Frontiers 2022: Noise, Blazes, and Mismatches – Emerging Issues of Environmental Concern


The United Nations Environment Programme (UNEP) published this report on February 17, 2022. This is the fourth instalment of the Frontiers series – begun in the year 2016 by UNEP – which examines “areas of emerging or ongoing environmental concern.” This 59-page report investigates three emerging environmental issues: noise pollution in cities, wildfires and phenological changes (such as migration, egg-laying, hibernation and flowering). Each of these themes has been divided into separate chapters.

Chapter 1 titled “Listening to cities: From noisy environments to positive soundscapes” has been written by Dr. Francesco Aletta, Research Associate at the Bartlett School of Environment, Energy and Resources, University College London. This chapter studies noise pollution – defined as loud and persistent sounds which are unwanted – as an emerging environmental issue. With a focus on urban areas, the chapter also describes the impact of noise pollution on human health and suggests ways in which to combat these effects.

Chapter 2 titled “Wildfires under climate change: A burning issue” has been written by researchers Andrew Dowdy, Luke Purcell, Sarah Boulter from Australia, and researcher Livia Carvalho Moura from Brazil. It investigates the phenomenon of wildfires and their impact on the natural and the man-made world. The chapter discusses the rise in cases of wildfires because of climate change and human activities such as deforestation, change in land-use and incorrect fire management techniques. It also recommends responses to wildfires in the face of worsening climate conditions.

Chapter 3 titled “Phenology: Climate change is shifting the rhythm of nature” has been written by Prof. Marcel E. Visser from the Netherlands Institute of Ecology. It investigates the ways in which recurring natural phenomena such as temperature, daylight hours and migration periods in relation to seasonal changes (studied under phenology) have altered because of climate change. The chapter analyses the concerning ways in which the natural world has been reacting to such shifts.


  1. Citing a document released by the European Environment Agency, Denmark, in the year 2020, the report states that long-term exposure to noise contributes to 48,000 new cases of ischemic heart disease and around 12,000 premature deaths in Europe every year.

  2. Noise pollution affects many animal species that rely on using acoustic signals to communicate. Due to disturbances caused by noise, species often change their vocalization timing, pitch or frequency. Species that are unable to adapt face the threat of being eliminated from their habitat, leading to ecological imbalances.

  3. In the year 2018, the World Health Organization, Regional Office for Europe, conducted a study to assess the impact of noise pollution on health. It stipulated the maximum level of exposure for different noise sources to prevent harmful health effects. Some of the exposure limits are: road traffic (53 decibels), railways (54 decibels), aircraft (45 decibels) and wind turbines (45 decibels).

  4. Government actions to curb the spread of Covid-19 such as reducing non-essential outdoor activities, travel and public transport caused a notable drop in noise levels in urban areas, the report notes. In 2020, noise levels in Mumbai during the Ganesh Chaturthi festival were observed to be around 28.5 decibels lower than the last two years.

  5. The report states that the frequency of wildfires is likely to keep rising. This is due to the increasing amount of greenhouse gases in the atmosphere and frequent 'fire weather conditions' like low humidity, strong winds and drought.

  6. Between the years of 2003 and 2016, there have been over 13 million fires across the globe, the report notes citing a 2019 article from Earth System Science Data, a scientific journal.  The same period saw roughly 423 million hectares of global land surface (farmland, pastures and natural vegetation) burning every year.

  7. Of the 13 million fires between 2003 and 2016, 9.8 million (77 per cent) occurred on savannahs and had the average size of 510 hectares. Agricultural fires were noted to be 1.6 million (13 per cent) with the average size of 340 hectares. Fires caused due to deforestation numbered 0.9 million (seven per cent) during this period and spread across 380 hectares on an average.

  8. Around 0.2 million fires occurred in boreal forests – spanning across Canada, China, Finland, Japan, Norway, Russia, Sweden and the United States – and had the average size of 540 hectares. Temperate forests saw 0.18 million (one per cent) fires having the average size of 410 hectares.

  9. The report states that phenological shifts are a visible consequence of global changes in temperatures. Different organisms respond to different ‘environmental drivers’ and thus it is impossible for all species to shift their development cycles at the same rate, or in the same way. This can cause ruptures in the predator and food dynamics eventually affecting entire ecosystems.

  10. Genetic changes in different species to adapt to shifting phenologies can be considered a ‘microevolution’, the report states. However, this rate of change is too slow compared to the speed of climate change.

    Focus and Factoids by Sowmya Vaidyanathan.

    PARI Library's health archive project is part of an initiative supported by the Azim Premji University to develop a free-access repository of health-related reports relevant to rural India.


Francesco Aletta, Andrew Dowdy, Luke Purcell, Sarah Boulter, Livia Carvalho Moura and Marcel E. Visser


United Nations Environment Programme, Kenya


17 Feb, 2022