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Mongol Empire rode wave of mild climate, says study

A recent study using ancient tree rings reveals that the Mongol Empire's rapid expansion was facilitated by a period of unusually mild and wet weather in central Asia. The findings suggest that this favorable climate allowed for increased grass production, which in turn enabled the Mongols to build their powerful horse-riding army.

SourceColumbia Climate School·JournalProceedings of the National Academy of Sciences·DateMar 10, 2014

First long temperature reconstruction for the eastern Mediterranean based on tree rings

Researchers reconstructed a 900-year temperature timeline in the Eastern Mediterranean, revealing a medieval warm period and modern warming trend that may not be regional. The study uses stable carbon isotopes in tree rings to analyze environmental conditions and find correlations between temperature fluctuations and tree growth.

Tree rings go with the flow of the Amazon

Researchers have used tree rings from cedar trees in Bolivia to record a 100-year history of rainfall across the Amazon basin. The study found that lowland tropical cedar trees provide a natural archive of data closely related to historic rainfall, allowing for a detailed understanding of past climate variability.

SourceUniversity of Leeds·JournalProceedings of the National Academy of Sciences·DateOct 1, 2012

UA scientists find evidence of Roman period megadrought

Researchers from the University of Arizona have discovered a long-lost megadrought in the southwestern US during the second century AD, lasting nearly 50 years. The study, using tree-ring analysis, reveals a previously unknown drought period that had significant implications for regional climate and water resources.

SourceUniversity of Arizona·JournalGeophysical Research Letters·DateNov 4, 2011

Did climate influence Angkor's collapse?

A study suggests that severe droughts and heavy monsoon rains may have weakened Angkor's economy and led to its downfall. The research, published in Proceedings of the National Academy of Sciences, found evidence of a mega-drought lasting three decades, which could have exacerbated crop failure and infectious disease.

SourceColumbia Climate School·JournalProceedings of the National Academy of Sciences·DateMar 29, 2010

Ancient high-altitude trees grow faster as temperatures rise

A recent study found that ancient high-altitude bristlecone pines in the western US are experiencing unprecedented growth rates due to rising temperatures. Trees growing near treeline, typically at elevations above 11,000 feet, showed wider annual growth rings from 1951 to 2000 compared to previous centuries.

SourceUniversity of Arizona·JournalProceedings of the National Academy of Sciences·DateNov 16, 2009

The least sea ice in 800 years

Researchers have reconstructed sea ice extent from 13th century to present using historical records and climate curves. The findings show a significant decrease in sea ice coverage since the start of the 20th century, with some record-breaking low levels in recent years.

SourceUniversity of Copenhagen·JournalClimate Dynamics·DateJul 1, 2009

Volcanoes cool the tropics, say researchers

Climate researchers show that large volcanic eruptions temporarily cooled the tropics over the past 450 years. However, recent eruptions may have been overridden by rising temperatures. The study found that higher latitudes are more sensitive to volcanism and are vulnerable to temperature shifts.

SourceColumbia Climate School·JournalNature Geoscience·DateJan 5, 2009

Global warming greatest in past decade

Researchers confirm that surface temperatures in the Northern Hemisphere were warmer over the last 10 years than any time during the last 1300 years. The study uses a variety of proxy data, including tree rings, marine and lake sediment cores, ice cores, and coral cores, to derive a long-term temperature record.

SourcePenn State·JournalProceedings of the National Academy of Sciences·DateSep 1, 2008

How long is a child a child?

A fossil juvenile from Jebel Irhoud, Morocco, dated to approximately 160,000 years ago, showed a modern human life history profile at almost 8 years of age. This finding suggests that prolonged childhood development may be linked to the origins of social and biological changes.

SourceMax-Planck-Gesellschaft·JournalProceedings of the National Academy of Sciences·DateMar 13, 2007

Coral layers good proxy for Atlantic climate cycles

Researchers have discovered that coral layers in the Atlantic Ocean hold a key to understanding the region's climate dynamics. By analyzing calcium carbonate skeletons, Dr. Lisa Greer and her team found a periodic pattern of oxygen isotope composition with peaks every 12-15 years, mirroring sea surface temperature data.

Archaeologists rewrite timeline of Bronze and Iron Ages

Researchers from Cornell University and the University of Reading have given a new kind of precision to the timeline of the Bronze and Iron Ages in the Aegean and Near East. The study, published in Science, dates certain artifacts from around 740 B.C., placing an early appearance of the alphabet outside Phoenicia at this time.

SourceCornell University·JournalScience·DateDec 19, 2001

More To Drought Than Meets The Eye

Studies found that tree species' moisture preference doesn't always correlate with their growth rate during droughts. Researchers used tree rings to analyze the energy stored in trunks, revealing inconsistencies between leaf physiology and radial growth.

Bark Beetle Infestation Spurs Multifaceted Study

Researchers are investigating the history of forests, fire incidence, and signs of early settlers in the Lake Tahoe Basin due to a bark beetle infestation. The study aims to reconstruct the forest structure before logging, the history of fire in the area, and the age of trees.