Download Climate Change

The potential effect of climate
change and global warming on
gardening and gardens
Information taken from:
An on-line Future Learn course
2014 IPCC report
RHS website
Lyn Beazley
Key principles of climate change:
Blanket earth
Climate and weather
Climate looks at how the weather changes over
a long period of time, typically around 30 years
Weather is the elements we see daily such as
temperature, rain and wind.
These can change hour by hour and day by day
The climate system, feedbacks, cycles
and self-regulation
Climate can be conceptualised as a system.
It's a system that self-regulates thanks to a
mixture of positive and negative feedback.
They link together the different components of
the climate system.
Past climate change
Earth has self-regulated for the past 4 ½
billion years by the process of chemical
weathering.
Past climate change
Carbon dioxide and rainwater forms a weak acid,
carbonic acid, that dissolves silicate rocks
The carbon in the form of bicarbonate ions washes
into the ocean, where it is used by many organisms
to form their shells, which are then deposited on
the ocean bed to form carbonate rocks
So, carbon dioxide from the atmosphere is
transferred through the hydrosphere (oceans) to be
stored in the lithosphere (surface of the earth’s
crust)
Recent past climate change
The last 2 million years is called the quaternary period
which has seen some really big climate changes.
How is climate change affected by natural factors?
Over the last 2.6 million years, the climate has been
affected by a range of types of forcing factors (eg a more
active sun during the medieval period; global volcanic
activity)
Evidence of changes found in tree rings and ice cores
Recent past climate changes
Predictable changes:
Earth’s orbit round the sun.
Unpredictable changes
Solar variability - variations in the amount of
energy that the sun puts out.
Global volcanic activity
Recent past climate changes
Temperature histories from paleoclimate data (green line) compared to the
history based on modern instruments (blue line) suggest that global
temperature is warmer now than it has been in the past 1,000 years, and
possibly longer. (Graph adapted from Mann et al., 2008.)
Temperatures continue to rise
Each of the past 3 decades has been successively warmer than
the preceding decades since 1850
Year
Globally averaged combined land and ocean surface
temperatures
AR5 WGI SPM
Current situation
170 years of data shows:
• Significant temperature rise over 20th century up to
the present day. Pattern for increasing ocean
temperatures is similar.
• Since 1880, there's been a steady rise in sea levels.
• Part of the world where temperature rises have been
their highest is the polar arctic region.
Our changing carbon cycle
Oceans absorb most of the heat
– More than 90% of the
energy accumulating in
the climate system
between 1971 and 2010
has accumulated in the
ocean
– Land temperatures
remain at historic highs
while ocean
temperatures continue to
climb
AR5 SYR
Our changing carbon cycle
The graph shows recent monthly mean carbon dioxide measured at
Mauna Loa Observatory, Hawaii.
Future projections
• Climate projections are made with climate
models, which, like weather forecast models,
break up the world into a number of boxes.
• They try to simulate how the temperature,
humidity, and wind in the atmosphere, and
how the temperature salinity and ocean
currents in the ocean vary through time
Future projections
Climate models tested to see if they can
reproduce the observed past.
They include aspects such as natural factors, eg
sun’s output; volcanic activity
When the natural factors are added, it’s found
that the models can reproduce aspects of the
climate, but only until about 1970.
Future projections
But when the human factors are added to the
calculations, particularly the increasing carbon
dioxide that’s been associated with burning
fossil fuels and deforestation, models reproduce
the observed warming extremely well.
Future projections
Intergovernmental Panel on Climate Change
(IPCC) has made quite definitive statements
about the causes of global warming.
They are able to say that there is a 95% chance
that the global warming we've seen today is due
to man-made greenhouse gases, and that is
despite the uncertainties we have in climate
models and in observations.
How much more will earth warm?
Model simulations by the IPCC estimate that Earth
will warm between two and six degrees Celsius over
the next century, depending on how fast carbon
dioxide emissions grow.
Scenarios that assume that people will burn more
and more fossil fuel provide the estimates in the
top end of the temperature range, while scenarios
that assume that greenhouse gas emissions will
grow slowly give lower temperature predictions.
How much more will earth warm?
The orange line provides an estimate of global temperatures if greenhouse
gases stayed at year 2000 levels. (©2007 IPCC WG1 AR-4.)
Projected climate changes
Continued emissions of greenhouse gases will cause further
warming and changes in the climate system
Oceans will continue to warm
during the 21st century
Global mean sea level will
continue to rise during the
21st century
It is very likely that the Arctic sea
ice cover will continue to shrink
and thin as global mean surface
temperature rises
AR5 WGI SPM
Future projections
IPCC’s full report can be found at:
• http://www.ipcc.ch/report/ar5/wg1/#.Updejc
QRB8E
Impacts on human systems
Human health and the built environment
• Urban heat islands
• Heat wave
• Body heat
Impacts – urban heat islands
Land surface temperatures in cities, particularly densely-developed cities,
tend to be elevated in comparison to surrounding areas -- a phenomenon
called an urban heat island. Credit: NASA
Impacts –Paris 2003
Impacts on human systems
• More links on urban heat islands
http://www.nasa.gov/topics/earth/features/h
eat-island-sprawl.html
• http://earthobservatory.nasa.gov/IOTD/view.ph
p?id=36227
Food security
Climate change and food security
40% of global agricultural land produces just
four types of crops:
• Rice
• Wheat
• Maize
• Potatoes
Food security
Since 1960s
Green Revolution
– Monocultures
•
•
•
•
•
fertilisers
herbicides
pesticides
fungicides
farm mechanisation
Food and plant security
Security of food supplies/plants at risk:
water (excess or droughts)
pests and diseases
weeds
fungi (moving over 7 kilometres per year
towards the poles in a warming world)
Food security
Some UK figures for 2009:
• we import 30% of our food
• our food wastage was 4.1M tonnes of food
nationally
• 60% of nitrates, 25% of phosphorus and 70%
of sediments polluting water bodies come
from farms
Food security
The global food security programme
• http://www.foodsecurity.ac.uk/index.html
Mitigation points
More efficient use of energy
Greater use of low-carbon and no-carbon energy
• Many of these technologies exist today
Improved carbon sinks
• Reduced deforestation and improved forest management
and planting of new forests
• Bio-energy with carbon capture and storage
Lifestyle and behavioural changes
Global weather predictions
More extreme weather events:
– More frequent wildfires
– Longer periods of droughts
– Increase in number, duration and intensity of
tropical storms (warm air holds more water)
– Increase in ‘extreme’ weather events
Local predictions
•
•
•
•
Floods
Droughts
Increased rain in winter/flash floods
Warmer, wetter winters (for each 1 degree C
rising of temperature = 100 miles move south.
Current rise from 1880 is 0.85 degrees C)
• Longer, dryer summers (Spring now 11 days
earlier compared to 30 years ago)
RHS advice
Might be opportunity to grow exotic fruits and
sub-tropical plants
BUT
Increased winter rainfall will make it difficult for
Mediterranean species which dislike water
logging
Sharp frosts still likely
RHS advice
• Warmer temperatures can bring new pests
and diseases:
lily beetles, rosemary beetle, berberis
sawfly, red spider mite, new vine weevil
species
• Fungal diseases thrive with wet winter
conditions
RHS advice
What are the endangered plants?
Those which require fertile, moisture-retentive
soil, such as:
delphiniums and lupins
Spring displays of bulbs and tuberous
plants which will be susceptible to problems
with wet winters
RHS advice
CO2 is processed by plants through
photosynthesis.
With increased CO2 in the atmosphere, plants
and especially trees can grow faster and
stronger
Planning for the future
• Plant for the future, using trees, shrubs and
hedges that are drought-tolerant
• Green spaces will be vital to counteract the
urban heat island effect
• Plant windbreaks to protect gardens from
stormier weather
Planning for the future
• Prepare soil thoroughly to maximise drainage,
adding organic matter, gravel or grit
• If planning for a new garden, allow for
irrigation
• Allow for plants that will offer shade in the
summer
Planning for the future
Set up water butts to conserve water
• Drinking water will be in increasingly short
supply
• Rainwater or grey water systems may become
the norm
• Blue amenity space will play an increasingly
important role
Planning for the future
• Create wildflower gardens with ponds and
water features for animals/birds during hotter,
drier, summers
• Don’t plant for the long term in flood areas
• If gardening on slopes, don’t clear too much of
the existing garden as this will create
problems with erosion
• Choose plants carefully and work with the
gardening environment
Planning for the future
RHS
https:www.rhs.org.uk/Advice/profile?piD=712
Planning for the future
Trees, consider:
Drought impact (limb drop)
Water logging (subsidence)
In warmer, wetter winters, root pathogens are
more active and roots become more seriously
damaged
Planning for the future
Use of Mediterranean plants and shrubs will
alter the character of gardens. May suffer from
unseasonable frosts.
Biodiversity affected:
insects and pollination
food chain (birds, insects etc)
The choices we make will create
different outcomes
IPCC
With substantial
mitigation
Without
additional
mitigation
Change in average surface temperature (1986–2005 to 2081–2100)
Anthropocene - the human epoch future
P.S.
The Guardian newspaper is currently publishing
a series of articles on Climate Change.
See
http://www.theguardian.com/environment/clim
ate-change
Events in Ambridge
Followers of The Archers will know the problems
currently facing Ambridge after unprecedented
flooding when the Am burst its banks.
http://www.bbc.co.uk/programmes/articles/4gnZ0
YZDdJW2NHHZ1vYz00y/uk-weather-warningborsetshire
Carbon footprint
You can check out your own carbon footprint
See
• http://www.energysavingtrust.org.uk/domestic/
• http://carboncalculator.direct.gov.uk/index.html