There’s nothing like looking at a timeline of Earth’s history to remind oneself that, relatively speaking, humans haven’t been around for very long. But while humans have only roamed the planet for a miniscule fraction of the planet’s 4.5 billion year history, geologists and paleontologists have learned an awful lot about different times in the ancient past. They’ve segmented time on Earth according to major events or changes that took place, such as mass extinctions or beginnings of ice ages. These events created periods of time so distinct that the effects can still be seen in layers of rock today. For example, the past 12,000 years of Earth's history are described as the Holocene epoch.
Scientists say that modern human influence is sending the planet into a new geological epoch — the "Anthropocene." Credit: YiFan Photography/iStock
Now, many scientists insist that recent human activity, beginning about 250 years ago, is having such a significant environmental impact on the Earth’s climate, geography, and biological composition that we have actually entered into a new period of geologic time. That means this change to the “age of man” — or the “Anthropocene” epoch — could be distinctly recognizable when future geologists sift through tiered cakes of rock thousands of years from now.
Nobel prize-winning chemist Paul Crutzen brought the idea of the Anthropocene into the scientific spotlight in 2002 (Crutzen is famous for having studied atmospheric chemistry relating to the hole in the ozone layer), but it is not yet an accepted term in geology vernacular. However, in the March 2011 issue of the P...
For tens of thousands of years, huge amounts of plant matter—roots, leaf fragments and the like—have been kept in cold storage underground in the northern parts of Alaska, Canada, Europe and Siberia. They're embedded in permafrost, or permanently frozen soil. Even when the top few inches of ground thaw out in the Arctic summer, permafrost never does. As the planet continues to warm, however, the "perma" in permafrost is looking less eternal. Scientist have known for years, in fact, that rising temperatures threaten to thaw the permafrost, allowing the plant material to decompose and release carbon dioxide (CO2) into the atmosphere, boosting the effects of CO2 from the burning of fossil fuels.
What they have never known is just how much of that deep-frozen CO2 is likely to emerge. Now, a study in the journal Tellus has provided an answer: by 2200, the extra CO2 could add up to about half as much (allowing for uncertainties) as we've produced through fossil-fuel burning since the dawn of the Industrial Revolution. I talked to the lead author, Kevin Schaefer, about what they learned.
Last week we provided you with a run-down of how January 2011 ranked against previous years in terms of average temperatures and precipitation in the U.S.. If you don’t remember the stats — or you’ve managed to block out the memory of how teeth-chattering cold you felt throughout the month — January was colder and drier than average.
Today, NOAA’s National Climatic Data Center (NCDC) released a global analysis of last month's temperatures and precipitation, finding that it was the 17th warmest January on record, with global average combined land and ocean surface temperatures running 0.68°F above the 20th century average.
A map of global temperature departures from average for January 2011. Blue markers indicate areas with below average temperatures; red markers indicate above average temperatures. Credit: NOAA.
The new data also shows the U.S. wasn’t the only country blasted by exceptionally cool air. China experienced their second coldest January, though complete records there only go back to 1961. On the other hand, most of Canada and Siberia — large expanses of land — experienced temperatures well above average, and as mentioned last week, Arctic sea ice extent reached its lowest January extent on record.
Overall, sea surface temperatures last month were the 11th warmest recorded for the month of January. Sea surface temperatures were, however, the warmest they've ever been during January when La Niña conditions were present, indicating that in spite of below average sea surface temperatures throughout the eastern equatorial Pacific, the waters in most other regions of the globe were warm enough to offset the effects of La Niña. La Niñ...
People take comfort in having a plan B; back-up plans can help people prepare for the possibility things might not work at as expected, or hoped. Which is why the subject of geoengineering keeps popping up in discussions of future climate change.
If humans don’t dramatically lower greenhouse gas emissions and stabilize the atmospheric concentration of carbon dioxide (CO2), then manipulating the planet to keep temperatures cool could be a good backup plan. (Note: even the staunchest proponents of geoengineering say that is still the way to think of it, as a plan B only to be put into effect if emissions aren’t sufficiently minimized).
One method of geoengineering is to increase the amount of sunlight that is reflected away from the planet, a strategy known as solar radiation management (SRM). Scientists have proposed a few different ways to achieve this, including putting reflective mirrors or aerosols into the atmosphere, increasing the reflectivity of clouds, or covering large areas of the ground with white or reflective material. If more of the sun’s rays are bounced back out of the atmosphere, then the planet should absorb less heat.
Recently, another po...
Sea level rise gives climate change an address.
That’s why I think it’s a crucial topic for really connecting with people about the risks posed by warming. Information registers better when it’s local. Scientists can project that fires, storms, heat waves and droughts will increase globally and regionally, but no other impact can be pinpointed quite like sea level rise.
And that’s why I approached Jeremy Weiss and Jonathan Overpeck, scientists at the University of Arizona, in autumn 2009. They had already developed a detailed map of low-lying coastal areas in the contiguous U.S. I proposed intersecting their map with the Census boundaries of towns and cities. Our initial results will be published this week in the scientific journal Climatic Change Letters. We believe these are the first estimates of vulnerability to sea level rise covering each and every major coastal city in the Lower 48 – the places where Americans live in our highest concentrations. (Click here for a slide show of the 20 biggest cities in the U.S. to be affected by sea level rise.)
For each city, we reported the percentage of its land under 1-6 meters in elevation (about 3-20 feet). We included only areas also connected to the sea by equal or lower areas – not isolated depressions. We did not factor in complications like erosion or building defensive levees.
What did we find? For coastal American cities with populations above 50,000 people, about nine percent of the land lies b...