The Shifting of Ecological Baselines

Bushfires like the ones that have ravaged Australia and California this year could become the new norm for the generation that has been born in the last decade, an example of how our perception of ecological change is defined by what has happened in our lifetime

Bushfires like the ones that have ravaged Australia and California this year, could become the new norm for the generation that has been born in the last decade, an example of how our perception of ecological change is defined by what has happened in our lifetime (Image Credit: dm4244, CC BY-SA 4.0, Image Cropped)

It’s no secret that our world has undergone rapid changes in the last few decades. Extreme weather events are becoming almost the norm and species seem to be going extinct every minute. But as depressing as this may seem, the general doom and gloom we hear about the world on a daily basis still only represents a small percentage of the ills we’ve inflicted on our planet since we’ve been here.

This comes down to a concept called shifting baselines. In ecology, shifting baselines lead to us underestimating the magnitude of change the earth has experienced. It happens because our concept of what is ‘normal’ for the planet (ie. our baseline) is influenced by what we’ve seen in only our lifetime. So today I’ll talk about some classic examples of this concept, why it’s so important to keep an eye on how much these baselines shift, and what can be done to keep them in place.

Bushfires have ravaged California this year, as they do every few years in Victoria, Australia. I went through most of my childhood and university years thinking that a severe bushfire season was the norm. Nowadays, fire warnings are standard in Victoria. And this year we’ve had bushfires in the tropics. I’m actually writing this on my way to Queensland, where the usual concerns around this time of year are tropical storms and flooding.

But the problem is that bushfires weren’t something that Victoria and California used to take with such begrudging acceptance. I’m not saying they weren’t a threat in either state previously. In 1926 fires killed over 60 people and destroyed 1,000 buildings. However neither state expected such disaster on a regular basis. But as Johanna Schmitt, Professor of Botany at the University of California states, “For kids today, these California wildfires will be the new normal”.

Forestation in the US in general is a great example. We spoke to Dr. Shannon McCauley in November, and she reminded us that “throughout a lot of New England and the upper Midwest, it’s more forested now than it was at the turn of the century, early 1900s. There’s work that’s been done in New England that shows we’re at the highest forest levels in 200 years. BUT, that’s because 200 years ago it was really deforested. Everyone’s perception is very much shaped by what we experience as kids.”


Forest levels might be at record highs for the last 200 years, but that only seems positive because we’re not measuring against pre-deforestation levels (Image Credit: US Fish and Wildlife Service, CC BY 2.0)

The Great Barrier Reef is a world-renowned environmental disaster zone, with extreme weather events having caused massive die-offs in the reefs coral populations in the last few years. The destruction of the reef is something that my generation has seen happen within our lifetime. Yet even before that, our baseline for a reef ecosystem had already shifted considerably. Reef systems worldwide had already seen massive reductions in species richness. As Sean Connolly of Townsville’s James Cook University puts it, “in Australia there are historical reports of people sitting in bays as a herd of dugong go by that would take half an hour. Our idea of a pristine reef is probably nothing like it would be if there had been scuba diving in the 1700s.”

The destruction of reef systems worldwide are an obvious example of why we need to be aware of how far our baselines have dropped. Anti-conservation political parties in Australia are already starting to posit bleaching as a regular annual occurrence, something that happens in summer. And it shouldn’t be. The small size of year to year changes in temperature are being used in line with the theory that the climate changes all the time, when looking at temperature increases from a historical perspective show a much more grim picture.

So how to we stop the ongoing shift of baselines? There’s only so much that listening to your grandparents talk about how many kangaroos or purple martins there used to be in the backyard can do.

I believe the answer lies in long-term population studies with easily tangible outcomes. Professor Paul Hebert of the University of Guelph thinks that “[w]e just need to become very good at counting organisms to generate the comprehensive trend data needed to reveal the extent of our impacts”. If we are able to easily remind people how much species populations have decreased worldwide, and how little bushfires of the severity we’ve seen this year used to happen, those changes become more apparent. People might still lack a personal connection to it, but the numbers will still be there, staring you in the face.

I’ve included articles which detail some great long-term studies below.

The problem is that long-term studies such as those above can be difficult to fund and maintain. They rely on long-term results, which are not always attractive to the organisations that provide funding. They also require dedicated researchers to keep them going, and pass the studies on to others after retirement, which isn’t easy.

Yet I’m confident that if we start to emphasise the importance of studies like these on a more regular basis, we’ll see more importance placed on them by ecologists, biologists and society at large. Shifting baselines could be so damaging to the planet at every timescale, and we need to start to take steps to keep them in place.


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