Mission Goals

Sea level is rising today at a rate of about 1 foot per century (Fig. 1), due to a combination of expanding ocean water from warming, the use of water by human populations, and the melting of small mountain glaciers and the ice sheets in Greenland and Antarctica (Fig. 2). All except water use is related to warming global temperatures caused primarily by rising levels of CO2 and other greenhouse gases emitted by humans (especially since 1950). 

Fig. 1. Global sea level rise measurements since 1860. Red curve is 
updated from Church and White, 2006. Blue curve is tide gauge 
measurements, and black curve is from satellite measurements.

Fig. 2. Causes of sea level rise today and as projected by 2090 under
IPCC RCP 4.5 (Table 13.5 in the 2013 5th Assessment Report), which is 
a very conservative estimate. Many glaciologists believe that the 
Greenland and Antarctic projections are too low. 

Greenland's contribution to sea level rise has been accelerating since 2005 (Fig. 3), due to an increase in the velocity of glaciers flowing into the ocean and a decrease in surface mass balance, with is the balance between snowfall and surface melting. Although snowfall rates have been increasing in many parts of Greenland recently, surface melting rates have been increasing even faster, causing a net decrease in the mass of the ice sheet.

Fig. 3. Published estimates of Greenland's temperature (black curve) and
contribution to sea level rise (colored rectangles) from Alley et al. (2010). 
Each rectangle represents a different published study. 
The length of each rectangle represents the time period covered in that study. 
The height of each rectangle represents the uncertainty of the sea level rise 
contribution estimate from that study.

Estimates of Greenland surface mass balance increasingly utilize climate reanalyses and high-resolution regional climate models to determine snow accumulation, surface melt and runoff/refreeze. These models show significant, and model-dependent, biases (differences from observations) along the steep edges of the Greenland Ice Sheet where the highest and most variable (in space and time) rates of accumulation and surface melt are observed. Thus, in order to improve our projections of Greenland's contribution to sea level rise in the future, we need to improve these models through validation and calibration with real data from the ice sheet, especially along the steep edges. 

To this aim, we will traverse the Western Greenland percolation zone over two field seasons in 2016 and 2017. We will develop continuous in-situ snow accumulation and firn density records using ground-based radar and shallow firn cores. The research objectives include:

  1. Determining the patterns, in time and space, of snow accumulation in Western Greenland over the past 20-40 years.
  2. Evaluating surface melt refreeze and englacial meltwater storage in the Western Greenland percolation
zone over the past 20-40 years.
  3. Quantifying the accumulation and surface melt biases of the most recent climate reanalysis models and their regional climate model counterparts.
Interactive Google My Maps (and downloadable Google Earth kmz file) showing the planned traverse route from Raven/Dye 2 (South) to Summit (North). We will be heavy hauling (purple line) all of our equipment 921 km (572 miles) with an additional 1477 km (918 miles) of radar profiling (red lines) as transects from our core sites (arrows). We also have three fuel caches that will be waiting for us at the Core 3, Core 5 and Core 7 sites. The red dots represent crevasses that we mapped before the expedition using satellite imagery.

Non-interactive map of 2017 traverse 

Non-interactive map of 2016 traverse in case the other one doesn't work...

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