The southwestern region of Hudson Bay is one of the last areas in the Hudson and James Bay lowlands region to become free of sea ice in the spring. This late breakup is due to the effects of winds and currents. By analyzing time series with three different statistical techniques, we found a statistically significant increase in the length of the ice-free season in this region from 1971 to 2003. Much of this increase was attributed to earlier breakup of the ice, which is consistent with increased spring temperatures in this region. The onset of breakup advanced by at least three days per decade over the study period.

Subpopulation growth rates and the probability of decline at current harvest levels were determined for 13 subpopulations of polar bears (Ursus maritimus) that are within or shared with Canada based on mark–recapture estimates of population numbers and vital rates, and harvest statistics using population viability analyses (PVA). Aboriginal traditional ecological knowledge (TEK) on subpopulation trend agreed with the seven stable/increasing results and one of the declining results, but disagreed with PVA status of five other declining subpopulations. The decline in the Baffin Bay subpopulation appeared to be due to over‐reporting of harvested numbers from outside Canada. The remaining four disputed subpopulations (Southern Beaufort Sea, Northern Beaufort Sea, Southern Hudson Bay, and Western Hudson Bay) were all incompletely mark–recapture (M‐R) sampled, which may have biased their survival and subpopulation estimates. Three of the four incompletely sampled subpopulations were PVA identified as nonviable (i.e., declining even with zero harvest mortality). TEK disagreement was nonrandom with respect to M‐R sampling protocols. Cluster analysis also grouped subpopulations with ambiguous demographic and harvest rate estimates separately from those with apparently reliable demographic estimates based on PVA probability of decline and unharvested subpopulation growth rate criteria. We suggest that the correspondence between TEK and scientific results can be used to improve the reliability of information on natural systems and thus improve resource management. Considering both TEK and scientific information, we suggest that the current status of Canadian polar bear subpopulations in 2013 was 12 stable/increasing and one declining (Kane Basin). We do not find support for the perspective that polar bears within or shared with Canada are currently in any sort of climate crisis. We suggest that monitoring the impacts of climate change (including sea ice decline) on polar bear subpopulations should be continued and enhanced and that adaptive management practices are warranted.

This paper critically reviews and intercompares land surface schemes (LSSs) as used in atmospheric general circulation models (AGCMs) to simulate soil moisture and its response to a warmer climate, and potential evapotranspiration approaches as used in operational soil moisture monitoring and in predicting the response of soil moisture to a warmer climate. AGCM predictions of overall soil moisture change are in broad agreement but disagree sharply in some regions. Intercomparison projects have sought to evaluate the LSSs used by AGCMs for both accuracy and consistency. These studies have found that different LSSs can produce very different simulations even when supplied with identical atmospheric forcing. As well, LSSs that produce similar surface results from present-day or control climates often diverge when forced with climatic change data. Furthermore, no single LSS has been identified that produces an adequate simulation of all of temperature, moisture, evapotranspiration and runoff. AGCM LSSs must resolve the surface energy balance (SEB) in order to compute realistic heat fluxes between with the atmospheric model. LSSs have been used with AGCMs in both on-line (fully coupled) and off-line modes. In off-line climatic change experiments, AGCM predictions of atmospheric temperature and precipitation have been used, along with model downward radiative fluxes at the surface, to drive their own uncoupled LSS. However, there are simple nonenergy-balance methods for estimating evapotranspiration that have been traditionally used in agricultural and meteorological applications. These schemes compute a potential evapotranspiration (PE) based on temperature and/or net radiation inputs, with the PE modified based on the availability of soil moisture. Operational PE approaches have also been used with AGCM data in off-line climate change experiments. The advantages of this approach are that it is simpler and requires less information, although (like the off-line SEB approach) it leaves out the simulation of feedbacks between the surface and the atmosphere. Although the SEB approach is essential for LSSs that must be coupled to AGCMs, this does not necessarily make it superior to an off-line operational PE LSS when it comes to Climatic Change (2007) Department of Geography, University of Toronto, 100 St. George Street, Toronto, ON M5S 3G3, Canada e-mail: cornwella@geog.utoronto.ca quantities such as soil moisture. The quality of current observational data is insufficient to demonstrate that either approach is better than the other. Both approaches should continue to be used and intercompared when predicting the impacts of climatic change on soil moisture.

No abstract

Ontario's 2017 Long-Term Energy Plan has identified the Wataynikaneyap Power transmission line as a priority project. The line will connect seventeen remote, off-grid, diesel-dependent First

Atmosphere–ocean general circulation models (AOGCMs) employ very different land surface schemes (LSSs) and, as a result, their predictions of land surface quantities are often difficult to compare. Some of the disagreement in quantities such as soil moisture is likely due to differences in the atmospheric component; however, previous intercomparison studies have determined that different LSSs can produce very different results even when supplied with identical atmospheric forcing. A simple off-line LSS is presented that can reproduce the soil moisture simulations of various AOGCMs, based on their modeled temperature and precipitation. The scheme makes use of the well-established Thornthwaite method for estimating potential evapotranspiration combined with a variation of the Manabe “bucket” model. The model can be tuned to reproduce the control climate soil moisture of an AOGCM by adjusting the ease with which runoff and evapotranspiration continue as the moisture level in the bucket goes down. This produces a set of parameter values that provides a good fit to each of several AOGCM control climates. In addition, the parameter values can be set to imitate the LSS from one AOGCM while the model is forced with atmospheric data from another, thus providing an estimate of the magnitude of variation caused by the differences in land surface parameterization and by differences in atmospheric forcing. In general, the authors find that differences in LSSs account for about half of the difference in soil moisture as simulated by different AOGCMs, and the differences in atmospheric forcing account for the other half of the difference. However, the LSS can be more important than differences in atmospheric forcing in some regions (such as the United States) and less important in others (such as East Africa).

No abstract