April 1 Arlington Cafe Scientique - Changing Climate and Trends in Extreme Events

1. The Relationship Between
Weather & Climate
Dr. Emily Jones Becker
Climate Prediction Center/NCEP/NWS/NOAA and Innovim
April 1, 2014

2. Weather & Climate
Thomas Cole - The Oxbow

3. 3
Weather: current conditions
• Timescale: minutes – hours – days; changes quickly
• Storms, including hurricanes, are weather
• Weather forecasts are specific
• Can vary wildly
and still be
“normal”
• “It’s very cold
today”
• “It’s going to rain
tomorrow”
• “A hurricane is
forecast to come
ashore this
weekend”
Edward Hopper – Ground Swell

4. Climate: Long-term average
Timescales: Months – years – decades etc.
• “It’s too hot here, I’m moving to Antarctica.”
• “This area gets a lot of rain during the summer.”
• “Last winter was so warm.”
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5. What is the difference between a weather forecast
and a climate forecast?
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Weather Forecasts:
•Event, location and time specific
•How warm, how much rainfall,
probability of rain
•Maximum of ten days into future
Climate Forecasts:
•“Average of weather” for a week,
month, season, …
•Likelihood of warmer/cooler
wetter/drier than average
•Month, season, year, multi-year,
decade 
www.cpc.noaa.gov

6. Climate Change
Maldives underwater cabinet meeting, 2009

7. Climate change
Climate change is the long-term shift in the average.
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• Can take place over millions of
years, or decades
• Caused by changes in incoming
solar radiation, volcanoes,
plate tectonics, ocean
circulation, human activities
• Earth’s climate is always
changing!

8. Is there global warming?
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Sources: NOAA, NASA
•Global surface temps have increased
~ 1.5°F since the late-19th century.
•The trend is +0.23°F per decade for
the past 50 years.
•The warming has not been uniform.
Some areas have cooled slightly.
•The recent warmth has been
greatest over high latitudes.

9. What is the Greenhouse Effect?
How is it related to Climate Change?
THE NATURAL GREENHOUSE EFFECT
Heat absorption by carbon
dioxide, water vapor and other
trace gases in the atmosphere
warms the earth to ~55°F (like
a greenhouse)
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THE ENHANCED GREENHOUSE EFFECT
Human activities have increased
greenhouse gases, hence have
artificially increased Earth’s
temperature by another 1.4oF

10. Mark Stevenson – fineartamerica.com

11. How do we know human activities are the
primary cause of the current warming?
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Both natural and human
factors can lead to climate
change.
Even if people burn no fossil
fuels, we would still see
changes in Earth’s climate
due to natural forces (e.g.
solar cycles, volcanoes).
The observed warming over
the last half-century is
primarily due to human
factors. IPCC 2007

12. Has global warming stopped?

13. Has global warming stopped?

14. Effects of Global Climate Change
• Rapid change in glaciers, ice sheets,
and sea level
• Changes to the water cycle, including
droughts; desertification
• Rapid release of methane
• Marine and land animal species are
moving north
• Northern Hemisphere Spring snow
cover has decreased by about 10%
since 1966.
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Climate Change that occurs quickly (a few decades or less)
and persists for decades to millennia poses a major challenge
to humans, animals, and plants
1913
2005

15. Global Climate Change – Arctic sea ice
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16. Global Climate Change – sea-level rise
last house on Holland Island – image via baldeaglebluff/flickr

17. Global Climate Change – hardiness zones

18. Global climate change - fisheries
60% of major fisheries have shifted north
Nye et al. 2009. MEPS 393: 111-139

19. 19
Increased atmospheric carbon:
ocean acidification
Atmospheric carbon
dioxide dissolves in
ocean water and
creates carbonic
acid. Shells and
skeletons of corals
and oysters can
dissolve.
Acidification has been detected in the Chesapeake, due to
atmospheric CO2 and from other sources; the Chesapeake is
a very complex system.

20. How can we predict climate if we
can’t predict the weather?
The same way we can predict the
tide, but not the individual waves

21. Extreme Weather and Climate Events

22. Billion Dollar Weather and Climate Disasters
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• Since 1980, the U.S. has seen a total of 151 weather-related disasters each totaling
over $1 billion dollars in damage.
• Total standardized losses since 1980 of billion-dollar disasters exceeds $800 billion.
• The nation is becoming more vulnerable to extreme events.
Number of Billion Dollar Weather/Climate Disasters
1980 – August 2011
NOAA/NESDIS/NCDC
NOAA/NCDC

23. 23 Temperature Extremes

24. Temperature
Extremes
Different types of
extremes:
― Daytime max
temperature
― Nighttime min
temperature
― Average temp. for the
month
― Average temp. for the
season
― Heat waves
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Maps from NOAA NCDC

25. 25
Temperature Extremes – observed changes
In the United States, record high
temperatures are now occurring more than
twice as often as record lows
• Daily minimum
temperatures are warmer
• More unusually warm days
and nights in recent
decades.
• Increasing number of heat
waves, but 1930s still most
severe

26. Temperature Extremes – future projections
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Extreme Weather and Climate Events in a Changing Climate
• More frequent warm
days and nights, and
heat waves
• Much less frequent
cold days and cold
nights
• Decrease in days with
frost
• Hot days currently experienced once every 20 years would
occur every other year or more by the end of the century.

27. Hydrological Extremes 27

28. Precipitation Extremes – observed trends
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Observed Trends in 1-day
Very Heavy Precipitation
(1958 to 2010)
NOAA/NCDC
NOAA/NCDC

29. Extreme precip. and flooding
• Flooding can result from
rapid snowmelt, heavy
thunderstorm rain,
tropical storm remnants
• Low-lying Eastern Shore
can flood from just a full-
moon high tide
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UMCES IAN (ian.umces.edu)

30. Drought
Droughts have
increased in area
and intensity over
the last century
over much of the
world
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IPCC

31. Hydrological Extremes – future projections
• An increase in
precipitation intensity
is expected
• Heaviest precipitation
is projected to
increase strongly.
• Lightest precipitation
is projected to
decrease.
• Drought is forecast to
increase, but many
questions remain
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32. Storms
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33. But their names make them sound
so friendly…
Atlantic Hurricanes in the last
decade
Local effects:
• Isabel (2003): 6-8’ storm surge
• Ivan (2004): 32 tornadoes in MD-VA area
• Ernesto (2006): 5-10” rain, ~4’ storm surge
• Nicole (2010): 7” rain
• Irene (2011): millions without power for days
• Lee (2011): intense rainfall and flooding
• Sandy (2012), East Coast: 285 deaths,
widespread & prolonged power outages,
coastal destruction
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We haven’t detected a long-term trend in the number of hurricanes.
It’s likely we’ll see an increase in intensity of hurricanes.

34. Tornadoes
• Record month – April
2011: 751 confirmed
tornadoes in US
• However, there’s no
detectable long-term
trend in tornadoes
• Maryland has 3rd-highest
concentration of
tornadoes in US (number
per 10,000 sq miles per
year)
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35. 35
Should we really attribute every extreme event
(heat wave, flood, hurricane) to climate change?
No individual weather event can be attributed to climate change.
• Changes in the number and intensity of some events (e.g. more intense
rainfall; warmer winter nights) have strong links to climate change.
• Changes in observing systems (e.g. introduction of satellites) have complicated
attempts to document trends (e.g. hurricanes over the Atlantic).
• Damage resulting from extremes can be exacerbated by climate change (e.g.
sea-level rise and coastal flooding)

36. Current weather and climate events

37. What the heck is going on with this
winter??!?
Globally, 4th warmest January
since records began in 1880
Locally, the 12th
coldest January!

39. California drought
oThis may be the driest
year in 500 years (from
tree-ring data)
o 90% of US tomatoes,
95% of broccoli, 99% of
almonds and walnuts are
grown in CA
o20th Century overall was
wettest in last 500 years
U.S. Drought Monitor

40. Ellen O via Flickr and Capital Weather Gang