Satellite images and shocking photos have both made the rounds to portray the drop in atmospheric pollution and greenhouse gases triggered by the lockdowns. But, as Katherine Cheng explores, it’s also important to tell a story.

As the novel coronavirus spreads, cities, regions and nations all around the world have decreed lockdowns with varying levels of severity. Without cars and factories, some of the most polluted areas in the world are now showing rapidly improving atmospheres. And satellites have taken note.

Publications have been linking public health measures to the environment, making extensive use of satellite images of pollution levels before and after the virus locked us home. This is a way to visually showcase how the decline of human activity has decreased pollution. But to what extent are satellite images useful to attain this goal?

Eye in the sky

Satellite images of tropospheric NO2 density over China

Satellite images reflecting pollutant drops in Wuhan, China

NASA Earth Observatory images by Joshua Stevens, using modified Copernicus Sentinel 5P data processed by the European Space Agency. 

Now scroll back up and check the image at the top of this post. Does it look familiar? Chances are you have seen either that or one of the images below multiple times in the past month as you were flipping through headlines at home.

One of the most commonly shared images came from NASA’s Earth Observatory. The shot shows how nitrogen dioxide (NO2) density has dropped after lockdown measures were put in place. NASA Earth Observatory images have been used over 25 billion times since they were first published and featured on March 2.

In an interview with Carbon Tracker, Dr. Simon Evans, the deputy and policy editor of Carbon Brief, spoke about how “there have been some really widely shared and very dramatic satellite image comparisons making the rounds. At the very start, it was the images from China which were the first ones that took off in terms of reach, and subsequently there have been lots of similar visualizations.”

Satellite Images: What’s it Good For, Anyway?

Satellite images of NO2 levels over China before, during and after the Chinese New Year holiday

Average atmospheric levels of NO2 (molecules per centimetre squared) measured by the NASA OMI instrument.

Speaking about the effectiveness and power of the pollution visualizations, Dr. Evans touched on two main strengths: the visualization of the invisible and the global aspect of the images.

“Greenhouse gases such as CO2 are invisible, which make it very difficult to visualize, and that’s one reason why air pollution visualizations are so useful… I’ve also seen some great side-by-side images of places with pre- and post-lockdown comparisons, such as the images of clear skies over Delhi or LA. However, these photos are tied to a particular place whereas satellite images show the impact over different countries on a global scale, giving you an immediate sense of ‘wow, this is big’”, he said.

In a 2016 Carbon Brief interview, Dr. Simon Keogh, head of the satellite data products and systems group at the British Met Office, already pointed this way, but hinted at the lack of coverage for sparsely populated areas.

“Satellites give us this unrivalled global view of what’s happening everywhere. The biggest problem with other kinds of measurements is the coverage: what’s happening in the southern oceans, what’s happening in the southern hemisphere generally in sparsely populated areas where nobody’s making any observations.”

But What About Photos?

Photography of two persons dragging a stretcher where a Covid-19 patient lies.

Photography of polluted and clean skies in New Delhi, India.

Screenshots of articles from ProPublica (April 13, 2020) and The Guardian (April 11, 2020)

At the same time, research has shown the importance of using photos to capture the viewer’s attention. A recent 2019 study by the Centre for Media Engagement and ProPublica found that Facebook ads that used straightforward photographs instead of illustrated graphics performed better among both liberals and conservatives.

In 2015 National Press Photographers Association looked at professional photographs in comparison to user-generated content. The study, led by Sara Quinn, found that the most memorable photographs and those which held viewers’ attention the longest were those that told a compelling story. The best-performing images showed emotion, captured a genuine moment, and provided a unique perspective of the world through rare access.

One 41-year-old male participant explained that “if (a photo) draws you in, it’s connected to a story and it makes you want to learn more, that’s important.”

But can satellites do that?

The Power of Using Both

In maximizing the power of visual imagery, there is an opportunity for editors to consider both of these strengths in communicating global stories such as Covid-19 and climate change. As a 2017 study shows, pairing local and global impacts of climate change can be an effective way for the reader to relate to the article without reducing the scale of the problem.

For example, the use of satellite imagery to track the increases and decreases of nitrogen dioxide in the first three months of 2019 vs. 2020 was paired with before and after photos of air pollution and traffic in Iran in a National Geographic article. This allowed the viewer to understand the scale of the phenomenon while being able to see the ground-level impacts of the data in a more relatable manner.

Satellite Images of polution variations in China and Wuhan

Screenshots of National Geographic ‘Pollution Made Covid-19 Worse. Now Lockdowns are Clearing the Air’ article published on April 8, 2020

In an interview with Climate Tracker, Professor Regina McCombs, a lecturer and senior fellow in visual communication and photojournalism at the Hubbard School of Journalism and Mass Communication, highlighted the values of each type of image being used for a different purpose. It is important, then, to include both.

“The maps are able to measure the course of a time period with hundreds of data points, whereas photographs capture a single moment in time,” she said.

Professor McCombs also explained that it’s important that the article and captions are able to come together with the images to tell a whole story, as there were instances of outlets posting “the before and after pictures without any context.”

In all of the articles featured in this analysis, the authors have made the clarification that “Covid-19 is not a silver lining for the climate,” oftentimes quoting Inger Andersen of the head of the UN Environment Programme (UNEP) to tell a greater story beyond the images – but using the images to catch the viewers’ eye.

The importance of captions for images was also highlighted in the 2015 NPPA Study, as it was found that captions received 30% of the average time a viewer spent looking at an image and that a well-written (or even just longer) captions increased the chances that a photograph received attention.

So What Does This Tell Us?

The complex connections between Covid-19 and climate change and atmospheric pollution cannot always be easily translated visually. Budget restrictions, time limitations, access to photos, and now home-quarantine measures create barriers to the inclusion of relevant photos in publications, which is oftentimes quickly relegated to the back of newsrooms’ priorities.

However, the mindful consideration of photographs and data mapping is important as audiences are overwhelmed with the daily updates of bite-sized news and statistics. In the communication of global issues such as Covid-19 and the climate crisis, a balance between an emphasis on global scientific data and its connection to humans through both satellite imagery and real-life photography is vital to capture the interests and attention of readers worldwide.

Katherine Cheng

About Katherine Cheng

Visual storyteller and activist. Dedicated to supporting environmental photojournalists around the world. Tries to travel and be in forests as often as possible.