Category: Global Warming

Climate Relicts: My new story for Yale Environment 360

By Carl Zimmer | August 29, 2011 9:54 am

I’m among the 800,000 people in Connecticut without power thanks to Irene, so I won’t be blogging much for the foreseeable future. But before I get to other matters like dragging branches around, let me point you to my latest piece for Yale Enivronment 360. I take a look at a new concept called the climate relict. Around the world, there are pockets of plants and animals living hundreds of miles away from their main species ranges. They were left behind in refuges at the end of the last Ice Age, as others moved towards the poles in response to the warming climate. As the climate now warms even more, climate relicts have a lot to teach us about how to manage biodiversity. Check it out.

[Update: bad link to Yale e360 fixed]

Warming up, turning sour, losing breath

By Carl Zimmer | April 19, 2011 2:49 pm

We like to think about risks with simple arrows. If A, then B. If wildfires break out, some people may lose their homes. If an oil pipeline leaks, it can pollute the soil. But if you put a wildfire and an oil pipeline leak together in the same place at the same time, the whole becomes a lot nastier than sum of its parts.

The world’s oceans face three different major risks from the carbon that we put in the air. That extra carbon (9.2 billion tons in 2009 alone) is acidifying the ocean, warming it, and possibly even stripping it of oxygen. I’ve written about all three of carbon’s impacts in recent years, but I’ve chosen to write about them independently. That’s standard practice in journalism: you select one narrowly defined topic and explore it as deeply as you can in the space you’ve got. But these three impacts are all hitting the same ocean all at once, and they’re interacting with each other as they do. In a new paper in the Philosophical Transactions of the Royal Society, the environmental scientist Nicolas Gruber warns that this “triple whammy” could prove to be more than the sum of its parts–especially in parts of the world where all three may hit particularly hard, such as the waters off the coast of California.

Over the past 250 years, the ocean has soaked up about 30 percent of all the carbon dioxide we’ve released. When carbon dioxide dissolves into sea water, it lowers the ocean’s pH. This process is known as ocean acidification, which is a bit of misnomer. After all, the ocean’s pH, which has dropped from 8.2 to 8.1 over the past two centuries, is still officially alkaline (acids have a pH below 7). But arguing over a label for this transformation is a pointless distraction from the magnitude of what we’ve done. The pH scale is logarithmic, meaning that sea water with a pH of 8 contains ten times more positively charged atoms than sea water with a pH of 9. We’ve raised the total number of hydrogen ions in the ocean by thirty percent. That’s a lot of ions.

If the rate of carbon emissions continues to rise, we will add even more. Under the most optimistic scenarios, the pH will drop to 7.9 or 7.8. All those extra ions will alter the lives of marine organisms. It will be harder for some animals to form calcium carbonate skeletons, for example. A lower ocean pH will alter photosynthesis as well, along with the growth of some fishes and other animals. While scientists have a clear understanding of the chemistry of ocean acidification, they’re only beginning to learn about the possible biological impacts. But the National Research Council warned last year that ocean acidification could have a big impact on people as well, as it slams the fisheries and aquaculture on which we increasingly depend.

The oceans can only sop up a fraction of the carbon dioxide we put in the air. As a result, the concentration of carbon dioxide in the atmosphere has steadily risen. And that CO2 has been trapping some of the sun’s energy, and thus warming the atmosphere. The oceans have warmed up as a result; the surface of the sea has warmed .7 degrees C over the past century. As the oceans continue to warm, the extra heat will have its own impact on life. It will allow some species to thrive in some places; it will shift the ranges where others can survive. And it will put stress on the species–such as corals–that are pretty much stuck in one place.

Global warming may also strip oxygen from the oceans. Warm water holds less dissolved oxygen, and as the ocean heats up, scientists expect that the circulation of water from its top to its bottom will slow down. As oxygen gets used up in the deep ocean, there will be less coming down to replace it. (Fertilizer run-off and other pollution on land is also producing low-oxygen dead zones in the Gulf of Mexico and elsewhere.)

Scientists are only starting to come to terms with how we’re altering the oxygen in the ocean, so the details are still fuzzy. They have yet to measure the world-wide trend of ocean oxygen, for instance. But they have managed to measure declines in some regions of the sea. There’s also an oddly high level of oxygen in the atmosphere, which may be coming from the ocean.

In his new paper, Gruber surveyed the projections over the next century for all three factors–temperature, pH, and oxygen–around the world. These projections spread across a wide range, in part because there’s still a lot of uncertainty in the science, and in part because the future of carbon depends on what our species chooses to do in the next few decades. But some patterns do look pretty clear, as illustrated in two figures I adapted from Gruber’s paper:

The warming of the oceans will not be uniform, for example. The biggest warming will come in the Arctic, as the sea ice disappears and can no longer bounce much of the incoming radiation away. It’s possible that the rise in termpature will cause a boom in photosynthetic plankton, which will support a bigger ecosystem. But the warmer temperature may speed up the chemistry of all life in the Arctic ocean, and much of the carbon drawn down by a booming Arctic ecosystem may quickly end up back in the atmosphere. What’s more, the surface of the Arctic ocean may mix even less with the deep ocean. If that happens, then less carbon dioxide will be stored in the deep ocean. Both changes could speed up the accumulation of carbon in the atmosphere.

Acidification will also hit some parts of the world harder than others, thanks to the temperature and chemistry of each region. Gruber warns that it will become seriously difficult for animals to form calcium carbonate skeletons in the Arctic Ocean surface waters in a decade. The ocean around Antarctica may cross this threshold in the second half of this century. By the end of the century, this acidified zone will spread into the North Atlantic and North Pacific as well. Corals, shellfish, and other organisms that depend on calcium carbonate for their skeletons could all be affected in these regions.

Projecting changes in oxygen is a much rougher science, Gruber warns, but all the models foresee a worldwide drop of somewhere between 1 and 7 percent of the ocean’s oxygen in the next century. Again, however, the real story is in the regional differences. In much of the world’s oceans, the oxygen levels may barely drop at all. But in some places, oxygen may drop far enough that it will threaten the well-being of animals that depend on high levels of the gas, such as fish and crustaceans. The impact in each part of the world will depend on how high oxygen levels are right now, and how rapidly new oxygen is delivered from other parts of the sea.

Each of these changes poses risks to the health of the ocean. But combined, each risk may be able to make the others bigger. Low oxygen speeds up ocean acidification, for example, while ocean acidification can speed up the loss of oxygen. As organic matter breaks down, it reacts more with oxygen that’s rich in carbon. Some studies also suggest that in a CO2-rich ocean, it’s harder to get energy from food. Animals under this stress will need more oxygen to survive–precisely when oxygen levels may be dropping. Making matters worse, the warmer water will speed up metabolism, increasing the demand for oxygen even more.

These synergies will be stronger in some parts of the world than others, because changes in temperature, pH, and oxygen are different in different parts of the world. Gruber put together this map shown below.

The circles mark hotspots where carbon’s triple whammy may hit hardest of all.  Along the coast of California, for example, marine life depends on nutrients that well up from the deep ocean, and a warming ocean will slow down that delivery. It’s also naturally at a low pH and has relatively few carbonate ions, making it especially vulnerable to acidification. Making matters even worse, the waters off of California are low in oxygen, so a further drop could have a big effect on them.

Gruber points out that up till now, scientists have focused on just one kind of impact carbon is having on the oceans. They’ve barely begun to explore how each impact mingles with the others. I see this mingling as a challenge in my own work as a writer. A tangled web of risks is hard to explain, let alone pitch in a lede. But nature doesn’t much care about a simple story.

Reference: Nicolas Gruber, “Warming up, turning sour, losing breath: ocean biogeochemistry under global change.” Phil. Trans. R. Soc. A (2011) 369, 1980–1996 doi:10.1098/rsta.2011.0003

Photo: Cocoa Dream at Flickr

CATEGORIZED UNDER: Global Warming, Top posts

Outlook: Warm, Grim, Cloudy: My story on global warming and extinctions in tomorrow's NY Times

By Carl Zimmer | April 4, 2011 6:30 pm

In tomorrow’s New York Times, I take a look into nature’s crystal ball. Scientists have long been warning that we may be headed into Earth’s sixth mass extinction. But most projections just carry forward the causes of recent extinctions and population plunges (overfishing, hunting, and the like). Global warming is already starting to have an effect on many species–but it’s a minor one compared with the full brunt that we may experience in the next century.

I’ve written in the past about studies scientists have carried out to project what that impact will be like. I decided to revisit the subject after reading a spate of provocative papers and books recently. While the scientists I talked to all agree that global warming could wreak serious havoc on biodiversity in coming decades, they’re debating the best way to measure that potential harm, and the best way to work against it. We all crave precision in our forecasts, but biology is so complex that in this case we may well have to live without it. Check it out.

[Image: Photo by DJ-Dwayne/Flickr]

Gasp! My new article on global warming and oxygen

By Carl Zimmer | August 5, 2010 9:22 am

gasping fish440It’s becoming increasingly clear that global warming may trigger many changes beyond the obvious change in temperature. Earlier this year I wrote about how rising carbon dioxide is driving down the pH of the oceans, with some potentially devastating consequences. Today in Yale Environment 360 I look at a potential change that’s also starting to get scientists very worried: a drop in the oxygen dissolved in the world’s oceans. Check it out.

[Image: Christopher Sebela on Flickr]

CATEGORIZED UNDER: Global Warming, Writing Elsewhere

Bacteria in the Greenhouse

By Carl Zimmer | June 1, 2010 10:36 am

Bacteria and other microbes suck up and blast out vast amounts of greenhouse gases. Over at Yale Environment 360, I take a look at how they will behave in a world warming up as we inject carbon dioxide into the atmosphere. Will they draw down some of the extra CO2, or will the heat spur them to spew out more? Or both? The answer isn’t clear yet, but it’s important. After all, it’s a microbial planet, and we just live on it. Check it out.


How To Recognize the Anthropocene

By Carl Zimmer | May 17, 2010 9:14 am

Elizabeth Kolbert writes this morning about the Anthropocene, a new geological epoch marked by the dominance of our species. It may be hard to precisely mark its beginning, but here’s why I think it will be easy for geologists 10 million years in the future to pinpoint layers of Anthropocene rocks.

This Is The Dawning of Aquarius–In South Dakota

By Carl Zimmer | February 26, 2010 1:24 pm

South Dakota, are you kidding me? Astrology in the classroom?

In the fine tradition of creationist legislation that claims that evolution is “just” a theory and that requires the teaching of alternatives, the South Dakota legislature has passed a resolution on the teaching of climate change. Here’s how it starts.

NOW, THEREFORE, BE IT RESOLVED, by the House of Representatives of the Eighty-fifth Legislature of the State of South Dakota, the Senate concurring therein, that the South Dakota Legislature urges that instruction in the public schools relating to global warming include the following: (1) That global warming is a scientific theory rather than a proven fact;
(2) That there are a variety of climatological, meteorological, astrological, thermological, cosmological, and ecological dynamics that can effect [sic] world weather phenomena and that the significance and interrelativity of these factors is largely speculative…

That red color is mine. This resolution was not just offered, folks. It was approved by a majority of the legislature. Astrology and all.

At least I know what astrological means. Someone’s going to have to help me with thermological, though. It’s not even in the dictionary. (Whoops–I found it in the Oxford English Dictionary. Having to do with heat. Still, though–what about cosmological? Is global warming from the Big Bang?)

Wow. That is all.

Update: Thanks to Loree for pointing out that this original language was amended before the vote. Here‘s what it ended up as:

A CONCURRENT RESOLUTION, Calling for a balanced approach for instruction in the public schools relating to global climatic change.

WHEREAS, evidence relating to global climatic change is complex and subject to varying scientific interpretations; and
WHEREAS, there are a variety of climatological and meteorological dynamics that can affect world weather phenomena, and the significance and interrelativity of these factors remain unresolved; and
WHEREAS,  the debate on global warming has subsumed political and philosophical viewpoints, which has complicated and prejudiced the scientific investigation of global climatic change phenomena:

NOW, THEREFORE, BE IT RESOLVED, by the House of Representatives of the Eighty-fifth Legislature of the State of South Dakota, the Senate concurring therein, that the South Dakota Legislature urges that all instruction in the public schools relating to global climatic change be presented in a balanced and objective manner and be appropriate to the age and academic development of the student and to the prevailing classroom circumstances.”.

Thankfully, those who don’t know the difference between astrology and astronomy didn’t get their way. But the “balanced” rhetoric that remains is straight out of the creationist playbook. For more, see Science Progress.

[via Think Progress]

Leaving Our Geological Mark

By Carl Zimmer | February 15, 2010 9:58 am

The warming climate may earn carbon dioxide all the headlines (including ones about senators who can’t tell the difference between a couple blizzards and a 130-year climate record), but the gas is having another effect that’s less familiar but no less devastating. Some of the carbon dioxide we pump into the air gets sucked into the ocean, where it lowers the pH of seawater. We’ve already dropped the pH of the ocean measurably, and as we burn more fossil fuels we will drop it more. Ocean acidification has the potential to wreak world-wide havoc on marine life.

Today in Yale Environment 360, I write about scientists comparing today’s ocean acidification to the last time something comparable happened–55 million years ago. Short answer: today’s is big. Really, really big. Check it out.

Multi-Layered Fact-Checking Process, Activate!

By Carl Zimmer | December 8, 2009 11:30 pm

Did the new Post op-ed by Sarah Palin on global warming get the same multi-layered fact-checking as George Will? Sigh. Deltoid has the details.

George Will: Uncheckable?

By Carl Zimmer | December 6, 2009 1:45 pm

Long-time readers of this blog will be aware of my Ahab-like obsession with George Will’s global warming errors in the Washington Post–and the Post’s hollow claims to have carefully fact-checked him. I confess that I’ve let a couple of his more recent columns slip by. But I had to stop to blog about his latest take on global warming, in which he jumps on the recently stolen emails among climate scientists. He does a remarkable job of making no sense at all.

In case you haven’t followed it, somebody stole thousands of private emails from the University of East Anglia, where the Climate Research Unit gathers and analyzes climate data. Suspicions are turning to Russian hackers, but there’s been no official word about who did it. The emails ended up on the Internet, and have become a big deal. The University of East Anglia, for example, is investigating both the theft itself and the accusations that have been leveled against UAE scientists as a result.

There’s been a huge amount of stuff published in newspapers and on blogs in the two weeks since the theft. I recommend a piece in Popular Mechanics by a geochemist at Columbia named Peter Keleman. Keleman carefully distinguishes between the possible ethical issues raised in the emails and where this controversy leaves the science of climate change.

Unfortunately, pieces like Keleman’s are not stopping the spread of myths that promote the notion that global warming is a fiction generated by a global (and centuries-old!) conspiracy. For example, US congressmen are claiming that the emails reveal a campaign of suppression that included the firing of the editor of a journal called Climate Research after the publication of a “skeptical” paper. Actually, the editor-in-chief resigned in protest over the paper, which he considered flawed, as well as the publisher’s unwillingness to let him write an editorial about that. (Three other editors resigned at the same time.)

George Will gets on the bandwagon, too, in his latest piece. He tries to fold the news about the email theft into his favorite errors, like the one about how global warming actually “stopped” in 1998, because 1998 was warmer than any other year since. He seizes on one email for his opportunity.

A CRU e-mail says: “The fact is that we can’t account for the lack of warming at the moment” — this “moment” is in its second decade — “and it is a travesty that we can’t.”

Will has put himself in a bind. He loves to tell us that it’s been over ten years that there has been no global warming. In an earlier column, he invoked the World Meteorological Organization as his source, linking to this document (pdf). But the climate record they show (on page 4) is the handiwork of none other than the Climate Research Unit at the University of East Anglia, the epicenter of those wretched climate scientists who, Will assures us, “compound their delusions of intellectual adequacy with messiah complexes.” If you look at analyses produced by other groups, 1998 does not appear as the warmest year on record–instead, it is much more recent. In NASA’s analysis, it’s 2006. The difference lies, in part, in the weather stations included in the analyses.

Will cannot have it both ways. He cannot pretend to speak with authority about the history of climate, but rely on people he considers cranks as authorities on that history.

None other than the Secretary General of Will’s beloved World Meteorological Organization himself wrote to the Post in March to explain why Will’s fixation on 1998 was misleading:

It is a misinterpretation of the data and of scientific knowledge to point to one year as the warmest on record — as was done in a recent Post column [“Dark Green Doomsayers,” George F. Will, op-ed, Feb. 15] — and then to extrapolate that cooler subsequent years invalidate the reality of global warming and its effects.

The difference between climate variability and climate change is critical, not just for scientists or those engaging in policy debates about warming. Just as one cold snap does not change the global warming trend, one heat wave does not reinforce it. Since the beginning of the 20th century, the global average surface temperature has risen 1.33 degrees Fahrenheit.

Evidence of global warming has been documented in widespread decreases in snow cover, sea ice and glaciers. The 11 warmest years on record occurred in the past 13 years.

The difference between long-term and short-term patterns was actually at the heart of the email Will quotes. Kevin Trenberth of National Center for Atmospheric Research was writing in reference to a paper (pdf) he recently published in which he wrote that, while the long-term trend in global warming is clear, scientists ought to try to monitor short-term variability more closely to understand its sources. In other words, Trenberth was not  part of a conspiracy to hide some embarrassing facts about the climate history. He was writing about it in public, and proposing ways to move the science forward.

I have no idea if Will was even aware that Trenberth wrote the email, let alone bothered to read the paper to get some context. But a fact-checker definitely should have, and should have raised a host of red flags.


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The Loom

A blog about life, past and future. Written by DISCOVER contributing editor and columnist Carl Zimmer.

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