Russia's Portentous Summer

Jeff Masters says, "one of the most remarkable weather events of my lifetime is unfolding this summer in Russia" where the current heat wave is pretty much entirely off the historical charts. For comparison, the 2003 heat wave across Western Europe killed more than 40,000 people - and the present heat wave in Russia is far more extreme than that:




Says Masters:

The past 25 days in a row have exceeded 30°C (86°F) in Moscow, and there is no relief in sight--the latest forecast for Moscow calls for high temperatures near 100°F (37.8°C) for the majority of the coming week. As I reported in yesterday's post, the number of deaths in Moscow in July 2010 was about 5,000 more than in July 2009, suggesting that the heat wave has been responsible for thousands of deaths in Moscow alone. I would expect that by the time the Great Russian Heat Wave of 2010 is over, the number of premature deaths caused by the heat wave will approach or exceed the 40,000 who died in the 2003 European Heat Wave. As seen in Figure 2, the Russian heat wave of this year is more intense and affects a wider region than the great 2003 heat wave, though the population affected by the two heat waves is probably similar.

Another commentator writes:

To put this in rough perspective -- and note this is not absolutely precise, it's purely ballpark to give you some feel for what the Russian people are enduring -- if this heat wave was hitting North America, it would be near 100°F in Fairbanks, Alaska. Most of Canada would be baking at 100° or higher, the northeast, from Maine to the Great Lakes region would be hitting upwards of 105° everyday, even the nightly low in the massive urban heat islands of New York and Chicago would be over 90°! The midwest grain belt and parts of the Pacific Northwest would not see a drop of rain for two months and pushing as high as 110° in places. The desert southwest, even some of the higher elevations of Nevada, Arizona, New Mexico, and West Texas, would be as uninhabitable as Death Valley or the Sahara.

It would mean nation-wide massive power brownouts, unprecedented crop failures, water rationing like you have never seen, record wildfires raging in dozens of states, thousands of deaths [Correction: Dr. Jeff Masters at WeatherUnderground informs me it would probably more like tens of thousands of deaths] and life threatening heat related illness, roads and highways clogged with broken-down, over-heated cars, and emergency services stretched beyond the breaking point across the US and Canada. The conditions could be so severe in places, especially if the wave persisted for a couple of years, that it could produce mass migration, i.e., refugees, the likes of which haven't been seen since the Great Depression.

Tens of thousands of deaths from the sort of weather event that will become more common as global warming continues apace. The usual caveat applies about the fallacy of attributing individual weather events to long-term climate trends, but needless to say, a warming planet will experience more severe heat waves. As Masters notes:

Looking back at the past decade, which was the hottest decade in the historical record, Seventy-five countries set extreme hottest temperature records (33% of all countries.) For comparison, fifteen countries set extreme coldest temperature records over the past ten years (6% of all countries).

Weather events like these heat waves have proven their capacity to have death tolls in the five figures. But perhaps the most ominous portent of the Russian heat wave has been the government's move to ban grain exports - a response to the decimation of wheat crops due to the wildfires and drought that have attended the heat wave. Natural calamity leading to resource nationalism, causing food prices to spike across the globe: this story will be written again in the decades to come.

First Half of 2010 is the Warmest on Record

June 2010 was the hottest June on record, 1.22°F above average. So was the period of April-June, 1.26°F above average. And January through June - the entire first half of 2010 - were also the hottest on record, 1.22°F above average. A trifecta!



Pop quiz: what do these facts, and the giant oil spill and ecosystem carnage in the Gulf of Mexico, and the environmental damage and civil unrest in the Niger Delta, among many other sordid, disturbing facts about life on Earth in the early 21st Century, have in common?

George Will, among others, would say: nothing. Nothing at all. Because he does not believe that the world is warming due to our burning of fossil fuels; indeed, he does not believe we are in a period of global warming at all, as he argued in an editorial last year. He stated there that

according to the U.N. World Meteorological Organization, there has been no recorded global warming for more than a decade, or one-third of the span since the global cooling scare.

This assertions was factually incorrect - the WMO said no such thing - as were pretty much all of Will's assertions in the editorial. But what would make Will not only believe this assertion, but decide to broadcast it to the world from his extremely authoritative position as an editorialist for the Washington Post? Perhaps it was his interpretation of the fact that the ten warmest years on record, according to NOAA, have been, in order, 2005, 1998, 2003, 2002, 2006, 2009, 2007, 2004, 2001, and 2008. Or perhaps it's just his reading of this chart:



These data points pretty strongly suggest that the world is in a period of warming, and the record for 2010 is clearly continuing the trend. But to correctly understand the data that are being represented here, you have to meet at least two sriteria: 1) Have the statistical acumen and general intelligence of at least a second-grader; and 2) Not be a disingenuous toady for the fossil fuel industry. On at least one of these points, Will has obviously failed.

The Coming Heat Wave Wave

The weather where I live - a large East Coast metropolis somewhere between Bridgeport, CT and Trenton, NJ - was notably warm last week, as it was for much of the East Coast. At Dot Earth, Andrew Revkin links to a study that predicts many more such heat waves in the future.



On the study:

"Using a large suite of climate model experiments, we see a clear emergence of much more intense, hot conditions in the U.S. within the next three decades," said Noah Diffenbaugh, an assistant professor of environmental Earth system science at Stanford and the lead author of the study.

Writing in the journal Geophysical Research Letters (GRL), Diffenbaugh concluded that hot temperature extremes could become frequent events in the U.S. by 2039, posing serious risks to agriculture and human health.

"In the next 30 years, we could see an increase in heat waves like the one now occurring in the eastern United States or the kind that swept across Europe in 2003 that caused tens of thousands of fatalities," said Diffenbaugh, a center fellow at Stanford's Woods Institute for the Environment. "Those kinds of severe heat events also put enormous stress on major crops like corn, soybean, cotton and wine grapes, causing a significant reduction in yields"...

In the study, Diffenbaugh and Ashfaq used two dozen climate models to project what could happen in the U.S. if increased carbon dioxide emissions raised the Earth's temperature by 1.8 degrees Fahrenheit (1 degree Celsius) between 2010 and 2039 – a likely scenario, according to the International Panel on Climate Change.

In that scenario, the mean global temperature in 30 years would be about 3.6 degrees F (2 degrees C) hotter than in the preindustrial era of the 1850s. Many climate scientists and policymakers have targeted a 2-degree C temperature increase as the maximum threshold beyond which the planet is likely to experience serious environmental damage. For example, in the 2009 Copenhagen Climate Accord, the United States and more than 100 other countries agreed to consider action to reduce greenhouse gas emissions "so as to hold the increase in global temperature below 2 degrees Celsius."

But that target may be too high to avoid dangerous climate change, Diffenbaugh said, noting that millions of Americans could see a sharp rise in the number of extreme temperature events before 2039, when the 2-degree threshold is expected to be reached.

"Our results suggest that limiting global warming to 2 degrees Celsius above preindustrial conditions may not be sufficient to avoid serious increases in severely hot conditions," Diffenbaugh said.

The study predicts that "an intense heat wave – equal to the longest on record from 1951 to 1999 – is likely to occur as many as five times between 2020 and 2029 over areas of the western and central United States." In other words, imagine you are 60 years old or so, and think of the absolute most extreme heat wave you've experienced in your entire life.

Twenty years from now, such heat waves will be occurring once every year or two.

And needless to say, there is zero evidence that we are prepared to seriously address the problem of global warming sufficiently enough to actually achieve the 2-degree goal. This is because we are a short-sighted, greedy, and not-quite-intelligent-enough species, and the world we bequeath to future generations will be severely damaged as a result. Very likely we will go down in history as a generation of obnoxious assholes who were too enthralled with our SUVs and plastic tchotchkes to make even the most minimally adequate moral calculations about our actions.

And if you think things might change once the effects of global warming actually start showing up in earnest... well, I have my doubts. Here is Revkin quoting social scientist Robert Brulle:

I’m up in New Hampshire, and the signs of climate change are everywhere, should you choose to see them. The strawberry season has already passed (it usually comes in late July), and you can now get fresh blueberries (3 weeks ahead of normal). The lake I am staying at has lost a lot of water clarity due to an excessive amount of tannic acid. The lake had its earliest ice out this year in memory, and so the leaves had had a longer time to decompose, thus releasing more tannic acid to the water. The water looks more like what you see in the Pine Barrens than in New Hampshire. These changes are all just taken in stride. Climate change remains something abstract and far away, both in time and space. In short, these changes are being normalized.

Cloudier lakes in New Hampshire today, an inundated Bangladesh tomorrow, and everything changing at the rate of one very slowly boiling frog. This is just a very difficult sort of calamity for our species to respond to.

Russians Call it 'Sneg'

I know what you're thinking. You're thinking: how much of the Northern Hemisphere is currently covered in snow, and can this information be represented in mustard yellow? Well, aren't you in luck:



That's from the Rutgers University Global Snow Lab. By way of commentary, Jeff Masters says:

We live in the United States of Snow. A rare Deep South heavy snowstorm whipped across the southern tier of states yesterday, dumping six-plus inches of snow over portions of Louisiana, Mississippi, Alabama, Georgia, South Carolina, and North Carolina. Even Florida got into the act, with up to two inches recorded in the extreme northwestern Panhandle. The snowstorm left 49 of the 50 states with snow cover, according to an article by Associated Press. Hawaii was the lone hold-out. David Robinson, head of the Rutgers Global Snow Lab, said that 67.1% of the U.S. had snow cover on Friday morning, with the average depth a respectable 8 inches. Normally, the U.S. has about 40 - 50% snow coverage during the 2nd week of February. January had the 6th greatest snow cover in the 44-year record over the contiguous U.S., and December 2009 had the most snow cover of any December on record. The current pattern of record heavy snows over the the Eastern U.S. is primarily due to a natural oscillation in the Earth's climate system called the North Atlantic Oscillation (NAO).

If one single person comments that this proves global warming does not exist, as God is my witness I will reach through the Internet and pop you right in the nose. I will then proceed to make a substantive argument as to why all this snow is actually just what you'd expect (in the short term) in a warming world, but I'd really prefer to not have to do that.

Global Warming is Gonna Be Bad for the Midwest

While bureaucrats from around the world are in Copenhagen haggling over an arcane agreement that may have profound effects on the state of the entire planet a century from now, you can enjoy this interactive map, which projects temperature rise across the the lower 48 states by the 2080s:



It's based on a "medium" projection of greenhouse gas emissions. It shows at least a 4F temperature rise relative to a 1961-1990 baseline pretty much everywhere and 6-8F in much of the Interior West and Midwest (a.k.a. where our food comes from). In fact the seven states that are expected to heat up the most are all in the Midwest or thereabouts: Nebraska and Iowa (9.4F according to the moderate scenario), South Dakota (9.3), Missouri (9.2), Illinois (9.1), Kansas (9.1), and North Dakota (9.0).

The maps are based on a report (pdf) from The Nature Conservancy:

To help average Americans, policy makers and other local stakeholders better understand how climate change will directly impact their states, The Nature Conservancy has analyzed the latest and most comprehensive scientific data available to calculate specific temperature projections for each of the 50 US states over the next 100 years.

The Nature Conservancy also worked with the University of Washington and the University of Southern Mississippi to develop a new on-line tool that combines the latest scientific data and climate models with geographic information systems (GIS), statistical analysis and web-based mapping services. This tool, Climate Wizard (www.climatewizard.org), represents the first time ever that the full range of climate history and future projections for specific landscapes and time frames have been brought together in a user-friendly format that is available to a mass audience.

It also predicts rainfall:



Bad news for California and Texas. Oh well, at least they're not the two most populous states in the country or anything.

Via Huffington Post.

El Niño Heats Up

El Niño is growing stronger:



This image, from the NASA/JPL Ocean Surface Topography Team, is based on measurements taken from a US/French satellite over ten days around November 1.

Says NASA:

El Niño is experiencing a late-fall resurgence. Recent sea-level height data from the NASA/French Space Agency Ocean Surface Topography Mission/Jason-2 oceanography satellite show that a large-scale, sustained weakening of trade winds in the western and central equatorial Pacific during October has triggered a strong, eastward-moving wave of warm water, known as a Kelvin wave. In the central and eastern equatorial Pacific, this warm wave appears as the large area of higher-than-normal sea surface heights (warmer-than-normal sea surface temperatures) between 170 degrees east and 100 degrees west longitude. A series of similar, weaker events that began in June 2009 initially triggered and has sustained the present El Niño condition.

This image... shows a red and white area in the central and eastern equatorial Pacific that is about 10 to 18 centimeters (4 to 7 inches) above normal. These regions contrast with the western equatorial Pacific, where lower-than-normal sea levels (blue and purple areas) are between 8 to 15 centimeters (3 and 6 inches) below normal. Along the equator, the red and white colors depict areas where sea surface temperatures are more than one to two degrees Celsius above normal (two to four degrees Fahrenheit).

"In the American west, where we are struggling under serious drought conditions, this late-fall charge by El Niño is a pleasant surprise, upping the odds for much-needed rain and an above-normal winter snowpack," said JPL oceanographer Bill Patzert.

Swell. More here, including a map animation.

Because I Haven't Gotten Extremely Depressed About Global Warming in the Last Couple of Weeks...

The British government recently came out with a new interactive map, posted by The Guardian here, that shows the likely impacts of global warming, assuming our species continues our sit-on-our-asses-till-we're-all-fried approach to this looming catastrophe:



Says The Guardian:

The map was launched to coincide with the London Science Museum's new Prove it climate change exhibition by David Miliband, foreign secretary and his brother Ed Miliband, energy and climate change secretary. It comes in advance of key political talks on climate change in December in Copenhagen, where British officials will push for a new global deal to curb emissions.

The Miliband brothers said a new deal needed to be strong enough to limit global temperature rise to 2C, although many involved in the negotiations privately believe this to be impossible. A joint press release from the government and the Met Office released to promote the map says the government is aiming for an agreement that limits climate change "as far as possible to 2C".

The map presumes a global average rise of 4 degrees Celsius, a disastrous scenario which is nonetheless where we are very probably headed (as the UK Met Office says itself). That is, again, assuming that we don't take significant action to thwart such a catastrophe.

I personally consider such action highly unlikely for a number of reasons, which is really too bad, because this forecast is a terrible one. It calls for temperatures to be 6-7C warmer across most of the continental US, for instance. That's about 10-13 degrees Fahrenheit; that's like the difference between spring and summer. The "hottest days of the year could become as much as 10-12C (18-22F) warmer [!] over eastern North America," says the map; it's even worse for the Arctic, where a rise of 15C is so off-the-charts huge that's it's just impossible to predict what sort of effects it will have; beyond the prospect of a positive feedback from Arctic methane release, it's really not much fun to think about it anymore.

I will just stand up on my little digital soapbox here and make the point, not for the first time, that this dystopic future is the price we're paying for our cheeseburgers and our SUVs. It is really a profoundly, spectacularly, stupidly high price to pay for a lifestyle that, frankly, is not all that great to begin with. But no doubt this lesson will sink in... oh, right about the time that Bangladesh does.

Via The Map Room.

Things Change

Yankee Magazine crowd-sources autumn:



Reports are made by people (qualification: have color vision!) around the northeastern US, who write in and say stuff like

Hi folks, Things around here are really starting to look diferent around here [sic]. We had those last few nights that got alittle [sic] cooler and it seemed like the swamp maples took the hint. Like popcorn when it starts to pop [sic]. The colors realy [sic] started to show, see ya for now [sic]

which you can read by clicking on the map. You can also register to do it yourself. It all strikes me as somehow breathtakingly wholesome.

I also like the existential connotations of the map legend.

Via Andrew Sullivan

Hot Hot Heat

Another map from that Jeff Masters post confirms something I had strongly suspected: Texas was hot in June!



But then, so was the Southeast, the Maritime Provinces, the North Pacific, the East Pacific, Western Europe, Eastern Europe, Siberia, China, India, the Middle East, just about all of Africa... in fact, Masters says, it was the second-warmest June in history, just a hair shy of 2005's blistering record. Says Masters:

The period January - June was the fifth warmest such period on record. Global temperature records go back to 1880. The most notable warmer-than-average temperatures were recorded across parts of Africa and most of Eurasia, where temperatures were 3°C (5°F) or more above average. The global ocean Sea Surface Temperature (SST) for June 2009 was the warmest on record, 0.59°C (1.06°F) above the 20th century average. This broke the previous June record set in 2005. The record June SSTs were due in part to the development of El Niño conditions in the Eastern Pacific. If El Niño conditions continue to strengthen during the coming months, we will probably set one or more global warmest-month-on-record marks later this year. The last time Earth experienced a second warmest month on record was in October 2008.

Of course, if you are Rep. Blaine Luetkemeyer (R-MO), you may see this as evidence that we are in a period of global cooling. But also you would be an idiot.

The Changing Hardiness Zones of the US

From the Baltimore Sun's B'More Green blog comes news (via the Sun's Garden Variety blog) that the US Department of Agriculture is planning to revise its map of plant hardiness zones across the country by this fall. But the Arbor Day Foundation has already updated changes in hardiness zones from 1990 to 2006, which they show in their interactive map:



This shows the changes in zone classification over that time period:



Some isolated areas of the interior West and Midwest have actually warmed enough to move up two zones, while a few areas in the Southwest have actually gone down a zone. But you can infer from the streaked pattern that most areas, especially in the eastern two-thirds of the country, have warmed by the equivalent of about half a zone. That actually strikes me as a bit extreme; zones are classified by average annual low temperature, as per the scale on the left; so if I'm reading it right, a half-zone change would correspond to the average annual low being about 5 degrees F warmer in 2006 than it was in 1990. Is that really plausible? Average temperatures certainly haven't warmed by that much; but maybe the climate has changed in such a way that especially cold snaps are less common at the height of winter. I don't know.

Snow

NASA's Earth Observatory has a map animation of global snow cover from 1999-2009.



It's surprising how much of the world's land area spends a big chunk of the year under a layer of frozen water. Guess we really are still in an ice age.

Survival Map for the Apocalypse

New Scientist maps the global warming apocalypse.



The accompanying article, by the aptly named Gaia Vince, depicts a scenario in which Earth warms by 4C by the end of this century. The future she foretells is a grim one: most of the world between about 40 degrees north and 40 degrees south will have become a vast desert, uninhabitable by humans, rendering most of the world's food-producing regions barren wastelands. The Sahara will spread into central Europe, and Japan and eastern China will become Gobified. South Asia will suffer from a fiercer but briefer monsoon, producing both more floods and more drought; much of Bangladesh will disappear altogether under rising seas. Rivers in Europe and Asia will wither. The Amazon might simply go up in a vast inferno. Vince suggests that 90% of the human population won't make it through these calamities.

Interestingly, there's a precedent for this kind of scenario:

The last time the world experienced temperature rises of this magnitude was 55 million years ago, after the so-called Palaeocene-Eocene Thermal Maximum event. Then, the culprits were clathrates - large areas of frozen, chemically caged methane - which were released from the deep ocean in explosive belches that filled the atmosphere with around 5 gigatonnes of carbon. The already warm planet rocketed by 5 or 6 °C, tropical forests sprang up in ice-free polar regions, and the oceans turned so acidic from dissolved carbon dioxide that there was a vast die-off of sea life. Sea levels rose to 100 metres higher than today's and desert stretched from southern Africa into Europe.

But of course, human civilization wasn't around back then to be shepherded through the bottleneck of dramatic ecological change. (Nor, presumably, did it happen as quickly as our present blitzkrieg against climatic stability.) How humans might adapt to a recapitulation of such changes will be, Vince suggests, the story of humanity over the next few centuries. The key to it will be an unprecedentedly massive migration. Even as the mid-latitudes wither into desiccated husks, storm systems will wander closer to the poles. With rising temperatures and greater precipitation, Canada, Scandinavia, and Siberia will become the most habitable places on the planet. They'll be our breadbaskets - vast agricultural areas peppered by dense, high-rise cities where most people will live.

Some of these predictions are a bit... horologically aggressive, let's say. Sky-rise cities popping up throughout a verdant West Antarctica? Not in this millennium. And even with a 10C rise, is it really reasonable to envision Siberia as the breadbasket of the world? A Siberia that's 10C warmer is still pretty damn cold. It's also unclear to me why there'd be total desertification near the equator; why would the tropical rain belt shut down? Nonetheless, it's worth noting that the 4 degree rise in global temperatures out of which this scenario is built is actually on the conservative side of current climate change predictions; a rise of 5 or 6C might be more likely. In any event, wake me when it is no longer conventional wisdom that the destruction of the planet is necessary to support a healthy global economy. Until then, I'll continue to assume that something like this apocalyptic scenario is pretty much destined to occur.

Incidentally, for some reason the article also has an interactive google map, which is mostly redundant.

A Map of Global Warming

A team of MIT researchers has just come out with a new projection of climate change over the course of the 21st Century.



Is this a map? I guess it's both a map and a graph. Anyways, it's a little tricky to read it at first, but look at it this way: every point on the map/graph represents a particular latitude and a particular year; the color of that point represents how much warmer it's likely to be at that given place and time. So, for instance, a location at 40 degrees north latitude (e.g., New York, Madrid, Beijing) is forecast to be about 2C warmer in 2050 and about 6C warmer in 2100. No doubt lots of local effects will come into play, but these temperatures would represent the latitudinal average.

What's immediately striking is how much greater warming is forecast to be near the poles, and especially the north pole. Temperatures there could be more than 10C warmer by the end of the century, a mind-boggling number. And a special added bonus effect of a dramatically warmer acrtic is that the melting of tundra could cause even more greenhouse gases to escape into the atmosphere, instigating a vicious cycle.

The projections are warmer than those made using the same model in 2003. As the paper's abstract says:

the median surface warming in 2091 to 2100 is 5.1°C compared to 2.4°C in the earlier study. Many changes contribute to the stronger warming; among the more important ones are taking into account the cooling in the second half of the 20th century due to volcanic eruptions for input parameter estimation and a more sophisticated method for projecting GDP growth which eliminated many low emission scenarios. However, if recently published data, suggesting stronger 20th century ocean warming, are used to determine the input climate parameters, the median projected warning at the end of the 21st century is only 4.1°C. Nevertheless all our simulations have a very small probability of warming less than 2.4°C

And what would a 4-5C rise in temperature look like?

Globally, a 4C temperature rise would have a catastrophic impact.

According to the government's 2006 Stern review on the economics of climate change, between 7 million and 300 million more people would be affected by coastal flooding each year, there would be a 30-50% reduction in water availability in Southern Africa and the Mediterranean, agricultural yields would decline 15 to 35% in Africa and 20 to 50% of animal and plant species would face extinction.

That's one of the somewhat optimistic scenarios in the MIT report. And the image above depicts a middle-of-the-road model for both climate change and economic development. But there's been a tendency for observed changes in climate patterns and sea ice to push the upper bounds of what scientists have been predicting. If that continues to be the case, then a merely catastrophic outcome may be the best that we can hope for.

Temperature Anomalies and Global Warming

Weather Underground updates this map every month.



It shows the temperature anomalies around the globe for January 2009 relative to the average between 1961 and 1990. As has usually been the case over the last ten or fifteen years, the global average temperature was above average for the month; it was the 7th warmest January on record, in fact. (And look at Siberia: it's been looking like that a lot lately - the climate seems to be changing there really dramatically.) However, among the few areas of the world that were below average were Western Europe and the Northeastern and Midwestern United States. For the US as a whole, it was only the 59th warmest January out of the last 114. (Note, too, the coolish temperatures over the central Pacific: a symptom of La Nina.)

One inevitable consequence of cold snaps during the winter is that global warming skeptics will say sarcastic things about the weather. And some people become more receptive to denialist claims - claims by people like George Will who recently wrote a denialist editorial that was pretty much entirely composed of falsehoods. But of course the fact that the temperature of the planet is gradually rising doesn't mean there will never again be any temperatures anywhere that are below average - and you can see clearly enough that a significant cold snap in some of the densely populated parts of the industrialized world is perfectly consistent with the world having temperatures somewhere in the neighborhood of the 5% warmest ever.

Ricky Rood makes a related point at his blog on Weather Underground, where he shows these maps of the continental US temperature anomalies from the Januaries of 2008 (top) and 2009. It so happened that in 2008, most of the big cities in the US were warmer than average, and this year they were colder (the major exception being the cities on the west coast). Overall, though, the months were similar for the country as a whole, and near average. But for two reasons, the denialists have had more fodder this year: 1) the colder weather disproportionately hit the places where lots of people live - if the map were a cartogram (which would make no sense) it would be overwhelmingly blue, including in big media centers where opinions tend to get amplified; and 2) the colder weather this year hit places that are naturally colder, which makes it seem more dramatic. Record lows in Oregon are gonna be chilly for the folks there, but not freezing; it's a lot more startling when it hits -40 degrees in Maine. As Rood says, "I don’t remember a lot of rhetoric that 'global warming is spurious' coming out in 2008, from say, Seattle."

Well, these points probably seem obvious to most people. And for that committed minority who don't believe in anthropogenic global warming, there is an entire industrial-media apparatus (of which George Will is obviously a card-carrying member) designed to confirm their views, and no amount of data is likely to win them over. But maps like these are still a good corrective to the impulse we all have to extrapolate global trends from the anecdotal events we read about in the news.

Ice Age Climate Map

That earlier post on human migration got me curious about the climate of the ice age. What sort of a world were our ancestors encountering as they spread inexorably around the world? Earth was in a glacial period for most of the time during which the expansion of our species occurred; the current interglacial period we all know and love didn't set in until after humans had colonized every continent (every decent continent, at least - sorry, Antarctica). So what was the world like for those prehistoric peregrinators?

Ask Wikipedia, and ye shall receive:



(You'll have to click on the map or follow the link to be able to read the legend.) This is a standard-issue vegetation map of the sort that always show up in the first section of world atlases, but it shows the world as it was ca. 18,000 years ago. And things were shockingly different. For instance:

-That purple in the eastern US indicates taiga, the coniferous forests which today are found right at the limit of the Arctic tree line in northern Canada. Apparently the Mississippi Delta of 18,000 years ago resembled the Yukon of today.

-Florida was a semi-arid temperate woodland, and the Atlantic coast of the US was boreal forest. Anything north of New York City and Chicago was under ice altogether.

-Much of Europe was under ice as well, and steppe-tundra extended all the way down to the Mediterranean coast. Tundra also had a foothold in the interior of the Iberian Peninsula.

-Interestingly, there were tropical forests and grasslands in many of the same areas as there are today. But the temperate regions really get pinched; it seems that between the subtropical deserts (also in most of the same regions as today) and the ice and tundra of the higher latitudes, there just wasn't much room for the expansive temperate forests which have more recently been characteristic of North America and Eurasia, especially. It seems that the world of 18,000 years ago just had a lot fewer trees.

-Australia? 'Bout the same, maybe a little chillier. The Southern Hemisphere in general, in fact, seems to have been less affected by the last period of glaciation.

Given all this, you can well imagine why humans spread first along the coast of the Indian Ocean, all the way to Australia: pretty much everything north of there was barren, windswept, and cold. It was the North Dakotafication of the world. In fact, as those first bands of humans finally left the amniotic comforts of southern Asia and Africa and soldiered into the frozen lands to the north, an interesting question to ask them would have been: why?