By Laura Watson
Coronavirus is on all our minds right now – but what does our changing climate mean for the future of outbreaks?
Disease incidence and climate change
We have known that climatic conditions affect disease spread throughout human history. Civilisations as early as the Romans knew to retreat to hillsides during the warmer summer months, as malaria was endemic to the lowland areas during the warmer season. Climate change is likely to change the pattern of transmission for all kinds of diseases. For example, some pathogens may no longer be able to survive in certain locations, while they may become more prevalent in others. The Wildlife Conservation Society has identified 12 diseases which are likely to spread and get worse with climate change, including cholera, Ebola, plague and tuberculosis.
Disease spreading vectors like mosquitoes have optimal climatic conditions at which they survive and reproduce. This means that climate change might expand their range to include a much larger geographic area. Amplified seasonal patterns could also put areas at risk for longer portions of the year.
Human exposure to waterborne diseases could also rise as climate change amplifies the contamination of water supplies, as extreme weather events such as hurricanes increase, and sea levels rise. There are also links between increasing prevalence of diseases and ocean warming (such as red tide disease, caused by toxic algal blooms) and increased precipitation in certain regions (such as rift valley fever, and Hantavirus pulmonary syndrome).
People could also become more vulnerable to disease as the climate changes, as the health impacts of increased temperatures (such as increased stress) take hold.
The following two case studies illustrate the effects of already occurring climatic changes.
The West Nile Virus
West Nile Virus is a vector-borne disease originating in the West Nile region, transmitted by mosquitoes. It was first reported in around 1937, with human outbreaks reported intermittently since then. Transmission of the disease is impacted by weather conditions, and climatic conditions (temperature, precipitation, humidity and wind) are driving the expansion of the range of the disease’s mosquito vector, and therefore the geographic area affected by the disease.
Recent trends in increased rainfall and ambient temperature, as well as changing migration patterns of bird species have meant that the disease has migrated further north to the USA, Southern Europe and further south to Australia. The first case in the USA occurred in 1999, in New York City. Since then, it has spread across the country, with a reported 39,557 cases of the disease in the USA as of 2013, and only 4 states not reporting a case in 2018.
Climate change has been a key factor here for two reasons. First, increased temperatures correlate with increased viral replication rates, population growth, and transmission. Secondly, increased precipitation and flooding correlates with increased mosquito abundance, due to the use by the insect of stagnant water as a breeding ground. These trends are likely to continue, and the range of the vector and disease will continue to increase, meaning that monitoring of this (and other vector borne diseases like malaria and Zika) is crucial.
Cholera is a waterborne bacterial disease which is likely to worsen with climate change. Its spread will be greatly affected by climate change as temperatures warm and precipitation levels rise, because cholera outbreaks, while sporadic, tend to occur in regions associated with higher temperatures and rainfall. In these conditions, water borne diseases can spread inland and thus into more densely populated areas. While there is as yet no clear understanding of the nature of the link between cholera and climate change, it is clear that with more weather extremes, cholera spread and incidence will be affected.
As well as the contamination of water supplies, the abundance and distribution of cholera is affected by sea surface temperatures, ocean currents and weather changes. It has recently been demonstrated that warming seas, a key impact of climate change, are linked to an increase in the presence of cholera bacteria in Europe and the USA. Overall it is clear there is a link between cholera and climate change – and like West Nile Virus, this could affect all of us.
What does this mean for the future?
While some diseases show clear links to climate change, the recent Covid-19 pandemic so far has not. This shows that not all diseases will necessarily become more prevalent as the climate changes. However, it is clear that monitoring, especially of vector borne diseases, remains crucial to understanding what the future will look like. Covid-19 has shown us that there are many diseases in the natural world which are currently unknown to humans. We must act urgently on climate change to lower the pressure on natural systems and to prevent dangerous future outbreaks.
Throughout Hilary term, the OCS blog was busy writing articles each week that related to the theme of all the Monday events on our term card! For each week there is an event summary, an article that tells you “what you need to know about…” a key climate-related issue, as well as a longer analysis piece.
Addressing climate change law to green finance, the articles cover a range of disciplines. We hope you use your spare time to have a read of some of the articles you might have missed!
Climate change law
Women and climate change
Growing a green economy
The state of the climate
Individual vs systemic action
By Emily Passmore
At the beginning of the year, it was easy to believe that 2020 would only see the zero-waste movement get stronger. After all, in the UK, 2019 saw commitments from ever more high street retailers, including major supermarkets such as Tesco and Morrisons, to cut down on their plastic usage. Furthermore, polling suggested half of Brits would be happy to pay more for a product if its packaging was eco-friendly. A similar pattern emerged globally, with Canada aiming to ban single-use plastics by 2021, and Peru banning single-use plastic at heritage sites.
Progress may have been slow, perhaps even dangerously slow, but progress was being made. In the time of coronavirus, that is no longer necessarily true.
The zero-waste movement strives towards a circular economy, where (almost) everything is reused rather than disposed. This means refillable packaging, repaired clothing and--for dedicated proponents of the lifestyle--a year’s worth of rubbish fitting into a single mason jar. But coronavirus can be spread through tiny droplets released from coughs and sneezes, and if a surface is contaminated by these droplets, anyone touching that surface is at risk. Reusable goods and containers might be handled by members of different households, and so are a clear example of potentially infected surfaces which could help spread the virus further.
Is it justifiable to continue promoting reusable goods during this pandemic? For the high street, the answer appears to be no. Schemes allowing customers to bring their own cups at stores such as Pret A Manger and Starbucks have been suspended since the early stages of the pandemic. This week, the US state of New Hampshire even banned the use of reusable shopping bags, a reversal of the usual trend towards banning single use plastic bags.
However, it is not clear just how necessary these steps are, given that an alcohol-based disinfectant will inactivate coronavirus within a minute, eliminating the risk posed by reusable goods. On the other hand, this process is itself likely to create waste, considering the environmental harm that can be caused by chemical production, as well as the fact that disinfectant tends to be packaged in disposable plastic containers. Moreover, this process requires a level of personal responsibility--it’s far from guaranteed that everyone would remember to disinfect, or more importantly, that everyone has access to the correct equipment to disinfect with. Single use plastic does not pose the same challenge.
It also does not guarantee sterility though. Plastic is handled throughout the production process, by an undetermined number of unknown people. Thus, it would be best practise to disinfect single use bags as well--especially as recent studies suggest Covid-19 can remain stable on plastic for up to three days. No similar research has been conducted on reusable bags, so it is impossible to truly know if the bans are warranted.
Nevertheless, single use plastic projects the illusion of sterility – and in a crisis where so much is uncertain, this should not be dismissed out of hand. Although regulations banning reusables may not be fully supported by scientific evidence, decisive regulation could help to quell public panic.
But is this a fair trade-off? The pandemic will end, and when it does, decisions such as the bans on reusable bags could have a lasting impact, stalling progress towards a circular economy. Some right-wing think tanks certainly seem to have this possibility in mind. Bans in the US were preceded by a lobbying campaign by organisations including the Manhattan Institute and the Competitive Enterprise Institute. Both groups accept money from fossil fuel companies, and both groups misrepresented the scientific research in their lobbying efforts. It doesn’t seem outlandish to suggest they may be more concerned with turning the tide on environmental policy than with public health.
This highlights the main issue the pandemic raises for the zero-waste movement: environmental concerns must take a back seat to urgent public health issues to some degree, but it is unclear exactly how much they should be discounted. Take clinical waste. Hospitals in Wuhan, the site of the first outbreak, generated six times as much waste at the peak of the virus compared to normal operations. The daily output was about 240 metric tons, about the weight of a blue whale, and a whole new waste plant had to be built to process it. But reusing medical equipment is impossible, and saving lives is clearly far more important in the short term than reducing waste production.
Single use bags do not carry the same importance--but should we not accept some uncomfortable policy decisions in the face of this public health emergency? To some degree, yes. But there is evidence that opponents of the environmental movement are using this moment to further their aims. A complete abandonment of the principles of the zero-waste movement seems an overreaction, and tactically unwise. Containing coronavirus must be the principal concern at the moment, but eventually, a vaccine will be developed and it will cease to be a concern at all. There seems to be no reason to renounce a zero-waste, circular economy as a goal to be strived towards, and no scientific backing to the suggestion that reusables are categorically less sterile than single use items. Thus, while coronavirus is undoubtedly a challenge to the zero-waste movement, as long as proponents take a compassionate but evidence-based standpoint throughout the crisis, it need not be the end of it.
OCS Media Team
The latest in climate science and policy from the OCS team.