Global Environmental Change: Its effects on the Climate, Sea Level, Geomorphology and Biosphere.

EXERCISE #3
DATE: Wednesday 1^st November, 2023. 

What is Global Environmental Change?

Global Environmental Change (GEC) is an integrative and cyclical process related to human actions which negatively transform natural systems, such as oceans, land, ice, the biosphere, atmosphere and elemental cycles on a planetary scale (Butler and McFarlane 2018, 454). 

Since modern society exists within the anthropocene, shifts upon environmental systems are increasing, specifically in the form of global warming and climate change. Deforestation, energy production and consumption, population growth, agricultural production (crop and livestock), urbanization, transportation, etc. are some human driven causes of Global Environmental Change (Pyhälä et al. 2016). 

Multiple large-scale and local physical and biological processes, for instance biodiversity loss, freshwater depletion, ocean acidification, aquifer contamination, ecosystem degradation, species extirpation and waste production have also driven Global Environmental Change. 

Image 1: Depiction of Global Environmental Change via timelapse of global rising temperatures (1880-2000) (left) and by increase in the size of the ozone hole over Antarctica (1980-2013) (right). 

Source: Khosla 2015 (matadornetwork.com).

What are the Effects of Global Environmental Change?

Global Environmental Change sporadically challenges environmental systems. Whether warming be induced by greenhouse gas emissions, deforestation, urbanization, etc., in which rapid population growth drives the aforementioned, the uneven geographic distribution of the rate and extent of such complex effects impedes damage on some nations more than others, such as Small Island Developing States (SIDS). 

Their size, geographic location, sensitivity to such effects and low adaptive capacity and resilience makes them more vulnerable than the United States, Europe, etc. to GEC. Notwithstanding, all ecosystem services and living flora and fauna are faced with adversities as their capacity to cope with such stresses overstretches their ability to adapt. Below lists common effects of Global Environmental Change:

v Rising Temperatures, Climate Change, Water Scarcity, Higher Death Rates, Land Degradation, Longer Drought Periods, Ocean Acidification, Rising Sea Levels, Health Impacts upon Humans, More Frequent and Sever Weather Events and Increased Rates of Wildlife Extinction (Biodiversity Loss). 

Diagram 1: Illustration of the main Effects of Global Environmental Change. 
Source: Swamirara 2017 (swamirara.wordpress.com). 

What are the Effects of Global Environmental Change on the Climate, Sea Level, Geomorphology and Biosphere?

THE CLIMATE

Global Environmental Change affects the climate when atmospheric greenhouse gases, being nitrous oxide (N₂O), methane (CH₄) and mainly carbon dioxide (CO₂), increases in concentration. Atmospheric CO₂, as reported by Allen and Allen (2017, 220), has risen from 320ppm during the 1950s to approximately 410ppm in 2016. As these gases multiply, they trap heat, warming the planet to cause climate change. Below lists the effects of Global Environmental Change on the climate:

Image 2: Simulation showing the movement of Carbon Dioxide throughout the atmosphere over a year. 

Source: Planet Aid Inc. 2014 (planetaid.org). 

Increased Temperatures

Global average temperature has risen by 0.9^o Celsius since the early 1900s. According to Svirejeva-Hopkins et al. (2004), approximately 90% of anthropogenic carbon emissions are generated in cities. As such, regions for instance the Arctic experiences pronounced warming conditions as amplified heating causes snow and ice melt, thereby reflecting less sunlight, but absorbing more sunlight. This rise in temperatures also affects ecosystems, biodiversity, agricultural crops and livestock and even human health (National Geographic Society 2015).

Image 3: Timelapse of "old" ice melt in the Arctic (1987-2013). 
Source: Planet Aid, Inc. 2014 (planetaid.org). 

Habitat and Wildlife shifts

The behavior and distribution of numerous fauna and flora are affected by GEC. Habitat fragmentation and loss cause some species to face possible extinction, whereas others are forced to migrate to higher latitudes in search of suitable conditions and food (MetOffice, n.d.). Such shifts disrupt food webs, ecological interactions, population growth and human culture and well-being, but instigates negative competition through survival of the fittest.

Diagram 2: Portrayal of the complex feedback loops between the climate, humans and ecosystems. Disruptions in one component due to Global Environemtal Change affects other components. 

Source: Pecl et al. 2017 (science.org). 

Modified Precipitation Patterns

Global Environmental Change modifies the intensity, amount, distribution and frequency of snowfall and rainfall worldwide. However, unlike some regions, for instance the Caribbean which face more natural disasters such as hurricanes, floods and soil erosion, others experience less water availability, severe droughts, lower crop production and even livestock death. This can be seen in semi-arid and arid regions like Southern Africa, the Mediterranean and South-Central U.S. According to Bralower and Bice (n.d.), water availability is estimated to fall by 10-30% by 2050 and regions that are already dry will most likely become drier by the next century.

Diagram 3: Predicted changes in global precipitation patterns by the end of the 21st century where wet regions would become wetter and dry regions would become drier due to Global Environmental Change. 

Source: Bralower and Bice (n.d.) (e-education.psu.edu). 

Amplified Extreme Natural Disasters

The frequency, intensity, trajectory and probability of adverse weather events, particularly hurricanes, blizzards, heat waves and wildfires, are increased by GEC. As seen globally and in Caribbean region, specifically in the Trinidad and Tobago, these natural disasters affect infrastructure, private and commercial property, ecosystems (both its systems and organisms) and especially human life. As such, these disasters exacerbate social inequality and vulnerable populations. 

Image 4: Presentation of the aftermath of an intense rainfall event in Greenvale, La Horqueta, Trinidad. 
Source: Ramdass 2018 (trinidadexpress.com).  

Ice Melt and Rising Sea Levels

Due to Global Environmental Change, ice sheets, glaciers, permafrost, sea ice, etc. melt at accelerated rates, giving way to sea level rise. This threatens ecosystems, human life, infrastructure and coastal communities. It must also be noted that sea level rise causes coastal erosion, coral reef damage, storm surges, saltwater intrusion and many more risks to flora, fauna and human society and assets (National Geographic Society2015).  

Image 5: Simulation showing sea level rise as an ice sheet melts due to warmer ocean temperatures cause by global warming. 

Source: NASA Tumblr 2020 (nasa.tumblr.com). 

SEA LEVEL

As aforementioned, Global Environmental Change causes rising sea level, however, this is done in two ways. Either through Thermal Expansion or Melting Ice. 

Warming ocean waters influences thermal expansion while rising temperatures, causing ice sheets, permafrost and glaciers to melt, adds more water to oceans. Nevertheless, both processes influence sea level rise which increases the volume of ocean waters. Sea levels are anticipated to increase > 26-82 centimeters by the end of the 21^st century (National Geographic Society 2015). Below briefly explains the effects of Global Environmental Change on Sea Level:

Loss of Ecosystem Services and Biodiversity

Marine and coastal habitats, such as salt marshes, mangroves, estuaries, seagrasses and coral reefs, provide crucial services to ecosystems, for instance tourism, storm protection, food, conservation of biodiversity and carbon sequestration (United Nations, n.d.). Due to rising sea levels, the growth and survival of plants and animals (biodiversity) are threatened. This can be seen in the Mediterranean vermetid reefs on the Israeli coast (Rilov et al. 2021, 148377).

Image 6: Depiction of changes in the biodiversity of the vermetid reef in the Mediterranean due to sea level rise. Source: Rilov et al. 2021 (sciencedirect.com). 

Coastal and River Erosion and Flooding

The depth, frequency, extent and probability of coastal erosion and flooding increases due to Sea Level Rise. This is paramount during storm surges and high tide conditions, reducing the natural protection wetlands, corals reefs and beaches provide. Damage to coastal property, ecosystems, infrastructure and communities occur, leading to displacement of persons, especially in low-lying areas (Lindsey 2022). This is evident in India where 4.5 million persons are affected annually due to river erosion (Prasad 2023).  

Image 7: Depiction of damage to land caused by river erosion and flooding. 
Sources: Prasad 2023 (downtoearth.org.in); Nath 2020 (indiatoday.in).

Industry, Economy and Social Impacts

The economy, agricultural, industrial and commercial buildings and industries are greatly affected by inundation and erosion as sea levels rise. This not only causes loss to beach amenities, impacting local tourism industries and local economies, but also existing and future coastal developments (Lindsey 2022). In Tobago, sea level rise affects its tourism industry as damaged reefs reduces tourist travel into the island, affecting its local economy in gaining foreign capital. Socially, the security, health, culture, safety and livelihood of human society is also affected by sea level rise. As such, having to adopt mitigation and adaptation measures for instance habitat restoration, building sea walls and individual and asset relocation is very costly, affecting economic stability.

Image 8: Portrayal of Tobago's shoreline and coral reefs potentially vulnerable to erosion due to sea level rise. 
Source: WRI 2008 (wri.org). 

Fresh Groundwater Depletion and Saltwater Intrusion

Decreased sea level lowers the groundwater table, specifically in coastal areas, causing difficulty in accessing freshwater resources. Also, the quality and quantity of potable irrigation and drinking water, even aquatic habitats, is affected by saltwater intrusion. Rising sea levels intrude freshwater sources of lakes, rivers and aquifers with saltwater. Moreover, in the case of reduced water availability due to GEC, certain areas become colder. This lowers the availability of freshwater as glaciers store ¾ of global freshwater (National Geographic Society 2015).  

Diagram 4: Illustration of saltwater intrusion and fresh groundwater depletion due to rising sea level. 

Source: Hawkey 2011 (ian.umces.edu). 

GEOMORPHOLOGY

Geomorphology studies the surface, evolution and processes that shape Earth. Modifications to the patterns and rates of weathering, erosion, plate tectonics and deposition are some ways in which Global Environmental Change affects landscape geomorphology. Below lists some effects of GEC on geomorphology:

Coastal landscapes

GEC alters the supply and transport of sediments along coasts, causes differences in tide and wave forces and leads to increased sea level. As seen in the latter, loss of wetlands, coastal erosion, flooding and even saltwater intrusion occurs. Also, dune formation and beach profiles are altered by the changing dynamics of waves and tides, resulting in the migration of barrier islands when storms, sediment supply, waves and sea level rise affects them. This is evident in the United States Atlantic Coast. Sea level rise is exacerbating the migration of barrier islands landward through over wash, meaning the sediments are being deposited onto the back barrier marsh (McNeill 2019).

Image 9: Sediment deposition due to sea level sire causing the barrier island along the Atlantic Coast to migrate. 

Source: McNeill 2019 (news.vcu.edu). 

Glacial and Periglacial Landscapes

Ice sheets, glaciers and permafrost melt and retreat due to global warming. Solifluction, frost heave, thermokarst and more are formed when permafrost melts, while moraines, outburst floods, eskers, ice-wedge casts and glacial lakes are formed due to glacial and periglacial melting. As such, the landforms, hydrology and ability to transport sediments are affected as temperatures continue to rise (Goudie 2010, 246).

Image 10: Timelapse of Columbian Glacier retreating in Prince William Sound, Alaska (1984-2011) due to global warming. 

Source: Planet Aid Inc. 2014 (planetaid.org). 

Aeolian Landscapes

The direction, variability, velocity and frequency of wind in aeolian regions are highly affected due to GEC. Amplified wind speed results in abrasion and deflation of landscapes, causing the presence of more dunes. As such, the deposition, transportation and erosion of dust and sand particles are affected when wind speeds increase. Also, the deposition of dust, increased vegetation cover and stabilized soils are more present when wind speed minimizes (Slaymaker et al. 2009).  

Image 11: Presentation of abrasion due to wind erosion (left) and the formation and migration of a dune due to high winds blowing in one direction (right). Sources: Giphy n.d. (giphy.com); Dakar 2009 (blocs.xtec.cat).

Fluvial Landscapes

Global Environmental Change affects the sediment load, morphology, discharge and flow of rivers. This is influenced by differences in runoff, evaporation rates and precipitation patterns of river basins. This in turn increases flooding, channel migration, erosion and damage to ecosystems. However, in the case of more warming conditions globally, channel narrowing, droughts and deposition proliferates when precipitation reduces.

 

BIOSPHERE

The Biosphere supports life on Earth, forming connections with the atmosphere, hydrosphere, lithosphere, pedosphere, etc. GEC affects the biosphere by causing habitat destruction, degradation, pollution, fragmentation, overexploitation and the invasion of foreign species, all leading to biodiversity loss. These decrease the ability of ecosystems to not only provide key services for flora, fauna and humans, being water, food, medicine, etc., but its resilience and adaptation capacities. Below examines how Global Environmental Change affects the Biosphere in more detail:

Altered Productivity and Ecosystem Functioning

The patterns and rates of nutrient cycling, energy flows and the provision of services, being water, food, etc. to humans, plants, animals and even microorganisms, is significantly impacted by Global Environmental Change. GEC increases the intensity and frequency of pest and disease outbreaks, wildfires, etc., and also triggers global climate change, limiting the storage of carbon and the ability of plants to photosynthesize.

Image 12: Reduction in erosion control where changing temperatures cause grass-eating marsh crab to reduce grass amounts. Source: UNEPA 2022 (epa.gov). 

Changing the Diversity and Distribution of Living Organisms

Some species are forced to migrate, shift their communities, occupy new habitats or may become extinct due to Global Environmental Change. This impacts the functioning of ecosystems and its structure, stability and ability of one ecosystem to form interactions with others (The Royal Society 2023).  

Image 13: Animation of biodiversity risk, specifically the % of species exposed to extreme climate change (2007-2100). 
Source: Trisos 2020 (it-online.co.za). 

Feedback and Uncertainties in the Earth System Created

By either dampening or heightening the effects of climate change on the biosphere and its counterparts, such feedback is generated because of Global Environmental Change. Also, difficulty in managing and predicting effects to the biosphere cause uncertainties in its outcomes and responses. In relation to feedback, an example is where more greenhouse gases are released into the atmosphere when permafrost melts which causes further global warming and ice melt (UNEPA 2022).  

 

Amplified Vulnerability and Exposure of Organisms to Stressors

Global Environmental Change exposes micro and macro-organisms to multiple stressors, for instance drought, extreme storms, pollutants, higher temperatures, invasive species, floods, heat waves, etc. (National GeographicSociety 2023). These increase organism vulnerability to other harsh conditions as the ability of organisms to adapt and be resilient to these stressors reduces, causing their population to decline or their mortality rates to increase.  

CONCLUSION

Global Environmental Change encompasses multiple complex challenges beyond increases in temperature which causes significant effects to the Climate, Sea Level, Geomorphology and Biosphere. As such, though humans primarily contribute toward such effects, it is humans which need to develop mitigative approaches to address these effects sustainably so that global environmental systems thrive. 

One more topic to go guys!!

The end is near, see you soon!

Gif images courtesy GIPHY: https://giphy.com/. 

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