EQ2 5.6 CLIMATE CHANGE IMPACTS THE HYDROLOGICAL CYCLE Flashcards
what does climate change cause
Climate change causes changes in weather patterns. This can result in changes in precipitation and evaporation, which can have significant impacts on a region’s hydrological cycle and ecosystems.
trends in precipitation
Climate change leads to changes that include increased precipitation in some regions, which results in flooding or change in ecosystems.
The likelihood of tropical storms increases, as sea levels rise and sea surface temperatures increase. The higher levels of rainfall mean that tropical regions near coastline are at risk of higher precipitation rates and flood risk.
Climate change can also reduce precipitation in regions that are used to having high rainfall.
trends in evaporation
Areas that see an increase in temperature from climate change can lead to evaporation happening with greater ease.
In contrast, areas that see a decrease in temperature may see a reduction in evaporation.
If temperatures decrease to below freezing, water may remain frozen and so be stored as ice.
how does climate change affect stores
Climate change affects global water stores capacity and their ability to recharge because of changes in temperature and precipitation rates.
recharge in reservoirs and lakes
Lakes and reservoirs are not being recharged as they previously were because of decreases in rainfall and higher temperatures in some areas.
Lake chad
Lake Chad and the Uzbekistan Aral Sea are drying up with devastating impacts on the ecosystem and the local residents. Chad, Cameroon, Niger and Nigeria all rely on Lake Chad as a water source.
Lake Chad was once the 3rd largest source of freshwater in Africa but is now 1/20th of the size it was 40 years ago.
snow and glaciers
Climate change has lead to an increase in average global temperatures, leading to a reduction in ice-forming seasons.
Early 2018 saw the smallest amount of winter Arctic ice since the 1960s.
Sea ice is not forming to the same extent and current sea ice is breaking off into large icebergs.
permafrost
We call the frozen ground found near the poles in high latitude regions permafrost (e.g. Siberia). Permafrost can hold water in the form of ice.
In summer, if the soil temperatures increase above freezing, permafrost can thaw and the ice within can melt. Thawing leads to percolation and through flow until water has left the ecosystem.
Climate change often leads to a rise in temperature in permafrost regions. So as soil temperatures increase, so will the amount of permafrost loss.
soils
Different soils in different climates will be affected by global warming differently, depending on the weather extremes.
Climate change offers an uncertain future.
Generally, soil moisture levels will decrease as less water will infiltrate the soil in droughts and in periods of intense rainfall because of the high runoff rates.
what does climate change increase the uncertainty of
Climate change and the ENSO cycles increase the uncertainty about weather patterns globally.
El Niño Southern Oscillation
El Niño Southern Oscillation (ENSO) cycles produce uncertainty for weather patterns as conditions change in different years.
El Niño sees winds decline and reverse direction, warm water moves towards South America, low air pressure increases rainfall and flood risk rises.
In contrast, ocean temperatures drop in Australasia meaning higher air pressure, less rainfall and increased drought risk.
La Niña events exaggerate normal weather and increase drought risk in South America and flood risk in Australasia.
increased uncertainty
Climate change increases the uncertainty with weather patterns across the world, resulting in higher or lower precipitation that leads to either drought and floods.
Sea level rise and warmer sea surface temperatures increase the chance of tropical storms and the floods associated with them.
drought risk projections increased drought
Areas that are at risk for future drought are the USA, Central America and the Mediterranean. These regions, all around similar latitude, could see a reduction in rainwater.
The Southern Mediterranean countries (i.e. Spain and Greece) are particularly at risk from drought because of their relatively high populations and reliance on the tourism industry.
drought risk projections decreased drought
Countries seeing a reduction in drought risk include northern Alaska, Asian countries and countries surrounding the Indian Ocean.
flood risk projections
South East Asia (i.e. India and Bangladesh) is seeing an increase in the likelihood of flooding.
70% of Bangladesh is on a floodplain and the majority of the nation is only 1 m above sea level.
Climate change is likely to cause Himalayan glacial meltwater to increase and flood the rivers. Sea level rise and the increased likelihood of tropical storms (referred to as Cyclones here) means Bangladesh is increasingly at risk from flooding.
