Visualizing Tipping Elements to Better Understand Climate Change – Part 3
Key elements of Earth's climate, including ocean circulation, tropical monsoons, and clouds, are at risk of crossing critical thresholds—tipping points that could dramatically alter the planet's climate and ecosystems. Understanding and mitigating the risks associated with these climate tipping points is essential to safeguard our planet's future and ensure a sustainable world for generations to come.
In the previous two posts of this blog series, we discussed the biome shift and ice melting tipping elements and their impact on Earth’s climate system if they crossed a certain threshold or tipping point. In this blog post, we will focus on the last group of tipping elements, namely circulation change in the ocean and atmosphere, and how we could benefit from using GIS to monitor and study them.
Tipping elements linked to circulation change in Earth’s climate system. AMOC is an abbreviation for the Atlantic Meridional Overturning Circulation. Note that the stratocumulus clouds are hypothetical locations for visualization purposes.
Circulation Change Tipping Elements
Tipping elements are parts of the Earth's system that can shift dramatically in response to climate change once they cross certain warming limits or "tipping points." The shifts might happen suddenly in geological terms (less than 20 years) or quickly (over a few decades), leading to significantly different long-term conditions in the Earth’s land and marine ecosystems. In the following sections, we will discuss the tipping elements linked to changes in the ocean and atmospheric circulations:
1) Slowdown of the Atlantic Meridional Overturning Circulation (AMOC):
AMOC is the Atlantic branch of the thermohaline circulation, sometimes referred to as the ocean’s “great conveyor belt”. It is a crucial driver of oceanic currents, facilitating heat and freshwater transfer by moving warm, saline water from the southern hemisphere and tropical regions towards the Northern hemisphere. The process involves the warmer surface waters travelling near the European coast, where they release heat and freshwater into the atmosphere, consequently increasing the density of the water. The current then circles west and as it approaches Greenland, the water has become salty and cold enough to sink into much lower depths of the ocean, forming the North Atlantic Deep Water. This colder, deep water then flows back towards the south, eventually rising to the surface in the Atlantic's southern regions. The AMOC system has been instrumental in maintaining Europe’s climate stability over millennia. Therefore, an abrupt AMOC collapse would cause significant and immediate changes in local climate patterns and hydrological cycles.
Reconstructions based on oceanographic data reveal that the AMOC is currently weaker than it was in the pre-industrial era (source). Potential consequences of an AMOC collapse encompass a downward shift of the tropical rain belt, diminished strength of African and Asian monsoons, and an intensification of Southern Hemisphere monsoons. Furthermore, such a collapse would influence the absorption and distribution of anthropogenic carbon in the atmosphere, significantly affecting the carbon cycle and ocean productivity. The most recent IPCC report suggests, with medium confidence, a probable decline of the AMOC within this century but considers a total collapse unlikely before 2100. The current and potential future weakening of the AMOC, as supported by recent studies, underscores the importance and justified concern regarding this climate tipping element.
Global thermohaline circulation shows the movement of surface and deep ocean currents around the globe. Credit: NASA Scientific Visualization Studio
There are many ways that you can use GIS to better understand the state of the ocean. For example, the Hycom Explorer app allows you to explore near real-time global oceanographic HYCOM data from the ArcGIS Living Atlas of the World and to view and compare seawater temperature, sea surface height, seawater salinity, or ocean currents at different times and depths. In addition, you can use the 3D Ocean Explorer to view ecological marine unit volumes along with the 6 ocean variables (Temperature, Salinity, Dissolved O2, Nitrate, Phosphate, and Silicate) used to classify ocean water bodies into the ecological marine units. The following story map will help you to learn more about ocean currents and how they influence our planet.
2) Disruption of Tropical Seasonal Monsoons:
Tropical seasonal monsoon rainfall serves as the dominant water source for nearly all tropical regions, playing a pivotal role in determining water availability and agricultural productivity for billions of individuals across vast areas spanning Africa, Asia, the tropical Americas, and northern Australia. Additionally, these regions are prone to severe weather events, including intense rainfall and cyclonic disturbances within the broad monsoonal air flows, which lead to devastating floods and landslides that threaten lives and property. The significance of monsoons for food security, water supply, and natural disaster risk has prompted worldwide research efforts aimed at forecasting how monsoon patterns and strengths may alter due to human-induced climate change.
The monsoon circulation, driven by the land-to-ocean pressure gradient, is further strengthened by the moisture it transports from adjacent ocean basins. Consequently, any factor that diminishes this driving pressure gradient risks destabilizing the entire monsoon system. For instance, a pronounced warming over land areas and in the Northern Hemisphere generally amplifies the monsoon. However, increases in the Earth's reflectivity (albedo) over continents due to aerosol emissions or land-use changes tend to diminish it. A 2021 Organisation for Economic Cooperation and Development (OECD) analysis predicts that, under scenarios of global warming, West Africa is poised to suffer the most significant reductions in rainfall worldwide. Such a trend could be aggravated by a slowdown or collapse of the AMOC, further disrupting the African monsoon system and potentially leading to extensive drought across the region. Additionally, a weakened AMOC could undermine the Indian summer monsoon, heightening the risk of droughts that could severely impact Indian agricultural outputs, particularly rice yields.
The ArcGIS Living Atlas of the world hosts multiple precipitation datasets from satellites and models that can assist you in studying and monitoring global trends and patterns. As you can see in the following video by NASA, rainfall and wind patterns can help us track changes in monsoons and their impacts from one year and location to another.
This visualization uses a combination of NASA satellite data and models to show how and why the monsoon develops over a specific region. Credit: NASA Scientific Visualization Studio
3) Warming due to Breakup of Stratocumulus Cloud Decks:
Stratocumulus clouds, prevalent low-level clouds found within 2,000 metres of the Earth's surface, form expansive "decks" that cover approximately 20% of Earth's tropical ocean regions. These clouds play a crucial role in cooling the planet by reflecting incoming sunlight back into space, thereby reducing the amount of heat that reaches the Earth's surface. Due to the small-scale formation and dissipation patterns of stratocumulus clouds, current global climate models struggle to accurately predict how increasing concentrations of greenhouse gases will affect these clouds. However, this study in 2019 suggested that under scenarios of high CO2 emissions (equivalent to 1200 ppm CO2), stratocumulus clouds could disintegrate due to a climate feedback mechanism, potentially leading to a rapid global temperature increase of up to 8°C. To date, there is no follow-up research that has robustly explored these findings under different model conditions. Therefore, further efforts are required to investigate this potential climate feedback in detail and better assess the conditions that may trigger cloud deck disintegration or other large-scale changes in cloud formation.
White stratocumulus cloud cover. Rising CO2 levels in the atmosphere could break out stratocumulus clouds and lead to a rapid global temperature increase.
GIS and Tipping Elements
GIS can be used as a key tool in addressing an important question: "How can we adapt and mitigate the risks associated with changes in biome shift, ice melting and circulation change tipping elements?" By providing a location intelligence framework and integrating data from various sources such as satellites, drones and models, GIS empowers us to make informed decisions, implement effective strategies, and make our planet more sustainable for generations to come. Here's how we could use GIS to respond to the impacts of these tipping elements:
1. Early Detection and Monitoring: GIS enables the collection and integration of data from various sources, helping researchers identify early warning signs of potential tipping points. By tracking changes in temperature, sea levels, habitat loss, and other indicators, we can monitor vulnerable regions and ecosystems to assess the risk of crossing critical thresholds.
2. Spatial Analysis and Resource Allocation: The ability to conduct spatial analyses with GIS is crucial for identifying areas where the impact of tipping points is likely to be most severe. This can help prioritize interventions and ensure that efforts and investments are directed where they can achieve the greatest benefit, optimizing the use of available resources and the impact of conservation and adaptation initiatives.
3. Scenario Planning: GIS can facilitate scenario planning by modelling different outcomes based on various human interventions. This strategic planning tool is instrumental in guiding resource distribution toward the most impactful and sustainable solutions.
4. Public Awareness: Maps are powerful tools for conveying complex environmental information to the general public. By presenting this information in easily accessible and comprehensible formats such as dashboards, story maps, and web applications, GIS can help increase awareness about the significance of avoiding tipping points and the collaborative efforts necessary to prevent them.
From this, it is clear that GIS professionals can play a crucial role in building a more sustainable future for our planet. I would like to conclude this blog series by sharing the following clip from the 2024 Esri Federal GIS Conference that demonstrates how GIS can be employed in different ways to create the world we aspire to see.