The Impact of Climate Change on Earth and Human Society During the Next Century

Executive Summary

Climate change represents one of the most significant challenges facing humanity in the 21st century. This report provides a comprehensive assessment of the current scientific understanding of climate change, its projected impacts on Earth's environmental systems and human societies over the next century, and the strategies available for adaptation and mitigation.

The scientific evidence is unequivocal that human activities, primarily through greenhouse gas emissions, have warmed the planet by approximately 1.1°C since pre-industrial times. Without immediate, rapid, and large-scale reductions in greenhouse gas emissions, global warming is projected to reach between 1.5°C and 4.4°C by 2100, depending on emission scenarios.

The environmental impacts of this warming are already observable and will intensify throughout the century, affecting biodiversity, ocean systems, freshwater resources, and agricultural productivity. These environmental changes will cascade into profound societal and economic impacts, including threats to human health, displacement of populations, economic losses, and potential conflicts over increasingly scarce resources.

However, this report also highlights that humanity has the knowledge, technology, and capacity to substantially reduce emissions and adapt to unavoidable impacts. A portfolio of mitigation strategies—including renewable energy transition, carbon capture technologies, and sustainable land management—combined with targeted adaptation measures can limit the worst impacts of climate change. The choices made in this decade will be crucial in determining the climate trajectory for the rest of this century and beyond.

The report concludes that addressing climate change requires urgent, ambitious, and coordinated action across all sectors of society. While the challenges are substantial, there are many feasible and effective options available that can create a more sustainable and resilient future for both human societies and Earth's ecosystems.

1. Introduction

Climate change is the defining challenge of our time, with far-reaching implications for current and future generations. The Earth's climate has always varied naturally over long time periods, but the rate and magnitude of current changes are unprecedented in human history. Scientific evidence has established beyond reasonable doubt that human activities—primarily the burning of fossil fuels and land-use changes—are the dominant cause of the observed warming since the mid-20th century.

This report aims to provide a comprehensive assessment of how climate change is projected to impact Earth's systems and human societies over the next century. It draws on the latest scientific research, including the authoritative assessments of the Intergovernmental Panel on Climate Change (IPCC), to present a detailed picture of potential futures under different emission scenarios.

The report is structured to first establish the scientific basis of climate change projections, then examine the cascading impacts on environmental systems, followed by an analysis of how these environmental changes will affect human societies. Finally, it explores the range of strategies available to both reduce emissions (mitigation) and adjust to unavoidable changes (adaptation).

Throughout this report, we emphasize that while climate change presents enormous challenges, it also offers opportunities for transformative change toward more sustainable and equitable societies. The severity of future impacts depends significantly on the choices made today and in the coming decades. By understanding the potential consequences of different pathways, decision-makers at all levels—from international bodies to national governments, businesses, communities, and individuals—can make informed choices that shape a more resilient future.

2. Climate Science and Projections

Current Scientific Consensus

The Intergovernmental Panel on Climate Change (IPCC) has provided the most comprehensive and authoritative assessment of climate change science. According to the IPCC's sixth assessment report (AR6), human influence on the climate system is now an established fact. The report states in the clearest and most evidenced detail yet how humans are responsible for the 1.1°C of temperature rise seen since the start of the industrial era.

The scientific consensus is unequivocal that this warming is caused by greenhouse gas emissions from human activities, primarily the burning of fossil fuels and land-use changes. The current rate of warming is unprecedented in human history, with each of the last four decades being successively warmer than any decade that preceded it since 1850.

Temperature Projections for the Next Century

The IPCC AR6 synthesis report provides clear projections for future warming based on different emission scenarios:

  1. Very Low Emissions (SSP1-1.9): If emissions are drastically reduced immediately, warming is expected to temporarily "overshoot" 1.5°C by "no more than 0.1°C" before returning to 1.4°C by 2100.
  2. Low Emissions (SSP1-2.6): Under this scenario, warming would be limited but still exceed 1.5°C during the century.
  3. Intermediate Emissions (SSP2-4.5): This pathway represents a middle ground of emission reductions.
  4. High Emissions (SSP3-7.0): Continued high emissions would lead to significantly higher warming.
  5. Very High Emissions (SSP5-8.5): Under this worst-case scenario, warming could reach 4.4°C by 2100.

Crucially, the report notes that policies in place by the end of 2021 (the cut-off date for evidence cited in the assessment) would likely see temperatures exceed 1.5°C this century and reach around 3.2°C by 2100. This projection highlights the significant gap between current policies and the actions needed to meet the Paris Agreement goals.

The IPCC has narrowed the range of uncertainty in these projections compared to previous assessments, due to improved understanding of climate sensitivity and better observational data of recorded warming to date.

Sea Level Rise Projections

Sea level rise is one of the most significant and long-lasting consequences of climate change. According to the IPCC:

  • By 2100, global mean sea level rise is projected to be around 0.1 meter lower with global warming of 1.5°C compared to 2°C (medium confidence).
  • Model-based projections suggest an indicative range of 0.26 to 0.77 m by 2100 for a global warming of 1.5°C, which is 0.1 m (0.04–0.16 m) less than for a global warming of 2°C.
  • A reduction of 0.1 m in global sea level rise implies that up to 10 million fewer people would be exposed to related risks, based on population in the year 2010 and assuming no adaptation.
  • Sea level will continue to rise well beyond 2100 even if global warming is limited to 1.5°C in the 21st century.
  • Marine ice sheet instability in Antarctica and/or irreversible loss of the Greenland ice sheet could result in multi-metre rise in sea level over hundreds to thousands of years. These instabilities could be triggered at around 1.5°C to 2°C of global warming.

Precipitation and Extreme Weather Event Projections

Climate models project robust differences in regional climate characteristics between present-day and global warming of 1.5°C, and between 1.5°C and 2°C. These differences include:

  • Increases in mean temperature in most land and ocean regions (high confidence)
  • Hot extremes in most inhabited regions (high confidence)
  • Heavy precipitation in several regions (medium confidence)
  • Probability of drought and precipitation deficits in some regions (medium confidence)

Specific projections include:

  • Temperature extremes on land are projected to warm more than global mean surface temperature: extreme hot days in mid-latitudes warm by up to about 3°C at global warming of 1.5°C and about 4°C at 2°C.
  • Extreme cold nights in high latitudes warm by up to about 4.5°C at 1.5°C and about 6°C at 2°C.
  • The number of hot days is projected to increase in most land regions, with highest increases in the tropics.
  • Risks from droughts and precipitation deficits are projected to be higher at 2°C compared to 1.5°C of global warming in some regions.
  • Risks from heavy precipitation events are projected to be higher at 2°C compared to 1.5°C in several northern hemisphere high-latitude and/or high-elevation regions, eastern Asia and eastern North America.
  • Heavy precipitation associated with tropical cyclones is projected to be higher at 2°C compared to 1.5°C global warming.

Tipping Points and Feedback Loops

The IPCC reports identify several potential tipping points in the climate system that could lead to abrupt and irreversible changes:

  • High-latitude tundra and boreal forests are particularly at risk of climate change-induced degradation and loss, with woody shrubs already encroaching into the tundra.
  • Limiting global warming to 1.5°C rather than 2°C is projected to prevent the thawing over centuries of a permafrost area in the range of 1.5 to 2.5 million km².
  • The probability of a sea ice-free Arctic Ocean during summer is substantially lower at global warming of 1.5°C when compared to 2°C. With 1.5°C of global warming, one sea ice-free Arctic summer is projected per century. This likelihood is increased to at least one per decade with 2°C global warming.
  • There is high confidence that warming amplifies the exposure of small islands, low-lying coastal areas and deltas to the risks associated with sea level rise.

3. Environmental Impacts

Impacts on Biodiversity and Ecosystems

Climate change has already altered marine, terrestrial, and freshwater ecosystems all around the world with very high confidence. According to the IPCC's Sixth Assessment Report (AR6), climate change has caused local species losses, increases in disease, and mass mortality events of plants and animals.

Species Extinction and Range Shifts

Local population extinctions caused by climate change have been widespread among plants and animals, detected in 47% of 976 species examined and associated with increases in the hottest yearly temperatures. The risk of species extinction increases with warming in all climate change projections for native species studied in biodiversity hotspots, being about 10 times greater for endemic species from 1.5°C to 3°C above pre-industrial levels.

For endemic species, extinction risk due to climate change is more common than for other native species:

  • ~100% on islands
  • ~84% on mountains
  • ~12% on continents
  • ~54% in the ocean (notably the Mediterranean)

At warming levels beyond 2°C by 2100, risks of extirpation, extinction, and ecosystem collapse escalate rapidly. The observed rate of range shifts since the 1950s is estimated to be 51.5 ± 33.3 km per decade and 29.0 ± 15.5 km per decade for organisms in the epipelagic and seafloor ecosystems, respectively.

Ecosystem Transformation

Climate change has already altered terrestrial, freshwater and ocean ecosystems at global scale, with multiple impacts evident at regional and local scales where there is sufficient literature to make an assessment. Impacts are evident on ecosystem structure, species geographic ranges, and timing of seasonal life cycles (phenology).

Approximately 4% of the global terrestrial land area is projected to undergo a transformation of ecosystems from one type to another at 1°C of global warming, compared with 13% at 2°C. This indicates that the area at risk is projected to be approximately 50% lower at 1.5°C compared to 2°C.

Vulnerable Ecosystems

Several ecosystems are particularly vulnerable to climate change:

  1. High-latitude tundra and boreal forests are particularly at risk of climate change-induced degradation and loss, with woody shrubs already encroaching into the tundra. Limiting global warming to 1.5°C rather than 2°C is projected to prevent the thawing over centuries of a permafrost area in the range of 1.5 to 2.5 million km².
  2. Coral reefs are at risk of widespread decline, loss of structural integrity and transitioning to net erosion by mid-century due to increasing intensity and frequency of marine heatwaves. Under SSP1-2.6, coral reefs are at risk of widespread decline, loss of structural integrity and transitioning to net erosion by mid-century.
  3. Biodiversity hotspots are impacted to differing degrees by human activities. Climate change impacts are exacerbating these impacts, with the most vulnerable species being those that are unable to disperse or adapt quickly enough to keep pace with the rate of climate change.

Impacts on Oceans

The ocean has warmed unabated since 2005, continuing the clear multi-decadal ocean warming trends documented in the IPCC Fifth Assessment Report. The warming trend is further confirmed by the improved ocean temperature measurements over the last decade.

Ocean Warming

  • The 0-700 m and 700-2000 m layers of the ocean have warmed at rates of 5.31 ± 0.48 and 4.02 ± 0.97 ZJ yr-1 from 2005 to 2017.
  • The long-term trend for 0-700 m and 700-2000 m layers have warmed 4.35 ± 0.8 and 2.25 ± 0.64 ZJ yr-1 from between the averages of 1971-1990 and 1998-2017 and is attributed to anthropogenic influences.
  • It is likely that the ocean warming has continued in the abyssal and deep ocean below 2000 m (southern hemisphere and Southern Ocean).
  • The rate of ocean warming has increased since 1993, with the 0-700 m and 700-2000 m layers warming by 3.22 ± 1.61 ZJ and 0.97 ± 0.64 ZJ from 1969 to 1993, and 6.28 ± 0.48 ZJ and 3.86 ± 2.09 ZJ from 1993 to 2017, representing at least a two-fold increase in heat uptake.

Ocean Acidification

The ocean is continuing to acidify in response to ongoing ocean carbon uptake. The open ocean surface water pH is observed to be declining by a very likely range of 0.017-0.027 pH units per decade since the late 1980s across individual time series observations longer than 15 years.

The anthropogenic pH signal is very likely to have emerged for three-quarters of the near-surface open ocean prior to 1950, and it is very likely that over 95% of the near surface open ocean has already been affected. These changes in pH have reduced the stability of mineral forms of calcium carbonate due to a lowering of carbonate ion concentrations, most notably in the upwelling and high-latitude regions of the ocean.

Ocean Deoxygenation

There is a growing consensus that the open ocean is losing oxygen overall with a very likely loss of 0.5-3.3% between 1970-2010 from the ocean surface to 1000 m. Globally, the oxygen loss due to warming is reinforced by other processes associated with ocean physics and biogeochemistry, which cause the majority of the observed oxygen decline.

The oxygen minimum zones (OMZs) are expanding by a very likely range of 3-8%, most notably in the tropical oceans, but there is substantial decadal variability that affects the attribution of the overall oxygen declines to human activity in tropical regions.

Changes in Ocean Circulation and Nutrient Cycles

In response to ocean warming and increased stratification, open ocean nutrient cycles are being perturbed and there is high confidence that this is having a regionally variable impact on primary producers. The upper ocean is very likely to have been stratifying since 1970. Observed warming and high-latitude freshening are making the surface ocean less dense over time relative to the deeper ocean and inhibiting the exchange between surface and deep waters.

Multiple datasets and models show that the rate of ocean uptake of atmospheric CO2 has continued to strengthen in the recent two decades in response to the increasing concentration of CO2 in the atmosphere. The very likely range for ocean uptake is between 20-30% of total anthropogenic emissions in the recent two decades.

Impacts on Freshwater Resources

Climate change is altering the water cycle in complex ways. Impacts include changes in precipitation patterns, increasing intensity of rainfall, accelerated melting of glaciers, and changes in river flows and groundwater recharge.

Precipitation Changes

Climate models project robust differences in regional climate characteristics between present-day and global warming of 1.5°C, and between 1.5°C and 2°C. These differences include increases in mean precipitation in several high-latitude regions, increases in heavy precipitation in several regions, and probability of drought and precipitation deficits in some regions.

Glacier Retreat and Snow Cover Changes

High Mountain areas are experiencing pronounced warming, leading to the retreat of glaciers and changes in snow cover. This affects the quantity and seasonality of water resources in regions dependent on meltwater, with implications for agriculture, hydropower, and ecosystems.

Freshwater Ecosystems

Freshwater ecosystems are particularly vulnerable to climate change impacts. Changes in water temperature, flow regimes, and water quality affect aquatic species and ecosystem functions. Warming rivers and lakes lead to shifts in species composition and can facilitate the spread of invasive species and waterborne diseases.

Impacts on Forests and Terrestrial Ecosystems

Climate change is affecting forests and other terrestrial ecosystems through changes in temperature, precipitation patterns, and the frequency and intensity of extreme events such as droughts, wildfires, and storms.

Forest Dieback and Composition Changes

Rising temperatures and changes in precipitation patterns are causing shifts in forest composition and structure. Some regions are experiencing forest dieback due to drought stress, pest outbreaks, and increased fire frequency. Tree mortality has increased in many areas, and the geographic ranges of many tree species are shifting toward higher elevations and latitudes.

Wildfire Increase

Climate change is increasing wildfire risk in many regions through longer fire seasons, more frequent heatwaves, and more intense droughts. This leads to greater burned areas, carbon emissions, and threats to biodiversity and human settlements.

Carbon Cycle Impacts

Terrestrial ecosystems currently act as a carbon sink, absorbing about 29% of annual anthropogenic CO2 emissions. However, the capacity of these sinks may diminish with continued warming, potentially accelerating the rate of climate change. Some ecosystems, such as permafrost regions, may switch from being carbon sinks to carbon sources as warming continues.

Impacts on Polar Regions

Polar regions are experiencing some of the most rapid and severe climate changes on Earth, with profound implications for global climate systems.

Arctic Sea Ice Decline

There is high confidence that the probability of a sea ice-free Arctic Ocean during summer is substantially lower at global warming of 1.5°C when compared to 2°C. With 1.5°C of global warming, one sea ice-free Arctic summer is projected per century. This likelihood is increased to at least one per decade with 2°C global warming.

Ice Sheet and Glacier Mass Loss

The Greenland and Antarctic ice sheets are losing mass at an accelerating rate. This contributes to sea level rise and may affect ocean circulation patterns. Marine ice sheet instability in Antarctica and/or irreversible loss of the Greenland ice sheet could result in multi-metre rise in sea level over hundreds to thousands of years. These instabilities could be triggered at around 1.5°C to 2°C of global warming.

Permafrost Thaw

Permafrost regions are thawing, releasing stored carbon and methane into the atmosphere and creating a positive feedback loop that amplifies warming. Limiting global warming to 1.5°C rather than 2°C is projected to prevent the thawing over centuries of a permafrost area in the range of 1.5 to 2.5 million km².

Impacts on Agriculture and Food Production

Climate change affects agricultural productivity through changes in temperature, precipitation, extreme weather events, and the geographic ranges of crop pests and diseases.

Crop Yield Changes

Climate change is already affecting crop yields in many regions. Increases in global temperature are projected to further reduce yields of major crops like wheat, rice, and maize in most regions, although some high-latitude regions may experience yield increases in the short term. The stability of food supply is projected to decrease as the magnitude and frequency of extreme weather events increase.

Livestock Impacts

Livestock production is affected by heat stress, changes in water availability, and changes in the quality and quantity of feed. Higher temperatures reduce animal productivity and increase disease susceptibility.

Fisheries Impacts

Ocean warming and acidification are affecting marine fisheries and aquaculture. Changes in water temperature alter the distribution and abundance of fish species, while acidification affects shellfish and other calcifying organisms. Marine heatwaves, including well-documented events along the west coast of North America (2013–2016) and east coast of Australia (2015–2016, 2016–2017 and 2020), drive abrupt shifts in community composition that may persist for years, with associated biodiversity loss and collapse of regional fisheries and aquaculture.

4. Societal and Economic Impacts

Impacts on Human Health

Climate change has adversely affected physical health of people globally (very high confidence) and mental health of people in the assessed regions (very high confidence). According to the IPCC AR6 Working Group II report, climate change impacts on health are mediated through natural and human systems, including economic and social conditions and disruptions.

Physical Health Impacts

Climate change has adversely affected physical health of people globally with very high confidence. The impacts include:

  • Heat-related mortality: Climate change has increased observed heat-related mortality with medium confidence and contributed to the observed latitudinal or altitudinal range expansion of vector-borne diseases into previously colder areas.
  • Climate-sensitive diseases: The burdens of several climate-sensitive food-borne, water-borne, and vector-borne diseases are projected to increase under further climate change, assuming no additional adaptation. These include diseases like malaria, dengue fever, Lyme disease, and West Nile virus.
  • Malnutrition: Climate variability and change contribute to food insecurity, which can lead to malnutrition, including undernutrition, overweight and obesity, and to disease susceptibility in low- and middle-income countries.
  • Air pollution: Hot extremes including heatwaves have intensified in cities, where they have also aggravated air pollution events.
  • Extreme weather events: Cascading and compounding risks affecting health due to extreme weather events have been observed, and risks are expected to increase with further warming.

Mental Health Impacts

Mental health impacts are expected to arise from exposure to extreme weather events, displacement, migration, famine, malnutrition, degradation or destruction of health and social care systems, and climate-related economic and social losses and anxiety and distress associated with worry about climate change.

Projected Health Risks

Climate change and related extreme events will significantly increase ill health and premature deaths from the near- to long-term. An excess of 250,000 deaths per year by 2050 attributable to climate change is projected due to heat, undernutrition, malaria and diarrheal disease, with more than half of this excess mortality projected for Africa (compared to a 1961-1991 baseline period for a mid-range emissions scenario).

Adaptation Options

With proactive, timely and effective adaptation, many risks for human health and well-being could be reduced and some potentially avoided. Early warning systems based on targeted climate services can be effective for disaster risk reduction, social protection programmes, and managing risks to health and food systems.

Climate Migration and Displacement

Climate change is increasingly driving migration and displacement, with significant implications for human security and well-being.

Current Trends

Since 2008, an average of more than 20 million people per year have been displaced by extreme weather events, many of which were exacerbated by climate change, according to the IPCC. Climate-related migration is already underway in areas like Pacific islands, sub-Saharan Africa, and South Asia.

Projected Migration Patterns

The IPCC report highlights several projections for displacement and migration due to climate change:

  • By one estimate, between 31 million and 72 million people across sub-Saharan Africa, South Asia, and Latin America would be displaced by 2050 due to water stress, sea level rise, and crop failure, even under an aggressive effort to cut global emissions.
  • Africa could have the largest scale of climate-induced migration within countries, with as many as 85 million migrants potentially coming from sub-Saharan Africa.
  • The vast majority of migration, from climate change or from other factors, occurs within the borders of a country rather than across international borders.

Complexity of Migration Patterns

Climate change effects on migration are not uniform or consistent across regions:

  • In Kenya, increased rainfall is linked to reduced rural-to-urban movement, whereas in Zambia, more precipitation is poised to drive more migration.
  • In Ghana, researchers found that drought led to fewer residents saying they were planning to move.
  • Migration is also a function of the economy; wealthier parts of the world are better able to hold their ground in the face of rising temperatures.

Migration as Adaptation

The IPCC has suggested that migration could provide a way for some people to escape the worst impacts of climate change. Migration is often a last resort, with people doing all they can to stay where they are. This means people are willing to try a lot of different strategies to deal with the effects of warming, even in precarious places like islands facing rising sea levels.

Economic Costs of Climate Change

Climate change is already having significant economic impacts and these are projected to increase substantially in the coming decades.

Current Economic Impacts

Economic impacts attributable to climate change are increasingly affecting people's livelihoods and causing economic and societal impacts across national boundaries. Climate-driven impacts on ocean and coastal ecosystems and their services have cascading and compounding effects that propagate through socio-economic systems.

Projected Economic Costs

Risks to global aggregated economic growth due to climate change impacts are projected to be lower at 1.5°C than at 2°C by the end of this century. The economic damages from climate change will increase with global warming level.

According to the IPCC, developing countries alone will need $127 billion per year by 2030 and $295 billion per year by 2050 to adapt to climate change. This represents a significant financial burden, particularly for countries with limited resources.

Sectoral Economic Impacts

Climate change affects various economic sectors differently:

  • Agriculture: Changes in crop yields, livestock productivity, and fisheries output directly impact food security and agricultural economies.
  • Infrastructure: Damage to buildings, transportation networks, and energy systems from extreme weather events and sea level rise requires costly repairs and adaptations.
  • Tourism: Changes in climate conditions affect tourism patterns, with some destinations becoming less attractive due to extreme heat, reduced snow cover, or ecosystem degradation.
  • Insurance: Increasing frequency and severity of climate-related disasters lead to higher insurance premiums or even uninsurability in high-risk areas.
  • Labor productivity: Heat stress reduces labor productivity, particularly in outdoor sectors like agriculture and construction, with significant economic consequences.

Impacts on Infrastructure and Urban Areas

Climate change poses significant risks to infrastructure systems and urban areas, affecting millions of people worldwide.

Infrastructure Vulnerability

Critical infrastructure including energy, water, sanitation, transportation, and telecommunication systems are vulnerable to climate change impacts. Extreme events like floods, heatwaves, and storms can damage or destroy infrastructure, disrupt services, and require costly repairs or replacements.

Urban Heat Islands

Urban areas are particularly vulnerable to heat-related impacts due to the urban heat island effect, which amplifies temperature increases. This affects human health, energy demand for cooling, and urban ecosystems.

Coastal Urban Areas

Sea level rise poses particular challenges for coastal cities and infrastructure. Many major urban centers are located in low-lying coastal areas and face increasing risks of flooding, erosion, and saltwater intrusion into freshwater supplies.

Adaptation Needs

Considering climate change impacts and risks in the design and planning of urban and rural settlements and infrastructure is critical for resilience and enhancing human well-being. Heat Health Action Plans that include early warning and response systems are effective adaptation options for extreme heat.

Effects on Global Security and Conflict

Climate change can exacerbate existing tensions and contribute to instability and conflict, though the relationship is complex and context-specific.

Climate-Security Nexus

The IPCC notes that climate change can indirectly increase risks of violent conflicts through pathways such as:

  • Resource competition
  • Livelihood insecurity
  • Migration and displacement
  • Extreme weather events
  • Food price volatility

Vulnerable Regions

Areas with high exposure to climate hazards, high vulnerability, and low adaptive capacity face the greatest security risks. This includes regions already experiencing conflict, political instability, or economic challenges.

Compound Risks

Climate change can create compound risks when it interacts with other stressors like poverty, inequality, and weak governance. These compound risks can overwhelm adaptive capacity and increase the likelihood of conflict.

Peace-Building Opportunities

While climate change presents security challenges, addressing it can also create opportunities for cooperation and peace-building. Collaborative approaches to managing shared resources like transboundary water systems can build trust and reduce conflict potential.

Impacts on Vulnerable Populations and Equity Issues

Climate change disproportionately affects vulnerable populations, exacerbating existing inequalities and creating new ones.

Vulnerability Factors

Approximately 3.3 to 3.6 billion people live in contexts that are highly vulnerable to climate change. Vulnerability is influenced by factors including:

  • Geographic location
  • Socioeconomic status
  • Gender
  • Age
  • Disability
  • Indigenous or minority status
  • Access to resources and services

Disproportionate Impacts

Climate change impacts are not distributed equally:

  • Low-income communities: Often have less capacity to prepare for, respond to, and recover from climate impacts.
  • Women and girls: Face specific vulnerabilities due to gender norms, roles, and inequalities.
  • Indigenous peoples: Experience threats to traditional livelihoods, cultural practices, and knowledge systems.
  • Children and elderly: Are physiologically more vulnerable to extreme heat and other climate hazards.
  • People with disabilities: May face additional challenges during extreme events and disasters.

Climate Justice Implications

The IPCC recognizes that those who have contributed least to climate change are often the most affected by its impacts. This raises important questions of climate justice and equity in both mitigation and adaptation efforts.

Compounding Inequalities

Climate change intensifies existing vulnerability and inequality, with adverse impacts on the most vulnerable groups. These impacts can create feedback loops that further entrench disadvantage and limit adaptive capacity.

Effects on Cultural Heritage and Indigenous Communities

Climate change threatens cultural heritage sites, practices, and knowledge systems around the world, with particular impacts on indigenous communities.

Threats to Tangible Cultural Heritage

Physical cultural heritage sites face risks from:

  • Sea level rise and coastal erosion
  • Flooding and extreme precipitation
  • Temperature changes and humidity fluctuations
  • Wildfires
  • Biological degradation due to changing environmental conditions

Impacts on Intangible Cultural Heritage

Climate change also affects intangible cultural heritage, including:

  • Traditional knowledge systems
  • Cultural practices tied to seasonal patterns
  • Language (as communities are displaced)
  • Spiritual connections to changing landscapes

Indigenous Knowledge and Adaptation

Indigenous knowledge systems offer valuable insights for climate adaptation but are themselves threatened by rapid environmental change. The IPCC recognizes the importance of integrating indigenous knowledge with scientific approaches to enhance climate resilience.

Loss and Damage to Cultural Identity

For many communities, especially indigenous peoples, climate impacts on cultural heritage represent not just material loss but profound damage to identity, well-being, and social cohesion.

5. Adaptation and Mitigation Strategies

Current International Climate Agreements and Policies

International cooperation is essential for addressing climate change effectively. The IPCC has assessed various international agreements and policies aimed at reducing greenhouse gas emissions and enhancing climate resilience.

The Paris Agreement

The Paris Agreement, adopted in 2015, is the most significant international climate agreement to date. Its central aim is to strengthen the global response to climate change by:

  • Holding the increase in global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C
  • Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience
  • Making finance flows consistent with a pathway toward low greenhouse gas emissions and climate-resilient development

The Paris Agreement operates through nationally determined contributions (NDCs), which are climate action plans submitted by each country outlining their efforts to reduce emissions and adapt to climate change impacts.

Other International Frameworks

Beyond the Paris Agreement, other important international frameworks include:

  • The United Nations Framework Convention on Climate Change (UNFCCC), established in 1992, which provides the foundation for international climate cooperation
  • The Kyoto Protocol, which set binding emission reduction targets for developed countries for the period 2008-2012, with a second commitment period from 2013-2020
  • The Sustainable Development Goals (SDGs), particularly Goal 13 on Climate Action, which integrates climate change into broader sustainable development efforts

Policy Effectiveness and Gaps

According to the IPCC, current policies in place by the end of 2021 would likely see temperatures exceed 1.5°C this century and reach around 3.2°C by 2100. This highlights the significant gap between current commitments and the actions needed to meet the Paris Agreement goals.

The IPCC emphasizes that enhanced international cooperation is essential for achieving ambitious climate goals, particularly in areas such as finance, technology transfer, and capacity building to support developing countries.

Renewable Energy Transition Pathways

The transition to renewable energy is a cornerstone of climate change mitigation. The IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation provides a comprehensive assessment of the potential role of renewable energy in reducing greenhouse gas emissions.

Current Status and Potential

Renewable energy sources currently supply approximately 20% of global energy consumption, with the largest contribution coming from traditional biomass. However, modern renewables (including hydropower, wind, solar, geothermal, and modern bioenergy) are growing rapidly.

The IPCC finds that the technical potential of renewable energy technologies exceeds global energy demand, suggesting that renewable energy could theoretically meet all global energy needs. However, the practical deployment depends on various factors including costs, policies, and integration challenges.

Key Renewable Technologies

The IPCC assesses several key renewable energy technologies:

  1. Solar Energy: Both solar photovoltaic (PV) and concentrated solar power (CSP) technologies have seen significant cost reductions and efficiency improvements. Solar PV is modular and can be deployed at various scales, from household rooftops to utility-scale power plants.
  2. Wind Energy: Both onshore and offshore wind technologies have matured significantly. Wind power has become one of the most cost-competitive energy sources in many regions.
  3. Hydropower: As a mature technology, hydropower provides the largest share of renewable electricity globally. However, its future expansion is limited by environmental concerns and the availability of suitable sites.
  4. Bioenergy: This includes traditional biomass, liquid biofuels, biogas, and modern biomass for power and heat generation. Sustainability concerns related to land use, food security, and biodiversity must be addressed.
  5. Geothermal Energy: This provides stable baseload power but is geographically limited to areas with suitable geological conditions.
  6. Ocean Energy: Technologies including tidal, wave, and ocean thermal energy conversion are still in early stages of development but offer significant potential.

Integration Challenges and Solutions

The integration of high shares of variable renewable energy (particularly wind and solar) presents challenges for existing electricity systems. The IPCC identifies several strategies to address these challenges:

  • Improved forecasting of renewable energy output
  • Enhanced grid infrastructure and interconnections
  • Energy storage technologies (batteries, pumped hydro, etc.)
  • Demand-side management and smart grid technologies
  • Sector coupling (integrating electricity with heating, cooling, and transportation)

Transition Pathways

The IPCC outlines various pathways for transitioning to renewable energy systems, emphasizing that no single approach will be sufficient. Successful transitions will likely involve a portfolio of renewable technologies tailored to specific regional conditions and integrated with energy efficiency measures.

Carbon Capture and Sequestration Technologies

Carbon capture and storage (CCS) technologies are increasingly recognized as essential components of comprehensive climate change mitigation strategies, particularly for hard-to-abate sectors.

Types of Carbon Capture Technologies

  1. Post-combustion capture: Removes CO₂ from flue gases after fossil fuel combustion
  2. Pre-combustion capture: Processes fuel before combustion to produce hydrogen and CO₂
  3. Oxyfuel combustion: Burns fuel in pure oxygen to produce a more concentrated CO₂ stream
  4. Direct air capture (DAC): Extracts CO₂ directly from the atmosphere

Storage Options

Once captured, CO₂ can be stored through various methods:

  • Geological storage: Injecting CO₂ into deep underground formations, such as depleted oil and gas reservoirs or saline aquifers
  • Ocean storage: Injecting CO₂ into deep ocean waters or the seabed (though this raises significant environmental concerns)
  • Mineral carbonation: Converting CO₂ to solid carbonates through reaction with metal oxides

Bioenergy with Carbon Capture and Storage (BECCS)

BECCS combines bioenergy use with carbon capture and storage, potentially resulting in negative emissions (removing CO₂ from the atmosphere). The IPCC notes that many pathways to limiting warming to 1.5°C rely heavily on BECCS, though there are concerns about its large-scale deployment related to land use, food security, and biodiversity.

Current Status and Challenges

While CCS technologies are technically proven, their deployment remains limited due to:

  • High costs compared to other mitigation options
  • Regulatory and legal uncertainties
  • Public acceptance concerns
  • Need for extensive infrastructure development
  • Energy penalties (CCS processes themselves require energy)

The IPCC emphasizes that CCS is likely to be most important for industries with process emissions that are difficult to eliminate otherwise, such as cement and steel production.

Adaptation Strategies for Urban Areas

Urban areas, where the majority of the global population lives, face significant climate risks but also offer opportunities for effective adaptation.

Urban Heat Management

As urban areas are particularly vulnerable to heat-related impacts due to the urban heat island effect, adaptation strategies include:

  • Increasing green spaces and urban vegetation
  • Cool roofs and reflective surfaces
  • Passive cooling design in buildings
  • Water features and misting systems
  • Heat warning systems and cooling centers

Flood Risk Management

To address increased flood risks from extreme precipitation and sea level rise, urban adaptation measures include:

  • Improved drainage systems and permeable surfaces
  • Flood defenses and barriers
  • Elevated infrastructure and buildings
  • Retention areas and wetlands
  • Managed retreat from high-risk areas

Water Security

Strategies to enhance urban water security in the face of changing precipitation patterns include:

  • Water conservation and efficiency measures
  • Rainwater harvesting and water recycling
  • Diversification of water sources
  • Drought-resistant landscaping
  • Improved water storage capacity

Infrastructure Resilience

Climate-resilient urban infrastructure incorporates:

  • Updated building codes and standards that account for future climate conditions
  • Redundant and decentralized systems for critical services
  • Nature-based solutions that complement traditional infrastructure
  • Flexible designs that can be adjusted as conditions change

Governance and Planning

Effective urban adaptation requires:

  • Integration of climate considerations into all aspects of urban planning
  • Participatory approaches that involve vulnerable communities
  • Coordination across different levels of government and sectors
  • Long-term planning horizons that account for climate uncertainties

Agricultural Adaptation Techniques

Agriculture is particularly vulnerable to climate change but also offers significant opportunities for adaptation.

Crop Management Strategies

Adaptation strategies for crop production include:

  • Changing planting dates to align with shifting seasons
  • Adopting drought-resistant or heat-tolerant crop varieties
  • Diversifying crops to reduce risk
  • Improving irrigation efficiency and water management
  • Implementing precision agriculture techniques
  • Using climate forecasts for agricultural planning

Livestock Management

For livestock systems, adaptation measures include:

  • Breeding or selecting animals with greater heat tolerance
  • Improving animal housing and cooling systems
  • Adjusting feed composition and feeding strategies
  • Managing pasture lands to improve resilience
  • Diversifying livestock species and breeds

Soil and Land Management

Practices that enhance soil health and land management include:

  • Conservation agriculture (minimal soil disturbance, permanent soil cover, crop rotation)
  • Agroforestry systems that integrate trees with crops or livestock
  • Terracing and contour farming to reduce erosion
  • Improved nutrient management
  • Restoration of degraded agricultural lands

Risk Management and Financial Tools

Financial and institutional mechanisms to support agricultural adaptation include:

  • Crop insurance and weather-indexed insurance
  • Early warning systems for extreme events
  • Agricultural extension services focused on climate adaptation
  • Access to credit for implementing adaptation measures
  • Diversification of income sources beyond agriculture

Water Management Strategies

Water resources are highly vulnerable to climate change, necessitating comprehensive adaptation strategies.

Integrated Water Resources Management

The IPCC emphasizes integrated water resources management (IWRM) as a framework for addressing climate impacts on water. Key elements include:

  • Basin-wide planning that considers all water users
  • Conjunctive management of surface and groundwater
  • Consideration of water quality and quantity
  • Ecosystem needs and environmental flows
  • Transboundary cooperation for shared water resources

Supply-Side Measures

Strategies to enhance water supply include:

  • Increased storage capacity through reservoirs and aquifer recharge
  • Water harvesting and conservation techniques
  • Desalination in coastal areas (with consideration of energy requirements)
  • Water reuse and recycling
  • Reducing water losses in distribution systems

Demand-Side Measures

Approaches to manage water demand include:

  • Water-efficient technologies in agriculture, industry, and households
  • Water pricing that reflects scarcity
  • Education and awareness campaigns
  • Water allocation systems that prioritize essential uses during shortages
  • Virtual water trade (importing water-intensive products from water-rich regions)

Flood and Drought Management

Specific strategies for extreme water events include:

  • Flood early warning systems and evacuation plans
  • Flood-plain zoning and development restrictions
  • Drought monitoring and early warning systems
  • Drought contingency planning
  • Insurance mechanisms for water-related disasters

Economic Policies and Market-Based Solutions

Economic instruments play a crucial role in both mitigation and adaptation efforts.

Carbon Pricing

Carbon pricing mechanisms aim to incorporate the social cost of carbon emissions into economic decision-making:

  • Carbon taxes: Direct taxes on carbon content of fuels
  • Emissions trading systems (ETS): Cap-and-trade systems that set overall emission limits and allow trading of emission permits
  • Carbon crediting mechanisms: Systems that generate tradable emission reduction credits

The IPCC notes that carbon pricing is most effective when prices are sufficiently high and when combined with other policies addressing market failures and distributional concerns.

Subsidies and Incentives

Financial incentives to promote low-carbon technologies and practices include:

  • Renewable energy feed-in tariffs and premiums
  • Tax incentives for energy efficiency improvements
  • Subsidies for climate-smart agricultural practices
  • Grants and low-interest loans for adaptation measures
  • Research and development funding for innovative technologies

Green Finance

Scaling up climate finance requires:

  • Mobilizing private sector investment through green bonds and climate-aligned investments
  • Redirecting financial flows away from high-emission activities
  • Disclosure of climate-related financial risks
  • Development of innovative financial instruments for adaptation
  • International climate finance for developing countries

Just Transition Policies

The IPCC emphasizes the importance of ensuring that climate policies do not exacerbate existing inequalities:

  • Programs to retrain workers from high-carbon industries
  • Social protection measures for vulnerable groups
  • Community engagement in transition planning
  • Targeted support for regions dependent on fossil fuel industries
  • Ensuring affordable access to energy and other essential services

6. Conclusion and Recommendations

Climate change represents one of the most significant challenges facing humanity in the 21st century. The scientific evidence is unequivocal that human activities have warmed the planet by approximately 1.1°C since pre-industrial times, with observable impacts already affecting ecosystems and human societies worldwide. Without immediate, rapid, and large-scale reductions in greenhouse gas emissions, global warming is projected to reach between 1.5°C and 4.4°C by 2100, depending on emission scenarios.

The environmental impacts of this warming are already observable and will intensify throughout the century, affecting biodiversity, ocean systems, freshwater resources, and agricultural productivity. These environmental changes will cascade into profound societal and economic impacts, including threats to human health, displacement of populations, economic losses, and potential conflicts over increasingly scarce resources.

However, this report also highlights that humanity has the knowledge, technology, and capacity to substantially reduce emissions and adapt to unavoidable impacts. A portfolio of mitigation strategies—including renewable energy transition, carbon capture technologies, and sustainable land management—combined with targeted adaptation measures can limit the worst impacts of climate change.

Key Recommendations

Based on the comprehensive assessment presented in this report, we offer the following recommendations for addressing climate change in the coming century:

  1. Accelerate Emissions Reductions: Immediate and ambitious reductions in greenhouse gas emissions are essential to limit warming to well below 2°C, preferably 1.5°C, as specified in the Paris Agreement. This requires rapid transitions in energy, transportation, industry, buildings, and land use sectors.
  2. Enhance Adaptation Efforts: Even with ambitious mitigation, some climate impacts are now unavoidable. Increased investment in adaptation is needed, particularly for vulnerable regions and populations. Adaptation planning should be integrated into all levels of decision-making.
  3. Prioritize Equity and Justice: Climate policies should address existing inequalities and ensure that the costs and benefits of climate action are fairly distributed. Special attention should be given to supporting vulnerable populations and ensuring a just transition for workers and communities dependent on high-carbon industries.
  4. Strengthen International Cooperation: Enhanced international cooperation is essential for addressing climate change effectively. This includes fulfilling and increasing climate finance commitments, facilitating technology transfer, and building capacity in developing countries.
  5. Integrate Climate Action with Sustainable Development: Climate policies should be designed to maximize synergies with sustainable development goals, including poverty reduction, health improvement, biodiversity conservation, and economic prosperity.
  6. Accelerate Innovation and Deployment: Continued research, development, and deployment of clean energy technologies, carbon removal approaches, and adaptation solutions are needed to reduce costs and enhance effectiveness.
  7. Mobilize Finance: Significantly increased public and private finance is needed for both mitigation and adaptation. This includes redirecting financial flows away from high-carbon activities and toward climate-resilient, low-carbon development.
  8. Engage All Stakeholders: Effective climate action requires the participation of all stakeholders, including governments at all levels, businesses, civil society, and individuals. Inclusive and participatory approaches to climate policy development and implementation should be prioritized.

The choices made in this decade will be crucial in determining the climate trajectory for the rest of this century and beyond. While the challenges are substantial, there are many feasible and effective options available that can create a more sustainable and resilient future for both human societies and Earth's ecosystems. By acting decisively now, we can limit the severity of climate change impacts and build a more equitable and sustainable world for future generations.

7. References

This report draws on the latest scientific research on climate change, with particular reliance on the authoritative assessments of the Intergovernmental Panel on Climate Change (IPCC). Key references include:

  • IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.
  • IPCC, 2022: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.
  • IPCC, 2022: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.
  • IPCC, 2023: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.
  • IPCC, 2018: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways.
  • IPCC, 2019: Special Report on the Ocean and Cryosphere in a Changing Climate.
  • IPCC, 2019: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.
  • IPCC, 2011: Special Report on Renewable Energy Sources and Climate Change Mitigation.

Additional references from peer-reviewed scientific literature, international organizations, and government reports have been incorporated throughout the report to provide the most current and comprehensive assessment of climate change impacts and responses.