Climate Change: Polluting Our Waterways

Water and climate change are inextricably linked. Climate change is already affecting water access for people around the world, causing more severe droughts and floods. Increasing global temperatures are one of the main contributors to this problem. Climate change impacts the water cycle by influencing when, where, and how much precipitation falls, leading to more severe weather events over time. As the climate warms, harmful algal blooms happen more often and become more severe, threatening the availability of source water and increasing the need for drinking water treatment.

Flooding and rising sea levels

Secondly, coastal cities are increasingly experiencing flooding, even on days with less extreme tides or calm weather. This type of tidal flooding is expected to intensify and become more frequent, causing road closures, reduced stormwater drainage capacity, and infrastructure deterioration. The rising sea levels contribute to this phenomenon by reducing the gap between the average sea level and the height of the land, making coastal areas more vulnerable to flooding.

Thirdly, the combination of melting glaciers and the thermal expansion of seawater due to rising temperatures leads to rising sea levels globally. This results in a higher baseline for storm surges, pushing deadly and destructive storms further inland than before. The increased frequency and intensity of storms pose significant risks to coastal infrastructure, including roads, bridges, subways, water supplies, and power plants.

Lastly, rising sea levels contribute to saltwater intrusion into freshwater aquifers, contaminating vital water sources for municipal and agricultural use. This contamination poses risks to human health, food production, and ecosystem sustainability. The intrusion of saltwater into aquifers, coupled with the increased intensity of storms, poses a significant threat to water security and sanitation, with far-reaching consequences for communities and natural habitats.

To address these challenges, cities like New York are implementing multi-layered approaches to protect their coastlines, including integrating coastal protection features into public spaces and updating building codes to account for flood risks. While these adaptations can help mitigate the impacts of flooding and rising sea levels, addressing the root cause of climate change through emissions reductions, as outlined in the Paris Agreement, remains crucial to preventing the worst-case scenarios from becoming a reality.

Increased droughts

Droughts, which are becoming more severe and frequent due to climate change, have a significant impact on water quality and availability. Reduced precipitation leads to lower water levels in rivers and streams, causing stagnation and a buildup of pollutants. This, in turn, creates ideal conditions for microorganisms and viruses to thrive, contaminating water sources and posing risks to human health.

Drought conditions also result in increased surface water evaporation, further depleting water supplies. This is particularly concerning in areas that rely heavily on groundwater, such as many parts of the United States. As groundwater supplies are not replenished at a typical rate, water scarcity becomes a critical issue.

The impact of droughts extends beyond water availability, also affecting agriculture and ecosystems. Farmers may struggle to irrigate their crops, leading to reduced yields and potential food insecurity. Additionally, drought-related wildfires can cause significant damage to natural water sources. The runoff from these wildfires carries sediment, ash, charcoal, and woody debris into surface waters, harming aquatic life by reducing oxygen levels.

Furthermore, droughts have been linked to various public health issues, including an increase in infectious diseases. The perceived or actual lack of water during droughts can compromise hygiene practices, facilitating the spread of acute respiratory and gastrointestinal illnesses. Drought conditions can also lead to elevated levels of naturally occurring arsenic in private wells and groundwater, posing long-term health risks to those who consume it.

The ongoing drought in the western United States exemplifies the severe consequences of water scarcity. Water restrictions have been implemented in several states, and natural bodies of water and reservoirs are being depleted at alarming rates. This situation highlights the urgent need to address water conservation and management practices to mitigate the impacts of climate change on water resources.

Harmful algal blooms

Algae need carbon dioxide to survive, and increased levels of carbon dioxide in the water can lead to the rapid growth of algae, particularly cyanoHABs, which can float to the surface of the water and take advantage of the increased carbon dioxide. Higher levels of carbon dioxide also increase the acidity of the water, which affects competition among algal species and impacts the organisms that feed on algae. These effects can combine to give HAB species a competitive advantage.

Coastal upwelling, where wind pushes warm surface water offshore and nutrient-rich deep water rises to replace it, is another factor contributing to HABs. Climate change is expected to alter the timing and intensity of coastal upwelling, leading to more algal blooms. Warmer water temperatures can also increase the salinity of inland waters, allowing the invasion of salt-tolerant and marine algae into inland lakes.

The impacts of HABs are wide-ranging and include negative effects on food security, tourism, local economies, and human health. HABs can kill fish and other aquatic animals, make people sick, and even lead to human deaths. They can also impact industries that rely on water, causing local waterfronts to shut down during blooms. As the climate continues to warm, HABs are expected to become more frequent and severe, further exacerbating these impacts.

Warmer air sucking up more water

Warmer air can hold more moisture than cooler air. As a result, in a warmer world, the air will suck up more water from oceans, lakes, soil, and plants. This has a profound impact on the water cycle, affecting when, where, and how much precipitation falls.

The increased evaporation caused by warmer air leads to higher levels of atmospheric water vapour, resulting in more frequent, heavy, and intense rainfall in the coming years. This shift will lead to more floods, as more water will fall than vegetation and soil can absorb. The excess water, or runoff, will drain into nearby waterways, picking up contaminants like fertilizer and pollutants, and eventually travelling to larger bodies of water, polluting the water supply and limiting access for humans and ecosystems.

In the Northern Hemisphere, warmer temperatures mean less snowfall, leaving less water available in local reservoirs after winter. This negatively impacts farmers, who are left without enough water to irrigate their crops during the growing season. Climate change is already causing more severe droughts and floods, affecting water access for people worldwide.

The complex impacts of climate change on the world's water supply will put pressure on drinking water supplies, food production, property values, and more. It is estimated that by 2050, 2.7 to 3.2 billion people will live in potential severely water-scarce areas. This scarcity will have major ramifications for water security and sustainable development.

Increased stormwater runoff

As global temperatures continue to rise, the water cycle is disrupted, leading to more severe weather events, including heavier rainstorms and increased flooding. This increase in intense rainfall contributes to higher levels of stormwater runoff, which has detrimental effects on water quality.

Stormwater runoff refers to the water that flows over the ground after a storm. As it moves, it picks up and carries various pollutants, sediments, and contaminants, such as fertilizer, dirt, and other harmful substances. This polluted stormwater then flows into nearby bodies of water, including rivers, lakes, and streams, degrading their water quality.

The increased volume of stormwater runoff can overwhelm stormwater management systems, leading to blockages and reduced storage capacity. It can also complicate the treatment processes at drinking water utilities, resulting in higher treatment costs. Additionally, the increased sedimentation caused by runoff can negatively impact water quality, affecting aquatic ecosystems and human access to clean water.

To mitigate the impacts of increased stormwater runoff, various measures can be implemented. These include the construction of retention ponds, extended detention wetlands, and underground storage systems. Retention ponds are engineered basins designed to store and gradually release stormwater, allowing sediments and pollutants to settle, thereby reducing their impact on water quality. Extended detention wetlands provide similar benefits, storing stormwater and releasing it slowly, reducing peak flows and providing natural water filtration. Underground storage systems, such as culverts or stormwater detention vaults, offer the advantage of utilizing existing spaces without occupying additional surface areas.

In addition to these engineered solutions, natural approaches can also be employed, such as building swales and rain gardens, which help direct and manage stormwater runoff while maintaining aquifers and reducing erosion. Tree planting is another effective method, as trees shade the ground, keeping water temperatures cooler and promoting infiltration, thereby reducing the amount of stormwater exposed to the sun.

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