Climate of Alaska: Past, Present and Future

Transcription

1 Climate of Alaska: Past, Present and Future Pond shrinkage in Alaska's Yukon Flats National Wildlife Refuge, Source: USGCRP (2009) Uma S. Bhatt, John Walsh for many of today s slides Dept. of Atmospheric Sciences, U. Alaska Fairbanks OLLI Class #4 Fairbanks, Alaska, Tuesday April 29, 2014

2 Reconstruction of 2000 years of summer Arctic temperatures north of 60N [Kaufman et al Science]

3 Proxy Record Locations Matched Proxy and climate observations from present [Kaufman et al Science]

4 Climate Proxy from Alaska last 10,000 years Lake core sediments in the Brooks Range Proxy for Precipitation minus Evaporation (moisture) and Temperature Proxy is at 100 year resolution [Anderson et al Quaternary Research]

5 Climate Proxy from Alaska last 10,000 years [Anderson et al Quaternary Research]

6 Tree Ring Sites Across the Arctic [Lloyd and Bunn 2007 Env. Res. Lett]

7 Recent Increase of Browning, Decline of Greening of Boreal Forest [Lloyd and Bunn 2007 Env. Res. Lett]

8 Air Temperature Warming Trend (GISS temperatures) Nov-April May-October Calculate your own trends:

9 Alaska Temperature Trends [Bieniek et al Journal of Climate]

10 Alaska Precipitation Trends [Bieniek et al Journal of Climate]

11 Pacific Decadal Oscillation: PDO EOF1 of North Pacific SST (poleward of 20N) with trend removed Reference: Mantua, N.J. and S.R. Hare, Y. Zhang, J.M. Wallace, and R.C. Francis 1997: A Pacific interdecadal climate oscillation with impacts on salmon production. Bulletin of the American Meteorological Society, 78, pp

12 PDO and Alaska Climate The PDO can explain much of the winter temperature variability in Alaska [Papineau, 2001] 12

13 Temperature in Alaska tied to PDO 13

14 Change in winter surface air temperature, observed vs. 15-model average J.E. Walsh

15 J.E. Walsh individual models Winter temperature changes, model composite

16 Projected changes of temperature: J.E. Walsh

17 How will the Alaska change hydrologically? [from L. Hinzman] J.E. Walsh

18 Precipitation increase over Arctic land areas: about 5% since 1950, mainly in summer, not statistically significant [SWIPA, 2011; from B. Rudolf, GPCC] J.E. Walsh

19 Annual river discharge to Arctic Ocean From NOAA Arctic Report Card 2011 [updated from Peterson et al., 2002, Science] J.E. Walsh

20 Changes in the atmospheric circulation play a leading role in driving increase of river discharge into Arctic Ocean In climatology, atmospheric moisture transport convergence into the Arctic river basins accurately capture gauged river discharges into the Arctic Ocean Record high atmospheric moisture transport into the river basins occurred in 2006 Record high river discharges into the Arctic Ocean occurred in 2007 J.E. Walsh Zhang et al., Nature Climate Change, 2013

21 Projected precipitation changes by season, minus [U.S. National Climate Assessment, 2013] J.E. Walsh

22 Sea ice retreats & warming in 21st Cent Winter 2010s Winter 2050s Winter 2090s Temperatures Summer 2010s Summer 2050s Summer 2090s J. Zhang et al.

23 Reduced winds over Alaska, increases over Arctic by end of 21st century Winter 2010s Winter 2050s Winter 2090s Winds Summer 2010s Summer 2050s Summer 2090s J. Zhang et al.

24 % change in precipitation falling in heaviest 1% of events, [U.S. National Climate Assessment, 2013] J.E. Walsh

25 Projected increase of frequency heavy precipitation events (presently once in 20-year events): minus [U.S. National Climate Assessment, 2013] J.E. Walsh

26 1-meter soil temperatures: reds = areas above freezing [from S. Marchenko, GI Permafrost Laboratory] J.E. Walsh

27 Drying of Arctic lakes [from L. Hinzman et al.] Yoshikawa and Hinzman 2003 in Permafrost Periglac. Process Council Alaska

28 Projected changes in Palmer Drought Severity Index by 2100 (from Wehner et al., 2011) J.E. Walsh

29 [from G. Juday, UAF]

30 MaxNDVI trend for Alaska

31 Future fire scenarios for Interior Alaska (from S. Rupp) J.E. Walsh

32 Conclusions Alaska has warmed but not in a simple manner. Alaska represents a complex location climatologically, impacted by various circulations. Climate research results are not always easy to explain in a simple way. We usually add many caveats!! Conclusions based on the preponderance of evidence suggest humans have impacted the climate. Controversy arises as people translate the science into policy change?