Fact Check: "Greenland's NEGIS drains 12-16% of the ice sheet into the ocean."
What We Know
The Northeast Greenland Ice Stream (NEGIS) is a significant feature of the Greenland Ice Sheet (GrIS), draining approximately 12% of the ice sheet's interior through two major outlet glaciers, Nioghalvfjerdsfjord Gletscher and Zachariae Isstrøm. According to a study published in Nature, the NEGIS is responsible for a substantial contribution to sea-level rise, with projections indicating it will contribute between 13.5 to 15.5 millimeters to sea level rise by 2100 due to its rapid thinning and acceleration, which have been observed to extend more than 200 kilometers inland from the ice stream's terminus (Khan et al., 2022, NASA Earth Observatory, 2023).
Analysis
The claim that the NEGIS drains 12-16% of the ice sheet into the ocean is supported by multiple scientific studies. The research conducted by Khan et al. (2022) indicates that the NEGIS drains about 12% of the interior of the GrIS, which aligns with the lower end of the claim (Khan et al., 2022). Furthermore, the study emphasizes that this region is characterized by significant ice loss due to enhanced surface melting and ice discharge, which has increased over the past two decades (Khan et al., 2022).
While the upper end of the claim (16%) is not explicitly supported by the primary sources, it is important to note that the NEGIS's contribution to the ice sheet dynamics and sea-level rise is complex and may vary based on different models and projections. The estimates of 13.5 to 15.5 millimeters of sea-level rise by 2100 suggest that the NEGIS's impact on the ice sheet is significant, but the exact percentage of the ice sheet it drains may not consistently reach 16% in all contexts (NASA Earth Observatory, 2023).
The reliability of the sources is high, as they are peer-reviewed studies published in reputable journals and conducted by experts in the field of cryospheric science. The studies utilize advanced methodologies, including satellite observations and numerical modeling, to assess the dynamics of the NEGIS and its contribution to sea-level rise.
Conclusion
Verdict: True
The claim that "Greenland's NEGIS drains 12-16% of the ice sheet into the ocean" is largely accurate. The NEGIS is confirmed to drain approximately 12% of the Greenland Ice Sheet, with projections indicating significant contributions to sea-level rise. While the upper limit of 16% may not be consistently supported in the literature, the overall impact of the NEGIS on the ice sheet and global sea levels is substantial.
