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The impact of climate change on ecosystems


Ecosystems are valuable resources and fundamental for sustaining life on our planet. There are numerous benefits to humans deriving from ecosystems such as recreational and marketable products, and ecosystems services such as flood control and water purification. But despite the key roles ecosystems have, they are more and more threatened by the impacts of a growing human population through the increase of local habitat destruction, air and water pollution. Here, one of Sweco’s graduate ecologists Claudia Ferreira looks at the main impacts of climate change on ecosystems.

As well as threats to community-scale ecosystems, our wider ecosystem is in crisis due to global climate change which is a result from the increased greenhouse gas concentrations in the atmosphere. This leads to changes such as climate variability, increased ocean acidification and rising carbon dioxide concentrations, which consequently threaten the viability and resilience of natural ecosystems and the humans who depend on them. Moreover, climate change affects individual species, which alters the structure and function of ecosystems as a whole, and in turn the goods and services that natural systems provide to us.

Read our Urban Insight report on Building for Biodiversity here

Three impacts of climate change on ecosystems

  1. Lower primary productivity
  2. Fewer and less diverse species interactions
  3. Compromised ecosystem resilience

Primary productivity

The majority of life depends on ‘primary producers’ which are the foundation of most food webs, and are also responsible for producing oxygen and regulating main components of carbon cycling and sequestration. For example, increase atmospheric CO2 leads to an increase of vegetation growth, but excess or lack of nutrients, water deficits, and air pollution can limit that growth too. High temperatures and increased atmospheric CO2 also affect belowground biogeochemical processes, such as carbon and nitrogen cycling, which can affect terrestrial production.

Species interactions and emergent properties

Climate change is enabling the introduction and spread of non-native invasive species. Numerous non-native invasive species are opportunistic generalists that can take advantage of changing conditions, colonize disturbed areas, and out-compete species, thus altering community composition, dominance, production, and increasing extinction risk in some cases. Furthermore, many non-native invasive plants have better responses to increasing CO2 than native plants, as well as nitrogen deposition, and temperature. Consequently, these species increase their competitiveness under increasing climate change. Stronger competitive abilities will likely lead to higher non-native invasive plant abundance and declines of native species abundances and community diversity.

Impact of extreme events on ecosystem resilience

Climate change has altered the duration, magnitude, and frequency of extreme events, including droughts, forest fires, and heatwaves. Many of these events have significant impacts on ecosystems and interact with other climate-driven changes, reducing ecological resilience. Drought weakens tree defences, increasing susceptibility to other disturbances, including insects, pathogens, invasive species, and wildfires. While drought impacts have direct long-term consequences, drought-facilitated disturbances can result in more immediate changes to forest ecosystem structure and function.

9 ways planners, designers and urban developers can reduce (and try to reverse) the impacts of climate change on ecosystems

  • Shift the focus from extracting benefits of natural world to integrating them
  • Plant trees and shrubs to provide food and shelter, and sequester carbon
  • Integrate bioliphic design such as ‘living’ walls and roofs
  • Introduce ‘placemaking’ elements like water features, parks and gardens
  • Mimic ecosystems and natural processes in the urban landscape
  • Eradicate invasive species and cultivate those native to the area
  • Commit larger areas to ‘wilding’ or re-wilding
  • Prioritise traffic-calming and active travel initiatives
  • Balance green/blue infrastructure design for optimum climate resilience

Resources:

Mahli, Y. et al., 2020. Climate change and ecosystems: threats, opportunities and solutions. Philosophical Transactions of the Royal Society, 375 (1794), doi.org/10.1098/rstb.2019.0104.
Malcolm, J. and Pitelka, L., 2000. Ecosystems & Global climate change: A Review of Potential Impacts on U.S. Terrestrial Ecosystems and Biodiversity [pdf] https://www.c2es.org/wp-content/uploads/2001/12/env_ecosystems.pdf.
Weiskopf, S. et al., 2020. Climate change effects on biodiversity, ecosystems, ecosystem services, and natural resource management in the United States. Science of The Total Environment, 733, doi.org/10.1016/j.scitotenv.2020.137782.