By most accounts, Mexico City is the largest urban area in North America (edging out the New York City metro area). The countries in red on this map have a smaller population than Mexico City. i.redditmedia.com/LzTwUYq_TOhOTnoDC5DU-KB0A_ZzvFfV7CaA0v_Y2uQ.png?w=1024&s=162924fa2399216df02e61157fd22ae0

"Post-glacial rebound" is the term used to describe the phenomenon of land that rises in elevation (or rebounds) after millennia of being weighted down by glaciers. Parts of Canada and Greenland, for example, continue to gain in elevation due to post-glacial rebound. This article is about post-glacial rebound in Sweden and Finland, where it is causing problems with river flow, property rights, and shipping. www.cntraveler.com/story/on-the-baltic-coast-of-sweden-and-finland-sea-levels-are-falling

This map compares when slavery was formally abolished in the Western Hemisphere. (Because of colonization patterns, not everything lines up neatly with contemporary nation-state borders.) hillfighter.deviantart.com/art/Abolition-of-Slavery-Americas-215869460

Sea-level rise isn't the only thing causing flooding in coastal cities: in many cities, the land is literally sinking as drinking water is drained from underground aquifers. Jakarta, for example, is sinking by 6.7" per year due to subsidence.  Inland areas like Mexico City and California's San Joaquin Valley are also sinking, differentially, causing major water infrastructure problems. This BBC (UK) article looks at  subsidence and what communities can do to stop it. www.bbc.com/future/story/20171130-the-ambitious-plan-to-stop-the-ground-from-sinking

Our geography is sometimes shaped by extraterrestrial events. This map looks at known impact craters in North America.  The Earth Impact Database provides information about each known impact -- where it is, when it occurred, how big it is -- not just in North America but around the world: www.passc.net/EarthImpactDatabase/Worldmap.html

The 2017 hurricane season is over, but this NASA video shows how this year's storm systems delivered not just wind and rain but also airborne particles, including sea salt and dust from the Sahara. www.youtube.com/watch?v=h1eRp0EGOmE

These GIFs show the steady progression in median ages in the Western Hemisphere and Europe from 1960 to 2060.  www.visualcapitalist.com/animation-rapidly-aging-western-world/

"We estimate the probability of having a magnitude 9 earthquake [in the Cascadian Subduction Zone] in the next 50 years is about 10 to 14 percent." The Cascadian Subduction Zone stretches more than 600 miles, from Vancouver Island, Canada, to Northern California and has a reputation for producing massive earthquakes (as well as the volcanic Cascade Range). The last major quake was 317 years ago, long before Seattle, Vancouver, and Portland were economically significant cities with large populations. news.nationalgeographic.com/2017/10/earthquakes-big-one-cascadia-seattle-geology-science/

By most accounts Mexico City is the most populous metropolitan center in North America (edging out the NYC metro area). However, Mexico City sits on a patchwork of volcanic soil and mud from an ancient lake, causing streets, buildings, and water pipes to shift and crack as infrastructure settles unevenly and exacerbating effects of the region's recurring seismic events, like last week's major earthquake. But last week's earthquake was anomalous, and this article explains why: www.newyorker.com/tech/elements/the-strange-tectonic-coincidence-of-mexicos-september-earthquakes

It seemed appropriate to do a map of the Caribbean today. The islands of the Caribbean are technically those that form an arc separating the Caribbean Sea from the Atlantic Ocean and the Gulf of Mexico. (The Bahamas and the Turks and Caicos are a separate island archipelago considered outside the Caribbean.) The smaller islands on the eastern and southern edge of the Caribbean arc are sometimes referred to as the Lesser Antilles -- in which case the larger islands on the northern edge of the arc, including Cuba, are the Greater Antilles. To further complicate things, the Lesser Antilles are occasionally divided into the Windward Islands (from Dominica south) and the Leeward Islands (from Guadeloupe north). Despite their name, which suggests they are out of the wind, the Leeward Islands took a direct hit from Hurricane Irma, which then proceeded through the Greater Antilles. ontheworldmap.com/north-america/political-map-of-caribbean.jpg

In June, the western coast of Greenland experienced a mega-tsunami when rock, that had been frozen in place, was loosed by melting and crashed into one of the fjords rimming the coast of Greenland, triggering a 100 m. wave that wiped away a small fishing village. Mega-tsunamis, like the one that is believed to have destroyed the Minoan civilization on Crete, occur when massive amounts of rock -- generally from landslides or volcanic eruptions -- are suddenly displaced into relatively shallow bodies of water, generating huge (up to 500 m. tall!) waves. www.nature.com/news/huge-landslide-triggered-rare-greenland-mega-tsunami-1.22374

Yesterday was Canada's sesquicentennial! While Canada, the country, is 150 years old, Canada also has one of the world's oldest populations, with a median age of roughly 42. (The median age in both Japan and Germany is nearly 47; the median age in the U.S. is about 38.) This map, from the Canadian magazine Maclean's, compares Canada's over-55 population with its under-25 population. www.macleans.ca/wp-content/uploads/2014/06/MAP-300dpi-old_young.jpg

The International Ice Patrol, created after the sinking of the Titanic to monitor icebergs in the North Atlantic, has recorded 976 icebergs off Newfoundland so far this year, more than double the average. The icebergs drift into shipping lanes (generally south of 48◦ north latitude) and pose a threat to trans-Atlantic maritime traffic. This article from The Economist notes that number of icebergs varies considerably from year to year, depending on a variety of physical geography cues, including water and air temperature, ocean currents, and wind strength. www.economist.com/blogs/economist-explains/2017/06/economist-explains-14

The U.S. has many Americans of Italian descent. It is less well known, at least in the United States, that South America has many more people of Italian descent. More than half (by some accounts nearly 2/3) of Argentina's population has at least one Italian ancestor, and São Paulo, Brazil, is believed to have the largest population of people of Italian ancestry outside of Italy. This map shows patterns of Italian ancestry across the Americas. img-9gag-fun.9cache.com/photo/a5bvx2r_700b.jpg

The New York Times recently ran an excellent story on how the physical and human geography of Mexico City, the biggest metropolitan area in North America and at considerable elevation and far from the coasts, is increasingly vulnerable to changes in climate. I am excerpting parts here but encourage you to read the whole thing: https://www.nytimes.com/interactive/2017/02/17/world/americas/mexico-city-sinking.html

"Mexico City, a mile and a half above sea level, [is] sinking, collapsing in on itself. ... Always short of water, Mexico City keeps drilling deeper for more, weakening the ancient clay lake beds on which the Aztecs first built much of the city, causing it to crumble even further. ... It is a cycle made worse by climate change. More heat and drought mean more evaporation and yet more demand for water, adding pressure to tap distant reservoirs at staggering costs or further drain underground aquifers and hasten the city’s collapse. In the immense neighborhood of Iztapalapa — where nearly two million people live, many of them unable to count on water from their taps — a teenager was swallowed up where a crack in the brittle ground split open a street. Sidewalks resemble broken china, and 15 elementary schools have crumbled or caved in. Much is being written about climate change and the impact of rising seas on waterfront populations. But coasts are not the only places affected. Mexico City — high in the mountains, in the center of the country — is a glaring example. ... The effects of climate change are varied and opportunistic, but one thing is consistent: They are like sparks in the tinder. They expose cities' biggest vulnerabilities, inflaming troubles that politicians and city planners often ignore or try to paper over. ... Mexico City now imports as much as 40 percent of its water from remote sources — then squanders more than 40 percent of what runs through its 8,000 miles of pipes because of leaks and pilfering. This is not to mention that pumping all this water more than a mile up into the mountains consumes roughly as much energy as does the entire metropolis of Puebla, a Mexican state capital with a population akin to Philadelphia’s. Even with this mind-boggling undertaking, the government acknowledges that nearly 20 percent of Mexico City residents — critics put the number even higher — still can’t count on getting water from their taps each day. ... 'We expect heavier, more intense rains, which means more floods, but also more and longer droughts.' If it stops raining in the reservoirs where the city gets its water, 'we’re facing a potential disaster,' [the director of Mexico City's water system] said. 'There is no way we can provide enough trucks of water to deal with that scenario. If we have the [drought] problems that California and São Paulo [Brazil] have had,' he added, 'there is the serious possibility of unrest.'"

"At the extreme, if climate change wreaks havoc on the social and economic fabric of global linchpins like Mexico City, warns the writer Christian Parenti, 'no amount of walls, guns, barbed wire, armed aerial drones or permanently deployed mercenaries will be able to save one half of the planet from the other.'”

Americans tend to think of Canada as that friendly country north of the U.S.  But this map reveals what would be a surprise to many: 1/2 of all Canadians live in a narrow band that is actually south of Washington state.  i1.wp.com/metrocosm.com/wp-content/uploads/2016/08/canada-population-line-map.png