kottke.org posts about climate
Climate scientists have been wrestling with a curious fact lately: the rise in global temperature has been flat over the past decade or more even as we pump ever-increasing rates of carbon dioxide into the atmosphere. The Economist discusses what that might mean for the climate and climate science.
Over the past 15 years air temperatures at the Earth's surface have been flat while greenhouse-gas emissions have continued to soar. The world added roughly 100 billion tonnes of carbon to the atmosphere between 2000 and 2010. That is about a quarter of all the CO₂ put there by humanity since 1750. And yet, as James Hansen, the head of NASA's Goddard Institute for Space Studies, observes, "the five-year mean global temperature has been flat for a decade."
Temperatures fluctuate over short periods, but this lack of new warming is a surprise. Ed Hawkins, of the University of Reading, in Britain, points out that surface temperatures since 2005 are already at the low end of the range of projections derived from 20 climate models. If they remain flat, they will fall outside the models' range within a few years.
The mismatch between rising greenhouse-gas emissions and not-rising temperatures is among the biggest puzzles in climate science just now. It does not mean global warming is a delusion. Flat though they are, temperatures in the first decade of the 21st century remain almost 1°C above their level in the first decade of the 20th. But the puzzle does need explaining.
You've likely seen the graph of the Earth's average global temperature over the past 2000 years...it's mostly a straight line until you get to the industrial revolution and then it shoots up. It looks like a hockey stick. In a study published today in Science, that graph has been extended back 11,300 years and you can really see the scope of the abrupt temperature change.
From a summary of the report at TPM:
The decade of 1900 to 1910 was one of the coolest in the past 11,300 years - cooler than 95 percent of the other years, the marine fossil data suggest. Yet 100 years later, the decade of 2000 to 2010 was one of the warmest, said study lead author Shaun Marcott of Oregon State University. Global thermometer records only go back to 1880, and those show the last decade was the hottest for this more recent time period.
"In 100 years, we've gone from the cold end of the spectrum to the warm end of the spectrum," Marcott said. "We've never seen something this rapid. Even in the ice age the global temperature never changed this quickly."
Using fossils from all over the world, Marcott presents the longest continuous record of Earth's average temperature. One of his co-authors last year used the same method to look even farther back. This study fills in the crucial post-ice age time during early human civilization.
Marcott's data indicates that it took 4,000 years for the world to warm about 1.25 degrees from the end of the ice age to about 7,000 years ago. The same fossil-based data suggest a similar level of warming occurring in just one generation: from the 1920s to the 1940s. Actual thermometer records don't show the rise from the 1920s to the 1940s was quite that big and Marcott said for such recent time periods it is better to use actual thermometer readings than his proxies.
PBS ombudsman Michael Getler calls out NewsHour for "a faulty application of journalistic balance" in a recent segment on climate change.
Although global warming strikes me as one of those issues where there is no real balance and it is wrong to create an artificial or false equivalence, there is no harm and some possibility of benefit in inviting skeptics about the human contribution and other factors to speak, but in a setting in which the context of the vast majority of scientific evidence and speakers is also made clear.
What was stunning to me as I watched this program is that the NewsHour and Michels had picked Watts -- who is a meteorologist and commentator -- rather than a university-accredited scientist to provide "balance." I had never heard of Watts before this program and I'm sure most viewers don't, as part of their routines, read global warming blogs on either side of the issue.
I'm not being judgmental about Watts or anything he said. He undoubtedly is an effective spokesperson. But it seems to me that if you decide you are going to give airtime to the other side of this crucial and hot-button issue, you need to have a scientist.
Where have I seen this before, a massive long-lasting Arctic storm that looks a lot like a hurricane? Oh right, The Day After Tomorrow.
The storm had an unusually low central pressure area. Paul A. Newman, chief scientist for Atmospheric Sciences at NASA's Goddard Space Flight Center in Greenbelt, Md., estimates that there have only been about eight storms of similar strength during the month of August in the last 34 years of satellite records. "It's an uncommon event, especially because it's occurring in the summer. Polar lows are more usual in the winter," Newman said.
Arctic storms such as this one can have a large impact on the sea ice, causing it to melt rapidly through many mechanisms, such as tearing off large swaths of ice and pushing them to warmer sites, churning the ice and making it slushier, or lifting warmer waters from the depths of the Arctic Ocean.
I love The Day After Tomorrow. I know it's a cheeseball disaster movie (which is pretty much why I love it) but it's also looking more than a little prescient. Well, as prescient as a cheeseball disaster movie can be anyway. In the Washington Post the other day, prominent climatologist James Hansen wrote that human-driven climate change is responsible for an increase in extreme weather.
My projections about increasing global temperature have been proved true. But I failed to fully explore how quickly that average rise would drive an increase in extreme weather.
In a new analysis of the past six decades of global temperatures, which will be published Monday, my colleagues and I have revealed a stunning increase in the frequency of extremely hot summers, with deeply troubling ramifications for not only our future but also for our present.
This is not a climate model or a prediction but actual observations of weather events and temperatures that have happened. Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.
In many ways, the phrase "global warming" is grossly misleading. "Oh," we think, "it's gonna be a couple degrees warmer in NYC in 20 years than it is now." But the Earth's climate is a chaotic non-linear system, which means that a sudden shift of a degree or two -- and when you're talking about something as big as the Earth, a degree over several decades is sudden -- pushes things out of balance here and there in unpredictable ways. So it's not just that it's getting hotter, it's that you've got droughts in places where you didn't have them before, severe floods in other places, unusually hot summers, and even places that are cooler than normal, all of which disrupts the animal and plant life that won't be able to acclimate to the new reality fast enough.
But pretty Arctic cyclone though, right?
If I could package a cool breeze into a newsletter, I'd do it. Because a lot of you are hot. How hot? In towns across the U.S., 942 temperature records have already been broken this month. In June, 3,282 temperature records were broken. And since the beginning of the year, 23,283 daily high records have been set. These two maps tell the pretty amazing story of the 2012, the year of the heat.
Russian scientists are seeing dramatically increased levels of methane coming from melting permafrost in the East Siberian Ice Shelf. If enough methane is released, that could really put a foot on the gas pedal with this whole global warming thing.
"Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we've found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It's amazing," Dr Semiletov said. "I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them."
Scientists estimate that there are hundreds of millions of tonnes of methane gas locked away beneath the Arctic permafrost, which extends from the mainland into the seabed of the relatively shallow sea of the East Siberian Arctic Shelf. One of the greatest fears is that with the disappearance of the Arctic sea-ice in summer, and rapidly rising temperatures across the entire region, which are already melting the Siberian permafrost, the trapped methane could be suddenly released into the atmosphere leading to rapid and severe climate change.
I'm slowly working my way through Charles Mann's 1493 and there are interesting tidbits on almost every page. One of my favorite bits of the book so far is a possible explanation of the Little Ice Age that I hadn't heard before put forth by William Ruddiman.
As human communities grow, Ruddiman pointed out, they open more land for farms and cut down more trees for fuel and shelter. In Europe and Asia, forests were cut down with the ax. In the Americas before [Columbus], the primary tool was fire. For weeks on end, smoke from Indian bonfires shrouded Florida, California, and the Great Plains.
Burning like this happened all over the pre-Columbian Americas, from present-day New England to Mexico to the Amazon basin to Argentina. Then the Europeans came:
Enter now the Columbian Exchange. Eurasian bacteria, viruses, and parasites sweep through the Americas, killing huge numbers of people -- and unraveling the millenia-old network of human intervention. Flames subside to embers across the Western Hemisphere as Indian torches are stilled. In the forests, fire-hating trees like oak and hickory muscle aside fire-loving species like loblolly, longleaf, and slash pine, which are so dependent on regular burning that their cones will only open and release seed when exposed to flame. Animals that Indians had hunted, keeping their numbers down, suddenly flourish in great numbers. And so on.
The regular fires and forest regrowth resulted in less carbon dioxide in the atmosphere and the atmosphere traps less heat. It's like global warming in reverse.
In a review in Prospect, Matt Ridley, who is no slouch as a science writer himself, calls Andrew Montford's The Hockey Stick Illusion "one of the best science books in years". Pretty high praise for what Ridley also calls "the biography of a graph". Specifically, this graph:
You may have seen it in An Inconvenient Truth in this form. The graph shows the dramatic rise in temperature in the northern hemisphere over the past 100 years caused, presumably, by humans. But as Montford details in his book, the graph is incorrect.
[The author] had standardised the data by "short-centering" them -- essentially subtracting them from a 20th century average rather than an average of the whole period. This meant that the principal component analysis "mined" the data for anything with a 20th century uptick, and gave it vastly more weight than data indicating, say, a medieval warm spell.
Talk about an inconvenient truth.
Update: As expected, ye olde inbox is humming on this one. Here are a few places to look for the other other side of the story: Real Climate, Climate Progress (2, 3), New Scientist, and RealClimate. (thx, reed, barath, aaron)
Due to "when will the ice break up" contests in Alaska and other records dating back more than 150 years, climate scientists are able to study the onset of spring thaws.
Seventeen lakes in Europe, Asia and the U.S. with records going back 150 years are thawing, on average, 13 days earlier now than when first recorded, said Wisconsin lake scientist Barbara Benson.
Frustrating that there's no charts associated with the story; this is a case where a picture would be worth 1000 words.
A report encompassing the work of thousands of climate experts says that "global warming will happen faster and be more devastating than previously thought". "The really chilling thing about the IPCC report is that it is the work of several thousand climate experts who have widely differing views about how greenhouse gases will have their effect. Some think they will have a major impact, others a lesser role. Each paragraph of this report was therefore argued over and scrutinised intensely. Only points that were considered indisputable survived this process. This is a very conservative document -- that's what makes it so scary."
The upper reaches of the northern hemisphere are warming so much that new islands are being discovered, including those once thought to be peninsula. "A peninsula long thought to be part of Greenland's mainland turned out to be an island when a glacier retreated."
Most of what we hear about global warming concerns the atmosphere and its carbon dioxide levels. In the New Yorker a few weeks ago, Elizabeth Kolbert wrote about what's happening in the ocean (
not online, unfortunately it is online (thx, tim)). It turns out that like all tightly coupled systems, the ocean and the atmosphere like to be in equilibrium with each other, which means that the chemistry of the ocean is affected by the chemistry of the atmosphere. Much of the extra carbon dioxide pumped into the atmosphere by humans over the past two hundred years is being absorbed into the ocean and slowly making the ocean more acidic.
The CO2 dissolves, it produces carbonic acid, which has the chemical formula H2CO3. As acids go, H2CO3 is relatively innocuous -- we drink it all the time in Coke and other carbonated beverages -- but in sufficient quantities it can change the water's pH. Already, humans have pumped enough carbon into the oceans -- some hundred and twenty billion tons -- to produce a .1 decline in surface pH. Since pH, like the Richter scale, is a logarithmic measure, a .1 drop represents a rise in acidity of about thirty per cent.
As Kolbert later states, "from the perspective of marine life, the drop in pH matters less that the string of chemical reactions that follow". The increased levels of carbonic acid in the water means there are less carbonate ions available in seawater for making shells, meaning that thousands of species that build shells or skeletons from calcium carbonate are in danger of extinction. As a particularly troubling example, coral use calcium carbonate taken from the seawater to construct themselves. Climate modeller Ken Caldeira believes that if humans keep emitting carbon dioxide into the atmosphere at the same rate as today, by 2075 the world's coral reefs will begin to disappear because their rate of natural erosion will surpass their ability to grow fast enough to keep up.
The truly worrisome thing about all this is that the ocean is an extremely slow moving machine and that once in motion, it's difficult to stop or change its course.
Using 100% of the profits from his airline and transportation companies, Richard Branson pledges $3 billion to fight global warming over the next decade. Will the billionaire philanthropists save us from ourselves? BTW, this happened at the Clinton Global Initiative's annual meeting; there's a live webcast (+podcasts) if you want to watch from home.
Sources cited by The Independent say that George W. Bush is planning "astonishing U-turn" on his global warming policies, which, as Elizabeth Kolbert notes in this week's New Yorker, have been anything but helpful. Those who oppose Bush will give him a lot of crap for doing this just so he can salvage something from his shoddy Presidency, but if something genuinely gets done on the issue, I'll be happy...who gets credit for what and when needs to take a backseat here.
Could global warming kill the internet? "The internet is a big network of servers, and servers are hot. They devour electricity, they run hot and they mainline air conditioning. When the global thermostat goes up, the servers start going down." (via migurski)
Having not ratified the Kyoto Protocol, the US is now refusing to work on its successor. Says Elizabeth Kolbert, "Without the participation of the United States, no meaningful agreement can be drafted for the post-2012 period, and the world will have missed what may well be its last opportunity to alter course."
Scientists have extracted ice cores from Antarctica that date back 650,000 years (the previous high was 400,000 years). The cores show that modern levels of carbon dioxide, methane, and nitrous oxide levels are the highest they have ever been.
Elizabeth Kolbert (who wrote three articles for the NYer on global warming earlier in the year) discusses global warming as a possible cause for Hurricane Katrina. Like the climate scientists on RealClimate contend, Kolbert notes that no particular storm can be caused by global warming, but that the long-term patterns don't look good...increased greenhouse gases = warmer oceans = more destructive hurricanes. Paul Recer downplays the connection as well and cautions environmental groups who want to make political hay with scientific evidence that doesn't support their claims.
The second of Elizabeth Kolbert's three-part series on global warming for the New Yorker. This one's about how relatively short-term climate change can affect entire civilizations.