Most governments claim to accept the ‘climate change is real’ studies, but clearly act as though any threat is decades away in a distant future and thus either needing little real action during their time in power or is simply less significant than many other issues.
At the other extreme to this apparent complacency, are government statements that climate change represents an ‘existential threat’. The exact meaning of an ‘existential threat’ and whether all life on Earth or their term in office what would cease to exist, is no more than repeated claims that +1.5oC warming would be ‘catastrophic’ mean by catastrophic.
There are many contradictions between words and actions.
It does not take great scientific research to realise the planet will most likely reach +1.5oC warming by around 2026 and given steps to prevent reaching +1.5oC warming target 2050 or later, that catastrophe must surely now be inescapable? Even my research in 2021, could see that +1.5oC by 2026 was likely, and finally other people are also now reporting this same conclusion.
So, is what we are experiencing now, the ‘catastrophe’? The rise in temperatures is very real and is remarkably close to reaching a point described as ‘catastrophic’, yet even many of those claiming it will be catastrophic, do not appear to be panicking.
Yes, Al Gore was really not saying that climate change is inconvenient, but rather that we find the truth inconvenient. However, there are many who now accept climate as real, who seem to feel climate change is only inconvenient. Are they right, and climate change is more an inconvenience than a significant issue? Statements like “sea level rise of 3.5mm per year“, hardly sound scary.
This page catalogs not just sea level rise, but other potential consequences, and then looks at whether these consequences could result in an ‘existential threat’ and what level of existential threat that would be and what it would mean
Hopefully this will help provide a more concrete picture of the potential problems humanity may face, depending on the rate of global warming over the next few decades. Even for those who, like me, find ‘it will be catastrophic’ somewhat vague.
However, there are two limitations to giving answer which mean that only by tracking data and updating this page as more data arrives, will it be possible to provide a clear picture.
The first problem is that the outcome will depend on whether countries meet commitments or not. The best option is to assume is to assume all countries achieve their current commitments, but if symptoms of climate change accelerate, there is a strong hope that measure will also accelerate.
The second problem is that the planet is such a complex system that modelling even the impact of CO2 on temperate has been a challenge. Modelling all the possible flow on effects is even more complex, and it is not like we can run planet scale experiments.
In the end, all that can be done is look at the range of possibilities, but this page will be updated as information is collected.
At this time, the big surprise is that there is a potential threat to the existence of all life on Earth. When work on this page began, I believed that the worst outcome was a threat to how humans exit, not a threat of a slightly earlier end to the existence of ‘life as we know it’.
The Climate Threats: Inconvenient or existential?
Sea Level rises: Inconvenient for some, and existential threat to others.
- Sea levels are rising, but they have been way higher in the past.
This biggest different between sea level rise now and those of past millennia, is that us humans have homes in fixed locations, and even farming in fixed locations. Our system is fragile, and not designed to cope with change.
Lost homes, lives and livelihoods are among the worst impacts of rising sea levels.
And by 2100, up to 410 million people could be at risk from coastal flooding as the warming climate expands the ocean, causing sea levels to rise even higher. Building and development in coastal areas, driving the expansion of coastal communities, also puts more people at risk.weforum: Sea level rise: Everything you need to know
A quite thorough explanation of the causes can be found on the NASA page.
The good news sea level rise is much easier to measure than most impacts of climate change. If a year has more heatwaves, it could just be a hot year, but if the sea level has risen, it is rising, as there are no year-to-year fluctuations.
More good news is that there does appear to be time to move people, and to limit the extent of the problem, with the prediction of 0.4 billion people only applying by 2100.
Thermal runaway: A worrying positive feedback loop.
The most dangerous threat of all, and perhaps the hardest to predict, are positive feedback loops. As explained in this climate specific online lesson, positive feedback loops are where something causes more of itself.
A positive feedback loop is a situation where A causes B that causes even more of A. Despite the name, a positive feedback loop can have either positive or negative impacts but tends to lead things to extremes.Simplicable: 12 Examples of a positive feedback loop.
Thermal runaway is when increased heat causes something that causes more heat.
Consider artic permafrost:
The vast amount of carbon stored in the northernmost reaches of our planet is an overlooked and underestimated driver of climate crisis. The frozen ground holds an estimated 1,700 billion metric tons of carbon – roughly 51 times the amount of carbon the world released as fossil fuel emissions in 2019, according to NASA. It may already be emitting as much greenhouse gas as Japan.
Permafrost thaw gets less attention than the headline-hogging shrinking of glaciers and ice sheets, but scientists said that needs to change — and fast.CNN: How the climate crisis is transforming the Arctic permafrost
Underlying this threat is the base fact that Earth originally had over 10,000 time more CO2 in the atmosphere, and it has been being squirreled away, preventing the Earth from burning up as radiation from the Sun continually increases.
A lot of the original CO2 went in to making oxygen and fossil fuels, but not all of it. Some is stored in place that include the permafrost. Needing to have so little CO2 on a planet that naturally has so much more CO2 but has much of it is now buried, is like sitting on a bomb that could explode.
This example of thermal runaway:
- Rising temperatures causes increased melting of the permafrost, releasing more CO2 in the atmosphere.
- The release of more CO2 into the atmosphere causes temperatures to rise.
- Go to step 1.
Floods, and more feedback loops.
Overwhelming flooding has affected at least 27.7 million children across 27 countries worldwide, with the number of children affected by flooding in Chad, Gambia, Pakistan and northeast Bangladesh, being the highest in over 30 years.UN: 8th Nov, 2022: Over 27 million children at risk from devastating record-setting floods
These are the floods putting children at risk. In 2022, there were also floods in Australia, Death Valley, Kentucky, California, Southern China, and I stopped looking for now, but there are more, and there are in addition to many record floods in 2021 including those in Germany.
Unlike sea level rises, it is harder to be certain of a trend, as record do get broken, however while it is impossible to be certain any one record breaking flooding event is due to climate change, the probability of so many at once seems unlikely.
Further, there is clear reason why record floods would be expected.
For every degree Celsius that Earth’s atmospheric temperature rises, the amount of water vapor in the atmosphere can increase by about 7%, according to the laws of thermodynamics.NASA, Steamy Relationships: How Atmospheric Water Vapor Amplifies Earth’s Greenhouse Effect
The temperate has risen further than 1oC already, so there is to be expected 7% more water vapour on average, but as this is not distributed evenly, there will be far more than 7% extra water vapour in some areas. In fact at the same time some areas are experiencing record floods, others are experiencing record droughts.
Repeated floods make areas unsuitable for housing, and for crops, reducing the available land for these purposes, and like sea level rises, forcing some people to relocate, on a planet already overloaded with refugees.
Further, evaporation rates from flooded land are higher from the shallower water of flooded areas than from the ocean, which means more floods further raises water vapour levels, creating another positive feedback loop.
And even further, the increased water vapour is itself a greenhouse gas, creating yet another positive feedback loop:
- Rising temperatures causes increased atmospheric water vapour, which is a greenhouse gas.
- Increased water vapour acting as greenhouse gas causes temperatures to rise.
- Go to step 1.
Storms: Cyclones/hurricanes/typhoons and tornados.
So far, I see these as an economic cost, but not as an existential threat. I will revisit this section after further research.
With insect extinctions, we lose much more than species. We lose abundance and biomass of insects, diversity across space and time with consequent homogenization, large parts of the tree of life, unique ecological functions and traits, and fundamental parts of extensive networks of biotic interactions. Such losses lead to the decline of key ecosystem services on which humanity depends. From pollination and decomposition, to being resources for new medicines, habitat quality indication and many others, insects provide essential and irreplaceable services.Research paper: Scientists’ warning to humanity on insect extinctions
The extinction of other species, particularly of insects, the loss to humans can include a major loss of food production capacity.
The threat is that we could end up with planet able to feed only a much smaller population of humans.
More research to follow.
An Existential threat to what exactly?
There are multiple interpretations or levels of ‘an existential threat’.
The phrase can refer to a literal threat to humanity’s existence, but also to the danger that unchecked climate change can pose to our ways of life and place in the natural world.MIT Climate portal: Why do some people call climate change an “existential threat”?
The mildest interpretation is not that humans cease to exist at all, but that something ceases to exist, or at least exist in their current form. To quote more from the same source:
Even if humanity does reduce greenhouse gas emissions enough to stave off the worst effects of climate change—and learn to adapt to some warming that is already inevitable—Setiya says that climate change remains an existential threat to a host of human cultures, traditions, and languages. One example he gives is the Inuit peoples who are indigenous to Arctic regions, and whose cold-weather culture is under threat as the amount of ice in polar regions continues to decline. Residents of low-lying islands face an immediate, existential threat to their cultures as rising sea levels could submerge their homelands.MIT Climate portal: Why do some people call climate change an “existential threat”?
“Their entire way of life is going to be changed,” Setiya says. “And that is going to happen whether or not we get close to the kinds of temperature changes that threaten human extinction. Ways of life that have been stable for hundreds of years or longer will start collapsing.”
It seems already inevitable that some that some things will cease to exist in their current form. The only thing yet to be determined is the significance of that which will cease to exist.
Creating A Scale for Existential Threats.
I searched online for an existing scale, and although I did find one paper, it has some very serious errors, and overall, I found nothing with sufficient credibility to adopt. So, I am creating my own scale, which of course has no existing credibility either, but this scale will contain only my errors, rather than simply adding mine to an existing already flawed base.
Hopefully, through revisions I will reduce any errors.
The scale I have created ranges from existential threats that have already been realised, though to the worst possible outcome.
Level 0: Loss of some species, cultures, traditions and possibly languages.
The reality is with globalisation, some of these would die even without climate change, but climate change is already real, and is already causing extinctions, with at least one extinct species already.
There is also already sea level rise, although at this stage is minor. Level 0 is more about not reaching level 1 than anything else, as with the lowest threshold for an ‘existential threat’, we are already there.
Status: Already reached.
Level 1: Disruption of society, with a loss of over 10% of occupiable and/or farming land.
Several factors can contribute to loss of land:
- Sea level rises.
- Repeated flooding can make previously residential or rural land unusable.
- Insect extinctions may make some agricultural land non-productive.
A huge problem is that this would create an even larger displaced person / refugee crisis than exists already. This increased the likelihood of conflict and even wars, which limit the ability to reduce emissions.
Currently there are around 100 million people effectively seeking refugee status and entry into the USA Europe or other developed nations, and this is already placing a strain on political stability. Imagine that number becoming 1 billion.
Managing this number of displaced be an existential threat to global political stability.
Status: Probably by at the latest 2070.
Level 2: A significant reduction of the human population beyond 10%.
The Earth’s human population will peak, perhaps even prior to 2050, but declining birth rates take a long time to have an impact on pollution and a fall of 10% this century would require many deaths, most likely from starvations as a result of reaching a level 1 existential threat. This level of population loss would entire redefine entire nations and be an existential threat to many nations.
Status: Possible by 2080.
Level 3: Collapse of civilization, mass extinctions.
This level of disruption would most likely require a degree of thermal runaway, and temperatures at beyond +5.0oC relative to pre-industrial levels. Given the positive feedback loops such as with water vapour, this level could be achieved with a little as twice current CO2 level, or CO2 levels which alone would only add +2.0oC or +3.0oC
Even if the Paris agreement is successfully implemented, the planet could still heat up by 5 degrees Celsius, scientists warn. This “hothouse” climate would make parts of the world uninhabitable.DW: Domino effect could heat Earth 5 degrees
Sea levels would rise 10 to 60 meters (33 to 197 feet), flooding numerous islands and coastal cities such as Venice, New York, Tokyo and Sydney. Such major population centers would have to be abandoned.
Scientists call this a “hothouse Earth” climate scenario.DW: Domino effect could heat Earth 5 degrees
At this point, well over 25% of the global population would be displaced, and in reality, feeding even 10% of the current population would be a huge challenge.
There is a Wikipedia list of cities by elevation, and although the elevation of a parts of a city may higher than the city elevation, it becomes clear that most major cities of the world would be at risk.
This level is an existential threat to our current civilization, and frighteningly, some models predict this is exactly the outcome that would result from current emissions commitments.
Status: Possible by 2080.
Level 4: Extinction of humanity.
This would require temperatures to rise to +10.0oC from current levels, largely making the Earth uninhabitable for humans, with even large areas of the by that time precious, Antarctica, under the sea.
If temperatures rise by +5.0oC, would it lead to unlocking most of the CO2 trapped beneath permafrost? If so, then levels of CO2 levels that would initially trigger +5.0oC, would then trigger the release more CO2 from permafrost, lifting temperatures to +10.0oC even without further emissions by humans.
The cumulation of positive feedback required for this quite dire possible outcome, would result that climate change beginning to accelerate now it has passed +1.0oC and that acceleration would become noticeable by 2026. If that acceleration does happen, it is unimaginable that there would not be a far greater focus on addressing climate change.
The biggest protection from this outcome should be that we would see it coming.
Status: Maybe even by 2080. We just don’t know yet, but it is possible if there is too little response.
Level 5: Extinction of all complex life on Earth.
It is expected all complex life on Earth would become extinct even with human induced climate change somewhere between 25 million to 100 million years from now, due to the gradual natural increase in radiation from the Sun. If climate change result in the release of sufficient CO2, this event could easily arrive early. Even returning to the level of CO2 of the days of the dinosaurs, would be sufficient with the current level of solar radiation to raise water vapour levels sufficiently to push temperatures over 60.0oC, result in the end of complex life on Earth.
I have not seen calculations on the temperature needed to initiate a water vapour based a positive feedback loop that would produce this result. I will research further.
Status: More research needed.
Counterpoint: Humans are not the biggest problem.
Even without no humans, complex life has as little as 25 million years left.
Certainly 25 million years is a lot better than perhaps only 100 years, but it is almost certain humanity will survive, and still almost certain life will survive even if humanity does not. The risk of all complex life being eradicated by anthropogenic climate change becomes more acceptable when you consider that without humans, complex life faces a certain death sentence in around 25 million years. We live on a finite planet, that only supports complex life within a narrow window of time that is closing.
If left to nature, all life ends. It took 4 billion years before the Earth supported complex life, and that support will end quite soon, with Earth having supported complex life for only around 5% of the lifetime of the sun as a main sequence star, and able to provide the Earth with the energy needed sustain life.
While 25 million years is an extremely long time for humanity, in geological time, the end is near. During those 25 million years, the amount of complex life will slowly decrease, as it has been doing for the past 500 million years. Unless a species with the society evolutionary capability of humans can come to the rescue, life is doomed anyway.
Why can’t plants handle this?
Plants have always managed to be bring down CO2 levels in the past, why not this time?
I have heard it suggested that clearing of forests will mean there are not enough plants left, but this is untrue, as most CO2 was sequestrated even before there were land plants. Photosynthesis in the oceans alone was sufficient in the past. This does not mean land clearing is OK, as the emissions from land clearing are still a big part of the emissions problem.
Photosynthesis by living organisms provides a negative feedback loop, and a stable system:
- Rising temperatures causes accelerate plant growth, which reduces CO2 levels.
- Falling CO2 levels reduce temperatures, slowing the growth of plants.
- Lower levels of plant growth allow increased solar radiation to heat the planet.
- Go to step 1.
If emissions cease, then it is logical that plants should be able to counterbalance the positive feedback loops, as plants have managed this for billions of years. The Sun is sending more solar radiation than ever, and there is more trapped CO2 that there was prior to land plants, but the system was still working 1 million years ago, which in geological time is so short that this means it should still be able work. Once we stop the emissions. Oh, and we should have to kill off all grazing animals, although it would be better if the mix had far less cows and sheep and more other grazing animals.
Despite over 20 years of climate conferences, CO2 levels continue to rise unabated. It is possible that without the measures agreed and taken over recent years, the increase in CO2 levels would have been even worse, but so far it feels like there has been very little progress.
Global agreements so far provide not the slightest hope of showing a trend towards a global net zero emissions any time soon.
Yes, climate activists are dismayed, but governments see activists as one interest group, and may take some actions to keep this group happy, but that is in balance with actions to keep economists, business and the fossil fuel lobby happy.
It seems that at a government level, that climate change is a significant threat is seen as just one opinion, not necessarily to be taken seriously. There is a general acceptance that:
- Greenhouse gasses can warm the planet.
- Burning fossil fuels can increase greenhouse gasses and thus raise the temperature.
What does not seem to be accepted by governments, is that, is that climate change is beyond just being inconvenient.
How quickly the perception changes to ‘it really could be an existential threat’ will largely determine how bad things get.
- 2022 Nov 16: First published.