Download Means, Extremes and the Changing Character of Maine`s Climate

Means, Extremes and the Changing
Character of Maine’s Climate
Bradfield Lyon
Climate Change Institute and School of Earth and Climate Sciences,
University of Maine, Orono
2016 Maine Sustainability & Water Conference
Augusta Civic Center, Augusta, Maine
29 March, 2016
Outline
• Changes in the mean can affect changes in extremes:
 Temperature
 Atmospheric Moisture and Precipitation
• A warmer climate increases precipitation intensity AND
the severity of drought (i.e., an enhanced hydrologic cycle)
• Impacts of extremes:
 Extreme precipitation
 Extreme temperature
 Tipping Points
• Conclusions
Means and Extremes -- Temperature
Maine’s
Climate Zones
Distribution of Monthly Temperature
Departures from Average 1981-2010
(all Maine climate zones)
Number of Months
140
120
100
80
60
40
20
0
Source: www.manomet.org
-10 -8 -6 -4 -2 0
2
4
6
8 10
Temp. Departure from Average (deg. F)
Source: climatenexus.org
Means and Extremes -- Temperature
Now consider temperature departures from an 1896-2015 average for
the two periods 1896-1955 and 1956-2015 separately…
120
1896-1955
Number of Months
100
1956-2015
80
60
40
20
0
-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12
Departure from 1896 to 2015 average (deg. F)
40
30
20
Number of Months
Compute
the differences
Divide
the number
of
between
the two
months
in each
category:
distributions…
latest
period/earlier period
2.5
18
16
2.0
14
12
1.5
10
8
1.0
6
4
0.5
2
0.0
0
10
0
A +10F departure is 16x
more frequent…
-12 -10
-8
-6
-4
-2
0
2
4
6
8
10
12
-10
-20
-30
-12 -10
-10
0 2 warm
2 4 4months
-40
-12
-8-8 cold
-6 -6months
-4 -4 -2 -2 0more
6 68
fewer
-50
Departure from 1896 to 2015 average (deg. F)
810
Means and Extremes -- Temperature
Number of Days with Maximum Temperature > 90 deg. F
1971-2000
2041-2070
Source: National Climate Assessment 2014
Means and Extremes -- Precipitation
120
100
80
60
40
20
0
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Number of Months
140
Precipitation Departure (inches)
5
0
-5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Difference:
Ratio:
Recent
Recent/Earlier
– Earlier
period
Period
Number of Months
10
-10
-15
-20
Precipitation Departure (inches)
Means and Extremes
Consider changes in 20-yr moving averages (mean & variability)
Avg.
4.5
Variability
2.5
***
1.5
2014
2004
1994
1984
1974
1964
1954
1944
1934
-0.5
1924
0.5
1914
Temperature
(all months)
Temperature (deg. F)
3.5
-1.5
-2.5
Avg.
Variability
**
1.5
1.0
0.5
-0.5
2014
2004
1994
1984
1974
1964
1954
1944
1934
1924
0.0
***
1914
Precipitation
(all months)
Precipitation (inches)
2.0
Atmospheric Water Vapor
Saturation Vapor Pressure (hPa)
A Warmer Atmosphere can Hold More Moisture
Atmospheric
Water Vapor
Increases ~7% for every
1°C of warming
Trends 1973-1995
Weather Balloons
Reanalysis (same locations)
Temp. (deg. C)
Trenberth et al. (2005)
Atmospheric Water Vapor
Low-Level temperature and Water Vapor Content over Maine 1979-2014
2.02.0
Temp. Departure (deg. C)
Water Content Departure (mm)
1.51.5
1.01.0
0.50.5
0.00.0
1979
1979
-0.5
-0.5
-1.0
-1.0
-1.5
-1.5
-2.0
-2.0
1984
1984
1989
1989
1994
1994
1999
1999
2004
2004
2009
2009
2014
Atmospheric Water Vapor -- Reminder
Rainfall (inches)
29 October, 2015
Water vapor may travel large distances
before arriving in Maine…
Atmospheric Water Vapor -- Conceptual
More water vapor = Heavier Precipitation
Atmospheric Water Vapor -- Models
• The
In climate
amount
models,
of energy
this required
results into
fewer
evaporate
light precipitation
water from the
days
earth’
and more
surface
heavy
is limited:
and extreme
In a warmer
precipitation
climate
days...
it takes more
time to “recharge” the atmospheric water vapor content
to its new, higher value…
Figure Source: US Climate Change Science Program
Atmospheric Water Vapor -- Observations
Observed trends in
precipitation over the
past 50 years show an
increase in the amount
of precipitation occurring
during extreme events…
Shaleen Jain et al.
Source: National Climate Assessment 2014
Drought
“dry”
“wet”
Maine State Average of the Palmer Drought Severity Index 1895-2015
“Severe Drought”
A warming climate exacerbates drought… Additional atmospheric heating further
drys the surface, increases temperature.
Greater heating from
greenhouse gases
Current Climate
Future Climate
Drought -- What Lurks Below the Surface
Drought Conditions in Maine, 1999-2002: A Historical Perspective, USGS 2004
*
*
Source: USGS
http://pubs.usgs.gov/fs/2004/3021/
Changing Character of Maine’s Climate
Source: Maine’s Climate Future 2009, University of Maine
Changing Character of Maine’s Climate
Climatological Snowfall
Change in SWE/Total Prcp Projected Change in Snow
Maine’s Climate Future
Source: Portland Press Herald
Huntington et al. 2004
Journal of Climate
Impacts -- Extreme Rainfall
Urban Flooding
Water Quality (DOC)
Flooding in Portland, ME Aug 13, 2014
Photo Source: earthsky.org
Balch et al., 2016
Erosion
Fecal Coliform
Bacteria
gulfofmaine.org
From Tilburg et al. 2015
Impacts – Temperature Tipping Points
Aug. 11, 2015
Water intake > 75F
Millstone Nuclear power station in CT
Water Intake too Warm…
www.centralmaine.com
Boston Globe
August 11, 2015
Boston Globe
... A power line failure knocked several power substations out
August 9, 2013
of commission, leaving 13,000 Central Maine Power customers without electricity…
During the height of last month’s heat wave, millions of
people in northern New England were urged to conserve
energy… at the same time, at least two wind farms in Maine
and Vermont were ordered to reduce the amount of
electricity they provided. …weakness in the rural system
linking wind turbines to the power grid mean wind
companies are routinely taken offline or have their output
reduced.
Conclusions
• Changes in the mean may accompany changes in the full
distribution of a climate variable: changes the probability of
extremes.
• A warmer atmosphere can hold more water vapor (7%/deg. C)
 Increased rainfall
 Increased extreme rainfall
• A warming climate is associated with an enhanced hydrologic
cycle: heavier precipitation and exacerbated drought
• Impacts are numerous and varied: erosion, water quality,
flooding, heat stress,…
• Tipping points: Non-extremes can have substantial impacts
•
(e.g., power generation, dissolved O2, SLR,...)
Supplemental Slides
Source: IPCC
Water Vapor Trends (SSMI)
IPCC Fourth Assessment Report
http://waterwatch.usgs.gov/
Water Vapor
Maximum Solubility
Soden et al. 2005
Climate models are able to capture this
effect…
How is Precipitation Changing in Maine by Season?
Look at 20-yr changes in the average & variability
Mar-May
Sep-Nov
*
Jun-Aug
*
***
Dec-Feb
*