. 5. Flood walls and forests help Djibouti adapt to climate change (UNEP) (accessed July 31, 2022) https://www.unep.org/news-and-stories/story/flood-walls-and-forests-help-djibouti-adapt-climate-change
  5. 6. Gilman, E. L.,  Ellison, J., Duke, N.C., Field, C., 2008. Threats to mangroves from climate change and adaptation options: A review. Aquatic Botany, Vol. 89, Issue 2. https://doi.org/10.1016/j.aquabot.2007.12.009.
Lesson 15: How to adapt to climate change better?
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According to UNEP’s adaptation gap report published in 2022, though the number of adaptation actions is growing worldwide, there is limited evidence for risk reduction [1]. In regard to ecosystem-based adaptation and nature-based solutions, though their benefits are well received, there are very few tangible plans [1]. We need Research and Development (R&D) to better understand the problems of climate change and the best solutions for mitigating and adapting to the problem. While we know that the transition to clean carbon-free energy can get us part of the way, we still need new solutions and ways to live with the changes that are already underway. In regard to adaption,

To adapt better, we need to understand risks better, invest in adaptation sooner than later, protect the most vulnerable, and have more locally led adaptation [2-6].

  1. 1. Adaptation gap report 2022 (UNEP, executive summary) https://wedocs.unep.org/bitstream/handle/20.500.11822/34726/AGR_en.pdf?sequence=35 (Webinar version) https://www.youtube.com/watch?v=IXmf8jxGdGg (2-min version) https://www.youtube.com/watch?v=-KhZ16QPv2c
  2. 2. 7 lessons on adaptation (UNEP) (accessed July 31, 2022) https://undp-climate.exposure.co/7-lessons-on-adaptation
  3. 3. Strong governance reduced risks (UNDP) (accessed July 31, 2022) https://undp-climate.exposure.co/strong-governance-reduced-risks
  4. 4. Adapt Now: global commission report  (accessed July 31, 2022) https://gca.org/wp-content/uploads/2019/09/GlobalCommission_Report_FINAL.pdf
  5. 5. Alliance for Hydromet (accessed July 31, 2022)  https://alliancehydromet.org/about/
  6. 6. ridging the digital divide will save our planet (UNDP) (accessed July 31, 2022)  https://www.adaptation-undp.org/bridging-digital-divide-will-save-our-planet

Lesson 16: What can I do?
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While actions from international organizations, governments, and corporations are essential to tackling the climate crisis, there is a lot we can do as individuals [1,2]. We encourage you to take action to reduce greenhouse gas emissions in your home, your community, and around the world. Be open to lifestyle changes because lifestyle emissions reduction has big potential in bridging the emission gaps, e.g., using more energy-efficient appliances and low-carbon fuels for your home, reducing the use of cars by shifting to public transport and increasing active travel (walking and bicycles), and using electrical vehicles that do not directly reply on fossil fuels [3].

 

1. Act Now (UN) (accessed July 31, 2022)  https://www.un.org/actnow?gclid=Cj0KCQjwwJuVBhCAARIsAOPwGAR40DNmTcMvOhesDwCRzh0a6eExC60qgymeyCMioNBy0b1iMvH7MCAaAjkPEALw_wcB

2. Lazy person’s guide (UN) (accessed July 31, 2022)    https://www.un.org/sustainabledevelopment/takeaction/

3. Emission gap report 2022 (UNEP) (accessed July 31, 2022)    https://wedocs.unep.org/xmlui/bitstream/handle/20.500.11822/34432/EGR20ch6.pdf?sequence=3

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