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Can Environmental Scientists Be Too Positive About The Future?


We environmental scientists are regularly encouraged to be positive and avoid all the doom and gloom in our messaging about global climate change and the environmental crisis more generally.  Constantly harping at people about the many possible forms of doom and gloom won’t encourage them to act to reduce our negative impacts.  In fact, too much doom and gloom and they will just turn off.

We marine scientists even have a hashtag, #OceanOptimism, to help us remember to be positive.  Under that hashtag, our colleagues keep posting tweets about wonderful glimmers of good news – a reef which did not bleach, a fishery which is not in decline, a population of endangered turtles, whales, or something else which has recovered its numbers.  But as well as conveying the idea that there are lots of wonderful things happening out in our oceans, these tweets help us scientists continue to ignore the shifting baselines – the abundant evidence of long-term decline here, there and everywhere.  I think we are beginning to shift from being optimistic to being pollyannas – people who see the positive in every circumstance, no matter how bad things really are – and I don’t think that helps the broader community come to grips with what we are doing to this planet.

Banning plastic straws may make us all feel good, and win kudos for the companies that do so, but that is a very tiny step to fighting the global environmental crisis – a glimmer of hope at best.  Image © Starbucks.

The media, from newspapers to Facebook, all put a high value on the new.  Old stories still get told, but always with a new twist, and what is new today is old by tomorrow.  Every environmental story that gets told references what has happened before, or what might happen in the future, but these references are often to the immediate past or future, and once that story is told it becomes part of the old, perhaps never referenced again.  But the events described did happen, the ice shelf did collapse or the forest did burn, and the fact that the media no longer comment does not mean that that event is washed away, the world dusted off and put back together.  This is the essence of how our environmental baselines slide; we are so busy attending to the new that we neglect to factor in the slights of yesterday or last year.

A recent report from UNEP (United Nations Environment Programme) makes an effort to summarize the suite of environmental changes we have caused in recent years.  Called Making Peace with Nature, its subtitle is A scientific blueprint to tackle the climate, biodiversity and pollution emergencies, and the opening words of its Executive Summary are: Humanity has been grappling with environmental challenges that have grown in number and severity ever since the Stockholm Conference in 1972.  The scientific assessments synthesized in this report show that those challenges now represent a planetary emergency.  While tackling the emergency is demanding, the report lights a path to a sustainable future marked with new possibilities and opportunities.

I’ll get to the optimism in that last sentence later, but the idea that an accumulation of ‘challenges’ over the last half century now are a planetary emergency – that’s the kind of message that is sent far too seldom.  Now Making Peace with Nature is not the only article to make this point.  In 2004, Will Steffan and co-authors produced a book, Global Change and the Earth System that is a 350-page source of information on the many ways in which humans have impacted the planet globally over the last several hundred years.  They point out that Earth is a system with a dynamic that depends on the interactions of its many component parts including those making up the biosphere.  That system varies in its state through time, within certain bounds determined by the nature of the interactions taking place.  However, humans have now become so numerous and so powerful that our activities have become a major driver of global system dynamics, enhancing, reducing, or completely overwhelming the effects of other components in the system.  Our ability to influence the planet has been growing since the dawn of civilization when we first began to cooperate in hunting big game.  That ability grew slowly but has expanded rapidly over the last century as our numbers, our economic activity, our consumption of raw resources, and our generation of waste products all increased exponentially.  Human actions have shifted the state of the planetary system so that, in some features, it is now well outside the range of states in which it had existed for millions of years.  Given that humans are not purposely causing these changes in system state, and given the extent and the speed at which departures from prior conditions are occurring, there is growing concern that we may be altering the planet in ways that do not bode well for our economy, our civilizations, and perhaps us.  In other words, we may be inadvertently screwing our chances for a bright future.

One aspect of this global change is the loss of biodiversity across the planet, often referred to as the sixth mass extinction.  There have been five occasions during the past 500 million years when the state of the planet became so extreme that substantial proportions of species of macroscopic life became extinct.  The end-Permian mass extinction, 250 million years ago, was the most severe, with an estimated 96% of then-living species going extinct.  That there have been mass extinctions confirms that this planet can at times become distinctly unfavorable for life.  The sixth mass extinction, which now appears to be commencing – based on the rising rates of extinction being recorded for many taxa – is the first caused by the activities of a single species of organism.  Only hubris allows us to assume this will have no impact on our own well-being!

When number of extinctions of mammals per million-species-years (E/MSY) is plotted against the number of years over which the ratio was calculated, there is a marked increase as time interval shortens.  Recent (since 2010), short-interval estimates are 10 to 1000 times higher than the rates of 1 or 2 extinctions per million species years for mammals in the Cenozoic.  Current rate estimates are what would be expected in a mass extinction event that takes out 75% or more of extant species.  More details in the original article in NatureFigure © A.D. Barnosky & Nature.

Biodiversity is not just measured in numbers of species; it refers to the extent of biological variation present.  We have caused substantial reductions of abundances of many species, and this reduces biodiversity by reducing the range of genetic variation within species even if no creature goes extinct.  So do our actions facilitating invasive species; their spread homogenizes the biota across regions, and therefore the genetic diversity among places.   I blogged about biodiversity loss back in 2015, and what I wrote then remains true. 

The loss of terrestrial megafauna at the close of the Pleistocene was the beginning of our misbehavior.  While climate change toward the end of the Pleistocene may have played an important part, human hunting was also a significant factor.  (The relative importance of climate change and hunting is subject to debate, but evidence from Australasia, which was colonized by humans earlier in the Pleistocene than were Europe or the Americas, strongly indicates an essential role for humans.) 

The pace at which we are diminishing biodiversity continues to increase.  WWF’s Living Planet Index, which monitors the sizes of over 20,000 populations of some four thousand species of mammal, bird, amphibian, reptile and fish, reveals an average 68% drop in abundance since 1970 – less than a third as many individuals in each of these populations today compared to fifty years ago.  That is a profound diminution, and humans and their few species of livestock are now so numerous that their biomass vastly exceeds the biomass of all other terrestrial vertebrates.

Total biomass currently on the planet, estimated as gigatons of carbon, is primarily in the form of plants.  Within the two gigatons estimated to exist as animals, most are arthropods (chiefly crustacea) and fish.  Humans and their livestock (0.16 Gt C combined) vastly outweigh the wild terrestrial vertebrates (0.005 Gt C combined for mammals and birds).  (There are 0.004 Gt C in marine mammals included in the wild mammals in the figure and amounts for reptiles and amphibia are both very small and not estimated with reasonable precision.) Image © YM Bar-On & PNAS.

The present pattern of mammalian biomass is very different to that estimated to exist before the Pleistocene megafauna extinctions.  In a 2018 review in Proceedings of the National Academy of Science, Yinon Bar-On and colleagues published detailed estimates of the distribution of biomass among categories of life.  While biomass of wild mammals is estimated to be 0.003 Gt C terrestrial and 0.004 Gt C marine today, these estimates are about 6-fold smaller than biomass of Pleistocene megafauna (0.02 Gt C) and pre-exploitation marine mammals (also 0.02 Gt C).  Our impacts on other vertebrates have been profound on both land and sea, while our own biomass and that of domesticated species have increased way beyond the wild mammalian biomass that has been lost.  These shifts in biomass coincide with profound loss of mammalian biodiversity because so many species have been replaced by just a few.  Nor is it just the mammals we have impacted.  On 5 March in Science, M.L. Forister of University of Nevada, and colleagues, report data for the western US showing a 1.6% per year rate of loss of numbers of butterflies over the last 40 years – a halving of numbers present.

Our changes to the landscape have also been enormous and continue apace.  Expansion of agriculture has impacted natural terrestrial systems, particularly in the tropics where 100 million hectares of tropical forest were lost between 1980 and 2000, primarily for cattle ranching in South America and palm-oil plantations in South East Asia.  Urban land area has doubled since 1992, and we have converted over 75% of all land for our uses.

The IPBES 2020 Global Report states we extract 60 billion tonnes of renewable and non-renewable resources annually, nearly double our extraction rate in 1980.  Over 80 per cent of global wastewater is being discharged back into the environment without treatment, while 300–400 million tons of heavy metals, solvents, toxic sludge and other wastes from industrial facilities are dumped into the world’s waters each year.  Oh, and there is an island of plastics larger than France in the mid-Pacific.

And then, of course, there is climate change and all the ramifications of that warming.  As I and others have repeated ad nauseum, the world is nowhere near being on track to achieve the Paris goal of no more than a 1.5oC increase in temperature and the pace of climate change continues to accelerate.  The +3oC world which looms (that is twice as much warming as the goal we are aiming for!) is menacing in many ways, and a number of profound impacts are already upon us.  2020 has tied with 2016 as the world’s warmest year despite being ‘ENSO-neutral’ (2016 was an el Niño year) and despite a reduced rate of emissions of CO2 because of a covid-crippled global economy.  The warming over recent years is measurably slowing ocean circulation as measured in the Gulf Stream and at the Atlantic Meridional Overturning Circulation (that site in the North Atlantic where cooling surface waters sink to feed the deep ocean circulation).  This slowing has been going on for some decades, and Johannes Lohmann and Peter Ditlevsen of the Niels Bohr Institute, Copenhagen had a recent report in Proceedings of the National Academy of Science (March 2021) arguing that the pace of change in temperature (which is very high relative to prior geological periods) may be sufficient to trigger a tipping point in which current pattern changes suddenly.  There may not be a critical threshold, just a critical speed sufficient to produce a chaotic reorganization.  I find that conjecture frankly scary! 

And, how warm is the planet getting?  On 8 March, Yi Zhang and colleagues at Princeton University reported in Nature Geoscience that failure to keep warming below 1.5oC (remember, we are at +1oC already) risks having a substantial swath of the tropics reaching extreme wet-bulb temperatures of 35oC.  What is the significance of a 35o wet-bulb temperature?  That is the temperature that is lethal to humans – standing outside or in any non-air-conditioned building in the tropics in a heat wave would lead to death in just a couple of hours.  This is not a slightly warmer climate; this is a slowly creeping catastrophe.

We also have to understand that all these bad things are happening together, that, in many cases the rate of deterioration is increasing, and that things we learned about years ago happened also, even though they are seldom talked about today.  There really is 90% less fish biomass swimming in the oceans, and 500 dead zones scattered around the world’s coastlines even if those two ‘facts’ have not been mentioned in recent headlines.  We have profoundly changed this planet already, and while we are now much more aware of what we have done, progress in repairing the problems is scant.  In 2000, the UN established the eight Millenium Development Goals and their 18 targets to be achieved by 2015.  Many of these addressed the growing environmental crisis and its effects on the quality of life of humanity.  We failed to achieve most of the targets even by 2020.

With failure of the MDG’s looming, in 2015 the UN, in its wisdom, replaced them with 17 Sustainable Development Goals to be achieved by 2030 – goals to bring societal development into line with the capacities of the planet to sustain us.  Talk about rearranging deckchairs on a sinking Titanic.  The world is not now on track to achieve many of these 17 SDGs and in several instances the situation has worsened.  Along the way, the world also failed to achieve any of the 20 Aichi Biodiversity Targets, designed to prompt reforms between 2011 and 2020 to reduce loss of biodiversity.  There were some tiny glimmers of success, but those targets now are also being replaced by new ones to be achieved in 2030.  I don’t have a lot of hope!

And so I come back to optimism – the optimism UNEP’s Making Peace with Nature report professes, and the optimism we environmental scientists are told we must find.  Yes, there is good news.  Yes, I am heartened that Quebec has recently granted legal rights to the Magpie River, a sign of an improving attitude towards Nature in my country.  Yes, I am pleased that there are signs of modest movement towards some of the SDGs, and that there is growing awareness of the need to act on climate change.  But all these glimmers of hope, so far, do not amount to a forest fire frenzy of action to curb the environmental crisis.  They are more like feeble flickers of a dying attempt to change our ways.

I do cling to a naïve optimism that ultimately we will skate through with a less disastrous outcome than we might expect, more because I cannot believe we can be so enormously stupid as to sit by and watch as our own extinction looms, than because I have faith in our ability to skate over very thin ice on the edge of a yawning precipice.  In other words, I remain optimistic only because I cannot wrap my head around the idea of humanity plodding onward to ultimate failure – a mere flash in the pan in the great sweep of evolution of life on this marvelous blue planet.

The Magpie River in Québec’s Côte-Nord region, culturally significant for the Innu of Ekuanitshit, has now been granted specific legal rights including the right to flow, to maintain its biodiversity, and to pursue legal action like any other person.  This first for Canada is one more small sign that humans are beginning to realign their attitudes towards the rest of the biosphere.  Such a realignment may be an essential step we must take in order to build the necessary political will to tackle the environmental crisis successfully.  Photo © Canadian Press.