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Global tipping points: Climate change and the coronavirus

Emil J. Bergholtz is a professor of theoretical physics at Stockholm University. Nele Brusselaers is an associate professor of clinical epidemiology at Karolinska Institute. Andrew G. Ewing, is a professor of chemistry and molecular biology at the University of Gothenburg and a member of the Royal Swedish Academy of Science.

An increasing number of experts are saying, “We have to learn to live with COVID-19.” However, as scientists, we see this is a fundamentally flawed idea — and one we have not chosen to follow with other similarly dangerous pathogens.

Similar arguments have been successful in the past, like claims that we must learn to “live with climate change.” And the COVID-19 debate is going in the same direction to those surrounding climate, albeit much more quickly.

Both these approaches have the same components: They sound reasonable and realistic at first, but they obfuscate that there is an alternative, and they do not account for nonlinear feedback loops — meaning further changes that are driven by the change itself, exponentially perpetuating a chain of cause and effect — thus the resulting assumptions are far too simplistic.

Economists often embrace such short-term ideas. For example, William Nordhaus, the 2018 Economics Nobel winner, had suggested that an increase of the Earth’s temperature by 3.5 degrees Celsius until the year 2100 would be optimal — the right balance between economic growth and climate protection — and based on this, he worked against climate action, which he finds too costly.

However, climate scientists have since shown Nordhaus’ estimate to be completely incorrect. Nordhaus’ calculations were linear, whereas passing tipping points like melted glaciers, changed ocean currents and deforestation, and their compounding effects, the amplifying feedback loops associated with each, would make it ultimately impossible to bring Earth back to normalcy. A 3.5-degree increase in global temperature might threaten our entire existence.

And just like the process of climate change, COVID-19 also has tipping points, in terms of the emergence of new, more transmissible virus variants, each of which lead to qualitatively fiercer challenges to humanity.

The recent appearance of the Omicron variant represents a new tipping point, with an R value significantly higher than the Delta variant and — equally worrying — signs of a lost political will to stop it. Underlying this is an assumption that the disease is not as severe. But this “linear” way of thinking is intellectually flawed, as it ignores the risk of other new variants, new tipping points and further feedback loops. Other variants that could cause more serious disease but do not spread as fast as Omicron can circulate at the same time — mutual immunity is not certain. But one thing does seem certain: Letting large amounts of infection circulate is like opening Pandora’s box. We should expect more unpleasant surprises to come. We have hardly seen the last variant.

When it comes to COVID-19, the issue of feedback loops emerge as the virus mutates due to random mistakes in the viral protein. The global mutation rate is dependent on the number of infections, and more infections result in more virus replication — hence a greater chance of mutation. And although mutations are mostly random, those new viruses that can propagate faster or are not as effectively cleared by the immune system — from vaccination or from previous infection — compete better, eventually taking over the population infection.

An irreversible tipping point we now face regarding COVID-19 is that, owing to more contagious variants like Omicron, sustainable non-pharmaceutical interventions, such as physical distancing or wearing face masks, are no longer enough to halt the pandemic. An even more serious tipping point would be a variant that is more virulent as well as more infectious. For example, a combination of the more infectious Omicron with the more virulent Delta could be catastrophic. 

Thus, the way forward is to suppress the virus to manageable levels while there is still time. Many in the West believe that almost everyone will get COVID-19, that there is no other option, despite several Eastern countries demonstrating that suppression does work. In fact, it has been convincingly shown that an elimination strategy entails superior outcomes in all respects: for health, the economy and civil liberties. Had all countries followed this strategy, we would have fared better and, with large certainty, ended the pandemic altogether by now. But with each tipping point, it’s getting harder to follow the elimination strategy, and herd immunity, a red herring underpinning the “flatten the curve” approach, remains a fata morgana — a mirage.

The other alternative is to wait for potentially better vaccines. But if we are to wait for vaccines, it must be the whole world or nothing. The first round of vaccines was developed and produced in record time; however, the concept of rapidly vaccinating the entire world before the vaccines wane has clearly proven impractical. And the race between vaccine development and virus mutation will become increasingly difficult to win. Giving vaccines that don’t completely stop infection to only part of the world will only allow new variants to emerge, and is likely to push us past a final tipping point, where it’s pointless to do something, where it makes sense to give up. But we are not there yet.

Both the COVID-19 pandemic and climate change are global in nature. Both are examples of the tragedy of the commons, with naive local and short-term optimization leading to a disastrous common outcome. But the obstacles are political, not scientific. Both can be managed with a coherent and science-based approach, yet this becomes more difficult with each tipping point passed.

For COVID-19, as is for climate, we must realize that the current approach is not sustainable. In each case, the challenge is nonlinear in nature, and passing a point beyond which the situation becomes qualitatively irreversible could be disastrous to current and future generations. 

At least for climate, we think we know some of the targets and dates where we will pass the tipping point of such irreversible change. For COVID-19 though, the tipping points are passed at random by the laws of evolution, thus they can occur at any time and place, with a probability proportional to the amount of virus circulating.

Though it may yet prove to be less virulent, the emergence of the Omicron variant, so close in time to Delta, is at best a strong warning that decisive action and elimination is needed. It is not yet time to give up. We need coordinated efforts across borders, and in addition to vaccination, we need to fully accept COVID-19 is an airborne disease and a plan to suppress transmission with clean air as previously done for clean water — with masks, ventilation and filters, as well as monitoring, testing and quarantine.

For both the pandemic and global climate change the question remains: Will we choose to act, or will we remain passive as we pass a final tipping point?



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