State of Climate Adaptation
City of Nelson
APPENDIX – CLIMATE DATA

July 2020

Photo: Jesse Schpakowski

Contents
About the Climate Data..................................................................................................................................................... 2
Technical Information ....................................................................................................................................................... 2
Figure A-1: Historic and projected average annual temperature....................................................................................... 3
Figure A-2: Historic and projected average spring temperature........................................................................................ 3
Figure A-3: Historic and projected average summer temperature .................................................................................... 3
Figure A-4: Historic and projected average fall temperature............................................................................................. 4
Figure A-5: Historic and projected average winter temperature ....................................................................................... 4
Figure A-6: Historic and projected annual number of days over 30 o C.............................................................................. 4
Figure A-7: Historic and projected number of summer days over 30o C .......................................................................... 5
Figure A-8: Historic and projected annual number of days with maximum temperature over 90th percentile in the
1961-1990 period................................................................................................................................................................ 5
Figure A-9: Historic and projected number of summer days with maximum temperature over 90th percentile in the
961-1990 period.................................................................................................................................................................. 5
Figure A-10: Historic and projected annual number of daily freeze-thaw cycles .............................................................. 6
Figure A-11: Historic and projected number of daily freeze-thaw cycles in winter ........................................................... 6
Figure A-12: Historic and projected growing season length .............................................................................................. 6
Figure A-13: Historic and projected growing degree days ................................................................................................. 7
Figure A-14: Historic and projected total annual precipitation.......................................................................................... 7
Figure A-15: Historic and projected total spring precipitation ........................................................................................... 7
Figure A-16: Historic and projected total summer precipitation ....................................................................................... 8
Figure A-17: Historic and projected total fall precipitation ................................................................................................ 8
Figure A-18: Historic and projected total winter precipitation .......................................................................................... 8
Figure A-19: Historic and projected maximum 1-day precipitation ................................................................................... 9
Figure A-20: Historic and projected maximum dry spell length ......................................................................................... 9
Figure A-21: Historic and projected annual precipitation above the 95th percentile in the 1961-1990 period................. 9
Figure A-22: Historic and projected number of days of precipitation above the 95th percentile in the 1961-1990 period
.......................................................................................................................................................................................... 10

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This appendix is additional climate data that supports the State of Climate Adaptation for the City of Nelson.
Please refer to the full report for more detail.

About the Climate Data

Climate data for the City of Nelson was provided by Climatic Resources Consulting, Inc. and comse from two
main modeling sources. Technical information is presented below. Climate projections for the 2050s in this
report include two scenarios: low carbon and high carbon. Climate projections for the 2050s indicate the
average for the 2041-2070 period. The low carbon scenario (RCP4.5) is considered to be optimistic and,
although insufficient to maintain global temperatures to below 2°C warming above pre-industrial temperatures,
would require significant international cooperation that exceeds current commitments of signatories to the Paris
climate agreement. 1 The high carbon scenario (RCP8.5) is also referred to as ‘business as usual’. Global
emissions are still moving along a trajectory that could lead to 3 to 5°C of global warming by the end of the
century, highlighting the significant gap between the emission reductions pledged by Paris Agreement
signatories and the reductions required to meet the 2°C global target. 2 Consequently, it is important to also
consider the high global emissions scenario (RCP8.5) in planning for climate change in the Columbia Basin
and Boundary regions. Climate trends, i.e. rates of change, are expressed in units per century, meaning the
change per 100 years.

Technical Information

Historical climate data was prepared using climate reanalysis ERA5. 3,4 Climate reanalyses combine past
observations with models to generate consistent time series of multiple climate variables. 5 They provide a
comprehensive description of the observed climate as it has evolved during recent decades, on 3D grids at
sub-daily intervals. The estimates are produced for all locations on earth, and they span a long time period that
can extend back several decades or more. Adjusted and Homogenized Canadian Climate Data (AHCCD) from
Environment Canada provides long-term (since the early 1900s) observed data. For total annual precipitation,
data from climate stations in Creston, Kaslo, Castlegar, Fauquier, Warfield and Grand Forks was referenced in
addition to ERA5 data. Climate projections are based on output from an ensemble of 12 statistically
downscaled Global Climate Model (GCM) projections 6 from the Coupled Model Intercomparison Project Phase
5 (CMIP5), 7 and downscaled using Bias Correction/Constructed Analogues with Quantile mapping recording 8
to a resolution of 10 km by 10 km.
Representative Concentration Pathways (RCPs) are numbered (e.g. RCP8.5 or RCP4.5) according to the
radiative forcing in W/m2 that will result from additional greenhouse gas emissions by the end of the century.
Modellers use RCPs to generate scenarios of future climate.

The following plots provide further insights on historic and projected climate for the City of Nelson. Seasons are
defined as follows:
•
•
•
•

Spring = March, April, May
Summer = June, July, August
Fall = September, October, November
Winter = December, January, February

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Figure A-1: Historic and
projected average annual
temperature

Figure A-2: Historic and
projected average spring
temperature

Figure A-3: Historic and
projected average summer
temperature

3

Figure A-4: Historic and
projected average fall
temperature

Figure A-5: Historic and
projected average winter
temperature

Figure A-6: Historic and
projected annual number of days
over 30 o C

4

Figure A-7: Historic and
projected number of summer
days over 30o C

Figure A-8: Historic and
projected annual number of days
with maximum temperature over
90th percentile in the 1961-1990
period

Figure A-9: Historic and
projected number of summer
days with maximum
temperature over 90th percentile
in the 961-1990 period

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Figure A-10: Historic and
projected annual number of daily
freeze-thaw cycles

Figure A-11: Historic and
projected number of daily
freeze-thaw cycles in winter

Figure A-12: Historic and
projected growing season length

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Figure A-13: Historic and
projected growing degree days

Figure A-14: Historic and
projected total annual
precipitation

Figure A-15: Historic and
projected total spring
precipitation

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Figure A-16: Historic and
projected total summer
precipitation

Figure A-17: Historic and
projected total fall precipitation

Figure A-18: Historic and
projected total winter
precipitation

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Figure A-19: Historic and
projected maximum 1-day
precipitation

Figure A-20: Historic and
projected maximum dry spell
length

Figure A-21: Historic and
projected annual precipitation
above the 95th percentile in the
1961-1990 period

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Figure A-22: Historic and
projected number of days of
precipitation above the 95th
percentile in the 1961-1990
period

United Nations Framework Convention on Climate Change. (2019). The Paris Agreement. Retrieved from
https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement

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Knutti, R., Rogelj, J., Sedláček, J. et al. (2016). A scientific critique of the two-degree climate change target. Nature Geoscience, 9,
13–18. doi:10.1038/ngeo2595
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European Centre for Mid-range Weather Forecasts (ECMWF). ERA5 data documentation. Retrieved from
https://confluence.ecmwf.int/display/CKB/ERA5+data+documentation#ERA5datadocumentation-Introduction

Copernicus Climate Change Service (C3S). (2017). ERA5: Fifth generation of ECMWF atmospheric reanalyses of the global climate.
Copernicus Climate Change Service Climate Data Store (CDS), Accessed August 2019.
https://cds.climate.copernicus.eu/cdsapp#!/home

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5

Climate Change Service. (n.d.). Climate reanalysis. Retrieved from https://climate.copernicus.eu/climate-reanalysis

Pacific Climate Impacts Consortium. (n.d.). Statistically downscaled GCM scenarios - BCCAQv2. Retrieved from
https://data.pacificclimate.org/portal/downscaled_gcms/map/
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Taylor, K.E., Stouffer, R.J., and Meehl, G.A. (2012). An overview of CMIP5 and the experiment design. Bulletin of the American
Meteorological Society, 93, 485–498. doi:10.1175/BAMS-D-11-00094.1

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Werner, A.T. and Cannon, A. J. (2016) Hydrologic extremes – an intercomparison of multiple gridded statistical downscaling
methods. Hydrololgy and Earth System Sciences, 20, 1483-1508. doi:10.5194/hess-20-1483-2016

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