Urgent Climate Red Flag: Global Warming Is Disrupting the Natural Flow of Rivers

Climate Change Alters Seasonal River Flows, Threatening Ecosystems and Water Security

Climate change is disrupting the natural seasonality of river flows in northern regions, posing significant threats to ecosystems and water security, with human-induced climate change identified as the primary cause. Credit: SciTechDaily.com

New research indicates that climate change is altering the seasonal river flows in the far northern regions of America, Russia, and Europe, presenting risks to water security and natural ecosystems.

A team of scientists led by the University of Leeds analyzed historical data from river gauging stations across the globe and found that 21% of them showed significant alterations in the seasonal rise and fall in water levels.

The study used data-based reconstructions and state-of-the-art simulations to show that river flow is now far less likely to vary with the seasons in latitudes above 50°N than previously, and that this could be directly linked to changes to the climate caused by human activity.

Human Impact on River Flow

Human activities are altering river flow patterns worldwide, both directly through flow regulations such as reservoirs, and indirectly through land use change and the impacts of climate change on air temperature, precipitation, soil moisture, and snowmelt.

Over two-thirds of the world’s rivers have already been altered by humans even without considering the indirect impacts of increases in greenhouse gases and aerosols.

River flow seasonality plays a critical role in the predicted cycle of floods and droughts. A weakening of these peaks and troughs can threaten water security and freshwater biodiversity. For example, a substantial portion of the early meltwater from snowpack depletion may quickly flow into oceans and therefore not be available for human use.

Weakening river flow seasonality – for example, due to a reduction in spring and early summer river levels in snowmelt regions – can also have an impact downstream on riverbank vegetation and organisms living in the river itself.

Gauging the Seasonal Flow

In northern North America, the researchers found that 40% of the 119 stations observed showed a significant decrease in river flow seasonality. Similar results were also observed in southern Siberia with 32% of stations showing a significant decrease.

There was a comparable pattern in Europe, with 19% of the river gauging stations experiencing a significant decrease – mainly in northern Europe, western Russia, and the European Alps.

In addition, regions in the contiguous United States (the lower 48 states in North America, including the District of Columbia) showed predominantly decreasing trends of river flow seasonality overall, except for rivers in the Rocky Mountains and Florida.

In central North America, the research showed significant decreasing river flow seasonality trends in 18% of the stations.

By contrast, the researchers found a significant increase in river flow seasonality in 25% of the gauging stations in southeast Brazil, showing that changes to the water cycle are having a different impact in some parts of the world.

Lead author, Hong Wang, a PhD researcher at the University of Leeds and the Southern University of Science and Technology in China, said: “Our research shows that rising air temperatures are fundamentally altering the natural patterns of river flow.

“The concerning aspect of this change is the observed weakening of river flow seasonality, and that this is as a direct consequence of historical human-induced emissions. This signals a sustained and considerable diminishment of river flow seasonality if air temperatures continue to rise.”

Dr Megan Klaar, an Associate Professor in the University of Leeds School of Geography and a member of water@leeds, co-authored the research. She said: “The highs and lows of river flow during the different seasons provide vital cues for the species living in the water.

“For example, a lot of fish use particular increases in the water as a cue to run to their breeding areas upstream or towards the sea. If they don’t have those cues, they won’t be able to spawn.”

The research concludes that there is a need to accelerate climate adaptation efforts to safeguard freshwater ecosystems by managing flows to try to recreate some of the natural systems and processes that are being lost.

Professor Joseph Holden, the Director of water@leeds and who supervised Hong Wang’s research, added: “A lot of concern is based upon what climate change will do in the future but our research signals that it’s happening now and that increases in air temperature are driving huge changes in river flow.

“We should be very concerned about what the future holds given accelerating climate change and begin to think about mitigation strategies and adaptation planning to alleviate the future weakening of seasonal river flow, particularly in locations such as western Russia, Scandinavia, and Canada.”

Reference:

“Anthropogenic climate change has influenced global river flow seasonality” by Hong Wang, Junguo Liu, Megan Klaar, Aifang Chen, Lukas Gudmundsson and Joseph Holden, 29 February 2024, Science.
DOI: 10.1126/science.adi9501

SDGs, Targets, and Indicators

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 6: Clean Water and Sanitation
• SDG 13: Climate Action
• SDG 15: Life on Land

The issues discussed in the article are directly connected to SDG 6, which focuses on ensuring availability and sustainable management of water and sanitation for all. The alteration of seasonal river flows poses risks to water security and natural ecosystems, which are key concerns of SDG 6.

Furthermore, the article highlights the role of climate change as the primary cause of these alterations in river flows. This connects to SDG 13, which aims to take urgent action to combat climate change and its impacts.

Lastly, the article mentions the impact of weakening river flow seasonality on freshwater biodiversity and riverbank vegetation. This aligns with SDG 15, which focuses on protecting, restoring, and promoting sustainable use of terrestrial ecosystems.

2. What specific targets under those SDGs can be identified based on the article’s content?

• SDG 6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity.
• SDG 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.
• SDG 15.1: By 2020, ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services.

Based on the article’s content, the following targets can be identified:

Under SDG 6, the target of increasing water-use efficiency and ensuring sustainable withdrawals and supply of freshwater (6.4) is relevant. The alterations in river flows due to climate change pose risks to water security, and addressing these changes is crucial for achieving this target.

Under SDG 13, the target of strengthening resilience and adaptive capacity to climate-related hazards (13.1) is applicable. The article highlights the need for climate adaptation efforts to safeguard freshwater ecosystems and manage flows to recreate natural systems.

Under SDG 15, the target of conserving, restoring, and sustainably using terrestrial and inland freshwater ecosystems (15.1) is relevant. The article emphasizes the impact of weakening river flow seasonality on freshwater biodiversity and the need to protect these ecosystems.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, there are indicators mentioned or implied in the article that can be used to measure progress towards the identified targets:

For SDG 6.4:
– Indicator: Water-use efficiency across sectors
– This indicator can be measured by assessing the efficiency of water use in various sectors such as agriculture, industry, and domestic use. Progress can be tracked by monitoring changes in water consumption patterns and implementing measures to reduce water waste.

For SDG 13.1:
– Indicator: Resilience and adaptive capacity to climate-related hazards
– This indicator can be measured by evaluating the ability of communities and ecosystems to withstand and recover from climate-related hazards such as altered river flows. Progress can be assessed through the implementation of adaptation strategies, disaster preparedness plans, and monitoring systems.

For SDG 15.1:
– Indicator: Conservation and restoration of terrestrial and inland freshwater ecosystems
– This indicator can be measured by assessing the extent of conservation and restoration efforts in terrestrial and inland freshwater ecosystems. Progress can be tracked by monitoring the protection of key habitats, restoration of degraded areas, and the implementation of sustainable management practices.

4. Table: SDGs, Targets, and Indicators

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Source: scitechdaily.com

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