Paradise Lost: Climate change and microplastics, two faces of the same coin

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by Anshika Singh – Climate change and environmental pollution (especially due to plastic) are the worst outcomes of rapid development and spread of humans on this planet. There have been reports of finding plastic pollution in regions  largely free of humans or with limited accessibility (such as polar waters and the Mariana Trench). Another striking instance of marine pollution is the great Pacific Garbage patch, which has been at times measured at sizes twice as the area of Texas. With the continued trend of leaving behind plastic waste and increasing the carbon footprint, humans have invited the end of their own world. Plastics (particularly the tiny pieces of plastics called Microplastics) have entered the food chain affecting more than 700 marine species, thus creating altogether a new ecosystem, “the plastisphere”. It has been predicted that plastic waste from coastal countries will be 20-fold by 2025 and there will be more plastics in the ocean than fishes by 2050.

Role of Climate change in Microplastics pollution

Recent studies have found that there are several factors linked to climate change, such as ocean currents and weather conditions that also affect the distribution of plastic waste (microplastics). Climate change is causing our glaciers to melt faster and release trapped microplastics. The melting glaciers create new sea routes that are likely to ramp up trade and tourism, which will further increase the problem of plastic pollution. It is important to know the type and chemical composition of the plastics as its density determines if it will float on sea surface or sink to the deep-sea sediment bed. For instance, at the points of freshwater inputs, there could be a drop in density of seawater resulting in a decrease in relative buoyancy of microplastics or other tiny plastics. This can result in the sinking of less dense microplastics to the sea bed. Moreover, climate change and global warming can lead to a high rate of evaporation, thereby increasing the density of seawater at these locations and allowing even denser plastics to remain in the water column for a longer time. To make the situation further complicated, the changes in temperature of sea surface waters also affect rainfall, cyclones, storms, floods etc. These phenomena influence the overall distribution of plastics in oceans and coastlines. Climate change also affects the interactions among the biota and plastics in the water column and the behaviour of contaminants adsorbed onto plastics.

Role of Microplastic pollution in Climate change

Recent findings have revealed that plastic pollution can also contribute to climate change. When bigger plastic materials (low-density polyethene or LDPE) break down into smaller particles, they emit powerful greenhouse gases during the degradation process. Since LDPE, which is the most common plastic type, has a less dense chemical structure, it can break down very easily, thereby releasing greenhouse gases such as methane. Although methane contributes to only 10% of greenhouse gases, it is about 21 times more potent than carbon dioxide. The increase in greenhouse gases leads to climate change, leading to more rapid degradation of plastics, releasing more greenhouse gases. This is how an alarming feedback loop is formed between climate change and microplastic pollution. Floating microplastic debris influence solar radiation, spectral reflectance and surface bright targets (whitecaps, foam and breaking waves) on the ocean surface. It can affect the warming or cooling of the water column by attenuation, scattering or polarization of sunlight, thereby affecting ocean heat uptake. At present, plastics and microplastics floating on the sea surface do not have a substantial influence on the heat budget or physical processes. However, if the plastic pollution continues at the same rate, this can soon become comparable to the distribution of phytoplankton in the oceans (especially at major gyres and coastal regions). To solve this problem effectively, research and innovation should be encouraged and supported by providing adequate incentives.

A better understanding of the cascading effects and feedback loops can be achieved by in situ experiments, field studies, and model simulations. Modelling can help to predict the sources and sinks of plastic pollution in the ocean and would allow for designing a targeted measure to tackle these risks. This data will be useful for stakeholders to make new environmental policies to mitigate these effects. In 2018, the fourth UN Environment Assembly held in Nairobi, Kenya focussed on the fight against plastic pollution as one of their main stream agendas. They published three reports to highlight:

  1. Impact of plastic on shallow-water coral reefs and list out the gaps to be filled in order to overcome this problem,
  2. A complete guideline for the monitoring and assessment of plastic pollution in the oceans so that a uniform protocol can be adopted internationally. This can allow comparative studies on the distribution and abundance of plastic litter in the marine environment, giving a correct estimation, reliable monitoring system and important information of the plastic waste
  3. A study to find out the gendered nature of use, manage and conservation of marine and coastal environment. It was found that there has been complete ignorance towards the important role of women in saving the ocean ecosystem and how empowering them can promote sustainable utilization of our marine resources.

Like climate change, microplastic pollution also needs everyone’s participation to prevent its devasting impact on our planet. We need to rethink our moral responsibility to our planet, and end single-use plastics. We need to adopt feasible, smart alternatives and develop economical and environmentally friendly recycling methods. Government, research institutions, and private industries should join hands to collaboratively solve the issues related to climate change and microplastics pollution.

References

Chiba, Sanae, Hideaki Saito, Ruth Fletcher, Takayuki Yogi, Makino Kayo, Shin Miyagi, Moritaka Ogido, and Katsunori Fujikura. “Human footprint in the abyss: 30 year records of deep-sea plastic debris.” Marine Policy 96 (2018): 204-212.

Ghisellini, P., Cialani, C., & Ulgiati, S. (2016). A review on circular economy: the expected transition to a balanced interplay of environmental and economic systems. Journal of Cleaner production, 114, 11-32.

Royer, Sarah-Jeanne, Sara Ferron, Samuel T. Wilson, and David M. Karl. “Production of methane and ethylene from plastic in the environment.” PloS one 13, no. 8 (2018): e0200574.

VishnuRadhan, Renjith, T. I. Eldho, and T. Divya David. “Can plastics affect near surface layer ocean processes and climate?.” Marine pollution bulletin 140 (2019): 274-280.

Wilcox, C., Mallos, N. J., Leonard, G. H., Rodriguez, A., & Hardesty, B. D. (2016). Using expert elicitation to estimate the impacts of plastic pollution on marine wildlife. Marine Policy, 65, 107-114.

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