Our planet is a complex, interconnected, and resilient system of natural processes, ecosystems, and human activities. Yet, as global warming and the impacts of climate change continue to rise, parts of our planet's system identified as tipping elements, such as the Amazon rainforest, boreal forest, coral reefs, and ice sheets, could cross key thresholds and shift or even disappear—rapidly or gradually, reshaping our world in profound ways.
In 2023, the world watched in alarm as devastating heatwaves, wildfires, and floods wreaked havoc in numerous parts of the world, including Canada, the US, Europe, and India. For example, Canada experienced its worst wildfire season on record in 2023, with over 18 million hectares of land burned and thousands of people forced to evacuate, according to the Canadian Interagency Forest Fire Centre. This sparked an important question: Have we surpassed a tipping point and pushed our climate into a new state where extreme weather events become the new norm, more frequent and intense than ever before? This conversation is currently a subject of heated debate, with claims of doom-mongering being countered with charges of complacency. To help answer the question, we need to examine the various climate tipping elements that could lead to profound socio-economic impacts and lasting changes in our climate system. In this blog post and the next two, we will explore the concept of tipping elements, their implications for our planet, and how GIS can play a pivotal role in understanding, monitoring, and mitigating climate tipping points.
Over the past two decades, geographers and climate scientists who assess the impacts of climate change have focused on studying and understanding the tipping elements of our planet. Definitions of what constitutes a tipping element or tipping point have varied somewhat in the scientific literature. This study attempted to resolve the confusion by applying the term “tipping element” to any Earth system component that, when its climate forcing pushed beyond a certain threshold (or tipping point), could experience significant changes. These changes could be abrupt (time lag of less than two decades between threshold transgression and system response), or rapid (time lag of several decades). Natural climate forcing (or climate drivers) includes changes in the sun’s energy output, regular changes in Earth’s orbital cycle, and large volcanic eruptions that put light-reflecting particles into the upper atmosphere. Human-caused, or anthropogenic, climate forcing includes emissions of heat-trapping gases (also known as greenhouse gases) and changes in land use that make land reflect more or less sunlight energy. Tipping elements often exhibit nonlinear responses to these climate forcing. Note that the term “tipping elements” itself does not imply whether these changes are reversible or irreversible.
A useful analogy to describe a tipping point is a ball being pushed up a seesaw. If the pushing ceases before it reaches the central pivot, the ball rolls back to where it started. However, once the ball passes the pivot (or tipping point), the seesaw tilts and the ball will continue rolling until it reaches a new position, regardless of whether the pushing has stopped.
An analogy of tipping climate points as a see-saw.
Tipping points are normally identified in terms of global mean temperature change (‘global warming’). For example, this 2022 study in Science shows that current global warming of ~1.1°C relative to the pre-industrial period is already within the lower end of the uncertainty range of five climate system tipping points, including the collapse of the Greenland and West Antarctic ice sheets, die-off of low-latitude coral reefs, and widespread abrupt permafrost thaw. This means that crossing tipping points is now more likely and could occur at lower levels of warming than previously thought.
Monthly global temperature anomalies (changes from an average) between the years 1880 and 2022 in degrees Celsius. Whites and blues indicate cooler temperatures, while oranges and reds show warmer temperatures. Credit: NASA's Scientific Visualization Studio
Most of the frequently cited tipping elements, which are illustrated in the map below, involve highly complex physical and biological systems, competing feedbacks in response to climate change, and large uncertainties. Furthermore, many of these systems are poorly resolved or omitted altogether in the current generation of climate models, resulting in ambiguity with regard to tipping elements in climate predictions and global climate sensitivity. However, a good understanding of potentially abrupt or fast tipping elements and how they may interact is important for conducting assessments that can help us to know how much change and risk our society is willing to accept.
Map of potential tipping elements in the Earth’s climate system. Note that the marine methane hydrate deposits and stratocumulus cloud deck breakup are hypothetical locations for visual presentation.
When climate system tipping points are triggered, they can lead to a changed climate state with characteristics that are potentially much less suitable for sustaining human and natural systems. For example, at the regional scale, these tipping points can be associated with areas of extreme heat, more frequent droughts, wildfires, and unpredictable weather patterns. At the global scale, these tipping points could cause increased levels of carbon in the atmosphere and a higher sea level. The tipping of one element has the potential to trigger the tipping of other elements, leading to a tipping cascade (or a domino effect), and the consequences can spread through the socio-economic system in a relatively short time, challenging our ability to adapt. This will have global impacts on trade, finance, supply networks, and achieving the 17 UN Sustainable Development Goals. Therefore, it is crucial to address and map climate tipping elements occurring at regional and global scales.
Tipping Elements in our Climate System
This recent study summarizes the state of 10 global and regional “core” tipping elements impacting the Earth’s climate system that could pass a tipping point this century. These tipping elements have been identified in the Earth’s biosphere, cryosphere (ice bodies), and the circulations of the oceans and the atmosphere. Unfortunately, some of these sub-systems may have already crossed or are being pushed to cross critical thresholds.
The selected 10 tipping elements could be grouped into biome shift, ice melting, and circulation change as follows:
- Loss of the Amazon Rainforest
- Boreal Forest Ecosystem Shifts
- Die-off of Shallow Tropical Coral Reefs
- Loss of Major Ice Sheets
- Permafrost Carbon Release
- Loss of Summer Arctic Sea Ice
- Dissociation of Marine Methane Hydrate Deposits
- Slowdown of the Atlantic Meridional Overturning Circulation (AMOC)
- Disruption of Tropical Seasonal Monsoons
- Breakup of Stratocumulus Cloud Decks
Biome Shift Tipping Elements:
1. Loss of the Amazon rainforest
The Amazon rainforest contains the world's largest expanses of old-growth tropical rainforest. This large ecosystem possesses rich biodiversity and represents a major terrestrial biological carbon sink. Studies have shown that climate change has the potential to change the air temperature and precipitation patterns, leading to a lengthy dry season and frequent wildfires in the Amazon region (source), while deforestation can affect vegetation by reducing evapotranspiration, which is critical for the maintenance of moisture levels in the forest (source). This could push the Amazon rainforest past a critical threshold, resulting in ecosystem collapse and turning the tropical forest gradually into a drier savannah state. Although there is uncertainty regarding temperature thresholds at which the Amazon would cross a tipping point, it is projected that continued deforestation, combined with a warming climate, raises the probability that the ecosystem will shift into a dry state during the 21st century (source).
You can view the impacts of deforestation on the Amazon rainforest using Esri’s World Imagery Wayback archive, found in the ArcGIS Living Atlas of the World. Read more on how GIS technology acts as a wayback machine for imagery of the globe Or check out this tutorial for a hands-on experience in mapping deforestation using ArcGIS.
Deforestation in the Amazon rainforest from 2014-2022. The trees of the rainforest, (green colour) are being transformed into agricultural areas (brown colour).
2. Boreal forest ecosystem shifts
Boreal forests play a crucial role in the regional and global climate systems, affecting biosphere-atmosphere interactions and large-scale circulation patterns. Like the Amazon, boreal forests also exhibit a potential to dieback beyond a given tipping point. Under climate change, increased peak summer heat and water stress could cause increased mortality, vulnerability to fire, as well as decreased reproduction rates, leading to large-scale dieback of the boreal forests. The latest IPCC report assesses with high confidence that warmer and drier conditions have increased tree mortality and forest disturbances in many temperate and boreal biomes, negatively impacting provisioning services (source). Projections show that boreal forests would transition to open woodlands or grasslands (source); however, these projections are based on models that must make simplifying assumptions about complex mechanisms such as precipitation, fire, and soil moisture availability and their effects on needle-leaved trees.
Boreal forests store 30% or more of the world's soil carbon, with up to 95% of organic carbon stored belowground (source). Although the climatic impact of worldwide changes to the boreal biome under expected future emissions remains challenging to assess, the boreal forest dieback and shifts represent one of the more potentially immediate and significant climate system tipping elements (source).
Geographic distribution of Boreal Forest in the northern circumpolar.
These unique ecosystems are essential for biodiversity as they provide habitat for countless plant and animal species. Additionally, they are culturally significant and offer sustenance to indigenous communities. For example, Birds Canada and the Nature Conservancy of Canada have created a Story Map showcasing the significance of the boreal forest for birds.
Listen to bird songs, learn about the challenges some boreal bird species face, and find ways to support their conservation.
3. Die-off of Shallow Tropical Coral Reefs
Ocean heatwaves have led to mass coral bleaching and to the loss of half of the shallow-water corals on Australia’s Great Barrier Reef. According to the IPCC special report on the impacts of global warming of 1.5 °C, a staggering 99% of tropical corals are projected to be lost if the global average temperature rises by 2 °C relative to pre-industrial period, owing to interactions between warming, ocean acidification, sea-level rise, storm damage, shifts in ocean circulation and pollution.
According to the International Union for Conservation of Nature, coral reefs host more than one quarter of all marine fish species despite covering less than 0.1% of the ocean floor area. The economic and societal impacts of coral reef loss to Indo-Pacific, Caribbean, and other communities can be expected to be substantial as an estimated 500 million people rely on coral reef ecosystems. Overall, coral reefs serve as critical factors for fishery productivity that sustains island communities and fisheries, hold cultural significance, and provide shoreline fortification from coastal erosion (source).
Recent findings suggest that severe coral reef degradation will likely continue throughout the current century even under optimistic climate mitigation scenarios, with coral abundance declining to 10%–30% of today's levels even with warming limited to 1.5°C relative to pre-industrial period (source). Although tropical corals may persist in some form, chances are high that future coral ecosystems may appear completely unrecognizable compared to their state today.
Global distributions of Coral reefs.
To learn more, check out the Predict Coral Bleaching Events tutorial and take a look at the Coral Reefs at Risk of Bleaching ArcGIS Dashboard for an example of how GIS can be used to monitor and communicate important information to the public.
In the next two blog posts, we will discuss tipping elements in the cryosphere, oceans, and atmosphere and explore how GIS can be a great tool in studying, monitoring, and raising public awareness about tipping elements and their impacts on our climate system.