What 2C of Warming Will Look Like: A Comprehensive Assessment

Human activities, mostly the burning of fossil fuels, are changing the climate faster than ever. As the world gets hotter, scientists and policymakers have agreed to try everything they can to limit warming to 2C above pre-industrial levels. But even 2C of warming will greatly impact life on Earth. Earth.Org looks at what will happen when we hit this warming milestone, what changes we can expect in extreme weather events, climate patterns, sea levels and temperatures, and what it means for ecosystems and human activities.

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The Earth’s climate is changing at a rate never seen in human history. The main driver of this change is the concentration of greenhouse gases in the atmosphere. Behind this are human activities like the burning of fossil fuels, deforestation, and industrial processes. With warming expected to continue in the years to come, we are now at a critical moment in human history where our choices will determine the future of life on this planet.

In 2015, world leaders met in Paris to address this global issue. The talks culminated in the Paris Agreement, an international treaty that set a big goal: to limit global warming to 1.5C or “well below” 2C above pre-industrial levels. The 2C benchmark was not chosen arbitrarily. It is the point beyond which various scientists believe the risks of catastrophic and irreversible changes to our planet’s systems will increase significantly.

But even if we meet this target, we need to understand that a world 2C above pre-industrial levels will still be a very different world. The changes will be far-reaching, affecting everything from weather patterns and sea levels to ecosystems and human societies. Some places will warm more than others; some will get wetter while others drier. Extreme weather events will become more frequent and intense, bringing about devastation and death.

Understanding 2C of Warming

Before we get into the details, let’s understand what 2C means in climate change terms. This is the average increase in global surface temperatures compared to pre-industrial levels (a period between 1850-1900). According to the US National Oceanic and Atmospheric Administration (NOAA), the planet has so far warmed 1.2C, with many projections suggesting we are “well on our way” to 2C. It is important to note that warming is not uniform across the globe. Some areas, like the poles, are warming much faster than others. Europe is the world’s fastest-warming continent, heating at double the rate than any other continent.

Similarly, the impacts of warming can vary greatly depending on local conditions and vulnerabilities.

Temperature Changes

A 2C warmer world will be a world of big temperature changes. According to the Intergovernmental Panel on Climate Change (IPCC), land will warm more than the oceans and the Arctic will warm 2-3 times faster than the global average.

Some of the temperature changes in a 2C scenario include:

1. More frequent and intense heatwaves in the tropics.
2. Fewer cold snaps in the high latitudes.
3. More warm days and nights globally.
4. More temperature variability in some areas, which will lead to more unpredictable weather.

These temperature changes will have cascading effects on various aspects of the Earth’s systems, from weather patterns to terrestrial and aquatic ecosystems.

Extreme Weather Events

One of the most noticeable impacts of 2C of warming will be the increased frequency and intensity of extreme weather events. These events can have devastating effects on communities, infrastructure, and natural systems.

• Heatwaves

Heatwaves will become more common, more intense, and longer-lasting in a 2C warmer world. Research suggests that the probability of experiencing a heatwave like the one that affected Europe in 2003, causing over 30,000 deaths, will increase from once every 100 years to once every 4 years under 2C of warming.

Regions already prone to high temperatures, such as the Middle East and North Africa, will experience “super heatwaves” with temperatures exceeding 50C (122F). This will make some areas potentially uninhabitable without significant adaptation measures.

An October 2023 study warned that heat and humidity levels will reach lethal levels for hours, days, and even weeks in some parts of the world by the end of the century – even below 2C of warming – making it impossible to stay outdoors. 

More on the topic: Silent Killer: Understanding the Risks of Extreme Heat

• Droughts

Droughts will become more frequent and more severe in many parts of the world. The IPCC projects that the area of global land affected by drought disasters will increase by 50% for 2C compared to 1.5C. The Mediterranean, southern Africa and parts of Australia and South America will be particularly affected. 

Besides affecting water resources, intense and prolonged droughts will decimate food crops and cause high rates of livestock deaths, leading to food insecurity.

• Floods

While some areas will get drier, others will get more flooded. With 2C of warming, the IPCC estimates that the global population exposed to river flooding will be up to 170% higher compared to a 1.5C scenario.

Heavy precipitation events will become more intense and frequent in many regions, particularly at high latitudes and in the tropics. This increase in extreme rainfall events will mean more flash floods and urban flooding.

• Tropical Cyclones

While the total number of tropical cyclones may not change much, they will be more intense. Studies suggest that in a 2C scenario, the proportion of Category 4 and 5 hurricanes will increase by 13% and the average intensity by 5%.

More powerful storms will bring stronger winds, more rainfall and higher storm surges, endangering coastal communities and infrastructure.

Climate Patterns

Beyond extreme weather events, 2C of warming will lead to significant shifts in global climate patterns, affecting precipitation and ocean currents.

• Shifting Rainfall Patterns

Generally speaking, wet places will get wetter and dry places drier, making water stress worse in many parts of the world. Changes will include:

1. More rain in high latitudes and parts of the tropics.
2. Less rain in subtropical dry regions, including the Mediterranean, southern Africa and parts of Australia.
3. Changes to monsoon systems, affecting billions of people who rely on seasonal rains for agriculture and water supply.

• Changes in Ocean Currents

Ocean currents help regulate the global climate and support marine ecosystems. With 2C of warming, big changes in ocean circulation patterns are expected.

One of the most worrying changes will be the weakening of the Atlantic Meridional Overturning Circulation (AMOC) which includes the Gulf Stream. Research indicates  that in a 2C scenario, the AMOC could weaken by 15-20%, making northwestern Europe cooler and affecting weather patterns across the Northern Hemisphere.

More on the topic: What the Slowdown of Atlantic Ocean Circulation Means for the Future of the Climate

Sea Level Rise

Sea level rise is one of the biggest long-term impacts of global warming. With 2C of warming, global mean sea level is projected to rise by 0.46-0.99 meters (1.51-3.25 feet) by 2100 compared to 1986-2005 levels. And even if we were to halt warming, sea levels would continue to rise for centuries.

This will not be uniform around the world because of local land subsidence and changes in ocean currents. Some implications of sea level rise in a 2C warmer world include:

1. More coastal flooding and erosion, threatening low-lying coastal areas and small island nations.
2. Saltwater intrusion into coastal aquifers, affecting freshwater resources.
3. Loss of coastal wetlands and mangroves, which provide important ecosystem services and natural buffers against storms.
4. Climate refugee crisis driven by the displacement of millions of people living in coastal areas.

Impact on Ecosystems

Thousands of species, both terrestrial and marine, will face increased extinction risks as they struggle to adapt to rapidly changing conditions. These disruptions will have cascading effects on biodiversity, carbon storage, and the many ecosystem services that human societies depend on.

Some key impacts include:

1. Coral reefs: Studies suggest that 99% of coral reefs will be lost due to the increased frequency of marine heatwaves and ocean acidification.
2. Arctic ecosystems: The rapid warming of the Arctic will lead to significant loss of sea ice and alter food webs, affecting species like polar bears and seals.
3. Forests: Increased temperatures and changes in precipitation patterns will lead to shifts in forest composition and increased risks of wildfires and pest outbreaks.
4. Biodiversity loss: The rate of species extinctions is expected to accelerate, with one study projecting that 18% of insects, 16% of plants, and 8% of vertebrates will lose over half their climatically determined geographic range with 2C of warming.

Human Life

The impacts of 2C of warming will be felt across all aspects of human society, from food and water security to health and economic stability.

• Agriculture and Food Security

Agricultural systems worldwide will face significant challenges. While some high-latitude regions might see increased crop yields because of conditions favouring longer growing seasons, many other areas will face decreased productivity because of heat stress, changes in precipitation patterns, and increased pest and disease outbreaks. These changes will lead to increased food prices and heightened food insecurity, particularly in vulnerable regions.

Key agricultural impacts include:

1. Decreased yields of major crops like wheat, rice, and maize in various regions, particularly in tropical and subtropical regions.
2. Shifts in suitable growing areas for various crops, potentially disrupting established agricultural practices.
3. Increased variability in crop yields because of more frequent extreme weather events.
4. Reduced nutritional quality of some crops because of elevated CO2 levels.

• Water Resources

Water resources and availability will be significantly affected, driven by changes in precipitation patterns and increased evaporation. Key impacts on water resources include:

1. Increased water scarcity in already dry regions, such as the Mediterranean and Middle East.
2. Changes in the timing and volume of river flows, affecting water supply for agriculture, hydropower generation, and urban areas.
3. Reduced water quality because of higher temperatures and changes in runoff patterns.
4. Increased competition for water resources, potentially leading to conflicts.

• Health

Human health will be affected both directly and indirectly. Some key health consequences include:

1. Increased heat-related mortality and morbidity, particularly in urban areas and among vulnerable populations.
2. Changes in the distribution and incidence of vector-borne diseases like malaria and dengue fever.
3. Increased respiratory problems because of higher levels of ground-level ozone and longer pollen seasons.
4. Mental health impacts related to extreme weather events and environmental changes.
5. Potential increases in malnutrition due to impacts on food security.

• Economic Impacts

The economic consequences of 2C of warming will be substantial and wide-ranging. While some sectors and regions might see benefits, the overall global economic impact is expected to be negative. Key economic impacts include:

1. Increased costs from extreme weather events and sea level rise, including damage to infrastructure and property.
2. Productivity losses because of heat stress and health impacts.
3. Shifts in tourism patterns, with some destinations becoming less attractive because of heat or other climate impacts.
4. Potential disruptions to global supply chains because of extreme weather events and changing resource availability.
5. Transition costs as economies adapt to a low-carbon future.

Studies suggest that mitigation efforts could reduce global economic damages by trillions of dollars annually by 2100 compared to a business-as-usual scenario.

More on the topic: Invasive Species Cost Global Economy $423bn Each Year, Threaten Ecosystems and Food Security

Mitigation and Adaptation

While the impacts will be significant, it is important to note that this scenario represents a substantial improvement over higher warming scenarios. Achieving this target will require rapid and far-reaching transitions in energy, land, urban, and industrial systems.

Key mitigation strategies include:

1. Rapid decarbonisation of energy systems, transitioning to renewable energy sources.
2. Improvements in energy efficiency across all sectors.
3. Changes in land use practices, including reducing deforestation and improving agricultural methods.
4. Development and deployment of carbon capture and storage technologies.

Simultaneously, adaptation measures will be crucial to reduce the vulnerability of human and natural systems to the impacts of climate change. These include:

1. Improving water management systems and increasing water use efficiency.
2. Developing heat-resistant crop varieties and diversifying agricultural systems.
3. Enhancing early warning systems for extreme weather events.
4. Implementing nature-based solutions for coastal protection and flood management.
5. Strengthening health systems to cope with changing disease patterns and extreme weather events.

You might also like: Assessing Global Progress on Climate Adaptation

Every Degree Counts

A 2C warmer world will be tough across all natural and human systems. More frequent and intense extreme weather events, changes in climate patterns, sea level rise, impacts on ecosystems – no matter what, the consequences will be far reaching and in many cases irreversible.

Limiting global warming requires immediate, big and coordinated global action to reduce emissions and build resilience to climate impacts. It means transformative change in how we produce and consume energy, manage our land and run our economies and societies.

As we enter a critical decade for climate action, the choices we make today will shape the world we live in tomorrow. Knowing what 2C will look like can help us take informed action that will protect our planet and everyone living on it.

Featured image: Georgina Goodwill.