1. Nick Rayner (Met Office Hadley Centre)
Representing the Arctic in Global Surface Temperature Time-series of Recent Climate Change
Emma Dodd
Dr Chris Merchant
Prof. Simon Tett
Nick Rayner (Met Office Hadley Centre)

2. Investigating climate change in the Arctic sea ice regions.
World satellite map Source: NASA

3. Climate Change
Global average surface temperatures have risen by 0.74°C in the past 100yrs.
From the BBC’s Frozen Planet

4. Climate Change Consistent with this, changes have been noted in:
Ice seasons and snow cover
Glacier mass and extent
Sea ice thickness and extent
Ocean temperatures
Sea level
And so on…

5. Temperature Anomalies
SAT over land SST over sea
Combined Global SAT and SST annual temperature anomalies from the IPCC AR4 report (chapter 3, Figure 3.7).

6. Climate Change in the Arctic
Annual temperature anomalies for land north of 65ºN from the IPCC AR4 report (chapter 3, Figure 3.7).
However, there is no agreed method for calculating the appropriate contribution of sea-ice regions in the Arctic to these temperature anomalies.

7. Understanding Climate Change in the Arctic is Important
More rapid warming predicted in the Arctic
Already many changes:
Rising temperatures
Melting glaciers
Changes in sea ice
Increasing precipitation
Changes in wind patterns
Shifts in vegetation
Available from:

8. But sparse in situ temperature data…
All GHCN mean temperature stations. Figure 3a from the NCDC Data Documentation
Available from

9. But sparse in situ temperature data…
All GHCN mean temperature stations. Figure 3a from the NCDC Data Documentation
Available from

10. And how should we represent areas of sea ice?
But how should sea ice regions be treated?
Should we treat sea ice areas as ocean or land?
How valid is it to interpolate and extrapolate available in situ data?
Can we use satellite derived temperatures to fill in gaps in data?
Should we exclude areas where no in situ data are available?

11. Representing areas of Sea Ice
And since there is a trend of decreasing sea ice extent, what is the impact of each choice on global or regional temperature trends?
Arctic sea ice extent for September 2011 (NSIDC, 2011).
Arctic Sea Ice Extent (NSIDC, 2012).

12. What I Aim to do:
Explore how seasonal sea ice areas should be treated in global and regional averages of surface temperature
Using various datasets (in situ, satellite, interpolated)
Quantify the uncertainties in extrapolation and interpolation of information over the Arctic
Produce an index of warming across the Arctic
Using a variety of different datasets

13. Work so far:

14. Thanks for Listening Any Questions? Pancake ice
From Nature (