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 changesSolar 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

YearGlobally averaged combined land and ocean surface

temperatures

Each of the past 3 decades has been successively warmer than the preceding decades since 1850

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 changesContinued emissions of greenhouse gases will cause further warming and changes in the climate system

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

Oceans will continue to warm during the 21st century

AR5 WGI SPM

Future projections

IPCC’s full report can be found at:

• http://www.ipcc.ch/report/ar5/wg1/#.UpdejcQRB8E

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/heat-island-sprawl.html

• http://earthobservatory.nasa.gov/IOTD/view.php?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 plantsBUTIncreased winter rainfall will make it difficult for Mediterranean species which dislike water loggingSharp 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 lupinsSpring 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 pollinationfood chain (birds, insects etc)

The choices we make will create different outcomes

IPCCWith substantial

mitigationWithout

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/climate-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/4gnZ0YZDdJW2NHHZ1vYz00y/uk-weather-warning-borsetshire

Carbon footprint

You can check out your own carbon footprint

See

• http://www.energysavingtrust.org.uk/domestic/

• http://carboncalculator.direct.gov.uk/index.html