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Home / Climate / Climate Prosperity / Degrees of Change: Climate Warming and the Stakes for Canada / Degrees of Change – 5.5 Communicating uncertainty and confidence in climate change impacts in Degrees of change

Degrees of Change – 5.5 Communicating uncertainty and confidence in climate change impacts in Degrees of change

5.5 Communicating uncertainty and confidence in climate change impacts in Degrees of change

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The NRTEE’s Degrees of Change diagram is a summary of some of the more important impacts, those we know most about, are most confident about, and those expected to occur this century. Collectively, these impacts are important because they give a picture of the scope and scale of the issue for Canada. The types of impacts on it are also well researched, although some more than others. Many of the impacts are already occurring and the rest are likely to occur in Canada over this century. The diagram does not present low probability yet catastrophic impacts, although we draw attention to these in several parts of our report.

An important difference exists between our degree of confidence on the collective of climate impacts and their ability to paint a scientifically robust picture, and in certainty and confidence in each of the 60 impacts plotted on the diagram at a specific temperature range, based on the research sources available and utilized for this report.

For impacts already occurring, we can say with more confidence that the trends will continue as the globe warms and can easily envision how these trends would unfold into the future. For example, glaciers will continue to lose ice and snow until conditions are such that ice and snow no longer accumulate. Winter road seasons will continue shortening until they are not a viable transportation option and others become cost-effective, such as all-season roads.

Future impacts are by definition more uncertain, and within these future impacts, statements with numbers attached to them can be even more uncertain in terms of absolute precision, given the state of research at this time. Confidence in these forecasted impacts is a function of understanding and learning more about the direction and magnitude (how much or how little) of change; the global temperature range associated with this change; delays between global temperature change and the response of our physical environment; and conditions under which the direction of change may flip, or the speed of change may actually accelerate, upon crossing a threshold.

The following table provides additional explanation for some of the impacts in the Degrees of Change diagram where questions of uncertainty and confidence may appear

IMPACT MAGNITUDE
OF CHANGE		 SPEED
OF CHANGE		 COMPLEX
INTERACTIONS/
LAGS		 CHALLENGE
MAPPING TO
SPECIFIC GLOBAL
TEMPERATURE		 OTHER REASONS / COMMENTS
SUMMER ARCTIC SEA
ICE EXTENT HALVED		 X X   X OBSERVED SEA-ICE DECLINE
HAS TAKEN PLACE FASTER
THAN PROJECTED BY GLOBAL
CLIMATE MODELS.
SUMMER THAW DEPTHS
IN PERMAFROST TERRAIN
INCREASE 15-40% IN THE
MACKENZIE VALLEY		     X   THERE’S A LAG BETWEEN
AIR TEMPERATURE CHANGE
AND GRADUAL RESPONSE
OF THE FROZEN GROUND.
WESTERN MOUNTAIN
GLACIERS LOSE OVER
50 % OF VOLUME AND
SOME DISAPPEAR		 X     X STUDY ON WHICH THE
50% FIGURE IS BASED USES
A SMALL SUB-SET OF
HIGH-LATITUDE GLACIERS,
NOT ALL FROM CANADA.
GLOBAL SEA LEVEL
RISES TO 1m		   X X   EVEN AT LOW TEMPERATURE
INCREASES, SEA LEVELS WOULD
CONTINUE TO RISE BEYOND THE 21ST
CENTURY. SEA-LEVELS ARE RISING
FASTER THAN EXPECTED.
RISK OF LOSING OVER 20%
OF BOREAL FOREST AND
OVER 10% OF TUNDRA		 X   X   MAGNITUDE OF CHANGE
(% LOSSES) COMES FROM
2 STUDIES, ON BOREAL AND
TUNDRA LOSSES RESPECTIVELY.
AREA BURNED IN WESTERN
WILDFIRES INCREASES
TWO TO FOUR TIMES		 X   X   SIGNIFICANT REGIONAL
VARIABILITY, SITE
SPECIFIC CONDITIONS.
FREQUENCY OF PRAIRIE
DROUGHT DOUBLES		 X     X  
RISK OF DESERTIFICATION
IN PRAIRIES
INCREASED 50%		 X       LIMITED NUMBER
OF STUDIES AVAILABLE.
HEAT WAVE DEATHS
DOUBLE IN PARTS OF
SOUTHERN CANADA		 X   X   NUMBER OF EXTREME HEAT DAYS
WILL INCREASE AND THIS WILL
LIKELY RESULT IN ADDITIONAL
DEATHS AMONG VULNERABLE
POPULATIONS, BUT DOSE RESPONSE
RELATIONSHIP INCLUDES
IMPORTANT ASSUMPTIONS ABOUT
ACCLIMATIZATION AND ADAPTATION
THAT MAY CHANGE.
EXTREME RAIN EVENTS
DOUBLE IN FREQUENCY		 X     X SIGNIFICANT REGIONAL
VARIABILITY LIKELY. LIMITED
NUMBER OF STUDIES AVAILABLE.
TIMBER GAINS FROM
ENHANCED TREE GROWTH
IN SOME NORTHERLY
LOCATIONS
     X X COMPLEX ECOSYSTEM
DYNAMICS INVOLVED. ENHANCED
PRODUCTIVITY STRONGLY
A FUNCTION OF ADEQUATE
MOISTURE AVAILABILITY, AS
WELL AS CAPACITY OF TREE
SPECIES TO THRIVE UNDER
DIFFERENT CLIMATE ENVELOPES.
ENHANCED CARBON FERTILIZATION
LIKELY SHORT-LIVED.
RANGE OF ARCTIC
CHAR RESTRICTED TO
NORTHEASTERN CANADA
     X X LIMITED NUMBER
OF STUDIES AVAILABLE.
ATLANTIC SALMON LOSES
HABITAT IN GULF OF ST.
LAWRENCE AND TAIL
OF GRAND BANK
     X X LIMITED NUMBER
OF STUDIES AVAILABLE.
INCREASED
ABUNDANCE OF ATLANTIC
COD NORTH OF 60		     X   COMPLEX INTERACTIONS
AND BASELINE VULNERABILITY
OF SPECIES MAKE PRECISE
FORECASTS CHALLENGING.
NORTHWEST
PASSAGE OPENS TO
COMMERCIAL SHIPPING
     X X TEMPERATURE AT WHICH
THE NWP IS EXPECTED TO
OPEN WITHOUT HAZARDS OF
ICE CHUNKS LEFT BEHIND IS
UNCERTAIN, AND CONTINGENT
ON COMPLEX ICE DYNAMICS NOT
FULLY UNDERSTOOD YET.
CRUISE VOYAGE POTENTIAL
INCREASES BY 50%		 X       LIMITED NUMBER
OF STUDIES AVAILABLE.
SKI SEASON REDUCED
15-25%, GOLF SEASON
INCREASED 7-20% IN PARTS
OF SOUTHEASTERN CANADA		 X       PERCENTAGE INCREASE /
DECREASE SEASON LENGTHS
EMBED SEVERAL MARKET
ASSUMPTIONS AND ASSUMPTIONS
ABOUT ADAPTATION THAT
MAY CHANGE.