Climate Change — A Glimpse Into the Science of Cataclysm (Part IV)
An Explanation of What the Scientists Told Us Decades Ago but Which We Chose To Ignore Anyway (Yeah, Very Bad Idea)
This series on climate change has FIVE parts.
In Part I of this series we were introduced to the essence of the unfolding climate change crisis and saw how its greenhouse gas scientific underpinnings could be traced back more than 150 years.
In Part II we looked for clues as to what we might expect to happen in the coming decades based on what has happened in times past when the concentration of greenhouse gases in the atmosphere was similar to what we see today.
In Part III we considered the implications of the prediction that we will shortly commit ourselves to a world that is eventually entirely free of ice — a state of affairs not seen on this planet for the last 14 million years.
In Part IV (this page) we look at the world’s current (highly inadequate) response to the climate crisis.
THE PARIS AGREEMENT: HUMANITY’S LAST HOPE, OR CLIMATE MIRAGE?
If it seemed there was any real prospect that burning fossil fuels might lead to a dangerous destabilization of the climate we have grown to depend on for the 10,000 year period leading back to the end of the last ice age you would think those in a position to limit human-caused greenhouse gas emissions would have done so.
After all, it is a big deal when the fresh water supplies go away, the crops fail, fertile landscapes turn to desert, the oceans turn acidic, local temperatures rise enough to make some parts of the planet uninhabitable, and species begin dying off in droves (more than half are forecast to go extinct by the end of the century).
But taking decisive action has not turned out to be what those in power do when faced with a crisis which might not arise for several decades. Instead, history shows they punt the can down the road, rather than take any responsibility on the issue. Let the next generation deal with it — that seems to have been the mentality thus far, while the response has often been denial of the existence of any threat to the climate at all.
We have known since at least the 1980s that by the middle of the 21st century the global average temperature would rise by as much as 3–5 degrees Celsius over pre-industrial if we continued “business as usual” and made no effort to wean ourselves off greenhouse gas-producing fossil fuels.
Knowing this, we should have begun to reduce our fossil fuel dependence out of a sense of caution. Instead, since 1980 we have dialed up our ongoing use of fossil fuels globally by more than 60 percent.
All along the way scientists have stepped forward to point out the potentially cataclysmic error of this approach. At every turn they have been met with skepticism from people with no training in science who nonetheless believe they are smarter than the scientists. Or at the very least morally superior, defending the rights of the populace to grow their country’s GDP with the assistance of cheap fossil fuels without interference from those whose “unproven theories” of global warming and calls to switch to clean sources of energy might hamper a century-long streak of wealth-building success.
It is hard to argue that the skeptics have not, so far, been very successful with their efforts.
Their strategy of muddying the waters with claims that climate science is “unsettled”, and needs further consideration, has largely been responsible for keeping the world from responding to the mushrooming threat of climate change.
But there comes a point when it becomes increasingly difficult to deny that “something” is happening today which looks an awful lot like what the climate “alarmists” predicted would happen if we waited long enough. This is no surprise to anyone who has studied physics. If you keep adding energy to a system, sooner or later it changes state. It does not just sit there as though nothing was happening to it. It reconfigures itself.
The climate of planet Earth is now reconfiguring itself, possibly at the fastest rate in its history.
In 2015, in recognition of the fact that many countries are now incurring heavy economic, environmental, and socio-economic burdens due to changing climatic conditions and rising global average temperature, 195 countries got together in Paris to hash out an international agreement to stem the damage. Parties to the Paris Agreement agreed to finally take action to “decarbonize” their economies so that each nation can begin reducing its contribution to greenhouse gas emissions.
The stated goal of the agreement [Ref. PARIS2015] is:
● To keep global temperatures “well below” 2.0 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial times and “endeavor to limit” them to 1.5°C● To limit the amount of greenhouse gases emitted by human activity to the same levels that trees, soil and oceans can absorb naturally, beginning at some point between 2050 and 2100● To review each country’s contribution to cutting emissions every five years for purposes of accountability● For rich countries to help poorer nations by providing “climate finance” to adapt to climate change and switch to renewable energy
The international scientific body which guides the participating countries in this endeavor is known as The Intergovernmental Panel on Climate Change (IPCC). It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988.
Not everyone agrees that the climate science used by the IPCC is state of the art. The reports it publishes tend to err on the conservative side and its predictions for climate change often fall short of what we see happening in the real world (the rate of disappearance of Arctic sea ice being a good example). But the IPCC climate status and forecast reports are the most widely agreed upon scientific proclamations about the realities of climate change.
So what do they tell us about where we are headed in the years ahead?
Perhaps the most important and easiest-to-remember visual to come out of the IPCC reports is this graph of expected temperature rise according to several possible future scenarios which involve different rates of fossil fuel consumption by human society as a whole:
To understand this graph we need to introduce the concept of a Representative Concentration Pathway or RCP. This is just the IPCC’s fancy terminology for describing different ways in which fossil fuels might be burned throughout the remaining century such that they result in a given final amount of greenhouse gases in the atmosphere.
To each RCP scenario is attached a number which represents the amount of radiative forcing introduced by that final amount of greenhouse gases.
For example, RCP8.5 corresponds to our current path, the “business as usual” scenario, wherein we take no measures to reduce our dependence on fossil fuels. At the end of the century the pursuit of RCP8.5 results in a radiative forcing (heating) of 8.5 watts per square meter and an atmospheric CO2 equivalent of about 1370 ppm.
The corresponding rise in temperature for an RCP8.5 pathway is about 3.2 to 5.4 degrees Celsius. The uncertainty in the final temperature reflects the fact that these forecasts are based on a large number of climate model simulations and it is only by looking at the aggregate forecasts that we gain some confidence in the likely evolution of the underlying system (i.e. the real world climate).
The IPCC settled on 4 representative pathways the world could dwell on as it tried to decide how to respond to the coming climate crisis.
The RCP8.5 pathway defines the upper limit of madness — the path we are on now. No rational person thinks we will continue to follow it all the way to the end of the century. There is also a reasonable argument to be made that the response of the climate to business as usual may even preclude this (meaning that an abrupt runaway climate response wipes out organized human society decades before we reach the year 2100 and brings fossil fuel burning to a swift end).
It is hard to imagine that as crops fail and coastal cities begin to submerge by the middle of the century we will keep on denying the evidence of our own eyes. On the other hand when scientists pointed out in the 1980s that continued use of fossil fuels could cause unmitigated climate disaster on this exact timeline they surely would not have expected the world to sail on with business as usual for the next three decades, accelerating our consumption of fossil fuels with every passing year.
So that you can better understand the goals of the Paris Agreement and the terminology employed to describe our options in the years ahead we will have a brief look at each of these “representative pathways”.
With any luck you will be hearing a lot more about these in the years ahead:
RCP2.6 is the ideal scenario, one in which everything that could possibly go right does. All the nations of the world undertake a World War II-scale industrialization effort to combat the greatest challenge human civilization has so far faced. As fast as they possibly can, they fully switch from fossil fuels to clean energy programs.
But recognizing that this is not enough to restore the climate to its former stable state they invent technologies to suck CO2 directly out of the skies on an enormous scale and commit to this goal for as long as it takes (possibly centuries). The temperature continues to rise for a decade or two, but then it eventually comes down to about 1.5°C above pre-industrial by the year 2100 — a world warmer, but not too different from the one we live in now.
Unfortunately this scenario, based on what many scientists regard as wishful thinking and non-existent pie-in-the-sky technology, is not presently regarded as realistic or achievable. Not by anyone sufficiently familiar with the scale of the challenge.
The RCP2.6 / 1.5°C scenario represents where we might have got to if we had taken the global warming threat seriously (and decided to do something about it) when it was presented by scientists in the 1980s as the climate disaster in waiting it is turning out to be.
The RCP4.5 scenario is closer to what the signatories of the Paris Agreement are likely to pursue in the long run, when they finally get serious about their commitment to the preservation of a world which supports the continued existence of human life (though the final global temperature is not guaranteed to support it).
Note that, according to James Hansen, 4.5 watts per square meter implies the eventual melting of all ice on Earth and sea level rise in excess of 200 feet — the same response that would have been brought about in the higher RCP scenarios 6.0 and 8.5, but at a much slower rate.
If the signatories hold to this pathway significant progress will be made in switching from fossil fuels to clean energy programs. To dampen the effect of our failure to switch away entirely from greenhouse gas-producing sources of energy we will plant billions upon billions of trees in an attempt to pull some of the offending gas back out of the skies. The temperature will rise to (hopefully) no more than 2.0°C by the end of the century.
There will still be undeniable damage to the climate but we may get lucky and find it is manageable (at least in the short-term). This assumes that global temperature tops out in the lower half of the projected range of 1.7°C to 3.2°C and does not push the world into a state of runaway global warming (discussed later in this article).
On the one hand there is likely to be widescale acknowledgement that we have skated up to the line but averted short-term disaster. On the other there will be the naysayers who decry all of the investment in infrastructure and call for further rounds of investment to be abandoned going forward — because there was never really a problem in the first place, their proof being that humanity still exists.
Currently (in the year 2021) it has been 6 years since the drafting of the Paris Agreement and there has been no discernible swing away from the business as usual path despite the pledges of the signatories. Still, many of these people have children and grandchildren who will inherit the mess their elders are poised to leave behind if their efforts to implement the Paris Agreement fail. So there is still hope for progress in the years ahead.
RCP6.0 is the pathway the most pessimistic climate scientists believe will be followed. It is characterized by a lack of will to make difficult political decisions at home. Considerations for short election cycles outweigh moral duty to future generations. Yet SOME progress is made at the city and state level, where local governing bodies act independently of short-sighted national policy makers beholden to corporate interests, especially those financed by the fossil fuel industry.
We continue to burn fossil fuels to the point where, by the end of the century, greenhouse gas concentration in the atmosphere has more than doubled from the 410 ppm of today to 850 ppm. Temperatures continue to rise and go beyond 3.0°C.
At this point the climate during the summer is unbearable across much of the globe. Parts of the planet, including the American Southwest and the eastern provinces of China, are not survivable outdoors for more than a few hours. Crop failure is routine. For large portions of the planet local populations are subject to sporadic famine and severe water shortages.
Now that it is impossible to deny the severity of the problem and our failure to adequately address it governments will see bloody rebellions. When citizens understand that with each passing year not only their children’s prospects for survival are diminishing, but their own prospects as well, they will want to take their anger out on someone.
More importantly, it is unlikely that global temperature can be stabilized above about 2.0°C and the runaway global warming scenario will be an ever-present threat that looms large in the minds of every informed citizen on the planet. When there is no future to build towards societies become unstable, chaos widespread.
At this point I tend to imagine that with each extreme climate event which claims the lives of tens of thousands of citizens the most vocal of the climate denialist political leaders (though it is hard to believe any still exist by this point) will be dragged into the streets and executed to the roaring cheers of the crowd. Executives of fossil fuel power companies will be forced to build private fortresses to protect themselves.
The “do nothing” RCP8.5 scenario is too bleak to speculate about. By the time we reach 2100 we more than triple the amount of greenhouse gases in the atmosphere today.
If the temperature continues to rise above 4°C it is hard to see how organized human societies can continue to hold together, let alone keep burning fossil fuels. But long before we get to this point it is likely the warming will have triggered positive feedbacks in the Earth’s natural carbon cycle and caused runaway global warming (which is exactly as bad as it sounds). All sentient life on Earth perishes within a time span of a few short years.
Note on RCP scenarios:
When considering these RCP scenarios it is worth keeping in mind that they assume a controlled management of fossil fuel burning activity (and greenhouse gas release) throughout the century.
The IPCC hews toward a more conservative view of global warming futures. These are scenarios in which unfactored positive feedbacks in the environment that might cause an escalation in the release of natural greenhouse gases (from, for example, rapidly thawing permafrost) DO NOT take place and unexpectedly push, say, an RCP4.5 pathway into something that more resembles an RCP12.0 pathway, or worse.
Unfortunately there is no guarantee that any pathway other than the unlikely RCP2.6 pathway will not lead to unexpected and unwelcomed surprises.
This is one of the reasons RCP2.6 is held out as the primary objective of the Paris Agreement. But runaway warming is rarely ever acknowledged publicly as a possible outcome of failing to act sufficiently swiftly to curb greenhouse gas emissions.
Nonetheless, it is a possibility that has been taken seriously by climate scientists for some time now and which deserves not to be ignored.
SANITY CHECK — COULD THOSE WORRISOME TEMPERATURE PROJECTIONS BE WRONG?
Before we discuss the implications of runaway global warming let us pause for a moment and consider the possibility that maybe the scientists have got it wrong…
Skepticism is the logical response to a prediction of what amounts to the end of the world for us.
If ecosystems, agricultural production (food), and fresh water supplies are projected to crash at around 3 degrees of warming and bring human civilization down with it then a reaction of alarm is natural. But so too is a healthly dose of skepticism.
Could the scientists have got it all wrong? Could there be a fundamental mistake somewhere in their interpretation of everything known about the way the planet will warm in response to the greenhouse effect?
My belief is that it is hard to see how this could be.
The basic prediction is that if nothing changes in the way we extract energy from fossil fuels global temperatures are going to rise between 4 and 6 degrees Celsius before the end of the century.
So, I think it is natural to ask whether there is any way we can verify this prediction without having to spend years studying for a degree in climate science.
And there is.
We can do another of those “back of the envelope” calculations which ought to be able to tell us whether the claims of the scientists are credible.
I am going to show you how to perform a very crude calculation of global temperature rise using nothing more than basic physics. I contend that a diligent high school student could perform this calculation in science class and get the same result.
The calculation of the expected temperature increase is going to rely on three pieces of information:
● The amount of energy it takes to raise a kilogram of water by 1 degree Celsius● The amount of water available in the oceans for warming● And the rate of energy transfer into that water caused by the greenhouse effect
Before I get to the simple calculation, let me explain the assumptions behind the simple model I am about to use.
We have already discussed the size of the radiative forcing (warming influence) we are experiencing today due to the greenhouse effect. According to the Environmental Protection Agency it is around 2.3 watts per square meter, for each square meter of the planet. So we know the total amount of energy currently being accrued by the planet per decade. It is roughly 370 billion trillion Joules (we did a per day calculation of this accrued energy in Part III).
Where does all that energy go?
The answer is most of it ends up in the ocean. Ninety three percent of it according to the climate scientists. Remember, 70 percent of the planet is covered in water, and energy absorbed on land is typically reradiated back into the atmosphere as infrared energy which then has a good chance of finding its way into the ocean. So let us simplify and assume all that decadal (per decade) energy goes into the ocean to warm it.
By how much does the ocean warm?
What we are after here is to learn the final surface temperature of the ocean. This is relevant because the ocean surface will be in constant contact with the atmosphere. So to a good approximation, it will share the same temperature. If the ocean surface increases by one degree then so too should we expect the atmosphere to warm by about the same amount.
Now comes the bit where we need to put on our oceanographer hat and ask what fraction of the ocean is warmed by the decadal energy being poured into it? Is it all of it?
As it turns out, no.
The ocean does not warm the way a pot of water on the stove does when you place it above a source of heat. In the case of the ocean the energy is applied from the top.
According to the National Oceanic and Atmospheric Administration (NOAA) it is only the water in the upper 200 meters of the ocean that mixes with the surface and maintains a uniform temperature (of roughly 13 degrees Celsius today). From a depth of 200 meters on down the temperature plunges quickly until it reaches about 4 degrees Celsius at 1000 meters depth (as shown in the following NOAA graph).
This topmost layer of ocean water is known as the epipelagic zone.
Energy transferred into the epipelagic will eventually fold into the lower water layers of the ocean, but the time span involved is of the order of centuries. If we wish to know how the surface water will warm in the following decades then we should concentrate on the epipelagic zone which contains approximately 71 thousand trillion cubic meters of water, or a thousand times as many kilograms of water.
The energy required to heat this amount of sea water by one degree Celsius (which is about 4,000 Joules per kilogram) is approximately 290 billion trillion Joules.
If we divide the decadal energy added to the ocean by this amount of energy required to heat the epipelagic by one degree we arrive at the decadal (per decade) temperature increase.
It comes out to 1.3 degrees Celsius.
So this very crude calculation of the amount of global warming we can expect to see in the years ahead is not miniscule. Our rough calculation which ignores any ocean mixing, and ignores any melting of the ice sheets over Greenland and the Antarctic (both of which would slightly lower the overall temperature rise) predicts more than a 10 degree Celsius temperature increase by the end of the century.
The IPCC is predicting about half that temperature rise by the year 2100 and now the numbers really do not look crazy at all.
RUNAWAY GLOBAL WARMING — IF NOT AVOIDABLE, THEN HOW SOON?
If you look back (in Part II of this series) at the sea sediment and ice core graphs showing climate variability for the last 400 thousand years you cannot help but notice the striking regularity of the sawtooth rise and fall of both temperature and atmospheric C02 concentrations.
Up until the end of the last ice age the Earth had settled into a highly regular climatic pattern. It is one in which a cycling of C02 between the atmosphere and the oceans caused a corresponding cycling of lower and higher temperatures which added and removed ice sheets to the land masses. That ice in turn lowered and raised sea level across the globe.
There is every reason to think this cycle would have continued on, essentially indefinitely. In other words the Earth’s climate had settled into a stable cycle where the difference in global average temperature (compared to today) varies between 0 degrees Celsius and approximately minus 5 degrees Celsius.
On the other hand, you might recall how James Hansen suggested a radiative forcing of just 4 watts per square meter could eventually take us from where we are now to a (plus) 5 degree Celsius world.
So how do we get from a stable (1.2 million year old) “temperature loop” that seems to want to persist, to a new temperature state in the near future that will reside well outside it?
The obvious answer is that we are pulling carbon out of the depths of the Earth — where it has been locked away for millions of years in the form of coal, oil, and gas, and where it would have continued to remain cut off from the climate system for millions, if not billions, of years more — and we have liberated it into the atmosphere in the form of C02 emissions.
We took a system with a regular thermodynamic cycle maintained with a fixed amount of (recycled) C02 and we destroyed the cycle by connecting it to a new source of C02 — a post-industrial civilization built on the burning of fossil fuels.
The coming together of the world in 2015 to sign the Paris Agreement was a recognition of the idea that, in order to avert climatic catastrophe, we have to change the status quo — to break our addiction to fossil fuels and instead use sources of renewable energy to run the “engine” of human civilization.
The reward for doing this, the theory goes, is that we can limit the rise in global average temperature to no more than 2 degrees Celsius.
But can we?
In 2018 Johan Rockström from the Stockholm Resilience Centre and more than a dozen other international climate scientists released a study [Ref. HOTHOUSE] suggesting there may be no such thing as an Earth climate stabilized at 2 degrees Celsius.
Instead, they suggest we may be beginning down a path that automatically pushes us well past the 2 degree world we are anticipating.
They think our current pursuit of 2 degrees might slingshot us into a “Hothouse Earth” state where the average global temperature is significantly higher than 2 degrees, and from which Earth’s climate may not be able to escape for thousands of years…
Needless to say, humans are no longer part of this story, having been a strict casualty of a rapidly heating world in search of a new thermal equilibrium.
In essence Rockström’s group is repeating the “ice-free world” story I related to you on the basis of James Hansen’s work from about a decade earlier.
The authors of the study point out that upsetting the balance of carbon dioxide available to trap the Sun’s energy has knock-on consequences for many other natural processes. Once started, these processes contribute their own source of CO2 and could cause an escalation in the process of global warming.
As an example, I have already pointed out (in Part III of this series) how the loss of Arctic sea ice will significantly increase the total radiative forcing, causing a sharp rise in the rate at which temperatures increase across the globe.
This rise in temperature may then thaw the permafrost areas of the northern latitudes of Alaska, Canada and Siberia. These frozen grounds contain huge amounts of non-decayed organic matter. Once thawed, these will be acted upon by bacteria to produce gigatons of methane and carbon dioxide. Possibly hundreds of gigatons.
Additionally, off the coast of Siberia in the waters of the Arctic is an area of shallow sea bed which covers an area of roughly 2 million square kilometers. Below that sea bed is believed to be more than 1500 gigatons of frozen methane which could be released if the waters above the sea floor are warmed sufficiently.
Until now these waters have remained close to zero degrees Celsius, the freezing point of water. But once ice in the Arctic disappears for good these waters will warm under the influence of the summer sun.
Compared to the deepest parts of the Arctic sea, which descends to 5,000 meters, the shallow regions range from about 50 to 100 meters in depth and will warm rapidly.
The only question is whether a warm Arctic sea will cause significant release of methane gas during the remainder of this century. If it does the consequences for humanity could be catastrophic. This is because, pound for pound, methane has more than 100 times the warming power that C02 does when the gas is first released. It is a potent greenhouse gas which takes about 8 years to break down into carbon dioxide and water [Ref. METHANE].
With all the extra carbon dioxide and methane released by these “thawing” events the average global temperature will rise even further, causing the forested regions of the world to dry out. This makes them increasingly susceptible to massive outbreaks of wildfires which consume the trees and render a good portion of them into more CO2 emissions.
Each time one of these carbon dioxide amplifying “tipping points” is crossed it causes additional global warming and increases the likelihood of the next tipping point also being crossed.
Another example: with higher atmospheric temperatures the upper surfaces of both the Greenland and Antarctic ice sheets will melt more rapidly. In the case of Antarctica, warmer seas will also eat away at the ice shelves of West Antarctica.
If the ice sheet over Greenland disappears it will have two significant effects. First, the loss of reflective ice will decrease the albedo of the planet and more of the Sun’s light will be absorbed to warm the Earth.
Secondly, all the ice water pouring into the North Atlantic will likely shut down the northward transport of heat from the southern oceans. This will cause the waters around Antarctica to warm up even more quickly. This in turn will release more CO2 from the oceans and also directly cause the West Antarctic ice shelves to collapse even faster, further reducing Antarctic albedo…
The authors of the 2018 study addressed ten such tipping points which could be triggered, one after the other, over a period of decades or longer, once we reach a critical point in the global warming process.
When we shall arrive at that point we do not yet know. But the authors suggest it could coincide with the 2 degrees Celsius limit of warming written into the Paris Agreement as the upper limit of global average temperature we should try hard not to cross.
The danger is that once the critical point is reached where natural carbon-cycle processes begin tipping, they may continue to do so as part of an unstoppable chain reaction. There may be no way to stop them from continuing to tip, even if we reduce our greenhouse gas emissions all the way to zero.
This is what we mean when we use the term “runaway global warming”. It represents a complete loss of control of the climate system, and results in regional temperatures eventually entirely incompatible with life as we know it — and very probably incompatible with the concept of human life, let alone organized human societies.
In his book Storms of My Grandchildren Dr. James Hansen refers to the concept of runaway global warming as the Venus syndrome, a reference to the fact that long ago carbon dioxide became the dominant gas in the Venusian atmosphere (of which it makes up 97 percent). On the surface of Venus today the temperature is around 450 degrees Celsius, hot enough to melt lead.
Hansen says of the prospect of a runaway climate on Earth: “I’ve come to conclude that if we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty.”
Here is the thing about exponential change, which applies to the rate at which runaway processes take hold. For the longest time they look meek and innocuous. Sea level is rising now at about 3 centimeters per decade. Big deal, right? But eventually it will ramp up to 10 centimeters per decade, then half a meter…
All of a sudden this weak effect is drowning our cities, washing away communities when seas ride in on storms of unprecedented size, and everybody is demanding to know why nobody saw any of this coming or did anything about it while there was still time to do so.
THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE MOVES UP THE TIMELINE FOR CONCERN
If you have read this far you know the magnitude of the climate change threat is immense. On the other hand, if the implications are so worrisome surely world leaders would have done something about it by now instead of just ignoring the problem for decades and hoping the fuss would all turn out to be due to one very big mistake on the part of scientists.
Well, unfortunately the situation has not turned out to be the equivalent of a 60 year clerical error on the part of climate scientists (thousands of whom have been seriously modeling climate for that entire period and casting fairly accurate predictions about what lies ahead).
With every year that goes by we learn more about the likely fate in store for us, and the predictions become both more specific and more dire. In other words we do not just continually reaffirm that the science is solid, we are repeatedly reminded that our predictions consistently underestimate the severity of the problem.
As an example of this, in October of 2018, as part of their 48th Session held in Incheon, Republic of Korea, the United Nations Intergovernmental Panel On Climate Change released a report summarizing possible emissions path scenarios for limiting climate change to no more than 1.5°C [Ref. IPCC2018].
The report, which took more than two years to prepare, was commissioned by representatives of low-lying island and nation states concerned that they would be submerged by rising seas long before the average global temperature reached 2 degrees Celsius. They asked for an assessment of the differences to be expected between a 1.5°C world and a 2.0°C world so that future climate governance could take the information into account.
The thrust of the report is that IPCC now realizes they should have used 1.5°C everywhere they used the 2.0°C figure in the Paris Agreement.
Basically the report says: Oops, the impacts on human civilization for a given rise in temperature are going to be worse than we previously believed and there is a lot less time left to tackle the problem (perhaps until the year 2030) before we are looking at being well on our way to locking in dangerous and irreversible changes to the climate. We thought 2.0°C was the guardrail against catastrophic change and now we see it is closer to 1.5°C, moving the crisis time frame from perhaps 2050 to 2030…
Ninety-one scientists from 40 countries prepared the report after analyzing 6,000 scientific studies.
Among the points made by the report, titled “GLOBAL WARMING OF 1.5°C”:
● The 2.0°C world will be significantly less hospitable than the 1.5°C world, so we should act now to avoid being saddled with the consequences of the warmer scenario.● No matter what we do, the 1.5°C world is likely to be reached as early as 2030 (and almost certainly by 2050). But if we fail to make sufficient changes (of “unprecedented scale”) to the world’s fossil fuel-based energy system by 2030 we can expect the global temperature to keep on rising well beyond 2040, the year by which we should anticipate catastrophic changes to the climate. For example…● At 1.5°C the Arctic is likely to be ice-free in the summer once per century. At 2.0°C the frequency changes to once per DECADE.● At 1.5°C the world’s coral reefs (on which 25 percent of marine life depend) will be bleached to 70–90 percent. At 2.0°C is it virtually all gone ( more than 99 percent).● At 1.5°C rising seas will displace 10 million fewer people from their homes. At 2.0°C small pacific islands and large parts of other countries (like Bangladesh) will be submerged beneath sea water.● Loss of access to fresh water supplies across the globe will be twice as great at 2.0°C compared to 1.5°C● Collapse of West Antarctica ice shelves and/or melting of the Greenland ice sheet could eventually result in multi-meter rise in sea level. These instabilities could begin to be triggered around 1.5°C to 2°C of global warming.● To limit warming to 1.5°C greenhouse gas emissions must be reduced by 45 percent from 2010 levels by 2030, and eliminated entirely (by 100 percent) by 2050.● The remaining carbon budget for limiting warming to 1.5°C with 66 percent probability of success is 420 gigatons — or 10 years of burning fossil fuels at the current rate of 42 ± 3 gigatons per year (thereby exhausting the 1.5°C carbon budget by 2030).● All pathways that limit global warming to 1.5°C with limited or no temperature overshoot assume carbon dioxide removal (from the skies, using currently non-existent technology) on the order of 100–1000 gigatons of CO2 over the 21st century.● Species under threat. The number of plant and vertebrate species losing half their habitat will be TWICE as great in the 2.0°C world as in the 1.5°C world. For insects, THREE times the number of species will be similarly affected.● The estimated cost to the world economy of damage wrought by climate change will be $54 trillion by the time we reach 1.5°C, $69 trillion by 2°C, and $551 trillion by 3.7°C (and no that’s not a typo, the collapse of civilization comes with a huge price tag).
While the media has given the report a lot of short-term attention for its “dire” tone, many experts familiar with the state of the climate and the IPCC’s reluctance to go too far out on a limb with their predictions think the report is understated.
Dr. Peter Wadhams, the Arctic sea ice expert thinks the predictions about the frequency of ice-free Arctic summers are laughable. He shakes his head at the notion of an ice-free sea once per century in a 1.5°C world. The first such event is likely just years away, he points out. And it is expected to be a recurring event.
The problem, of course, is that IPCC does not issue proclamations on the more debatable points of climate science, like those which involve forecasting events which depend on “tipping point” scenarios such as the collapse of the Arctic sea ice. Or the release of methane from the Arctic sea floor once the ice is gone. You will find very little talk of runaway global warming in IPCC documents.
An interesting statement about the stark reality of the inertia of greenhouse gas warming can be found near the beginning of the summary version of the report [Ref. IPCCSR15,A2.1]: “Anthropogenic emissions (including greenhouse gases, aerosols and their precursors) up to the present are unlikely to cause further warming of more than 0.5°C over the next two to three decades (high confidence) or on a century time scale (medium confidence).”
The IPCC is saying that if the world shuts off overnight all fossil-fuel based sources of C02 emissions — all electricity-generating coal- and gas-fired power generation plants, all cars, trucks, planes, ships, all domestic and industrial heating systems — if the world stops in its tracks and does not start back up again, then it is likely the global average temperature will not rise by more than another half a degree Celsius over the next 30 years. Not will not rise by more than that amount, but probably will not.
And they are less sure about it not happening if the time scale is stretched out to a full century. In other words, unless we suck CO2 out of the skies there is a good chance we will get to experience the 1.5°C world described in the report no matter what we do. Because of course the world is exceedingly unlikely to reach the IPCC’s suggested goal of zero global emissions by the year 2050, let alone power down overnight to do it.
Much of the focus of the media has been on the cost of diminishing the world’s dependence on fossil fuels by investing in clean energy, improving energy efficiencies, and adjusting practices that would allow us to draw down more of the carbon dioxide emissions already present in the atmosphere. The IPCC has said that if nations invested 2.5 percent of their GDP, or about $2.4 trillion globally each year, in the restructuring they may be able to perform the required transition in 20 years.
It is a lot of money. On the other hand, if we do not invest adequately now in climate-friendly infrastructure a similar amount will likely be paid out in the years ahead on disaster relief and rebuilding efforts and we will be no closer to solving our climate problem. We will merely be a whole lot poorer, just as vulnerable, and still looking down the barrel of ever-worsening climate.
It is also worth noting the estimate of 100–1000 gigatons of C02 that might need to be sucked out of the skies to keep warming within acceptable limits (although as we saw in Part I, in 2021 another estimate has put that climate-stabilizing figure at 2000 gigatons of drawn down CO2).
Assuming a cost of $100/ton for recovered CO2 (roughly the cheapest we can do it today at any kind of scale) this would amount to a minimum cost of $100/ton x 100 billion tons = $10 trillion. The larger cost estimate (pulling back 1000 gigatons) would be 10 times this number.
This dollar figure is a good indicator of how much damage we have allowed the fossil fuel companies to inflict on the environment while we all turned a blind eye to what was going on. Admittedly that covers about two centuries worth of cumulative damage. But about half of it took place in just the last three decades or so — after the point at which we were fully aware of what we were doing.
The logic used by the polluters, of course, was that the cost of the clean up should be left to future generations to deal with. Well, the future is here and we and our children are the generations which will be forced to pay whether we like it or not. Either in dollars, or as increasingly seems to be the case, dramatically shorter life expectancy.
So, given the bad news, is there any good news to offset it? For instance, are signatories to the Paris agreement keeping up their pledges? How well are they combating carbon emissions at home?
According to the 2018 IPCC report: “Estimates of the global emissions outcome of current nationally stated mitigation ambitions as submitted under the Paris Agreement would lead to global greenhouse gas emissions in 2030 of 52–58 gigatons CO2 equivalent per year.”
In other words the IPCC is predicting roughly 30–45 percent HIGHER emissions in 2030 than in 2010. That is not 45 percent LOWER than the 2010 emissions, which is the required reduction suggested by the IPCC to limit global warming to 1.5°C.
So you can see the problem and how much of a challenge we have ahead for ourselves. Right now we are going in totally the wrong direction.
Given this bad news one has to wonder if there is any hope at all that we can turn this situation around.
In the next and final part of this series we consider what options we have as individuals to make any kind of changes to the less than encouraging path we seem destined to tread.
Next Up, in Part V:
● THE ROLE OF THE INDIVIDUAL — WHAT CAN YOU DO? WHAT SHOULD YOU DO?● WORLD SCIENTISTS' WARNING TO HUMANITY: FINAL NOTICE● A NOTE ON WHAT TO THINK ABOUT THE SKEPTICS AND THE DENIERS
Click Here to Proceed to Part V
REFERENCES[PARIS2015] What is in the Paris climate agreement?[EPIPELAGIC] What is a thermocline?[HOTHOUSE] Trajectories of the Earth System in the Anthropocene[METHANE] CRITICAL THINKING ACTIVITY: THE METHANE CYCLE[IPCC2018] Global Warming of 1.5 °C — Full Report (IPCC October 2018)[IPCCSR15] Global Warming of 1.5 °C — Summary for Policymakers
