13 08 2021

## Interval between extremely wet years increasing?

16 07 2021

The other day I was playing around with some Bureau of Meteorology data for my little patch of the Adelaide Hills (free data — how can I resist?), when I discovered an interesting trend.

Living on a little farm with a small vineyard, I’m rather keen on understanding our local weather trends. Being a scientist, I’m also rather inclined to analyse data.

My first question was given the strong warming trend here and everywhere else, plus ample evidence of changing rainfall patterns in Australia (e.g., see here, here, here, here, here), was it drying out, getting wetter, or was the seasonal pattern of rainfall in my area changing?

I first looked to see if there was any long-term trend in total annual rainfall over time. Luckily, the station records nearest my farm go all the way back to 1890:

While the red line might suggest a slight decrease since the late 19th Century, it’s no different to an intercept-only model (evidence ratio = 0.84) — no trend.

Here’s the R code to do that analysis (you can download the data here, or provide your own data in the same format):

```## IMPORT MONTHLY PRECIPITATION DATA

## CALCULATE ANNUAL VECTORS
precip.yr.sum <- xtabs(dat\$Monthly.Precipitation.Total..millimetres. ~ dat\$Year)
precip.yr.sum <- precip.yr.sum[-length(precip.yr.sum)]
year.vec <- as.numeric(names(precip.yr.sum))

## PLOT
plot(year.vec, as.numeric(precip.yr.sum), type="l", pch=19, xlab="year", ylab="annual precipitation (mm)")
fit.yr <- lm(precip.yr.sum ~ year.vec)
abline(fit.yr, lty=2, lwd=2, col="red")
abline(h=mean(as.numeric(precip.yr.sum)),lty=2, lwd=3)

## TEST FOR TREND
# functions
AICc <- function(...) {
models <- list(...)
num.mod <- length(models)
AICcs <- numeric(num.mod)
ns <- numeric(num.mod)
ks <- numeric(num.mod)
AICc.vec <- rep(0,num.mod)
for (i in 1:num.mod) {
if (length(models[[i]]\$df.residual) == 0) n <- models[[i]]\$dims\$N else n <- length(models[[i]]\$residuals)
if (length(models[[i]]\$df.residual) == 0) k <- sum(models[[i]]\$dims\$ncol) else k <- (length(models[[i]]\$coeff))+1
AICcs[i] <- (-2*logLik(models[[i]])) + ((2*k*n)/(n-k-1))
ns[i] <- n
ks[i] <- k
AICc.vec[i] <- AICcs[i]
}
return(AICc.vec)
}

delta.AIC <- function(x) x - min(x) ## where x is a vector of AIC
weight.AIC <- function(x) (exp(-0.5*x))/sum(exp(-0.5*x)) ## Where x is a vector of dAIC
ch.dev <- function(x) ((( as.numeric(x\$null.deviance) - as.numeric(x\$deviance) )/ as.numeric(x\$null.deviance))*100) ## % change in deviance, where x is glm object

linreg.ER <- function(x,y) { # where x and y are vectors of the same length; calls AICc, delta.AIC, weight.AIC functions
fit.full <- lm(y ~ x); fit.null <- lm(y ~ 1)
AIC.vec <- c(AICc(fit.full),AICc(fit.null))
dAIC.vec <- delta.AIC(AIC.vec); wAIC.vec <- weight.AIC(dAIC.vec)
ER <- wAIC.vec[1]/wAIC.vec[2]
}

linreg.ER(year.vec, as.numeric(precip.yr.sum))
```
Read the rest of this entry »

## Losing half of tropical fish species as corals disappear

30 06 2021

When snorkelling in a reef, it’s natural to think of coral colonies as a colourful scenography where fish act in a play. But what would happen to the fish if the stage went suddenly empty, as in Peter Brook’s 1971 Midsummer Night’s Dream? Would the fish still be there acting their roles without a backdrop?

This question is not novel in coral-reef science. Ecologists have often compared reef fish diversity and biomass in selected localities before and after severe events of coral mortality. Even a temporary disappearance of corals might have substantial effects on fish communities, sometimes resulting in a local disappearance of more than half of local fish species.

Considering the multiple, complex ways fish interact with — and depend on — corals, this might appear as an obvious outcome. Still, such complexity of interactions makes it difficult to predict how the loss of corals might affect fish diversity in specific contexts, let alone at the global scale.

Focusing on species-specific fish-coral associations reveals an inconsistent picture with local-scale empirical observations. When looking at the fraction of local fish diversity that strictly depends on corals for food and other more generic habitat requirements (such as shelter and reproduction), the global picture suggests that most fish diversity in reef locality might persist in the absence of corals.

The mismatch between this result and the empirical evidence of a stronger coral dependence suggests the existence of many hidden ecological paths connecting fish to corals, and that those paths might entrap many fish species for which the association to corals is not apparent.

Read the rest of this entry »

## Is the IPCC finally catching up with the true severity of climate change?

24 06 2021

I’m not in any way formally involved in either the IPCC or IPBES, although I’ve been involved indirectly in analysing many elements of both the language of the reports and the science underlying their predictions.

Today, The Guardian reported that a leaked copy of an IPCC report scheduled for release soon indicated that, well, the climate-change situation is in fact worse than has been previously reported in IPCC documents.

If you’re a biologist, climatologist, or otherwise-informed person, this won’t come as much of a surprise. Why? Well, the latest report finally recognises that the biosphere is not just some big balloon that slowly inflates or deflates with the whims of long-term climate variation. Instead, climate records over millions of years show that the global climate can and often does shift rapidly between different states.

This is the concept of ‘tipping points’.

Read the rest of this entry »

## A domesticated planet

15 06 2021

The abundance of wild animals is regressing speedily as the number of domesticated animals and persons keeps escalating. Such demographic contrast signals that we urgently need to modify our model of subsistence and our interaction with Mother Nature.

If we had to choose between a biodiverse landscape and one hosting a monoculture of pine trees with ruminating cattle, many would take the first option. Biodiversity has an aesthetic value to humans, and also gives us free services like pollination, climate regulation, freshwater depuration or soil formation (1, 2). That is why the mounting rates of biodiversity loss have propelled a multi-angled debate about whether the Earth is experiencing the sixth mass extinction (3, 4) and how biodiversity should be managed to secure our access to ecosystem services (5, 6).

Think individuals, not species

A different way of approaching the biodiversity crisis consists of examining trends in the number of wild animals, with not so much emphasis on the variety of species. Thus, the Living Planet Report 2020, published by the World Wildlife Fund, has compiled thousands of scientific studies about > 21,000 populations of wild vertebrates studied over time (> 4,000 species represented) and concluded that, on average, the number of individuals per population has diminished by 70% since the 1970s (7).

On the other hand, Yinon Bar-On et al. (8) quantified that the biomass of humans and our domesticated mammals currently multiplies the biomass of wild mammals by a factor of 10, and there are 3 kg of humans and poultry for every kg of wild birds (see video featuring this study).

Not only that, during the last 100,000 years through which anatomically modern humans have thrived from a handful of bands of African hunter-gatherers to complex societies living in metropolis, the cattle industry has ended up quadrupling the global biomass of mammals (8).

Read the rest of this entry »

29 05 2021

## Citizens ask the experts in climate-change communication

7 02 2021

In the second of two consecutive interviews with climate-change experts (see the first one here), readers of the Spanish magazine Quercus have a chat with Katharine Hayhoe. Her words blend hope with the most putrid reality of economics and politics. May this interview inspire some environment-friendly changes in our daily routines and in how we see the beautiful life that surrounds us.

PhD in climate science, professor in political science and co-director of the Climate Centre at Texas Tech University (USA), Katharine Hayhoe works on climate projections and mitigation (1-3). Her prominent profile as communicator (4-6) made her one of the 100th most influential people in the world. To the left, Katharine has “A conversation on climate change” with citizens at the Lyndon Baines Johnson Presidential Library and Museum (Austin). Photo credits: Artie Limmer (portrait) & Jay Godwin (talk).

Interview done 20 October 2020

Below we italicise each question and the name of the person asking the question and cite a range of publications we deem relevant per question. For expanding on Katharyne Hayhoe’s views on climate change, see a sample of her public talks here and here, interviews here and here, and newspaper articles here and here. We love one of the titles of her newspaper articles “A thermometer is not liberal or conservative”. A spanish version of this article and interview has been published in the February 2021 issue of the magazine Quercus.

Question 1 of 4: There are extraordinarily influential people on a global scale who have a utilitarian perspective of nature, and think that climate change (be it of anthropogenic origin or not) entails advantages and opportunities to Western economies, and that we will be able to adapt whether changes are reversible or irreversible. Can we engage or use those influential people in any possible way to abate climate change? (7, 8) Iñaki García Pascual (Environmental geologist)

Hayhoe:

Climate change has some localised, short-term, specific benefits (9). One example is increased access to oil and gas resources in a melting Arctic (10). This temporarily profits oil and gas industries, provides some financial benefit to local communities in Greenland and Alaska short-term, and harms both them and everyone else in the long term. A book called Windfall by Mackenzie Funk describes who is “profiteering” from climate change, and how.

Overall, however, climate change already harms the majority of people today. The poor, the vulnerable, and the marginalized are affected first and foremost. Since the 1960s, for example, climate change has increased the gap between the richest and poorest countries in the world by as much as 25 per cent. In 2019, UN Special Rapporteur on extreme poverty and human rights, Philip Alston, warned that climate change “threatens to undo the last 50 years” of development, global health and poverty reduction.” (11)

And while the rich may be able to temporarily “buy their way out of rising heat and hunger”, as Alston put it, the truth is that we all live on this planet, no matter how wealthy and influential we are. The air we breathe, the water we drink, the food we eat and all the resources we use come from our shared home.

Climate change threatens the ability of our planet to support human civilisation as we know it. It is a threat multiplier, attacking our health, our economy, our resources and even our security. As climate change intensifies and economic markets crumble and refugee crises surge, even those who may temporarily benefit from a warmer world will be negatively impacted by these changes long-term.

That’s why it makes so much sense to take practical steps to limit carbon pollution now. Many of these actions also provide us with short-term benefits that can be quantified in economic terms: like energy savings through efficiency, cheaper electricity from renewables, more jobs, better public transportation, and even faster cars (like Tesla). Climate action also provides less tangible but arguably even more important benefits: cleaner air and water, better health, poverty reduction, and a host of other co-benefits that substantively move us towards meeting key UN Sustainable Development Goals.

To care about climate change, we don’t have to be a certain type of person or live in a certain place or vote a certain way: all we have to be is a human living on this planet, and we’re all that.

Read the rest of this entry »

## Worried about Earth’s future? Well, the outlook is worse than even scientists can grasp

14 01 2021

Anyone with even a passing interest in the global environment knows all is not well. But just how bad is the situation? Our new paper shows the outlook for life on Earth is more dire than is generally understood.

The research published today reviews more than 150 studies to produce a stark summary of the state of the natural world. We outline the likely future trends in biodiversity decline, mass extinction, climate disruption and planetary toxification. We clarify the gravity of the human predicament and provide a timely snapshot of the crises that must be addressed now.

The problems, all tied to human consumption and population growth, will almost certainly worsen over coming decades. The damage will be felt for centuries and threatens the survival of all species, including our own.

Our paper was authored by 17 leading scientists, including those from Flinders University, Stanford University and the University of California, Los Angeles. Our message might not be popular, and indeed is frightening. But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face.

## Getting to grips with the problem

First, we reviewed the extent to which experts grasp the scale of the threats to the biosphere and its lifeforms, including humanity. Alarmingly, the research shows future environmental conditions will be far more dangerous than experts currently believe. Read the rest of this entry »

## Time for a ‘cold shower’ about our ability to avoid a ghastly future

13 01 2021

I wish it need not have happened in my time,” said Frodo. “So do I,’ said Gandalf, “and so do all who live to see such times. But that is not for them to decide. All we have to decide is what to do with the time that is given us.”

Frodo Baggins and Gandalf, The Fellowship of the Ring

Today, 16 high-profile scientists and I published what I describe as a ‘cold shower’ about society’s capacity to avoid a ghastly future of warfare, disease, inequality, persecution, extinction, and suffering.

And it goes way beyond just the plight of biodiversity.

No one who knows me well would mistake me for an optimist, try as I might to use my colleagues’ and my research for good. Instead, I like to describe myself as a ‘realist’. However, this latest paper has made even my gloomier past outputs look downright hopeful.

And before being accused of sensationalism, let me make one thing abundantly clear — I sincerely hope that what we describe in this paper does not come to pass. Not even I am that masochistic.

I am also supportive of every attempt to make the world a better place, to sing about our successes, regroup effectively from our failures, and maintain hope in spite of evidence to the contrary.

But failing to acknowledge the magnitude and the gravity of the problems facing us is not just naïve, it is positively dangerous and potentially fatal.

It is this reason alone that prompted us to write our new paper “Underestimating the challenges of
avoiding a ghastly future
” just published in the new journal, Frontiers in Conservation Science.

Read the rest of this entry »

## Citizens ask the expert in climate physics

24 11 2020

In the first of two consecutive interviews with climate-change experts, authors, editors and readers of the Spanish magazine Quercus have a chat with Ken Caldeira, a global-ecology researcher at the Carnegie Institution for Science (Washington, USA). His responses attest that the climate system is complex, and that we need to be practical in dealing with the planet’s ongoing climate emergency.

SARS-Covid-19 is impacting the world. In our home country, Spain, scientists argue that (i) previous budget cuts in public health have weakened our capacity to tackle the pandemic (7), and (ii) the expert panels providing advice to our government should be independent of political agendas in their membership and decisions (8). Nevertheless, the Spanish national and regional governments’ data lack the periodicity, coherence, and detail to harness an effective medical response (9). Sometimes it feels as if politics partly operate by neglecting the science needed to tackle challenges such as the covid pandemic or climate change.

Having said that, even if a country has cultivated and invested in the best science possible, people have difficulties coming to terms with the idea that scientists work with probabilities of alternative scenarios. As much as there are different ways of managing a pandemic, scientists differ about how to mitigate the ecological, economic, and health impacts of a high-carbon society.

Thus, a more and more common approach is to make collective assessments (elicitations) by weighing different points of view across experts — for instance, to establish links between climate change and armed conflict (10) or to evaluate the role of nuclear energy as we transition to a low-carbon energy-production model (11). The overarching goal is to quantify consensus based on different (evidence-based) opinions.

The questions we here ask Ken Caldeira could well have different answers if asked of other experts. Still, as Ken points out, it is urgent that (of the many options available) we use the immense and certainty-proof knowledge we have already about climate change to take actions that work.

Interview done 23 January 2020

We italicise each question and the name of the person asking the question and cite one to three relevant publications per question. For expanding on Ken Caldeira’s views on climate change, see a sample of his public talks here and here and newspaper articles here and here.

26 10 2020

## Climate explained: humans have dealt with plenty of climate variability

23 09 2020

(originally published on The Conversation)

How much climate variability have humans dealt with since we evolved and since we started settling (Neolithic times)? How important was migration to human survival during these periods?

The climate always fluctuates as variation in the Sun’s heat reaching Earth drives glacial-interglacial cycles. Over the past 420,000 years there have been at least four major transitions between ice ages and relatively warmer interglacial periods.

Modern humans emigrated from Africa to populate the rest of the globe between 120,000 and 80,000 years ago, which means our species has had to adapt to many massive climate transitions.

## Warming and cooling

The Last Interglacial 129,000–116,000 years ago was a period of intense global warming (from around 2 ℃ higher than today to as much as 11 ℃ higher in the Arctic), leading to a large reduction of the Arctic, Greenland and Antarctic ice sheets, and a 6–9 m rise in sea level.

The Last Glacial Maximum from 26,500–19,000 years ago coincided with a large drop in atmospheric CO₂ and a 4.3 ℃ cooling globally.

Read more: Climate explained: will the tropics eventually become uninhabitable?

Low temperatures turned much of the world’s water into ice and expanded glaciers.

Read the rest of this entry »

2 09 2020

## 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.

## 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.

## Successful movers responding to climate change

16 06 2020

Ecologists often rely on measuring certain elements of a species’ characteristics, behaviour, or morphology to determine if these — what we call ‘traits’ — give them certain capacities to exploit their natural environments. While sometimes a bit arbitrarily defined, the traits that can be measured are many indeed, and sometimes they reveal rather interesting elements of a species’ resilience in the face of environmental change.

As we know, climate change is changing the way species are distributed around the planet, for the main (and highly simplified) reason that the environments in which they’ve evolved and to which they have adapted are changing.

In the simplest case, a warming climate means that there is a higher and higher chance you’ll experience temperatures that really don’t suit you that well (think of a koala or a flying fox baking in a tree when the thermometer reads +45° in the shade). Just like you seeking those nice, air-conditioned spaces on a scorcher of a day, species like to move to where conditions are more acceptable to their particular physiologies and behaviours.

Ecologists use life-history traits to predict which species have the highest probability of moving to new areas in response to climate change. Most studies into this phenomenon have largely ignored that range shifts in fact occur in sequential stages: (1) the species arrives in a new place for the first time, (2) its population increases in size (and extent), and (3) it can continue to persist in the new spot. Read the rest of this entry »

31 05 2020

## 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.