Cartoon guide to biodiversity loss LXII

2 09 2020

The fifth set of biodiversity cartoons for 2020. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Many animals won’t cope with climate change without access to ample drinking water

12 08 2020

Climate change implies change in temperature and water, and both factors shape species’ tolerances to thermal stress. In our latest article, we show that lack of drinking water maximises differences in tolerance to high temperatures among populations of Iberian lizard species.


Climate change is a multidimensional phenomenon comprising temporal and spatial shifts in both temperature and precipitation (1). How we perceive climate change depends on whether we measure it as shift in (i) mean conditions (e.g., the mean air temperature or rainfall over a decade within a given territory), (ii) magnitude or frequency of extreme conditions (e.g., the frequency of floods or tornados or the number of days with temperatures or rainfall above or below a given threshold), or (iii) speed at which mean or extreme conditions change in space and/or time.

In aquatic ecosystems, climate change further alters water acidity, oxygen dissolution and melting of ice. However, many people, including some scientists, tend to equate climate change erroneously with increased mean temperatures. Psychologists have made the semantic point that the use of the expressions climate change and global warming as synonyms can give mixed messages to politicians, and society in general, about how serious and complex the climate emergency we are facing really is (2, 3) — see NASA’s simple-worded account on the subject here.

In our latest article (4), we reviewed the ecological literature to determine to what extent ecologists investigating the tolerance of terrestrial animals to high temperatures have looked at thermal effects over water effects. It turns out, they were five times more likely to examine temperature over water.


Frequency of correlations between climate (air temperature versus precipitation) and tolerance to high temperature of terrestrial fauna in 64 papers published in the ecological literature (thickest link = 36, thinnest link = 2) following a systematic literature review in Scopus (4).

This is counterintuitive. Just imagine you have been walking under the sun for several hours on one of those dog days of summer, and you are offered to choose between a sunshade or a bottle of water. I’d bet you’d choose the bottle of water.

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Double standards: climate change vs. COVID-19

3 08 2020

Both anthropogenic climate change and the coronavirus pandemic entail serious health risks. Why then do climatologists lack the public credibility and political repercussions that doctors have? Preventing the aggravation of the climate emergency is possible if we react to it in the same way we are reacting to the pandemic, essentially, following the advice of the scientific community.


We have as much uncertainty regarding the coronavirus COVID-19 that causes acute respiratory failure (SARS-CoV-2) as we do about human-made greenhouse gases causing climate change.

Both problems are currently costing (and will cost) trillions to national economies. But the main difference between the two when it comes to public perception is not economic but temporal. The virus has changed our lives in days to months whereas climate change is taking years to decades to do so. This short-termism about how we respond to the pace of an emergency has been sculped in our genes by evolution (1) and contaminates politics.

Early this year, after deriding the onset of the pandemic, many climate change-denialist leaders (the obvious picks are Trump, Bolsonaro, and Johnson [note that Johnson modified his public views on climate change when becoming UK foreign secretary in 2016]) had to swallow their own words and honour their political profession when human corpses started to pile up in their hospitals. Read the rest of this entry »

The only constant is change

27 07 2020

I just wrote a piece for the Flinders University alumnus magazine — Encounter — and I thought I’d share it here.


As an ecologist concerned with how life changes and adapts to the vagaries of climate and pervasive biological shuffling, ‘constant change’ is more than just a mantra — it is, in fact, the mathematical foundation of our entire discipline.

But if change is inevitable, how can we ensure it is in the right direction?

Take climate change for example. Since the Earth first formed it has experienced abrupt climate shifts many times, both to the detriment of most species in existence at any given time, and to the advantage of those species evolving from the ashes.

For more than 3.5 billion years, species have evolved and gone extinct, such that more than 99% of all species that have ever existed are now confined, permanently, to the vaults of the past.

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Cartoon guide to biodiversity loss LXI

31 05 2020

The fourth set of biodiversity cartoons for 2020. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Never let a good crisis go to waste

11 05 2020


First published in the Millennium Alliance for Humanity and the Biosphere Blog on 5 May 2020.

by Professor Dan Blumstein (University of California at Los Angeles), Professor Paul Ehrlich (Stanford University), and Corey Bradshaw (Flinders University)

Winston Churchill’s words have never been more important than today as we experience the society- and life-changing consequences of the COVID-19 pandemic.

The extent and severity of the disease is a result of ignoring decades of warnings by scientists about the general deterioration of humanity’s epidemiological environment, and specific warnings about confining live, wild animals in markets. The situation was made even more lethal by ignoring the warnings from epidemiologists and disease ecologists once it became clear that an imminent pandemic most likely arose from this practice. Many countries, including the United States, are still ignoring those warnings and the required actions to lessen the impact.

Accordingly, we should ask ourselves, “what else are we missing?” What other huge problems are hiding in plain sight where science could guide policy to avoid catastrophic future failures? For instance, there are two principal health threats that must be addressed immediately, and we must strike while the iron is hot.

The overuse of antibiotics in agriculture will cause widespread deaths from formerly treatable bacterial diseases because of the evolution of antibiotic resistance in microbes. The evolution of resistance is well-known, predictable, and obvious — not in retrospect, but now. By feeding antibiotics to otherwise healthy livestock, animals can be housed in higher densities and they grow faster. Read the rest of this entry »

Cartoon guide to biodiversity loss LX

8 04 2020

The third set of biodiversity cartoons for 2020 (plus a video treat). See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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How I feel now about climate change

10 03 2020

‘Bleak No. 2’ by David Vogler

Five years ago I was asked by a researcher at the Australia National University, Joe Duggan, how I ‘felt’ about climate change.

This was part of an original initiative that put a human face on the scientists working on elements of one of society’s greatest existential threats.

Thus, Is This How You Feel? became a massive success in terms of bringing to the world the idea that scientists are also deeply affected by what they see happening around them.

Five years later, Joe asked me and all the other scientists who participated to provide an update on how we feel.

Here’s what I wrote: Read the rest of this entry »

Cartoon guide to biodiversity loss LIX

24 02 2020

The second set of six biodiversity cartoons for 2020. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Heat tolerance highly variable among populations and species

14 01 2020

Many ecological studies have examined the tolerance of terrestrial wildlife to high and low air temperatures over global scales (e.g., 1, 2, 3). This topic has been boosted in the last two decades by ongoing and predicted impacts of climate change on biodiversity (see summary of 2019 United Nation’s report here and here).

However, it is unfortunate that for most species, studies have measured thermal tolerance from a single location or population. Researchers interested in global patterns of thermal stress collect those measurements from the literature for hundreds to thousands of species [recently compiled in the GlobTherm database] (4), and are therefore often restricted to analysing one value of thermal tolerance per species.


Three of the 15 species of Iberian lacertids sampled in our study of thermal tolerance (9), including the populations of Algerian psammodromus (Psammodromus algirus), Geniez’s wall lizard (Podarcis virescens) and Western green lizard (Lacerta bilineata) sampled in Navacerrada (Madrid), Fuertescusa (Cuenca) and Moncayo (Soria), respectively. Photos by S. Herrando-Pérez

Using this approach, ecologists have concluded that cold tolerance is far more variable than heat tolerance across species from the tropics to the boreal zone (5-8). Consequently, tolerance to heat stress might be a species trait with limited potential to change in response to global warming compared to cold tolerance (5). Read the rest of this entry »

Cartoon guide to biodiversity loss LVIII

4 01 2020

The first set of six biodiversity cartoons for 2020. This special, Australia-is-burning-down-themed set is dedicated to Scott Morrison and his ilk. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Cartoon guide to biodiversity loss LV

4 07 2019

The fourth set of six biodiversity cartoons for 2019. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Cartoon guide to biodiversity loss LIV

17 05 2019

The third set of six biodiversity cartoons for 2019. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Cartoon guide to biodiversity loss LIII

25 03 2019

The second set of six biodiversity cartoons for 2019. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Thirsty forests

1 02 2019

Climate change is one ingredient of a cocktail of factors driving the ongoing destruction of pristine forests on Earth. We here highlight the main physiological challenges trees must face to deal with increasing drought and heat.

Forests experiencing embolism after a hot drought. The upper-left pic shows Scots (Pinus sylvestris) and black (P. nigra) pines in Montaña de Salvador (Espuñola, Barcelona, Spain) during a hot Autumn in 2015 favouring a massive infestation by pine processionary caterpillars (Thaumetopoea pityocampa) and tree mortality the following year (Lluís Brotons/CSIC in InForest-CREAF-CTFC). To the right, an individual holm oak (Quercus ilex) bearing necrotic branches in Plasencia (Extremadura, Spain) during extreme climates from 2016 to 2017, impacting more than a third of the local oak forests (Alicia Forner/CSIC). The lower-left pic shows widespread die-off of trembling aspen (Populus tremuloides) from ‘Aspen Parkland’ (Saskatchewan, Canada) in 2004 following extreme climates in western North America from 2001 to 2002 (Mike Michaelian/Canadian Forest Service). To the right, several dead aspens near Mancos (Colorado, USA) where the same events hit forests up to one-century old (William Anderegg).

A common scene when we return from a long trip overseas is to find our indoor plants wilting if no one has watered them in our absence. But … what does a thirsty plant experience internally?

Like animals, plants have their own circulatory system and a kind of plant blood known as sap. Unlike the phloem (peripheral tissue underneath the bark of trunks and branches, and made up of arteries layered by live cells that transport sap laden with the products of photosynthesis, along with hormones and minerals — see videos here and here), the xylem is a network of conduits flanked by dead cells that transport water from the roots to the leaves through the core of the trunk of a tree (see animation here). They are like the pipes of a building within which small pressure differences make water move from a collective reservoir to every neighbours’ kitchen tap.

Water relations in tree physiology have been subject to a wealth of research in the last half a decade due to the ongoing die-off of trees in all continents in response to episodes of drought associated with temperature extremes, which are gradually becoming more frequent and lasting longer at a planetary scale (1). 

Embolised trees

During a hot drought, trees must cope with a sequence of two major physiological challenges (2, 3, 4). More heat and less internal water increase sap tension within the xylem and force trees to close their stomata (5). Stomata are small holes scattered over the green parts of a plant through which gas and water exchanges take place. Closing stomata means that a tree is able to reduce water losses by transpiration by two to three orders of magnitude. However, this happens at the expense of halting photosynthesis, because the main photosynthetic substrate, carbon dioxide (CO2), uses the same path as water vapour to enter and leave the tissues of a tree.

If drought and heat persist, sap tension reaches a threshold leading to cavitation or formation of air bubbles (6). Those bubbles block the conduits of the xylem such that a severe cavitation will ultimately cause overall hydraulic failure. Under those conditions, the sap does not flow, many parts of the tree dry out gradually, structural tissues loose turgor and functionality, and their cells end up dying. Thus, the aerial photographs showing a leafy blanket of forest canopies profusely coloured with greys and yellows are in fact capturing a Dantesque situation: trees in photosynthetic arrest suffering from embolism (the plant counterpart of a blood clot leading to brain, heart or pulmonary infarction), which affects the peripheral parts of the trees in the first place (forest dieback).

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Cartoon guide to biodiversity loss LII

2 01 2019

The first set of six biodiversity cartoons for 2019 to usher in the New Year. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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With a Rebel Yell, Scientists Cry ‘No, no, more!’

29 11 2018

Adrenaline makes experiences hyper-real. Everything seems to move in slow motion, apart from my heart, which is so loud that I am sure people can hear it even over the traffic.

It’s 11:03 on a sunny November morning in central London. As the green man starts to shine, I walk into the middle of the road and sit down. On either side of me, people do the same. There can only be about 50 of us sitting on this pedestrian crossing, and I murmur ‘are we enough?’

‘Look behind you,’ says a new friend.

I turn. Blackfriar’s Bridge, usually covered in cars and buses, is filling with people. Citizens walking into the road and staying there, unfurling colourful flags with hourglass symbols on them. The police film us, standing close, but make no move to arrest anyone. Later, we discover that at least some of them encourage our disobedience.

Messages start coming in — 6,000 people are here, and we’ve blocked five bridges in central London with Extinction Rebellion, protesting for action to stop climate change and species extinctions. I’m a scientist participating in my first ever civil disobedience, and for me, this changes everything.


Left to right: protestors include kids, company directors, and extinct species.

What makes a Cambridge academic — and thousands of other people — decide that sitting in a road is their best chance of being heard? In short, nothing else has got us the emissions cuts we need. The declaration that global warming is real and that greenhouse-gas emissions need to be cut came in 1988, when I was a year old. Since then, scientists have continued to be honest brokers, monitoring greenhouse gases, running models, presenting the facts to governments and to the people. And emissions have continued to climb. The 2018 IPCC report that shocked many of us into action told us we have 12 years to almost halve emissions, or face conditions incompatible with civilisation. How did we end up here? Read the rest of this entry »

Global warming causes the worst kind of extinction domino effect

25 11 2018

Dominos_Rough1-500x303Just under two weeks ago, Giovanni Strona and I published a paper in Scientific Reports on measuring the co-extinction effect from climate change. What we found even made me — an acknowledged pessimist — stumble in shock and incredulity.

But a bit of back story is necessary before I launch into describing what we discovered.

Last year, some Oxbridge astrophysicists (David Sloan and colleagues) published a rather sensational paper in Scientific Reports claiming that life on Earth would likely survive in the face of cataclysmic astrophysical events, such as asteroid impacts, supernovae, or gamma-ray bursts. This rather extraordinary conclusion was based primarily on the remarkable physiological adaptations and tolerances to extreme conditions displayed by tardigrades— those gloriously cute, but tiny (most are around 0.5 mm long as adults) ‘water bears’ or ‘moss piglets’ — could you get any cuter names?


Found almost everywhere and always (the first fossils of them date back to the early Cambrian over half a billion years ago), these wonderful little creatures are some of the toughest metazoans (multicellular animals) on the planet. Only a few types of extremophile bacteria are tougher.

So, boil, fry or freeze the Earth, and you’ll still have tardigrades around, concluded Sloan and colleagues.

When Giovanni first read this, and then passed the paper along to me for comment, our knee-jerk reaction as ecologists was a resounding ‘bullshit!’. Even neophyte ecologists know intuitively that because species are all interconnected in vast networks linked by trophic (who eats whom), competitive, and other ecological functions (known collectively as ‘multiplex networks’), they cannot be singled out using mere thermal tolerances to predict the probability of annihilation. Read the rest of this entry »

Cartoon guide to biodiversity loss LI

23 10 2018

The six set of six biodiversity cartoons for 2018. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Cartoon guide to biodiversity loss L

3 08 2018

The fifth set of six biodiversity cartoons for 2018. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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