Science: How Climate Change Affects Animals

David A. Fahrenthold
Washington Post Staff Writer
Monday, September 17, 2007; 12:00 PM

Washington Post staff writer David A. Fahrenthold was online Monday, Sept. 17 at Noon ET to discuss evidence that climate change is affecting how animals live, eat migrate and grow.

Read more in the story: Climate Change Brings Risk of More Extinctions (Post, Sept. 17)

The transcript follows.

This discussion is part of the monthly series In the Greenhouse: Confronting a Changing Climate


David A. Fahrenthold: Hello all, and thanks for visiting. I'm looking forward to your questions.


Herndon, Va.: Can you clarify why the limited rise in ocean volume and sea level owing to glacial melting caused the flooding of the wetlands attributed to it in this article?

Even if there was flooding due to rising sea waters, wouldn't that be offset by the establishment of new marsh in other areas as the sea waters rise up the land?

Simply put: where is the proof that this lost wetlands is due to global warming related sea level rise rather than other factors such has natural erosion, land settling (as describe in the article), etc.?

David A. Fahrenthold: Thanks for asking this--as we alluded to in the story, the loss of the marsh at Blackwater is not caused by sea-level rise alone. Other factors included an infestation of nutria, a South American rodent that eats the roots of marsh plants, and the sinking land. And you're right that it does seem logical that marsh would simply move back as the water got higher.

But what I'm told is that, in cases like this, the water is actually rising slightly faster than the marsh can move back. This is a verrry slow race, I've been told, but in the end the rising water seems to be winning.


Washington, D.C.: The effects of global warming can already be seen in our national parks. Appalachian parks, such as Great Smoky Mountains and Shenandoah, provide islands of wildness in the most populated part of country. People head for the mountains to get away from it all, to bird watch, to fish, and to ski in the northern reaches of the Appalachians. But the mountains that generations have treasured and relied upon may be fundamentally diminished as a result of climate change.

For example, more droughts, floods, and warmer streams could hurt native trout populations in Shenandoah National Park. In addition, if carbon dioxide levels increase, conditions in Great Smoky Mountains National Park would become unsuitable for red squirrels, southern red-back voles, and northern flying squirrels.

Check out the new report by the National Parks Conservation Association at

David A. Fahrenthold: I'm really interested in learning more about this topic as well. What I've heard is that the mountains to the west of the D.C. area are often home to plants, animals and entire ecosystems that really belong further north: they're leftovers from colder periods, even the last Ice Age. It's only cold mountain winters that let them live on this further south. Now, it seems, just a little bit of warming can shift them out of their comfort zone. Thanks for your question--it's a topic I'll hopefully be able to report more on in the future.


Re: American Robins :"American robins arrive two weeks earlier than they used to"

I live on an Alexandria, Va. golf course. These birds are year long residents now, no longer migratory. In my childhood, robins were the first sign of spring. You only saw them during a certain time of year. I see them year long now.

David A. Fahrenthold: Wow--a really interesting local case study. I've read about other such cases involving short-distance migrant species, which would usually go a few hundred or a few dozen miles, instead of to South America and back. Now, some of them don't seem to be going anywhere.


Munich, Germany: Supposing that the ice cap in the Arctic melted completely and then Global Warming was somehow overcome and the ice caps began to form again.

Do you think that it'd be possible to repopulate the Arctic with polar bears, walruses and seals from captivity if they'd become extinct in the wild? Would the natural instincts of these animals be retained during generations in captivity, do you think?

David A. Fahrenthold: Interesting idea. I would say (being absolutely no expert on animal behavior) that it might be hard for these animals to re-learn their old behavior, after several generations in captivity. But...if we're talking about a day when we've managed to somehow re-freeze the polar ice caps (would it take a giant air conditioner? A global sun visor?), then I'd say anything would be possible.


Jim, Lansing, Mich.: Larger plants, animals, and insects are supported by microbes in the soil and algae in the sea. How are these small creatures with a large biomass expected to handle the radical changes?

David A. Fahrenthold: The examples I know best are from the ocean. One is coral: I corresponded with an expert named Ove Hough-Guldberg at the University of Queensland in Australia, who studies the ways that the tiny animals in coral interact with small plant-like organism called zooxanthella. Usually, these plant-like things trap the sun's light and turn it into energy, which the coral use to build their homes on the reef. But when it gets too hot, this symbiotic relationship breaks down, and the coral dies. These events, called coral "bleachings," can have disastrous impacts on the vibrant reef ecosystems. ANd they're happening more often now: in just one year, 1998, 16 percent of the world's coral perished in large bleaching events.

The other example is plankton: scientists have seen plankton populations declining, in general, and shifting toward the poles, as ocean temperatures have slowly risen.


Washington, D.C.: I'm a wildlife biologist here to make a small yet important point. Our species, Homo sapiens, is part of the biological kingdom Animalia -- i.e., we're animals, too!

David A. Fahrenthold: A very interesting point: my research didn't include much on how the human animal's behavior and habitat might change. But some of my colleagues _have_ written about a few of these potential impacts, like the decline of glacier-fed rivers like the Ganges or Indus, or the encroachment of rising seas on human settlements in Micronesia or coastal Asia. In the local area, the biggest loss of human "habitat" will probably on the mid-Eastern Shore of Maryland, the area around Blackwater, where a large area of southern Dorchester County (lightly populated, but still populated) could be underwater at some point decades from now.


Clifton, Va.: From roughly 1300 to 1850 we were in a mini ice age? Now we may have some effect on global warming but couldn't this also be happening because of natural causes. And if I remember correctly back in the 70s they were talking about another mini ice age by now!

My herding dogs and my herding instructor's dogs do a great job of predicting the severity of the winter by the fullness of their coats. They can't predict how much snow we will get but by Dec. 1 we know how cold it will be.

David A. Fahrenthold: Thanks for the question: there have definitely been long periods of both cooling and warming in the earth's history, all accomplished without any help from people. And you're right that there was (I've read) a period in the 1970s where people (including scientists) were concerned that the earth might be headed for a significant cooling period. But in the current situation, scientists say, both the change in the climate--and the scientific consensus about it--are different. There now seems to be widespread consensus in the scientific community that the earth is warming now, and that it will get warmer in the future, and that man-made greenhouse gases are playing a significant role in causing it. The United Nations reports on climate change this year are probably the best indication of how wide this consensus is--they have dozens of authors, and include independent research from around the world.

As for the warming that's predicted for the next few decades, I'm told that it will probably be faster than most warming trends in previous millennia. And, as far as animals are concerned, there will be an extra difficulty. In previous warming periods, many of them could simply migrate to more comfortable places. Now, at least here in the U.S., they could find homes, roads and Wal-Marts in the way, which makes adaptation much harder.


Washington, D.C.: A close reading of your article suggests that it should have been entitled: "Most animals adapting successfully to warmer temperatures." That is the main theme that emerges from the article once you have stripped it of the negative spin that is now the norm in most journalistic coverage of climate change. In one paragraph you mention that evolution is often unable to keep up with the latest warning spell, and then quote a study as concluding that nearly 60 percent of animal species appear to have changed in some way. Isn't that evolution?

And what about the new species that will be nurtured by temperature changes? It seems to me that you have started out to write a negative article, and then disregarded evidence that is on the whole quite positive. Malcolm D

David A. Fahrenthold: An interesting take on this research! You're right that some species _do_ seem to be taking advantage of the changes being made in the climate, and this change even seems to be possible at the genetic level--a kind of evolution. Prof. Skelly at Yale has, as we mentioned in the story, even done research on wood frogs in New England that shows populations are able to adapt when temperatures change (in those cases, the temperature changes were caused by shade trees growing or falling over, not climate change. But the effect is the same.)

The concern, though, is that some species won't be able to adapt, or won't be able to adapt as quickly as they'll need to. As we pointed out in the story, polar bears and walruses have adapted to live in one kind of world, where ice covers the sea for long periods each year. Since the ice has begun receding in the space of a few decades, they have not had time to react: it takes a few generations for a seal-eating polar bear to become a brown bear eating salmon!

The professors who study these species are often quite dispassionate about what they're seeing--often much more so than the environmentalists who use their research to push for changes. To the professors, change is just change--something new has come up, and nature is shifting to adapt. But it _could_ be a bad thing for us, they say, since we've gotten used to the nature that we have, and we might miss its creatures (or, in some cases, miss eating them) if some of them declined or actually disappeared.


coral: Coral = zooxanthella + cnidarian polyp in a symbiotic relationship.

Coral is 2 organisms living together rather than coral living with zooxanthella.

The algae are "expelled" from the cnidarian when temps are too high.

similar to lichen = ascomycota fungi + algae

David A. Fahrenthold: So there you have it: a further explanation of the item about coral above.


Houston, Tex.: While visiting Glacier National Park this past summer, I saw a Ranger program that said the glaciers in the park will have melted in the next 30 years at the current rate of global warming. That made me wonder about the impact of the loss of glacial melt water on the lakes, rivers, and habitats down stream.

David A. Fahrenthold: The impacts of receding mountain glaciers could be serious for rivers that depend on the slow drip of glacial melting to get them through the year. I've read that Glacier National Park, particularly, is trying to become a kind of showpiece for climate change, explaining to visitors exactly what's happening both there and downstream.


Alexandria: I suggest the readers here watch Tom Brokaw's discovery channel two-hour show on global warming.

There is a segment about an island in the pacific that only recently is mostly underwater during high tides. there are scenes with kids swimming in their front yards. there is a lot of science and data presented. interviews with lots of scientists. before and after pictures of places like Muir glacier. it'll make the hair on your neck stand up.

David A. Fahrenthold: Thanks for the suggestion. In the Chesapeake Bay, the extremely low-lying waterman's community on Smith Island has similar worries about being washed away in future years (there, as at Blackwater, this area's sinking land is making the situation worse). Nobody's swimming in their front yards there yet, but they are squishing around in them, as the land gets wetter from rising water all around.


attn: Malcolm D: do some research on r/K selection theory. larger organisms have fewer offspring, longer gestation, and shorter turnaround with evolution. it might take 100 generations and centuries for a polar bear, elephant, or rhino to adapt where a fruit fly, bacteria, dandelion, etc. with faster gestation and several offspring could adapt to a change in the environment very rapidly.

David A. Fahrenthold: I pass on, without endorsement (my last serious exposure to the science of genetics was a long-ago college course) this reference to why some animals might be capable of adapting more quickly than others.


Rise Of Infectious Diseases?: How large is the threat of increased global infectious diseases caused by insect vectors not dying out as our winters warm? Will we see diseases like malaria, dengue, yellow fever, etc. be more of a danger in the mid-Atlantic states such as Va.?

David A. Fahrenthold: This, unfortunately, is a subject I know little about. Please stay tuned, though, to our "In the Greenhouse" series, appearing every month on the Post's science page. I'm told that a later installment will deal, in significant detail, with the impact of warming on human disease.


Washington, D.C.: You say that "we've gotten used to the nature that we have." But who is to say that this nature represents some kind of immutable ideal? It is interesting that environmentalists who are the most alarmist about global warming are also usually among those who condemn creationists for not believing in evolution. But what we are witnessing is evolution in action. To insist that the world must be maintained as it is in every detail is a fundamentally conservative point of view.

David A. Fahrenthold: You're right: nature today is different than it was a millennium ago, and it would likely have continued to change (eliminating some species and raising up others) even if the climate didn't. The choice here really is ours. Once we understand the kinds of shifts that are likely to occur because of climate change, we will have to figure out what (if any) of that we can't live with.


Columbia, Md.: I've also heard that Blackwater may also be experiencing a greater than normal subsidence as a result of the tapping of the aquifer to support the incredible amount of housing that has been built on the eastern shore this past decade or so. Are hydrologists monitoring this situation?

David A. Fahrenthold: This isn't a theory that I've heard from the folks at Blackwater, but that's not to say it's been considered and rejected. I'll have to learn more about this possibility.


David A. Fahrenthold: Thanks so much for reading this chat--I've really enjoyed your questions (and learned a few things about coral). If you're interested in this topic, you might also check out the "In the Greenhouse" page on, to read other stories in the series. And, if you'd like to hear my sonorous voice talking about the impact of climate change on animals, you can find today's "In the Greenhouse" podcast, on and iTunes.


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