This Century Is An Era Of Climate Retreat, Both Managed & Unmanaged

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This century has already seen the significant retreat of populations from areas subject to climate change impacts. Many of those retreats have been unmanaged, but the conversation has been turning inexorably to managing them instead.

New Orleans flooded in the aftermath of Hurricane Katrina
New Orleans flooded in the aftermath of Hurricane Katrina. Image courtesy

Let’s consider a few examples that have already occurred. Hurricane Katrina hit New Orleans in August of 2005. It was a Category 5 tropical cyclone when it made landfall, and tore through the under-engineered protection surround this fabled US city, causing 1,200 to 1,800 deaths. The aftermath still lingers on former President George W. Bush’s legacy. 50 breaches and 80% flooding of this in many places below sea level urban area of the richest country in the world drove home the fact that no one is immune. Katrina triggered some of the earliest broad public discussion of the potential impact of global warming on extreme weather in the United States. It’s part of an increased trend of intensity if not frequency of hurricanes in the North Atlantic, and part of a clear global trend to increased intensity. However, it’s not the linkage to global warming per se which is important in terms of the discussion of managed retreat.

Before Hurricane Katrina, New Orleans had a population of almost 500,000. Over half were evacuated or left. Many never returned.

“The population of New Orleans fell from 484,674 before Katrina (April 2000) to an estimated 230,172 after Katrina (July 2006) — a decrease of 254,502 people and a loss of over half of the city’s population. By July of 2015, the population was back up to 386,617 — 80% of what it was in 2000.”

This is an example of unmanaged retreat. A populace experiences a natural disaster. While some have the means to leave under their own power, others are evacuated by the government. Some have no economic choice to return, some have no economic ability to return and others have the choice.

We see the same pattern in the Canadian Fort MacMurray wildfire evacuation of 2016. 88,000 people evacuated, leaving behind homes and belongings, much of which were destroyed. 2,400 homes burnt to the ground and two years later, only 20% had been rebuilt. The population of the region around Fort MacMurray is still 11% below that before the fire, exacerbated by the jobless recovery in the oil sands. Many residents and temporary ‘shadow populace’ simply left and never returned, some with insurance payments in their pockets, others without.

Both communities remain at risk. New Orleans slipped free of another existential threat this year, when Hurricane Barry made landfall 80 miles to the east of the city. At that moment in 2019, the New Orleans and Mississippi flood control dykes were a foot from overtopping due to a year of greater than average rainfall in the eastern United States, precipitation changes that are attributed to climate change. Yet New Orleans was not abandoned and bulldozed, but rebuilding efforts continue. It’s unlikely that it will exist beyond 2050, but as humans and organizations we persist in fighting to retain what we have. The climate-change exacerbated drought that has been causing wildfires up and down the western seaboard persists, and fires continue to burn in the months-longer fire season in the United States and Canada. It’s only a matter of time before another fire comes to claim the northern community known best as a hub for fossil fuel extraction.

But there’s an alternative. Managed retreat.

We are gaining a better and better understanding of the threats which face each geographical region. The CoastalDEM machine learning study I wrote about in CleanTechnica earlier this year shows us not only that much more coastal land is at threat of frequent flooding than previously understood, but more clearly where those threats exist. That study found that on average we had overestimated the elevation of land within 20 meters of sea level by 1.9 meters globally. Urban areas in rich countries are typically accurately measured, but the quality of measurements decreases as we move further from wealth and major cities.

The threats are many, however. We are seeing increased river flooding. Two examples from Canada spring to mind, the Point Gatineau, Quebec and Grand Forks in British Columbia. Despite the lessons of major flooding in the 1950s in Toronto that led to urban development that avoided flood plains, homes and business had been built or allowed to persist in areas which were at risk, and in the past five years, both communities have seen massive flooding. Now, they are in semi-managed retreat, with homes being bought out and buildings destroyed. The threat was foreseeable, as was the inaction until the inevitable occurred.

We are also seeing a loss of permafrost in northern countries. In the Yukon Territory of Canada, an area larger than California is seeing buildings collapse and roads crack, buckle, and sink as the assumed-to-be-permanent subsurface layer of frozen soil melts back into quagmire. There are three challenges with this. Some communities simply see their buildings and infrastructure break and collapse. Others see slopes destabilized, with landslides sheering tons of earth onto buildings and roads. And others are simply isolated, unable to depend on the ice highways that allowed inexpensive trucking of essential goods and fuel into remote areas where people have lived for often hundreds of years.

The UN IPCC has been looking at adaptation since its inception in the 1980s. Typically, they have been focused on protection, accommodation and relocation. The first is straightforward: if the sea is rising, build higher dykes. That doesn’t work in southern Florida, where the land is porous limestone and brackish water seeps under the dykes. Enter accommodation. Where you can’t prevent harm, you can makes homes and business resilient to it. In many flood prone areas, governmental programs help fund sump pumps for basements and valves which prevent sewage from backing up into buildings as waters rise. Relocation and retreat are critical.

But there’s a fourth approach, avoidance, and it becomes more important as climate impacts increase and our knowledge increases. Brent Doberstein and his co-authors from the University of Waterloo talk about the PARA framework: prevent, accommodate, retreat and avoid. That last one means looking into the future in our dim crystal ball and not building in areas likely to be suffering one of the many impacts of climate change.

As we talk about moving communities in Alaska back from coastlines torn both by sea-level rise exacerbated erosion and by permafrost melt, we have to be very careful that we aren’t simply creating a problem for 30 or 50 or 80 years from now. The coastline of today and tomorrow is not the coastline of 2100. The firm land of 2019 is not necessarily the firm land of 2100.

And there’s another aspect. I have spent a lot of time on social license for rural transformation in the face of renewables over the past decade. Most recently, I’m delving into social license for pumped storage hydro, yet another subject that runs into NIMBYism. But rejecting change in your community pales in comparison to being asked to move your entire community somewhere else, or to abandon your homes while nearby homes are allowed to persist. The seesaw in Crescent Beach in Surrey, BC is evidence of this. It’s a coastal neighborhood in the rich Lower Mainland, but it’s a flat area at the base of steep hills and is already protected by high dykes. The city had decided after consultation to abandon it to sea level rise, and pay the owners for their properties. And now they have abandoned that plan.

This will tie into the ongoing political challenges of the increasing rural urban divide as well. Rich, dense cities will be protected much more than sparsely populated rural communities. Undoubtedly populist politicians will prey upon this to further discord in our elections and further lack of intelligent responses to issues that are global, but felt locally.

A key research group in this space are Miyuki Hino et al from Stanford, whose work brings into focus the necessity of understanding who benefits from retreat and who initiates it. My work in this space makes it clear that the reality of both of those statements is often very different from the manipulable perception of them.

And in North America there’s another wrinkle. This land belonged to another people before the current wave of immigrants started arriving in 1500. In most cases, our forefathers bundled them off to treaty reserves, some of which overlapped with their original territory, many of which didn’t. And these lands that they are tied to by complex webs of culture and law are deeply threatened in many cases. Robin Bronen, Senior Research Scientist, Institute of Arctic Biology, University of Alaska, spends much of her time working with the First Nations of Alaska to try to find pathways to effective adaptation, but it’s even more difficult than for non-indigenous communities. There’s an ugly history of forced relocation in Canada that only ended in the mid-1990s and it’s still a fresh memory in merely middle-aged people today. The challenge is not ancient history, and managed retreat discussions compound.

Entire conferences are now devoted to the topic of specific risks and related managed retreats. In June 2019, Columbia hosted a three-day conference, At What Point Managed Retreat? Resilience Building in the Coastal Zone. It’s not the only major gathering of researchers and policy makers agonizing over this challenge.

What do we protect? What do we make resilient? What do we abandon, and how? What do we avoid? These are major global questions for the 21st Century, made more pressing by our refusal to act swiftly and decisively in the 20th Century when we already knew the scope of the problem of climate change.

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Michael Barnard

is a climate futurist, strategist and author. He spends his time projecting scenarios for decarbonization 40-80 years into the future. He assists multi-billion dollar investment funds and firms, executives, Boards and startups to pick wisely today. He is founder and Chief Strategist of TFIE Strategy Inc and a member of the Advisory Board of electric aviation startup FLIMAX. He hosts the Redefining Energy - Tech podcast ( , a part of the award-winning Redefining Energy team.

Michael Barnard has 651 posts and counting. See all posts by Michael Barnard