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Climate change could increase the risk of disruptions, damages, and failures across the global transport sector. 

How does climate change impact transportation?

The global transport sector is well exposed and vulnerable to the impacts of extreme weather events; Climate change, which causes sea-level rise, extreme precipitation, coastal storms, landslides, extreme temperatures, and inland flooding, may exacerbate future risks.

Globally, average sea levels have swelled over 50 cm since 1880, with about seven of those centimetres gained in the last 25 years. Every year, the sea rises another .33cm. Transportation infrastructures in many coastal cities across the United States are extremely susceptible to sea-level rise. Boston, Virginia Beach, Charleston, Atlantic City, Miami, New Orleans and New York City are already facing frequent inundation with thousands of kilometers of roads submerged. A report from the U.S. Department of  Transportation states that transport infrastructure in Delaware, Florida, Georgia, Maryland, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, and Virginia would be the most vulnerable to sea-level rise in the coming decades.

Roads and railway lines around the coast of England are predicted to be swamped due to rising tides. Committee on Climate Change — the UK’s public advisory body — estimates that 1,600km of major roads, 650km of railway lines and 92 stations will be underwater by 2080.  Another study reveals that the most vulnerable rail line in the UK may be the stretch between Dawlish to Teignmouth in London, which would face frequent disruptions because of floods.  

The Economic Commission for Latin America and the Caribbean (CEPAL) states that more than 7,000km of roads in South America and the Caribbean Islands would be destroyed if sea levels rise by 50cm. The United Nations Development Programme (UNDP) predicts that the Caribbean region would lose almost 600km of roads and every fourth airport in their territory.

Climate change is expected to cause local changes in average and extreme temperatures, as well as changes in rainfall patterns, duration, and intensity. These changes can destroy roads, rail tracks, and airports across the world. 

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Sea-level rise is occurring much faster than scientists expected – exposing roads to the destructive floods. A scene from Florida, USA.

Intense rainfall already brings Mumbai, India’s largest city, to a halt. More than 20,000 cars and 200 buses were submerged while hundreds of kilometers of roads were flooded following extreme precipitation in 2005. Mumbai, which receives around 250cm rainfall annually, has its main airport and hundreds of kilometers of roads and rail lines located in low lying areas.   Even a slight increase in rainfall can bring substantial damage to the infrastructures in the city.

The combination of intense hurricanes and tropical storms brings significant devastation to the transport sector worldwide. When Hurricane Mitch ripped through Central America, roads and rail lines were ruined across many countries. Nicaragua witnessed heavy and long-lasting rainfall for weeks, which caused landslides and floods, causing serious damage to the country’s infrastructures; more than 3,000 km of roads and 100 bridges were destroyed.

Rising temperatures also have adverse effects on the transport sector as extreme heat causes the roads to soften and expand creating ruts and potholes, particularly in high-traffic areas. More frequent and severe heat waves may cause rail tracks to expand and buckle resulting in quick detrition of the infrastructure.

Governments worldwide should play an elementary role in increasing the absorptive and restorative capacities of their transport sector in the wake of climate change. Building resilient systems in the light of natural disasters and extreme weather events should be the basis of their economic decision-making process. Upgrading construction standards for roads, bridges, rail lines, and culverts can reduce the impacts of the climate crisis. 

Research suggests that groundwater reserves in sub-Saharan Africa are more resilient to climate change than previously understood. But overexploitation by humans could still dwindle them.

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Previous studies that indicated climate change caused rapid depletion of groundwater — the largest source of freshwater resource on the planet — had raised serious concerns among climate scientists and conservationists. But new research by a consortium of international hydrogeologists suggests that climate change may not deplete groundwater in sub-Saharan Africa.

The study — the first regional assessment to look at how climate change has influenced groundwater across sub-Saharan Africa — examined patterns of groundwater replenishment in 14 multidecadal groundwater level records from nine African countries that represent a range of climates from hyper-arid to humid. Researchers found that groundwater was consistently replenished every year regardless of the amount of annual precipitation. The replenishment process has been more sensitive to the intensity of rainfall than to the overall amount of rain.

Although the climate crisis is expected to cause less overall rainfall, the research suggests that groundwater supplies in Africa will survive because of the heavier and more intense rainfall caused by global warming. Even if annual rainfall is low, periods of intense rain will be sufficient enough to replenish local groundwater resources.

Groundwater Levels in Africa

In Africa, groundwater reserves are 20 times larger than the water stored in lakes and reservoirs above ground. A vital source of drinking water for millions of people in cities and villages across the continent, these reserves are accessed through wells, boreholes, and springs. People rely more on them during droughts than other water sources on the surface, which often remain dried up during the summer.

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Multi-decadal groundwater levels across Sub-Saharan Africa show that groundwater recharge due to intense periods of rainfall.

The researchers determined groundwater levels analysing a relative balance between recharge — the process by which groundwater is replenished — and discharge — the flow of groundwater to springs, streams, wetlands and the sea. Individuals and companies collecting water for irrigation and drinking also contribute to reducing the amount of stored groundwater.

A comparative analysis revealed that groundwater is mostly replenished by rainfall that trickles down through the soil to the water table in wetter regions of Africa. This phenomenon occurs consistently across large areas on the continent. But in drier regions, groundwater is mostly recharged locally by water leaking from temporary streams and ponds, which usually start overflowing after heavy rains.

Scientists consider these findings path-breaking because previous studies had ignored an important fact about groundwater replenishment. “Previous regional-level assessments of groundwater resources using large-scale models had ignored the contribution of leaking streams and ponds to groundwater supplies, underestimating its renewability in drylands and resilience to climate change,” says co-lead of the study Dr. Mark Cuthbert from Cardiff University.

Those studies based on computer models had earlier predicted that freshwater will become scarcer in African drylands as climate change continue to reduce rainfall. But, the reality appears to be the opposite as per these findings: global warming is making rainfall come in fewer but heavier bursts accelerating overall groundwater replenishment. 

These findings debunk myths of groundwater depletion in Africa and will encourage policymakers to adopt new strategies to meet the United Nations’ Sustainable Development Goals (SDGs) like food security and access to clean water. Food production on the continent can be improved by allocating groundwater for irrigation through sustainable resource management, which can also ensure safe drinking water for generations to come.

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