HomeMy WebLinkAbout191029_Important_Climate_Trends_Projections_MN's_Water_SectorMinnesota’s Changing Hydro-Climatology
Kenny Blumenfeld | Sr. Climatologist, Minnesota DNR
Flooding in Rushford, MN, Aug 2007. Courtesy MN DNR Floodplain Program
Items to bear in mind
1. Our climate story differs from other parts of US & world
2. Observations & Projections are different
3. We can (and do have)Variability and Trends
simultaneously – they do not disprove each other!
4. Seek more info and refresh frequently!
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Minnesota’s pronounced OBSERVED trends
1. Minnesota is becoming wetter and warmer
•Major shift observed, projected to continue
2. Lowest temperatures are increasing fastest
•Rapid loss in cold extremes, projected to continue
3. Extreme precipitation increasing
•More and larger “big” events, projected to continue
These important hazards affect us but
are not “worsening”…YET
1. Hot days, warm nights, heat waves not yet increasing
•But PROJECTIONS indicate future increases likely
2. Drought
•Future increases possible
3. Tornadoes, severe convective storms
•Future unclear; scientific uncertainty
MN Getting Warmer and Wetter
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35 36 37 38 39 40 41 42 43 44 45 46Annual Precipitation (in.)Annual Temperature (F)
Minnesota Average Temperature and Precipitation
1895-1986
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20
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35 36 37 38 39 40 41 42 43 44 45 46Annual Precipitation (in.)Annual Temperature (F)
Minnesota Average Temperature and Precipitation
1987-2018
1895-1986
2016
8/1/2019 Courtesy B. Gosack, MN DNR WHAF program 8
A new precipitation regime?
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12
17
22
27
32
37
42
(Precip. Inches)Precipitation, Lamberton (Cottonwood River Watershed)
Lambtn, Jul-Jun, 62-82
Lambtn, Jul-Jun, 83-2018
•mean precip diff =
+3.48 inches annually
•Precip diff per square
mile =8.08 million ft3 p
(60 mil gallons) per
year
Much of MN Currently experiencing wettest
decade on record
8/1/2019 10
25.39
29.33
27.15
24.71
23.14
27.95
25.88
27.73
26.79 27.27
30.89
28.82
31.35
20
22
24
26
28
30
32
Precipitation (inches)Average Annual Precipitation by Decade,
MN River Area
https://arcgis.dnr.state.mn.us/ewr/climatetrends/#
0
25
50
75
100
125
150
175
200
225
250
275
300
325
19161919192219251928193119341937194019431946194919521955195819611964196719701973197619791982198519881991199419972000200320062009201220152018Census of 1-inch precip days by year at 39 long-term stations
More 1” precip events
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2” and 3” precip events increasing too
0
10
20
30
40
50
60
70
80
191619221928193419401946195219581964197019761982198819942000200620122018Census of 2-inch precip days
by year
at 39 long-term stations
0
5
10
15
20
25
30
191619221928193419401946195219581964197019761982198819942000200620122018Census of 3-inch precip days
by year at 39 long-term
stations
Even 4-inchers increasing
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0
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6
8
10
12
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19161919192219251928193119341937194019431946194919521955195819611964196719701973197619791982198519881991199419972000200320062009201220152018Census of 4-inch precip days by year at 39 long-term stations
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19161920192419281932193619401944194819521956196019641968197219761980198419881992199620002004200820122016Max Rainfall size (inches)39-station max rainfall by year
Dry Period
Heaviest rain in state: most years same as always
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19161920192419281932193619401944194819521956196019641968197219761980198419881992199620002004200820122016Max Rainfall size (inches)40-station max rainfall by year
But some years now extraordinary
Dry Period
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5
6
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8
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19161920192419281932193619401944194819521956196019641968197219761980198419881992199620002004200820122016Max Rainfall size (inches)40-station max rainfall by year
Heaviest rain in state often larger, more variable
Before
Source MPR
After
Source MPR
Before
Source MPR
After
Source MPR
Projections: Continued increase in “upper
2 percentile” rainfall
Source: 2014 National Climate Assessment, Midwest Chapter
Winter warming WAY faster than summer
Season Temperature
Metric
Avg. change
per decade
since 1895
Avg. change
per decade
since 1970
Winter
(Dec - Feb)
Seasonal Avg.+ 0.40°F + 1.11°F
Summer
(Jun - Aug)
Seasonal Avg.+ 0.13°F + 0.12°F
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-8
-4
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1896190619161926193619461956196619761986199620062016Temperature (F)Season Beginning
Minnesota Average Winter Minimum
Temperatures 1896-2019
Avg Min Temp 7-yr moving avg 1896-2019 Trend: +0.49 F/decade
More freeze-free days and longer growing
seasons
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1910s1920s1930s1940s1950s1960s1970s1980s1990s2000s2010s Annual above-freezing days# Days between spring and fall freezesFreeze-Free Characteristics at Milan, MN
Average number of above freezing days per year (right axis)
Days between last freeze of spring and first freeze of fall (left axis)
-42
-39
-36
-33
-30
-27
-24
-21
-18
-15
-12
-9
-6
-3
0
Degrees FLowest Lows of Winter, Milan (MN), 1895-2018
Avg of 15 coldest
10-yr avg (15 coldest)
Coldest of winter
10-yr average
(coldest)
0
1
2
3
4
5
6
Daily Average T Degrees Below 10F 1959-1978
Length and Magnitude of 10 F Temperature Season, Duluth MN
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Daily Average T Degrees Below 10F 1959-1978
1979-1998
Length and Magnitude of 10 F Temperature Season, Duluth MN
0
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6
Daily Average T Degrees Below 10F 1959-1978
1979-1998
1999-2018
Length and Magnitude of 10 F Temperature Season, Duluth MN
Lake ice season decreasing
•Long-term state-avg
decline is 1.8 days
per decade
•Decline from 1987-
2017 is -4.2 days
per
•(Source DNR
internal analyses)
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1895190519151925193519451955196519751985199520052015Temperature (F)Year
Minnesota Average Summer Maximum
Temperatures 1895–2018
Avg Max Temp 7-yr moving avg
Heat Extremes
Extreme heat not increasing--yet However, additional days above 95 F projected by mid-century
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1895190519151925193519451955196519751985199520052015PDSI Value Year
Minnesota Palmer Drought Severity Index,
1895-2017: no drought increase
Wet years Dry years
Additional consecutive dry days projected by
mid-century, though no “smoking gun”
Source: 2014 National Climate Assessment, Midwest Chapter
In Summary
1. Minnesota has gotten much wetter and warmer, and is
projected to continue doing so.
2. Increased wetness has been driven in part by more frequent
and larger heavy rains, with further increases expected.
3. The coldest conditions have eroded the fastest.
4. Hot weather has not “worsened,” but erosion of winter cold
will set us up for hotter summers in years/decades ahead
→Remember, we don’t know exactly when this will begin (2040?)
Thank You!
Kenny Blumenfeld
Kenneth.Blumenfeld@state.mn.us
651-296-4214
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