A recent study by the University of Cambridge reveals a mechanism by which climate change may have influenced the emergence of SARS-CoV-2 and its passage from animals to humans.
According to this work, global warming and the increase in greenhouse gases have caused changes in the vegetation of the Chinese province of Yunnan (as well as in Myanmar and Laos) during the last century. These modifications have allowed bats to extend their habitats and live in new territories. Its presence is associated with a greater number of coronaviruses.
The climate emergency and the zoonotic pandemic are a consequence of human activity, which causes environmental degradation. The Lancet medical journal has monitored and reported more than 40 global indicators that measure the impact of climate change on health. In a recent editorial, he highlights that the causes of the climate crisis and COVID-19 have common elements and their effects are convergent.
In its 2018 report, The Lancet already warned that if the reduction of greenhouse gas emissions is not accelerated, health systems could be overwhelmed to meet the foreseeable increase in the incidence of diseases that would occur.
Curbing the effects of climate change will help suppress the emergence and reappearance of zoonotic diseases. These are more likely due to intensive agriculture, international trade in exotic animals, and increased human encroachment on wildlife habitats, which in turn increase the likelihood of contact between people and pathogens.
The report concludes by stating that decisions made now must address both crises together to ensure the most effective response to each.
The reality of global warming
The highest historical frequency of extreme events that we are experiencing (such as the recent storm Filomena) is associated with the new reality of global warming on the planet.
The average temperature of the Earth is continuously rising because we have replaced the thin natural blanket of gases that stabilized the atmosphere with a duvet of gases. These are the product of the burning of fossil fuels (coal, oil, natural gas), generated for just over a century.
The world’s specialized scientific observatories have been measuring for years that the sustained increase in temperature especially affects the enormous mass of ice at the poles, which melts, and the vast expanse of water in the oceans, which evaporates.
Global warming has modified the gradients on a large scale, more or less stable, of temperature, pressure and salinity, causing climate change.
The past days of penalties added by the snow and cold storm brought by the storm Filomena have been conducive to some, including politicians, questioning climate change.
Of the various informative and simple proposals that are possible to help understand the difference between climate and meteorological weather, I like the one of a person (weather) who takes a long walk back and forth along a wide beach holding a dog (meteorological weather ) with an extendable strap. The person’s trajectory of events (weather) is nearly linear, consistent, and predictable. That of the dog (meteorological weather) arbitrary, chaotic and very little predictable. Both have a physical tie and close the cycle together.
The climate engine
The basic scheme of a heat engine consists of a hot source, a cold source and a fluid (gas-liquid) that is forced to cycle between the two sources subject to temperature and pressure gradients (differences).
The Earth receives thermal energy from the Sun, but its spherical shape, the daily rotation and the inclination (23.5⁰) of its axis with respect to the plane of the solar orbit makes the intertropical zone of the equator much warmer throughout the year and much less the poles.
When air is heated, it becomes lighter and rises leaving a depression. On the contrary, when it cools, it becomes more dense, descends and increases the pressure. Thus, in each hemisphere, the air in the lower layers of the atmosphere would move from the poles to the equator and in higher layers it would close the cycle by moving from the equator to the poles.
But the rotational movement of the Earth around its axis breaks this symmetry, originating in each hemisphere two intermediate zones of high and low pressure and deviating the direction of the winds as shown in figure 1. It is the general circulation of winds in the Earth’s atmosphere.
The oceans occupy almost two thirds of the earth’s surface and have a high heat capacity; they absorb most of the excess heat. Its density depends on the temperature and salinity, which in turn vary due to freezing, evaporation or the supply of fresh water.
The warmer and less saline waters move in superficial layers pushed by the winds. When they reach very cold areas and salinity increases, they precipitate to the bottom. In warmer waters, where the water softens, they ascend slowly completing a long cycle, as shown in figure 2. It is the thermohaline (or thermosaline) circulation that runs through the oceans, a highway that freely transports heat to distribute it throughout the planet.
When the bulbs heat up, affecting the poles to a greater extent, as we are doing, the temperature, pressure and salinity gradients vary, the general wind currents and the oceanic water highway are modified, the global climate changes, extreme events change. they multiply by land, sea and air and many ecosystems and species disappear.
Global warming and zoonoses
In the upper layers of the atmosphere above the Arctic, a kind of winter polar cap forms of icy air masses that rotate counterclockwise, which is why it is called a polar vortex.
When anomalous warming occurs in the Arctic, as has happened recently, the vortex expands. In this way, it surrounds with cold air and pushes the polar jet stream that circulates below and that can reach mid-latitudes, bringing waves of extreme cold to North America, Europe or Asia. The high humidity of the storm Filomena due to the warmth of the climate does the rest to cause the great snowstorm and cold that we have suffered.
Scientific data on global warming and its origin have widely referenced at least three consequences that affect the generation and spread of pandemics:
- The deterioration of habitats, ecosystems and the extinction of species of animals and plants.
- The melting of glaciers and permafrost, which releases dangerous pathogens that are in permanent hibernation.
- The high pollution of the atmosphere, which affects the greater spread of viruses and mortality.
In May 2019, the UN Environment Program presented the report of the Intergovernmental Science and Policy Platform on Biodiversity and Ecosystem Services (IPBES), prepared by 145 experts from 50 countries and based on the systematic review of about 15,000 scientific and governmental sources.
The co-chair of the evaluation, Professor Josef Settele (Germany), stated:
“Ecosystems, species, wild populations, local varieties and classes of domesticated plants and animals are shrinking, deteriorating or disappearing. The essential and interconnected web of life on Earth is getting smaller and more segmented. This loss is a direct result of human activity and constitutes a direct threat to human well-being in all regions of the world ”.
The interesting report of the World Wide Fund (WWF) Loss of nature and pandemics affirms that climate change amplifies the threats that affect biodiversity, favoring the spread of viruses and bacteria, or their vectors. In well-preserved habitats, viruses are distributed among species and do not affect humans as there is a balanced relationship. In addition, the report points out that the melting of the planet releases viruses of different types that have been retained for centuries.
A Harvard University study shows that more people die from COVID-19 when they have been exposed to high levels of fine particle pollution, which are mainly generated by fossil fuel vehicles.
There is only one vaccine to bend the curve of global temperature rise: stop the production and burning of fossil fuels as soon as possible. The damage produced is enormous and there is less and less time to act.
