MITIGATION VS ADAPTATION: IT IS ALL ABOUT TIME SCALES!

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
(years)
CO2 Carbon Dioxide50 – 200
CH4Methane12
N2ONitrous Oxide120
NF3Nitrogen Trifluoride50 – 740
CHF3Trifluoromethane250 – 390
C3F8Perfluoropropane2600 – 7000
C4F8Octafluorocyclobutane3200
SF6Sulfur Hexafluoride3200
C2F6Hexafluoroethane10000
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
CH4Methane21
N2ONitrous Oxide310
CF4Carbon Tetrafluoride6500
C3F8Perfluoropropane7000
NF3Nitrogen Trifluoride8000
C4F8Octafluorocyclobutane8700
C2F6Hexafluoroethane9200
CHF3Trifluoromethane11700
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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WHAT’S HAPPENING WITH THE 2021 ATLANTIC HURRICANE SEASON?

Historically close to 90% of named tropical cyclones during the annual Atlantic hurricane season, develop from August through October, with the statistical peak around the second week in September.

After an early start, the seventh year in a row with early starts of the season, when Tropical Depression #1 formed in the western Atlantic around 14 May 2021 and later became tropical Storm ANA, we had seen five-named tropical cyclones by early July a little over a month into the “official” season. Then there was a lull in tropical cyclone activity for about a month until 9 August when Tropical Depression #6 formed in “hurricane alley” near Barbados, and the became Tropical Storm FRED in the eastern Caribbean. Over the last couple of days in rapid succession two other tropical depressions have generated Tropical Storm GRACE in the Caribbean and Tropical Storm HENRI in the Atlantic near Bermuda. So here we are barely past mid-August, in 17 August, and Atlantic cyclogenesis has already generated eight named tropical cyclones.

This image has an empty alt attribute; its file name is GRACEandHENRI0817at1710caribbean22.jpg
Tropical storms HENRI, near Bermuda, and GRACE, near Jamaica, are on the move respectively in the Atlantic and the Caribbean this Tuesday 17 August, 2021. The remnants of Tropical Storm FRED are visible in the upper left corner of this photo.

To put this number of named storms in 2021 in perspective, consider that in 1992 when infamous major Hurricane ANDREW hit Florida it was 24 August, and that was the FIRST named storm of that season. In contrast, last year by 17 August we had already see eleven named-tropical cyclones in 2020.

So yes, we have had quite a bit of tropical cyclone activity this year, but not really anything we have not seen before. What is important is to focus on the burst of activity over the last week and to look toward the far east in the Atlantic, ‘hurricane alley’ and the ‘tropical wave assembly line’ in Equatorial Africa where most of the seeds that end-up as tropical cyclones in the Atlantic get their initial start. Satellite imagery from NOAA show a long train of tropical waves and disturbed weather cells, all seeds for potential tropical cyclones, spanning all the way from the ‘horn of Africa’ into the eastern Atlantic southwest of the Cape Verde Islands: a distance of more than 8000 kilometers. So there is plenty of fuel for potential cyclogenesis that will be at work over the next tw0 – three weeks. Not only that, but even farther east the Indian Ocean is populated by plenty of storm cells and disturbed weather, which typically contribute the initial impulses that move over Africa and generate tropical waves.

This satellite image (courtesy of NOAA) shows the ‘tropical wave assembly line heavily populated with a train of storm cells and disturbed weather extending for approximately 8000 kilometers, from the ‘Horn’ of Africa to way into ‘hurricane alley’. Plenty of fuel for cyclogenesis.

It is clear the total framework for cyclogenesis is already in place and working just as we approach the historical peak of the annual Atlantic hurricane season. Related to this recent data shows a lowering of temperature of surface waters in the central and eastern Pacific as well as strong east-west trade winds, which together usually are a presage on a developing La Nina conditions over the eastern Pacific. It is well known that La Nina contributes to favorable conditions for cyclogenesis in the tropical north Atlantic. Granted, it may be late this Fall or even Winter before a La Nina event takes hold, if it indeed develops at all, but on the other hand existing pro-La Nina ocean-atmospheric conditions are already more favorable to tropical cyclone development in the Atlantic as we start to get into what historically is the peak of the season.

Against this background let us consider what is happening this Tuesday 17 August 2021 on the tropical cyclone front. There is FRED, or better said “the remnants of FRED, a tropical depression over northern Georgia and Tennessee moving generally northeast at a rapid clip of 45 kph and still packing 40 kph sustained winds. Then there is a strengthening Tropical Storm GRACE in the Caribbean between Jamaica and the Cayman Islands, mowing westward toward the Yucatan Peninsula of Mexico with 80 kph maximum sustained winds, higher gusts, and plenty of rain. And last, but not least, there is a very strong Tropical Storm HENRI to the South of Bermuda, moving westward with 110 kph sustained winds.

Elsewhere, over the eastern central Pacific Hurricane LINDA is moving away from the coast of Mexico in the general direction of Hawaii. In summary, there is plenty to monitor in terms of actual and potential tropical cyclone activity, especially in the Atlantic basin. So, we must remain alert. get ready. be prepared, and above all MITIGATE!

Beyond these situations, and over the longer term, we need to closely monitor how the possible La Nina evolves so we all may be better prepared for anticipated climate effects. From past episodes of La Nina we all know about the adverse climatic consequences throughout the United States, which may be exacerbated by the rapid pace of global warming and other extreme events triggered by climate change.

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