Lizard Climate change may be too hot for this cold-blooded critter to handle.
Image: FLICKR/LIP KEE
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
A new study warns that cold-blooded land animals like lizards and insects in the tropics may wither as the world warms. "Cold-blooded" is the layman's term for ectotherms—animals whose body temperature is contingent on the surrounding environment, rather than internally regulated like that of warm-blooded creatures. They thrive in temperatures ranging from 68 degrees to 104 degrees Fahrenheit (20 to 40 degrees Celsius), above which they overheat. As the globe warms, researchers warn they may be forced to swelter in burrows and under bushes with little time to eat, find mates or rear young.
"Our models suggest that for many reptiles, the room to move may be pretty small," says Rick Shine, an evolutionary biologist at the University of Sydney in Australia and co-author of the study published recently in Proceedings of the National Academy of Sciences, USA. "They are likely to be in trouble with climate change," he adds, noting they will be confined to shrinking shady patches under disappearing forest canopy and in bodies of water where they can cool off.
The resultant loss of tropical ectotherms could be "catastrophic," Shine says, noting that it could tear apart entire ecosystems from food webs to pollination. The reason: ectotherms range from food sources like insects to top predators like snakes and crocodiles, the loss of which would have "major flow-on effects," Shine says.
Using painted, water-filled pipes of different diameters as stand-ins for lizards and other cold-blooded critters, Shine and colleagues calculated their surface areas and reflectivity to determine how much heat they absorb and release in different environments. They tested them in three Australian climate zones from tropical to temperate, measuring variables like wind speed and solar radiation in three shade levels: the open (no shade), 90 percent shade under a forest canopy, and variable, by shuttling the pipes back and forth between the two extremes to approximate the way ectotherms regulate their body temperature.
The researchers tested their model's predictions against real animals until they were satisfied it worked. Then, to give the model its global scope, they mixed the numbers with worldwide climate data and notched up the average temperature by 5.4 degrees F (3 degrees C). (The Intergovernmental Panel on Climate Change, or IPCC, predicts a global temperature increase of 2 to 11.5 degrees F, or 1.1 to 6.4 degrees C, by the end of the century.) The researchers then ran the numbers through a heat-exchange model developed by co-author Warren Porter, a zoologist at the University of Wisconsin–Madison.
"It's not just the air-temperature increase—three degrees [Celsius] in the shade is not that much. What does kill you is the sun," Porter says. "Not only do you deal with a huge amount of radiation but your water requirements skyrocket."
Shade may be the key to cold-blooded survival in the tropics, as animals will need roomy, contiguous swathes of leaves to shelter them from the sun. The double prongs of a warming climate and the loss of rainforests to farmland and pastures, however, may confine overheating ectotherms to shrinking amounts of shade.
Raymond Huey, a zoologist at the University of Washington in Seattle who was not involved in the study, says the research is the first to examine how an animal's behavior can either buffer or exacerbate the effects of climate change on a large scale. "I don't know any other team who could pull off this project, or come close to doing it as well," he praises, adding, "Porter has no peers at this type of modeling."
All this begs the question of why the dinosaurs didn't overheat. At the close of the Triassic, as the curtain opened on the age of the dinosaurs, global average temperatures may have been in the 70s F (20s C), higher even than those projected in this model—62.4 degrees F (16.8 degrees C).
"Shade would have been extremely important for them," Porter says. They must have been tied to water and dense vegetation to keep cool, they may have migrated with changing seasons, and they must have had lower metabolisms, he speculates. Large animals cool more slowly than smaller ones in hot climates, so "The big animals could not possibly have had a high metabolic rate like we do," he says, "or they would have cooked themselves." Alternatively, some paleontologists believe the dinosaurs were endotherms – that is, they regulated their body heat internally like we do.
See what we're tweeting about
15 Comments
Add CommentIt must be wonderful to so ignorant of the real world that the above research is concidered remarkable.
Reply | Report Abuse | Link to thisCold blooded animals have survived 100's of millions of years of climate change. Hot peroids and cold. Slow changes and quick ones.
The equatorial regions change temperature very little no matter what the overall planet temperature average is. The vast oceans are a heat sink that resists serious temperature swings and large changes in atmospheric chemistry. Maybe some day the collage boys (and girls) will do an indepth study of the real connection of the hydrosphere and atmosphere in the creation and maintainance of climate and oxygen enriched atmosphere.
AAA+ - Another Asinine Alarmist Article - Editors be ashamed...be very ashamed.
Reply | Report Abuse | Link to thisIs Sesame Street writing for this mag? What a load of crap!
Reply | Report Abuse | Link to thisClimates change and organisms adapt or migrate in response. The distribution of forest species in North America changed radically after the last ice age. As the glaciers moved north, so did the distribution of species. The resulting communities were different from the pre-ice age communities, but they still functioned well.
Reply | Report Abuse | Link to thisIt could be insightful to realize that in Earth's biosphere, ectothermy is the norm, not endothermy. Endothermy is a relative recent invention in mammals and birds, together maybe a few thousand species. This is a tiny fraction compared to the number of cold-blooded species (including invertebrates).
Reply | Report Abuse | Link to thisEcotherms and reptiles probably have seen worse times and done pretty well then. They might not be as vulnerable as models predict.
OK as far as the Dinosaurs are concerned. They may have had a hollow bone breathing system that also helped regulate their internal temperature. And speculating. The smaller ones may have had pours that allowed the skin to breath enabling heat transfer. What about the possibility of changing the apparent skin color as in the Chameleon. This would allow a small Dinosaur the ability to darken in the cool or lighten in the heat. Finally Feathers could insulate when lying flat against the skin but cooling when either lifted away from the skin. To amplify this effect if the feathers were a light color they would reflect sunlight. Conversely if the skin was dark it would absorb sunlight. How about if the feathers were set in motion in a fan like way. The air movement at the skin surface would carry away heat. Nature is indeed very ingenious we can not assume that when given enough time evolution cannot find an answer.
Reply | Report Abuse | Link to thisFor once I would love to read a climate change article that didn't have a "may" in it. Wake me up when this climate change thing starts to happen. I "may" be dead by then. BTW, when did SciAm become a left leaning rag??
Reply | Report Abuse | Link to thisNot to be personal but what does it take to understand that we are already in a global warming trend. How can it be that for well over 100 years we all drive cars, heat our houses, generate electricity, cook our food, raise domestic animals, burn down our forests, dump organic waists, process chemicals, fly aircraft, ply the water in boats, over populate the world with 5,000,000,000, breathing drinking eating organisms called man and expect that nature can just go on like it was before we showed up? To tell you the truth people that now see global warming are a little late. Those of us that don't, probably believe that we didn't land on the moon or that the earth is flat. Like the monetary crash it will happen when we least expect it. Because like the crash greed and money will be hiding the truth from us all until it is too late. Wake up people!
Reply | Report Abuse | Link to thisNot to be personal, but what does it take to understand that global warming is a political hoax?
Reply | Report Abuse | Link to thishttp://wnd.com/index.php?fa=PAGE.view&pageId=83799
If global warming is such a huge problem, then please give me empirical evidence of how much we, humans, have warmed the earth. I dare say you will find little real evidence; instead, you will find countless computer-generated predictions that (surprise) give results that the people who are running the programs want it to give. I am all for keeping the world free of "waists" and "process chemicals" [sic], but this political agenda that is global warming is simply outrageous. Those who defend is as not political, tell me: where did the global warming scare begin? In UK politics with Margaret Thatcher! Is Al Gore a scientist? No! He's a politician! It's also not too inconvenient that he is the chairman and co-founder of a business that sells carbon credits!
So, Papa T, greed and money are hiding the truth from so many until the air we breathe out is taxed. Stop being such a blind follower of political propagandist rubbish!
I really don't want to use this forum as a place for this topic but I ask you this. Have you ever visited Northern Canada? Have you ever talked to an aborigine about the changes in the north? Well I have and I have no agenda. I first visited Northern Ontario 30 years ago and went back 5 years ago and saw a huge change in the snowfall amount. When you see the changes in the climate and snow fall physically you can call it temporary or some anomaly or call it what it is. Climate change. In Canada we are realizing that when we use one single gas powered ice cleaner in a very large enclosed ice rink the quality of the air inside suffers. Even with some ventilation. The earth is like a giant version of the same. It only stands to reason that multiply this scenario a million fold and over 100 years and well you get it don't you. The livable atmosphere is thin and the world is not infinite. Why don't you get off your rump and physically go and see for yourself. Ask the people who are experiencing real change not speculation and empty words. Actions speak loader then words! Remember whatever you or I believe in the end won't matter that much. But the effects of what we are doing will. Like Earth If you continue to mess up your house without cleaning it up it becomes unlivable. Extreme weather and heating from carbon dioxide, methane etc. is a consequence of mostly man. Do you own a car? If so how many times do you fill up the tank? Once a week? How many times a month? A year? The last decade? Where do you think that all goes? Remember we are only talking of you and your one car not many 100,000,000's of others. You are just one example. Earth is very resilient but I believe that she is reaching her limit. You can stick your head in the sand or blame it on the system or say that "they" have an agenda or how about if I don't look I won't see. Maybe it will go away. Probably is all made up anyway right. Right?
Reply | Report Abuse | Link to thisWhy is it that the people who refuse to see the facts for political reasons accuse others of being alarmist and falling for a hoax? I don't get it. Is that political SOP or what?
Reply | Report Abuse | Link to thisGlobal warming is a fact. The data is on the table and irrefutable. It is well known what the greenhouse effect of carbon dioxide and methane is and it is just as well known how much of it is emitted by human activity.
Now if you refuse to accept that 1+1=2 and demand proof, that's your prerogative, but that's not how the science works since we have exactly one planet to experiment with. We will have proof by the end of the century. It's up to you how you want to leave this place to your children and grandchildren.
Ralf123:
Reply | Report Abuse | Link to thisActually science does demand proof. Anything else is politics. Thanks for making the point.
Proof exists only in mathematics.
Reply | Report Abuse | Link to thisScience has experiments, data, hypotheses and theories.
Ralf123:
Reply | Report Abuse | Link to thisPlease explain to me why the computer models and hypotheses that are fueling this climate insanity are unable to make predictions that are even remotely reflected by the real world data?
In my world, models that don't match reality are wrong and useless. Basing policy on these flawed models is not just wrong, it is irresponsible and inexcusable... unless you have a hidden political agenda, in which case it is perfectly fine, as the ends then justify the means.
And I guess that's what the country is moving towards, an abandonment of science and logic in favor of fear and political expediency.
Ralf123:
Reply | Report Abuse | Link to thisWhat Data and or computer models are you talking about? What specific findings are you pointing too? If I could read them then I could be more informed of your view.
Look it's very simple. If you burn all the fossil fuel that the earth has locked up in her belly. Then destroy most of her ability to balance what we are doing with the excess carbon dioxide. This by killing off jungles, and polluting the Oceans etc. then what? Logic would dictate that what goes up must come down. Point is we are talking about a vast world ecosystem that is far to difficult to model accurately.
As an example let me remind you that just very recently many in science were telling us that cigarettes don't cause cancer. They sighted the many unproven research findings and fear mongering that was circulating at the time. Since many of the tests and research could not substantiate it one way or another they claimed that it was a non issue. We now know that it's certain that burning chemicals within cigarettes are proving to be responsible for encouraging the formation of cancer and many other diseases. How many people died and are dieing needlessly because of our inability to read "the writing on the wall" and act quickly?
The moral is that we must act now on whatever evidence that we can garner. Right or wrong we have more to lose doing nothing now. The fact is that we will run out of oil and coal sooner or later. Why not move to other clean renewable forms of energy now? If you are right then we will at least ensure ourselves plentiful energy for ourselves and our children at a small price. But if I'm right then the same thing holds true. That plus the possible minimizing and or averting a global catastrophe. Your choice!