Ressourcen

Intergovernmental Panel on Climate Change (2022). Climate Change 2021: The Physical Science Basis

Intergovernmental Panel on Climate Change (1990). Climate Change: The IPCC 1990 and 1992 Assessments.

Intergovernmental Panel on Climate Change (2022). Climate Change 2022: Impacts, Adaptation and Vulnerability

Intergovernmental Panel on Climate Change (2022). Climate Change 2022: Mitigation of Climate Change

Food and Agriculture Organization of the United Nations (2021). The impact of disasters and crises on agriculture and food security: 2021.

Food and Agriculture Organization of the United Nations (2020). Global Forest Resources Assessment 2020: Main report.

World Meteorological Organization (2020). State of the Global Climate 2020 Provisional Report.

Intergovernmental Panel on Climate Change (2019). IPCC Special Report: Climate Change and Land.

UN Development Programme (2019). NDC Global Outlook Report 2019: The Heat is On.

World Meteorological Organization (2020). United in Science 2020.

Intergovernmental Panel on Climate Change (2018). Global warming of 1.5°C.

Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (2019). Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.

Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (2019). Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.

Intergovernmental Panel on Climate Change (2014). Energy Systems. In: Climate Change 2014: Mitigation of Climate Change.

United Nations Environment Programme (2020). Emissions Gap Report 2020.

To understand how our climate looks today and what it might look like in the future, scientists study what Earth’s past climates looked like. Climate researchers examine every possible clue to study the full history of Earth’s climate, from the latest satellite observations to samples of prehistoric ice extracted from glaciers and ice sheets.

When scientists look to understand what Earth’s climate was like long ago, they use clues from what’s been preserved in Earth’s crust, such as fossils of corals found in the desert signifying that a sea once existed there. Scientists also use ice cores, tree rings, and deep sediment samples from the ocean floor to uncover indicators about Earth’s past climate. Over the years scientists have developed a range of more advanced testing, like isotope ratios, elemental analyses, biomarkers, and biogenic silica. Taken together, all of this research extends our knowledge of Earth’s past climate back hundreds of millions of years. This knowledge helps us uncover natural cycles, such as carbon cycles or water cycles, that may one day influence Earth’s future.

In 2018, the IPCC found that the world had already warmed by 1.2ºC (2.1ºF) since 1850. But what does that mean?

Regional Differences

A 1.2ºC (2.1ºF) warmer Earth looks and feels different in every region of the world because of a long list of differences in such things as tree cover, distance from the ocean, distance from the equator, and so much more. Some places will warm while others cool, and some places will receive more rainfall while others have more droughts. These changes have huge impacts on the health and safety of people and ecosystems.

Here are some key ways different places in the world experience 1.2ºC (2.1ºF) of global warming differently:

• It takes more heat to warm water than air or land. This means that the ocean is not warming as fast as the land but will continue to warm even if the global temperature is stabilized.
• Coastal places are warming slower than regions farther inland.
• Depending on which side of a mountain range you are on, the way you experience 1.2ºC (2.1ºF) of global warming will be different.
• The farther away from the equator, the faster a place will warm. The Arctic, for example, is heating up about twice as quickly as the global average.

Extreme Weather Events

An extreme weather event is something that falls outside the realm of normal weather patterns. It can range from super powerful hurricanes to torrential downpours or extended hot dry weather and more. Extreme weather events are themselves troublesome, but the effects of such extremes, including damaging winds, floods, drought, and favorable conditions for wildfires, can be devastating. Some of the most visible and disruptive effects of global climate change are extreme weather and resulting disasters, such as wildfires and flooding.

Here are some examples of extreme weather events we’ve experienced at 1.2ºC (2.1ºF) of global warming:

• The Southwest United States, Central and South America, Asia, Europe, Africa, Australia, and other regions have experienced increases in frequency or intensity of heat, drought, insect outbreaks, and wildfires.
• Regions like small islands and coastal areas are experiencing more flooding, salt water poisoning of drinking water, and more intense storms.
• Warmer ocean temperatures means all storms become more intense, including winter storms that bring massive snowfall once they hit land.

What will future climate change look like? That depends on how much warmer the planet becomes, which is directly connected to our emissions. The impacts will vary at different amounts of warming, becoming more severe at higher levels.

For example:

• 1.5°C (2.7°F) of Global Warming
  • Water: Water shortages in Mediterranean, Australia, Brazil, and Asia
  • Food: Wheat, rice, maize, and soybean production suffer
  • Flora and Fauna: 9 out of 10 tropical coral reefs at risk from severe degradation
  • Sea Level Rise: Rising sea levels displace 46 million people: sea level rise of 48cm
• 2°C (3.6ºF) of Global Warming
  • Water: 8% of the global populations face severe water shortages
  • Food: Agricultural yields fall rapidly
  • Flora and Fauna: All tropical coral reefs disappear
  • Sea Level Rise: Fewer opportunities to protect coastal areas from flooding: sea level rise of 56cm
• 3°C (5.4ºF) of Global Warming
  • Water: Almost half of Himalayan high mountain glaciers lost
  • Food: Fish species go extinct locally
  • Flora and Fauna: Marine ecosystems may collapse
  • Sea Level Rise: Near complete melting of the Greenland ice sheet: sea level rise of 7+ meters
• 4°C (7.2ºF) of Global Warming
  • Water: More frequent and severe droughts
  • Food: High levels of food insecurity, growing number of people living in poverty
  • Flora and Fauna: Half of all plant and animal species face local extinction
  • Sea Level Rise: Rise of nearly 9 meters puts 460-760 million people at risk

Burning fossil fuels like oil or coal and thus producing greenhouse gases cannot continue to be the main way humans make energy if we want to slow global warming.

Our current energy systems rely primarily on burning fossil fuels, which are a major contributor to global warming. To transform our energy system, we need:

• Renewable energy. There are many forms of renewable energy including solar power, wind power, tidal power, and geothermal power. These power sources have low to no emissions. Transitioning from burning fossil fuels to using Earth’s natural systems to create sustainable, non-extractive, self-renewing energy is an essential part of limiting global warming.
• Energy efficiency. Using less energy to perform the same task is not only possible but necessary to reduce greenhouse gas emissions. It will likely take the world some time to transition to renewable energy. In the meantime, energy efficiency reduces the amount of energy needed to do the same task and saves money.
• Electrification. As more electricity is produced from sustainable energy, transitioning activities that are powered by fossil fuel combustion, like gasoline-powered vehicles, with alternatives that run on electricity, like electric vehicles, can be an important option for reducing emissions.

To be specific, land is all parts of the Earth that aren’t oceans and it includes swamps, permafrost, mountains, farmland, and more. Land use is what we do with this land, from farming, to developing cities, to preserving wild spaces. Many land areas have profound benefits for humankind. Scientists call these benefits “ecosystem services,” and they include:

Wetlands. These ecosystems are immensely important for water filtration and carbon sequestration (storing carbon in the ground). Wetlands also provide habitat for unique species around the world.

• Permafrost. Permafrost is land that remains frozen for at least two years straight. Much of the world’s permafrost has been frozen for thousands of years and stores a huge amount of plants and animal remains (carbon) in its icy underground — just like a freezer. When it thaws due to global warming, the remains are decomposed, releasing greenhouse gases and ancient viruses and bacteria into the atmosphere.
• Forests. These ecosystems are vitally important for their role in absorbing carbon and also provide vital habitat for millions of species around the world from the tropics to the taiga.
• Grasslands. The ecosystem services of grasslands are less commonly known, but no less important and include water storage, pollination, erosion control, and carbon absorption.

To truly transform our land use, we need to think about sustainability and how to manage and balance all of the activities we use and need land for, such as storing carbon, preserving habitats, enabling recreation, producing food, and raising livestock or cattle.

Nature-based solutions are a powerful tool for combating global warming and the climate changes it causes. Nature-based solutions promote sustainable land use, ocean management, and enhancement of nature’s many ecosystem services as a method of reducing our global emissions or limiting the impacts of a changing climate.

These are only some examples of how nature is being used to protect against a changing climate:

• Carbon storage. Carbon dioxide is the most commonly produced greenhouse gas. Carbon storage is the process of naturally capturing and storing carbon dioxide. The largest source of carbon storage on the planet is the ocean, which has taken up 20-30% of human-induced carbon dioxide emissions since the 1980s, causing ocean acidification. Other natural stores of carbon include wetlands, seagrass meadows, kelp forests, trees, grasslands, and permafrost. Without these natural sources of carbon storage, the Earth would be far warmer than it is today.
• Preventing coastal flooding & sea level rise. Coastal ecosystems can act as natural sea walls protecting against two primary threats of rising seas: coastal flooding and erosion. Mangroves and coral reefs, for instance, cause waves to break before they hit the shore, lowering both the force and height of the swell, and in the process reducing the likelihood of the sea breaching over, flooding streets and buildings.
• Absorbing heat. Cities are significantly warmer than the surrounding countryside. This “urban heat island effect” has many causes, including the ability of concrete and asphalt to absorb heat. Increasing the number of trees in cities is a win-win solution. Trees cool the surrounding air by releasing water through their leaves, similar to how humans keep cool by sweating. They also create shade, reducing the amount of heat city concrete and asphalt need to absorb. Additionally, they cut down use of air-conditioning systems, which produce large amounts of carbon emissions.
• Storing water. To protect water supplies, societies have traditionally used “gray infrastructure” such as pipelines, dams, and human-made reservoirs. However, “green infrastructure” uses natural or semi-natural systems to provide similar benefits with positive long-term environmental consequences. For example, wetlands, streams, lakes, and other natural spaces act as sponges, drawing water down through the ground and restoring the water table. When healthy, these ecosystems capture huge amounts of water during intense rainfall and store it for times of drought. Forests recharge groundwater supplies as well, absorbing water through their roots, and in doing so, filtering drinking water for millions of people worldwide.
• Limiting Desertification & Sandstorms. Desertification is the drying and degradation of land and is an ongoing threat in places where there is overgrazing and biodiversity loss. When we cut down forests and overgraze plants, the land loses moisture and deserts expand. Since 1920, the Sahara has been expanding, destroying waterholes and good farmland. This was the motivation behind the Great Green Wall in Africa, supported by the United Nations Convention to Combat Desertification , which aims to halt the spread of the Sahara and its consequent sandstorms. By 2030, the ambition of the initiative is to restore 100 million hectares of currently degraded land, sequester 250 million tons of carbon, and create 10 million green jobs.

Biodiversity is the variety of life on Earth, or in a particular ecosystem, and is necessary for life on the planet. The more diverse an ecosystem is, the more resilient it usually is to shock and disruption. However, climate change is negatively affecting plant, animal, and insect biodiversity around the world.

Even small changes in average temperatures, weather patterns, and human activity can have a significant effect upon species, and the changes occurring today are drastic. The planet’s health depends on the species that inhabit it. The loss of even one of these species can create a ripple effect that derails entire ecosystems.

Climate change is affecting biodiversity in many ways.

Temperature changes: Many species are vulnerable to extreme temperature changes such as heat waves.

• As land temperatures rise, many species are migrating to find colder, more suitable climates in regions closer to the Earth’s poles or further uphill, changing species distributions and habitats.
• Warming and changes in ocean chemistry are already disrupting species throughout the ocean food web. Fish are migrating toward colder water near the Earth’s poles, leaving empty ocean areas behind and competing with ancestral species in their new territories. This not only causes changes in migration patterns of whales, sharks, and other animals, but it also leaves empty nets in small-scale fisheries within warming ocean regions.
• Warmer seawater also stores less oxygen, making the ocean less habitable for all animals that rely on oxygen for breathing. Sharks, tuna, billfish, and many other hunters of the sea are hit especially hard since they need oxygen-rich water to be able to catch prey.

Ocean acidification: The ocean stores more carbon dioxide than any other ecosystem on Earth. However, when this carbon dioxide dissolves in seawater it increases the water’s acidity with profound implications for marine ecosystems.

Ocean acidification is a major challenge for organisms like corals, oysters, and crustaceans, as more acidic seawater makes it harder to build exoskeletons and shells.

• Calcifying zooplankton, an important foundation of the marine food web, are also negatively affected by more acidic seawater. The effect of mass zooplankton die-off has profound implications for the entire marine food web.
• Fishes living in acidified ocean water hear and smell less and show strange behavior such as not fleeing from predators anymore.

Extreme weather: Predicted changes in the intensity, frequency, and extent of natural disasters such as wildfires, cyclones, hurricanes, heat waves, droughts, and floods will cause stress on plants and animals on land.

• Nearly 3 billion animals were killed or displaced by Australia’s devastating bush fires in 2019 and 2020.
• Months of sustained wildfires in the largest wetland on Earth, Brazil’s Pantanal region, have already consumed 30% of the biome since October 2020. This wetland provides important water filtration and carbon sequestration services and is also home to unique species like the jaguar, macaw, and capybara.

The effects that human impacts on the environment, such as climate change, pollution, and deforestation, have on people around the world are different based on their ethnicity, social setting, and wealth.

Climate risks are not distributed equally in this world, affecting people who are poor, vulnerable, and discriminated against more severely. Ensuring the global response to climate change is equitable requires an acknowledgment of the unique challenges marginalized communities face and an integration of the traditional knowledge of Indigenous peoples, which has been crucial to protecting the natural world for thousands of years.

• Much of the world’s biodiversity lies in areas safeguarded by Indigenous peoples for thousands of years. However, the rights of Indigenous peoples to inhabit and steward their ancestral lands are sometimes limited by external factors.
• Although developing countries have relatively low greenhouse gas emissions, their vulnerability to climate change is significantly higher due to multiple factors limiting their ability to prevent and respond to climate change challenges.
• The IPCC reported in 2018 that climate change worsens existing poverty and exacerbates inequalities, especially for those disadvantaged by gender, age, race, class, caste, and disability.
• Climate change affects poorer subsistence communities disproportionately through decreased crop production and quality, increases in crop pests and diseases, and disruption to culture.

The majority of the world’s population lives in cities or informal settlements, which are major contributors to climate change. The good news is that cities around the world have taken measures to reduce their emissions, find solutions to their climate change contributions, and protect their communities from the impacts of global warming.

Cities are where major human-perceived climate change impacts occur. Occupying only about 3% of the Earth’s land surface, urban areas accommodate more than 50% of the world’s population, consume 78% of the world’s energy, and produce more than 60% of global greenhouse gas emissions. Many globally recognized environmental problems, such as heat stress, water scarcity, air pollution, and energy security, are amplified in built areas through the uniqueness of urban climates and high population density.

Billions of people live in towns and cities, which generate wealth. But demographic changes and social and economic pressures also drive inequality in cities, exposing people to flooding, temperature extremes, and water and food insecurity. Many cities are also built on the coast to take advantage of shipping lanes, which increases their vulnerability to extreme weather and sea level rise, both consequences of global warming.

Cities bring together many activities, such as energy and transportation use, so an integrated approach can help address climate change. Carefully planned actions to improve our resilience to a changing climate in cities can also reduce poverty and emissions without increasing inequality.

Sustainable city solutions include:

• Transforming energy usage throughout the city, including businesses, industries, and individuals, to sustainable sources.
• Renovating infrastructure to reduce greenhouse gas emissions, such as by making buildings more energy-efficient.
• Improving transportation systems and accessibility, such as public transit accessibility, bike shares, and pedestrian walkways.
• Building resilience to climate impacts, such as improving drainage for heavy rainfall and planning for sea level rise.
• Increasing green space and urban tree planting to reduce urban heat effects.
• Improving resilience to storm surges, such as using nature-based sea walls such as coral reefs, oyster reefs, and sand bars.
• Increasing carbon storage in areas near cities, such as through wetland restoration and forest protection.

The Sustainable Development Goals (SDGs) are a set of 17 global goals agreed to by all governments at the United Nations in 2015 to be a “blueprint to achieve a better and more sustainable future for all.”

The Sustainable Development Goals are:

1. No Poverty
2. Zero Hunger
3. Good Health and Well-being
4. Quality Education
5. Gender Equality
6. Clean Water and Sanitation
7. Affordable and Clean Energy
8. Decent Work and Economic Growth
9. Industry, Innovation and Infrastructure
10. Reduced Inequality
11. Sustainable Cities and Communities
12. Responsible Consumption and Production
13. Climate Action
14. Life Below Water
15. Life on Land
16. Peace, Justice and Strong Institutions
17. Partnerships for the Goals

Climate change and sustainable development are fundamentally connected. IPCC reports found that climate change can undermine sustainable development and that well-designed policies to reduce emissions and improve our ability to live in a changing climate can support poverty alleviation, food security, healthy ecosystems, equality, and other dimensions of sustainable development.

An example of synergy between sustainable development and climate action is sustainable forest management, which can prevent emissions from deforestation and improve carbon storage in forests, reducing global warming at reasonable cost. It can work well with other sustainable development goals as well, by providing food (SDG 2) and clean water (SDG 6) and by protecting ecosystems (SDG 15). Other examples of synergies are when climate adaptation measures, such as coastal or agricultural projects, empower women and benefit local incomes, health, and ecosystems.