The scariest things about climate change are what we don't know

Some argue that, when it comes to climate change, we should play down our uncertainties -- because climate-change deniers will just seize on those unknowns as an excuse for inaction.

Clinging to survival

Clinging to survival

But in a brief, highly topical essay just published today, TESS director Bill Laurance argues that scientists have to be entirely frank about uncertainty -- and that many of the scariest things about climate change are in fact the things we don't know.

Read the essay here

In just three minutes you can get a sense of what we we know, what we don't know -- and what we don't know we don't know about climate change.

 

Could tropical species be intensively vulnerable to global warming?

On 12 January 2002, Cambridge University doctoral student Justin Welbergen was studying the behavior of a large colony of flying foxes in subtropical eastern Australia.  What he witnessed that day shocked him.

Doesn't like the heat... a grey-headed flying fox.

Doesn't like the heat... a grey-headed flying fox.

It was a hot afternoon, and as the thermostat climbed above 40 degrees Centigrade, the giant bats became obviously distressed.  They began fighting over shady spots in the canopy.  Then they began licking their wrists and flapping their wings in a desperate effort to cool themselves.  

Finally, as the temperature hit 42 degrees C, they began to die -- in the thousands.  On that day at least 3,500 bats died, in nine different nearby colonies.  Females and juveniles were especially vulnerable.

What Welbergen observed was a phenomenon that has now been seen elsewhere -- from mass disappearances of lizards in Mexico to the dramatic population collapse of the white lemuroid possum in north Queensland rainforests.

Possum in peril... the white lemuroid ringtail  (photo (c) Michael Trenerry)

Possum in peril... the white lemuroid ringtail (photo (c) Michael Trenerry)

There are two striking conclusions from these observations.  First, to the surprise of many, tropical species may be the most vulnerable of all organisms on the planet to global warming.  Second, it isn't a steadily rising thermostat that endangers most species, but short, intense pulses of unusually warm conditions -- heat waves.

Why are tropical species so vulnerable?  In short, many are thermal specialists.  Think, for instance, about a polar bear -- our traditional icon for global warming.  It has to deal with temperatures ranging from, say, minus 50 degrees C in winter to plus 35 degrees C in summer -- a huge range of temperatures.

But tropical species are different.  Lowland tropical species, for instance, might see temperatures ranging from just 25 to 35 degrees during the course of a normal year -- a far narrower range.  As a result, they can become much more thermally specialized.

Where temperatures vary the most in the tropics is as a function of elevation.  On average, for every thousand meters that one goes up in elevation, the temperature drops by 6 degrees C.  

What that means is that tropical species are not just thermal specialists, they also tend to be elevational specialists.  Species tend to be adapted for the very warm lowlands, or for the cooler mid-elevations, or for the wet, cloudy high elevations, where conditions are almost chilly.

And it's the high-elevation specialists -- such as the white lemuroid possum -- that a lot of scientists are really worried about.   

Many tend to be locally endemic species, because their populations are genetically isolated from other populations on different mountaintops.  Hence, they have small geographic ranges and, often, small population sizes.

And they may be intensely vulnerable to global warming.  As temperatures rise, the geographic ranges of many high-elevation species in the tropics are predicted to shrink and fragment -- potentially disappearing altogether.  For instance, in the Australian wet tropics, most upland-endemic species of mammals, birds, reptiles, and amphibians are predicted to disappear entirely if temperatures should rise by more than 4-6 degrees C.

It's a frightening prospect, and it suggests that global warming could have far wider-reaching impacts than many might suspect -- especially in the tropics, the world's biologically richest real estate.

ALERT member Pierre-Michel Forget has just given a wonderful 30-minute interview on this topic.  Forget is a highly authoritative scientist -- a former president of the Association for Tropical Biology and Conservation and now Vice-President of the Society for Tropical Ecology.  He asks, what would just a 1 degree C increase in temperature do to tropical forests and their species?

It's definitely worth a half-hour to hear this enlightening lecture -- and to share it with your colleagues and students. 

The bottom line is this: Given that tropical ecosystems are so rich in species and thermal specialists, the best icon for global warming might not be a polar bear -- but a tropical white possum or flying fox.

 

Obama eco-speech infuriates Aussie conservatives

Can somebody please bring Australia's right-wingers a crying towel?

Climate-deniers spit the dummy...

Climate-deniers spit the dummy...

In addition to attending the G20 Global Leaders Conference in Brisbane last week, U.S. President Barack Obama gave a hard-hitting speech on climate change at the University of Queensland. 

This had Australia's right-wingers in a tizzy, because Australian Prime Minister Tony Abbott had specifically ruled out climate change as a topic for discussion at the G20 summit.

Obama, fresh off a major deal to reduce carbon emissions with China -- now overwhelmingly the world's biggest greenhouse-gas emitter -- wasn't willing to be gagged on the issue.  Hence his speech at the University of Queensland.

Abbott and company were especially annoyed by Obama's assertion that climate change threatened the iconic Great Barrier Reef, as suggested by a number of studies of coral bleaching and mortality during past heat waves, as well as rising ocean acidification.

Abbott is notorious as a pro-coal, pro-mining, no-more-parks, no-carbon-tax leader who considers global warming a minor annoyance -- a manageable environmental problem that's been massively overstated by wild-eyed greenies.

So perturbed was Abbott by Obama's assertions about global warming and the reef that he had his arch-conservative Foreign Minister, Julie Bishop, attempt to rebuke Obama

Bishop -- well-known for other anti-environmental tacks such as her heated opposition to Australia's illegal-logging act -- decried Obama's speech and claimed that Australia was actually looking after the reef very nicely, thank you very much.

So nicely, in fact, that UNESCO has repeatedly threatened to declare the Great Barrier Reef a World Heritage Site in Danger.

So nicely that Distinguished Professor Terry Hughes, director of the ARC Centre for Excellence in Coral Reef Studies at James Cook University, immediately labeled Bishop's comments as "not credible".  

"I loved Obama's speech," said Hughes.  "I thought it was spot on."

Such exchanges show that the Abbott government is sorely out of touch -- not just with many Australians but with the leaders of many other industrial and developing nations. 

Abbott and his colleagues are now clearly part of the problem rather than part of the solution on climate change.  And no amount of crying on their part will change that.

 

Climate change could threaten our beer

OK, now it's getting serious.

Enough is enough!

Enough is enough!

We all know that climate change is threatening our environment.  And our economies.  And our livelihoods. 

But now it appears that climate change could imperil the very foundations of our society.

Our beer.

That's right -- in a recent meeting with Australian Green Party Leader, Senator Christine Milne, researcher Peter Gous emphasized the likely impacts of global warming on beer production.

"It only takes one hot day" to destroy a crop of grain, said Gous.

This is a frightening prospect given that state-of-the-art climate models project up to a 1.5-degree Centigrade (2.7 degrees Fahrenheit) increase in average temperature by 2030. 

Add that on top of your average heat-wave, and you could get a serious crop-killer.

This is just one example of the complex -- and often highly disturbing -- ways that climate change could affect our future.

A forthcoming book, Climate Peril, by author John J. Berger, attempts to tease out many of these potentially alarming effects -- on nature, the economy, human health, society, and national security.

According to Berger, we're missing the boat by failing to consider critical interrelationships among effects such as drought, fire, disease, water shortages, habitat destruction, endangered species, resource collapse, energy production, and the economy.

Although a top-flight scientist and energy expert, Berger's book is remarkably easy to read. 

He argues at the outset that there's almost no way we're going to limit global warming to a 2-degree Centigrade (3.6-degree Fahrenheit) increase in average temperature, as many have hoped.

He then shows, again and again, how climate change is likely to provoke cascades of destabilizing changes.

To select just one from a wealth of examples: a strong drought can destroy crops and livestock, which in turn impacts on food processors, farm-equipment suppliers, and labor markets. 

This in turn can grind down local and regional economies, depressing real-estate values.

And this can then force economically stressed people to migrate elsewhere, weakening the social fabric of a community, harming mental and physical health, and promoting domestic violence.

Berger's book is one of the very best I've seen on climate change -- on understanding how it could impact on virtually every facet of our life, society, economy, and environment.

There's a lot more at stake here than just our beer.