The aviation industry faces a binary choice for meeting the climate cleanup targets set for 2050; the climate change strategy will fail, or it will succeed. Airlines, lessors and investment institutions would benefit from knowing which one it will be. SASI used scenario analysis to develop three scenarios to find out. The net-zero emissions scenario, the accelerated zero emissions scenario, and the legislated emissions scenario. Each is built on a range of inputs.

The observations from all three scenarios highlight both positive and negative events. These events present a range of challenges such as what would happen if a carbon stigma were linked to airlines, in ways similar to the oil and tobacco companies, or what would be the financial loss if gas turbine powered aircraft suffer premature obsolescence and abandonment.

Scientists used scenario analysis before to good effect with nuclear waste and ozone depletions. The global community successfully came together to solve these problems.

The aircraft net-zero emissions scenario. The aircraft net-zero emissions scenario is the one where a reduction in emissions is achieved but no capital investment has to be made to upgrade or replace commercial aircraft. The get-out-of-jail card is the price paid to buy carbon credit offsets. The accelerated zero emissions scenario. The accelerate zero emissions scenario is one whereby public opinion coalesces around the belief that the energy producers and airlines are greensplaining and will fail to reach emissions standards by 2030, 2035 or 2050. (The literature is replete with accounts of the the attitude of oil companies, who are zealous in explaining the causes of the climate environmental problem, and who judge the behavior of others by serving up psuedoscientific technology strateies, and making them feel guilty, and that can only be relieved by the consumer paying the cost of the cleanup! Public hostility reaches a point where Nation States, politicians and regulators are put under such intense public pressure, that they require the polluter to to pay for the cleanup. If that scenario does materialize, airlines and by default lessors will be forced to re-fleet, investors will have to factor in obsolescence into aircraft investment portfolios, on a time scale not of their liking.” “There are two precedents for this, the case with nuclear energy and ozone depletion. The scientific community warned about the damage to life from nuclear energy and the damage to the ozone shield. As was the case with nuclear energy and ozone depletions, and in response to public pressure, nation states have the power to enter into a treaty, backed by domestic legislation and strict regulations that obligate airlines to replace gas turbine engines with zero-emissions technologies, and they could do so by 2027.

The crisis alert went out decades ago. Warming of the planet has begun, UN Expert told the US Senate in 1988. The international air law scenario. The international air law scenario arises in circumstances where CORSIA fails and persuasion fails. The term treaty is generic. Conventions, agreements, protocols, and exchange of letters or notes may constitute treaties, enforceable under international law. The absence of writing does not affect the legal force of international agreements. They are mostly employed as instruments of some gravity and solemnity. Treaties are entered into between two or more States; international organizations with treaty-making capacity and States; or international organizations with treaty-making capacity. The 1944 Chicago Convention, the 1953 Convention on the international recognition of rights in aircraft, and the 2001 Convention on International Interests in Mobile Equipment are treaties based on international aviation law.

Addressing the global rise in air temperatures and the effects of climate change on air travel can be addressed using such a legal structure, especially when volumtary agreements do not work.

ICAO’s 2016 CORSIA is an offsetting mechanism is not a treaty. The measure enables countries to give permissions to airlines, registered in their jurisdictions, to offset CO2 emissions that exceed the relevant baseline, and to do so by buying international carbon credits. Due to the COVID-19 pandemic, the ICAO Council decided in June 2020 that 2019 emissions should be used as baseline in 2021-2023 instead of the average of 2019-2020 emissions.

The 2016 Paris Agreement is implemented via national policy. The purpose of the treaty is to agree on ways to improve energy efficiency, to decrease the energy intensity of the global economy, to decrease fossil fuel burning, and to increase the share of sustainable energy in growing the global economy.

The application of the term treaty, to an international agreement to regulate aircraft emissions, concluded between States, in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments, and whatever its particular designation, is intended to create rights and obligations relating to aircraft greenhouse emissions, enforceable under international law.

The binary choice for the aircraft market over the next quarter century, is that if the Paris Agreement target for capping global temperatures is not met, then the aircraft market will trade gas turbine powered aircraft. If the temperature targets are met, the gas turbine powered aircraft will be obsolete, and the fleet will have been successfully transitioned to zero-emissions conditions. Aircraft design and uses are changing for multiple reasons including the knock-on effects of external causes.

It is not just high temperatures and climate change that are the problem for air transportation, or the curse of fossil fuel greenhouse gas emissions, it's the compound and knock-on effects of black swan events such as 9/11, the financial crisis, the Pandemic, warfare, upset of the supply chain, labor upskilling requirements, inflation and interest rates, and defective aircraft designs, that have the potential to undermine investment in net-zero and zero-emissions aircraft technology.

Five-part question scientists struggle to communicate.

If nature is a self-correcting system that has been producing GHGs to regulate the Earth's temperature for billions of years;

If almost half of the CO2 release is absorbed by the oceans and the terrestrial biosphere, mitigates the level of global warming;

If industry has been producing GHGs in the last three hundred years; and

If Jet aircraft have been producing GHGs for seventy years;

how do atmospheric scientists know climate change is not part of the long-term climatic cycle?

The answers.

The Earth one huge interconnected and self-regulating system, governed by moderate temperatures, and clean air.

Nature produces GHGs in a chemical process that has sustained the world as a place to live. The GHGs are carbon dioxide, methane (CH4), nitrous oxide (N2O), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and hydrofluorocarbons (HFCs).

In time the global population went from zero to about 630 million in 1750, to 2.5Bn in 1950, to 7.6Bn today, and is projected to reach 10Bn by 2050 and 11bn by 2100.

Industrialization expanded to meet the needs of the growing population through the agricultural, industrial, the digital and now, the internet of things revolutions.

As industry grew, nature's production of GHGs remained in equilibrium, but our output of GHGs increased to the level, that nature's stewardship of the Earth has been disrupted.

However, no one was aware of the level of damage being done to the climate until the mid-20th century.

“From the 1950s onward, scientists began to realize, even though nature had been self-regulating the Earth's atmosphere over billions of years, that in the last three hundred years of industrialization, the damage caused to the atmosphere is so great that the world is at risk of losing the benefits of its location in the goldilocks zone of the solar system.

“It is undisputed that nature had no responsibility for the crisis, because what it has taken nature to provide over billions of years, humanity has brought to the brink of destruction in a little less than three hundred years.”

The gas turbine engine (the Jet) is the optimum powerplant for aircraft.

“No technology has been developed that could improve on its capabilities.”

Fossil fuel, in the form of aviation kerosene, a turbine fuel (ATF) called Jet-A, is the optimum energy for powering the engine.

“No energy source has been developed that could improve on its performance.”

A fuel is a substance that produces heat and light energy on burning.

Two important characteristics of a fuel are its calorific value and efficiency. The higher the calorific value of a fuel, the more heat it produces when burned.

The higher the calorific value of a fuel, the better fuel it is. Not all combustible substances can be used as fuels for all applications. Although all fuels produce heat and light on burning, some produce more energy than others.

No machine offers 100% fuel burn efficiency. When a fuel is burnt, some of the energy produced is given off as waste heat. This heat cannot be used for home, industry, propulsion or other purposes. The amount of waste heat produced affects the efficiency of a fuel. A good fuel has the following characteristics:

1. It should have a high calorific value.

2. Its ignition temperature should be low but well above the room temperature.

3. If its efficiency as measured by temperature is too low, the fuel will catch fire very easily rendering it unsafe. If it is extremely high, the fuel has to be heated for a long time before it can catch fire.

4. It should have a moderate rate of combustion and should release heat in a controlled manner.

5. It should be fairly cheap and easily available. A fuel may have a very high calorific value but if it is expensive and not easily available, it cannot be used on a day-to-day basis.

6. It should be safe to handle, store, and transport.

7. It should not cause pollution on burning.

The top fuels, that can be used for transportation purposes, measured by the calorific value or the amount of heat produced in kilo joules (kJ), when one gram of a fuel is completely burned are: hydrogen (150 kJ/g), methene (55 kJ/g), LPG (50 kJ/g), kerosene (49 kJ/g), petrol (48 kJ/g) and biogas (35-40 kJ/g).

The Achilles heel of aircraft technology.

The Achilles heel of aircraft technology is that:

(a) because the technology is so expensive to own and operate, air travel is not accessable by eighty percent of the population. Less than one percent of the global population is responsible for half of aviation emissions.

(b) As the jet engine burns the Jet-A fuel, it produces GHGs, that affect the climate by emitting gasses such as CO2 that block heat from passing through the atmosphere, causing temperatures to rise, and: NOTE: Many industries produce reflective aerosols which have the opposit effect. They prevent the sun's rays reacing the surface of the earth and have a cooling effect. Climatologists typically consider the chemical composition of aerosols. Key aerosol groups include sulfates, organic carbon, black carbon, nitrates, mineral dust, and sea salt, that can mix together to create hybrid particles. Automobiles, incinerators, smelters, and power plants are prolific producers of sulfates, nitrates, black carbon, and other particles. Deforestation, overgrazing, drought, and excessive irrigation can alter the land surface, increasing the rate at which dust aerosols enter the atmosphere. Despite considerable advances in recent decades, estimating the direct climate impacts of aerosols remains an immature science. Of the 25 climate models considered by the Fourth Intergovernmental Panel on Climate Change (IPCC), only a handful considered the direct effects of aerosol types other than sulfates. (NASA).

(c) The Jet-A fuel is refined from oil, one of the three fossil fuels, coal, natural gas and crude oil. Oil has a limited supply because it took millions of years for the reserves of oil to form in the Earth's crust.

Two precedents point to added value for the airline industry if the climate is cleaned up?

“Aircraft can be affected by climatic extremes such as acid rain, smog, and hot temperatures.”

The first human engineered global climatic crisis was the creation of nuclear energy giving rise to the fear of a nuclear waste and nuclear winter. Nuclear technology is an energy and an instrument of war. Uranium is the core material and is obtained by mining. As the awareness grew that a nuclear war could destroy the Earth, a global movement emerged in the 1960s, that curtailed the use of uranium.

Method: The instruments used to control nuclear technology are encoded in global treaties, comprehensive nation state legislation and regulations that are strictly enforced.

Climate damage is greatest in two of the five layers in the atmosphere. The troposphere is where we live and breathe which is damaged by acid rain and smog caused by Oxides of Sulphur (SO2 and SO3) and nitrogen (NO2, NO), The oxides react with water in the presence of atmospheric oxygen to form nitric acid (HNO3) and sulphuric acid (H2SO4), which leads to the formation of 'Acid rain.

The next is the stratosphere which extends about 50Km above the Earth. The ozone layer is located at the lower end of the stratosphere. It acts as a shield to protects all life from the sun's harmful ultraviolet radiation (light) (UV). Over time, excess UV lead to higher skin cancer and cataract rates, and damages crops (EPA).

Closest to the surface of Earth, the troposphere is between 8 and 14 km high, depending on where you are on Earth. It is thinnest at the North and South Pole.

“The troposphere layer is where the weather resides. The stratosphere is where the ozone shield resides.”

The weather is constantly changing and mixing up the gases in this part of our atmosphere.

Ozone depleting substances (ODS) are used in the production of many products. They are generally very stable in the troposphere and only degrade under intense UV in the stratosphere.

ODS include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, hydrobromofluorocarbons, chlorobromomethane, and methyl chloroform.

Weather activity uplifts the ODSs to the ozone layer. As the ODSs degrade, they damage ozone shield.

Once scientists established that ODSs caused the ozone damage, the public outcry that followed, resulted in two treaties in 1985 and 1987, which we are incorporated into national law and enforced through strict regulation.

Method: The instruments used to control ODS are the same as those adopted to regulate nuclear energy technology - global treaties, comprehensive nation state legislation and strictly enforced regulations.

On a positive note, new data confirms that the emissions of ozone depleting substances are falling, and the ozone layer is expected to be fully healed near the middle of the 21st century (EPA).

The interconnection between aviation and climate change.

Almost half of the carbon dioxide that humans release into the environment is taken up by the world's oceans and the terrestrial biosphere. In this manner, industrial greenhouse gases are partially extracted from the atmosphere, which alleviates the process of global warming.

However, this may not be enough. Scientists are concerned that the land and the seas will be unable to continue storing carbon dioxide in the future. Changes in ocean circulation, woodland clearances and stress reactions in forests could reduce their capacity to act as carbon sinks.

Two major influencers are driving aviation climate change policy.

The clarion call has gone out from the United Nations for every country, industry, city and individual to heed the warning that climate change is real.

The aviation industry has responded by supporting host-states that are signatories to the Paris Agreement, which addresses domestic greenhouse gas emissions, and the ICAO Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), both agreed in 2016.

CORSIA presumes that no agreements will be made to require changes to, or modifications of the gas turbine engine to address greenhouse gas emissions. It is designed to cap the annual net emissions of international airlines at around 915 million tonnes of CO2. The method employed is for these airlines to buy carbon offset credits from industries such as forestry that act as sinks for CO2 emissions. In that way ICAO expects international airlines to achieve carbon neutral growth by 2035.

CORSIA is limited to addressing emissions from international flights by commercial airlines. In its first phase, the CORSIA scheme is voluntary, effective from 1 January 2021. One hundred and thirteen countries, with about 1,000 registered airlines, and representing about eighty-eight percent of international aviation operations, have signed on to the scheme.

The scheme is being implemented in three phases: (a) phase one is a voluntary pilot program. Countries can opt out at any time between 2021 and 2026, (b) phase two is mandatory for those countries that do not opt out. It covers the period 2027 to 2035.

An estimated two hundred civil society groups (CSOs), Non-Governmental Organizations (NGOs) and some investment institutions that invest in the aircraft leasing business, strongly oppose the CORSIA scheme because: (a) airlines already get generous breaks such as zero tax on fuel and received about two hundred billion in government aid during the COVID crisis, (b) an offset scheme does not stop aircraft emissions. Airlines can pay, what is in effect a fine, and continue to produce greenhouse gas emissions, (c) it does not account for one third of all airline emissions because domestic flights are not included in the scheme (d) the structure is an exercise in greenwashing, (e) the emissions goals are so low that aircraft coming off the production line in the mid-nineteen nineties met the emissions standards, (f) in the final analysis past crisis show how powerful public opinion is in terms of one prominent scenario:

Accelerated zero emissions.

As was the case with nuclear energy and ozone depletions, and in response to public pressure, nation states have the power to enter into a treaty, backed by domestic legislation and strict regulations that obligate airlines to replace gas turbine engines with zero-emissions technologies, and to do so by 2027. The takeaway from climate change for airlines, lessors and investment institutions?

ust as the modern world would not exist in its current form without industrialization, the global trade that industry depends on, would not be possible without air transportation.

This is a symbiotic relationship, in which no one stakeholder in the supply chain can carve out special exemptions without disrupting the system. The closer the economy gets to the 2050 climate change deadline; the greater will be the demand for all industries to be treated equally.

The accelerate zero scenario is one whereby the United Nations, ICAO, Nation States, politicians and regulators will be under such intense pressure, that they will force airlines to meet zero-emissions standards. If that scenario does materialize, airlines and by default lessors will be forced to re-fleet, on a time scale not of their making.

From its earliest days aviation has been perceived as an advanced, clean technology. Between the late 1930s and the 2020s, aircraft technology improved continuously. Fuselage pressurization enabled aircraft to fly in the stratosphere, which is the optimum height for cruise flight. Airframe fail safe structures improved safety. Swept back wings reduce drag and vibration and improves lateral stability.

The performance, the thrust and the noise of the jet engine improved, as the technology advanced from zero, to low, to high bypass engines. Avionics were digitized improving mean time between repairs. Cockpits were upgraded from analog to digital instruments and automation has eased pilot workloads. Fly-by-wire flight controls replaced manual controls.

Aircraft productivity increased as measured by payload, range and speed. Fuel burn efficiency improved by an average of about one percent per annum. Cockpit crew size fell from four to two pilots. Aircraft maintenance costs improved as airframes were switched to on-condition overhauls and the engine time on wing went from a few hundred hours to around ten thousand hours.

The overall result is that more people are able to fly at lower prices. More people can fly to far off destinations and arrive faster than ever before. High value, low volume goods fill the cargo holds for additional revenue.