Human Geography Images

Environment

 

The images below provide some additional information to the course regarding environmental issues. 

 

A combined graph of numerous studies of the historical climate for the last 2000 years.  The black line that appears late on the right hand side represents recordings from scientific instruments, which appeared in the mid-1800s.  Other data has been gathered from tree-ring data, samples of the past atmosphere from ice cores, coral reef growth patterns, lake sediments and other methods.

 

The earliest records of temperature measured by thermometers are from western Europe beginning in the late 17th and early 18th centuries. The network of temperature collection stations increased over time and by the early 20th century, records were being collected in almost all regions, except for polar regions where collections began in the 1940s and 1950s. A set of temperature records from over 7,000 stations around the world has been compiled by the NOAA National Climate Data Center to create the Global Historical Climatology Network - GHCN (GHCN Version 2 data set; Peterson and Vose 1997). About 1,000 of these records extend back into the 19th century.

Three widely recognized research programs have used the available instrumental data to reconstruct global surface air temperature trends from the late 1800's through today. All use the same land-based thermometer measurement records from the GHCN, but the reconstructions contain some differences. These differences are due to different approaches to spatial averaging, the use and treatment of sea surface temperature data (from ship observations), and the handling of the influence of changes in land-cover (i.e., increases in urbanization). However, all three show the same basic trends over the last 100 years.

 

Although each of the temperature reconstructions are different (due to differing calibration methods and data used), they all show some similar patterns of temperature change over the last several centuries. Most striking is the fact that each record reveals that the 20th century is the warmest of the entire record, and that warming was most dramatic after 1920.

The similar characteristics among the different paleoclimatic reconstructions provides greater confidence in the following important conclusions:

  • Dramatic global warming has occurred since the 19th century.
  • The recent record warm temperatures in the 1990's are indeed the warmest temperatures the Earth has seen in at least the last 1000 years.

 

Building on recent studies, we attempt hemispheric temperature reconstructions with proxy data networks for the past millennium. We focus not just on the reconstructions, but the uncertainties therein, and important caveats. Though expanded uncertainties prevent decisive conclusions for the period prior to AD 1400, our results suggest that the latter 20thcentury is anomalous in the context of at least the past millennium. The 1990s was the warmest decade, and 1998 the warmest year, at moderately high levels of confidence. The 20th century warming counters a millennial-scale cooling trend, which is consistent with long-term astronomical forcing.

 

NOAAs Global Warming website, from which many of these graphs were taken:

http://www.ncdc.noaa.gov/paleo/globalwarming/home.html

 

Open pit copper mine in Ajo, Arizona.

 

Channelized Stream in Tamasi, Hungary.

 

Arroyo likely caused by overgrazing in central New Mexico.

 

Islands forming in the sediment behind Ship Creek Dam, in Anchorage.

 

Contour Farming in SW Wisconsin.

 

The Tisza River at low water in Szeged, Hungary.

 

The Tisza River at high water in Szeged Hungary.  It’s the same bridge.

 

 

 

 

 

 

All graphs mooched off the internet, all photos by David Snyder.

 

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