There is a tendency within certain sectors to come up with terms that describe given areas of action without carefully or fully defining them. With time and use some of these terms are adopted by others for their own discourse, and farther down in the periphery of their origin yet by others for their own purposes. Over time, what may have started as a term coined to describe research findings, or policy, or some other aspect of human activity, gets adopted, referred to, and repeated with such frequency that it becomes generally accepted and becomes part of everyday vocabulary.

Often, perhaps with more frequency than many of us would imagine, some terms are adopted by advocates of particular movements or by elected officials and others to support their own agendas and proposed programs or pieces of legislation. Collaterally politicians, subject-matter experts, and other so-called stakeholders, get quoted by the media or invited by journalists to give their opinions based on questions involving some of these terms.

The dynamics involved in the adoption and use of specific terms are most probably known to some, but what becomes evident when we carefully analyze particular statements, quotes used, or promises made by some, is that a given term may have been assigned different meanings by various users. Absent a clear and generally accepted definition, a term ends-up meaning different things to different people or gets used with the assumption that the public understands what is being said, when in fact members of the audience may end up with varying interpretations of what was said.

In similar fashion, a term may be used without a proper context or without clarification of nuances or its exact meaning. As a result, many will believe they have understood what was said when in fact they do not.

These misunderstandings or varying interpretations arising from the misuse of a term, whether unintentional or purposely, are a cause for concern. Concerning indeed, not so much when the problem shows-up in casual conversation, but when it happens in the context of important messaging that may lead to critical decision-making.

Mitigation and adaptation are two terms in use in the climate change conversation for some time, which have fallen victims to the lack of clarity in definition or use described above.

In the context of climate change, mitigation and adaptation refer to the two classes of actions humans can take in order to protect our planet and life on Earth from the adverse effects of climate change.

For purposes of this discussion adaptation and mitigation are defined as follows:

Adaptation = actions humans take to reduce damage from climate impact.

Mitigation = actions humans take to reduce human impact on climate.

A critical consideration when discussing adaptation and mitigation is: how long will it take for specific actions to produce results? Let us take a look!

There is scientific and empirical data showing natural hazards are exacerbated by damaging components of climate change. For example, global warming is contributing to more frequent and intense wildfires, more frequent and prolonged droughts, and extreme rain events, as well as driving sea level rise which exacerbates storm surge, wave impacts, and coastal flooding during hurricanes.

Hazard mitigation measures effective in reducing the potential for damage from these natural hazards are considered to be adaptation to climate change. Many of these adaptation measures are taken on a building by building basis, either when designing a new building or by retrofitting an existing building. Other adaptation measures may involve major civil works to protect and entire region or community.

Examples of adaptation measures include: elevating a building to prevent damage from flooding or storm surge and wave impact, using insulating materials to reduce the heat load on a building, or building a dyke to protect and entire community from coastal flooding and sea level rise.

A common characteristic of these adaptation measures is that as soon as they are built they start providing the protection they were designed for. More clearly, climate adaptation measures produce immediate results as soon as they are implemented, and will continue doing so during the service life of each project.

Mitigation of climate change has become synonymous with reducing emissions of greenhouse gases (GHG). Humans have no capacity to change or significantly alter natural processes at a global scale such as those that drive climate change and have cycled Earth between glacial and interglacial extremes, but we do have the capacity for altering the rate of change on a global scale and significantly altering climate and environmental conditions on local and regional scales. There is ample scientific evidence to show human activity use of and generation of energy from hydrocarbon fuels (coal, oil and natural gas) is a major contributor to global warming and climate change.

This is why a main focus of the Paris Accord signed in 2016, at the United Nations Framework Convention on Climate Change Conference of Parties or COP 21 for short, was the commitments of nations to reduce GHG emissions by specific amounts by given dates. GHG emissions reductions is also the main focus of the upcoming COP 26 to be held in Glasgow, Scotland from 3` October to 12 November 2021.

When will we see results from specific GHG emissions reduction measures? The United States pledged to cut GHG emissions by 50% to 52% from 2005 levels by 2030, when it rejoined the Paris Accord earlier this year. So, say it is 2030 and the U.S. has met this goal, and that all other countries have also met their respective GHG emissions reduction objectives. When will the world begin to see a measurable reduction in the rate of global warming, or an actual reduction in annual global average temperatures?

The answer to that questions is we really do not know, but what we know is that the expected results will neither be immediate nor will they become measurable in the short term after achieving a specific GHG reduction objective on a global scale.

One of the reasons for this answer is that GHG have two important characteristics that must be taken into account: atmospheric lifetime and global warming potential which vary from one greenhouse gas to another. We need to understand these GHG properties before we can begin to estimate when our emissions reduction efforts may translate into actual results.

Atmospheric lifetime refers to how long a greenhouse gas remains in the atmosphere before it decays driven by chemical processes. Excepting water vapor which remains in the atmosphere only for a few days, 4 to 10 depending of a range of factors, and whose presence in the atmosphere is governed mainly by evaporation and precipitation in the hydrologic cycle, all other greenhouse gases once emitted will stay in the atmosphere for lifetimes ranging from a few years, to more than a hundred and even thousands of years. The table below illustrates this fact:

Chemical SymbolGreenhouse GasAtmospheric Lifetime
CO2 Carbon Dioxide50 – 200
N2ONitrous Oxide120
NF3Nitrogen Trifluoride50 – 740
CHF3Trifluoromethane250 – 390
C3F8Perfluoropropane2600 – 7000
SF6Sulfur Hexafluoride3200
CF4Carbon Tetrafluoride50000
Carbon Dioxide, Methane, and Nitrous Oxide are naturally occurring chemicals whose concentration in the atmosphere has been changed by human activity. All of the other greenhouse gases listed are the product of human activity and present in the atmosphere only in trace (extremely small) amounts, and are also highly resistant to decay and therefore have long atmospheric lifetimes.

From information in the table above we begin to have part of the answer on when we can see results from greenhouse gas emission reduction efforts. It is clear that if humans were able to stop emitting CO2, CH4, and N2O, the most abundant greenhouse gases (except for water vapor) today, it would be decades and even more than a century before what has already accumulated in the atmosphere decays enough to slow down the current accelerated rate of global warming.

Global warming potential (GWP) refers to the capability of a greenhouse gas to trap heat in the atmosphere relative to that of Carbon Dioxide over a period of time, which is given a value of GWP = 1 and is used as the baseline. Science shows us that all other greenhouse gases have higher capabilities for trapping heat in the atmosphere than CO2, in some cases quite a bit higher, we are talking of hundreds, thousands, even tens of thousand times higher. The table that follows illustrates the wide ranging GWP disparities among greenhouse gases:

Chemical SymbolGreenhouse GasGlobal Warming Potential (GWP)
CO2Carbon Dioxide1
N2ONitrous Oxide310
CF4Carbon Tetrafluoride6500
NF3Nitrogen Trifluoride8000
SF6Sulfur Hexafluoride23900
From this table it is clear that the so-called ‘fluorinated‘ gases (those with ‘fluoro’ or ‘fluoride’ in their names) are extremely much more capable of trapping heat in the atmosphere than Carbon Dioxide or any of the other naturally occurring greenhouse gases. So even if the fluorinated greenhouse gases are only present in trace amounts their actual impact is considerable when both their GWP and atmospheric lifetime are taken into account. For example, available data indicate greenhouse gas emissions in 2020, excluding water vapor, consisted of 81% Carbon Dioxide and only 3% fluorinated gases, a ratio of 27:1. But when you consider fluorinated gases on average can trap 10000 more heat in the atmosphere per molecule and can persist in the atmosphere a lot longer than Carbon Dioxide, their actual impact as contributors to global warming is brought into perspective.

This rather brief discussion on GWP of greenhouse gases is also helpful in getting to an answer on how long it may be before we see results from our greenhouse gas emissions reduction efforts. It confirms that we may at best be looking at hundreds of years, if not longer, especially when most of our reduction efforts appear to be aimed at Carbon Dioxide, Methane, and Nitrous Oxide, but pay less attention to the fluorinated gases that are not only much more capable of contributing to global warming for a longer time, but are also critically linked to important processes in human activity.

In summary, next time you hear a speaker advocate for GHG emission reductions be mindful that results may only become apparent over the long term, most probably for future generations to see. When you read in a climate assessment report that ‘the more we invest in climate change mitigation the less we will need climate adaptation’ be sure this statement is in error. It is critically important we understand that adaptation and mitigation work on totally separate and different time scales. We could say climate change adaptation generates results in real time while climate change mitigation will produce results over the long term.

While this conclusion may be viewed as a damper by some, I would argue it really is an incentive to increase our urgency in renewing our efforts toward implementing solutions on both fronts, climate change mitigation and adaptation. This conclusion is one important reason for the code red alarm issued by the Secretary General of the United Nations and others as the world gets ready to convene at the end of this month of October in Glasgow at COP 26!

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