EG5506Development Geographies

Climate Change & Vulnerability

Dr Mark Cresswell

TOPICS

• Introduction to Climate Change

• Sea level Rise

• Health

• Extreme Weather

• Economic Impacts & the Stern Report

• Resources for Further Reading

Introduction

• A necessarily simplified abstraction of the real-world• Comprises the known fundamental sources of causality

within a natural system• Disregards factors of little or no importance• Uses assumptions• Uses parameterisations where factors are not known or

hard to calculate

What is a (climate change) Model?

Sea-Level Rise• The term “sea-level change” refers to a change in

the mean-sea-level for sentinel ports across the globe

• MSL is the average of high and low water marks

• Tidal surges may occur as a result of storm events – making coastal zones vulnerable but not necessarily due to a change in MSL

• Sea-level change is primarily due to thermal expansion and not “more water”

Measuring Sea-level Change

Measuring Sea-level Change• Sea-level is routinely measured from altimetric

satellites such as TOPEX-POSEIDON and JASON

• The significant wave height is determined from the return time of energy emitted from TOPEX

• As water expands in response to thermal forcing, TOPEX can be used to derive a proxy of SST as well as wave height

Measuring Sea-level Change

Some facts

Some facts• Global mean sea-level has risen by about 0.1-

0.2mm a year over the past 3000 years and by about 1-2mm a year since 1900 with a central value of 1.5mm per year

• It is believed (IPCC) that sea-level will rise by 0.09-0.88 metre between now and 2100

• Higher MSL will increase the frequency of existing extreme levels associated with storm waves and surges.

Some facts• Sea-level will tend to increase in association with

a warmer climate as a result of:

– Thermal expansion of seawater– Melting of small mountain glaciers and ice caps– Melting of the Greenland ice cap– Changes in the mass balance of the Antarctic ice cap

Some facts• As seawater warms, its density decreases – thus

a given mass of ocean water will occupy a greater volume as the ocean warms – thereby tending to increase the average sea level

• A globally uniform ocean warming by 3ºC would cause a sea-level rise of about 2.4 m

• Complete melting of all mountain glaciers and ice caps is estimated to raise sea level by some 50± 10 cm (Harvey 2000 after Warrick et al. 1996)

Some facts• Greenland is of particular concern because of its

large ice mass – enough to raise sea-level by about 7.4 m if it were to melt

• A regional warming of about 6ºC would be sufficient to provoke the eventual melting of the entire ice mass (Letréguilly et al. 1991)

• Some models show that increased temperatures lead to enhanced snowfall over both Greenland and Antarctic ice sheets – however Greenland ice cores show a reverse relationship

Human Health• Many countries are vulnerable to diseases directly

influenced by the weather

• Vector-borne diseases (like malaria)

• Respiratory illnesses (like meningitis)

• Water-borne diseases (like cholera)

• Stress illnesses (heat-stroke or hypothermia)

• Illnesses caused by “mechanical” effects of extreme weather events

Some Terminology• Mortality refers to deaths

• Morbidity refers to cases of disease who subsequently recover – but nevertheless present the symptoms of a disease

• A DALY is a Disability Adjusted Life Year and can be used to measure the economic impact of disease on the human population and for countries as a whole

Vector-Borne Diseases• Malaria is an example of a well known tropical

vector-borne disease

• Any agent of transmission of a bacterium, virus or pathogen is a vector

• Diseases transmitted by insects are known as vector-borne

• Malaria is caused by a parasite of the genus Plasmodium

• The parasite enters the human host after biting from a female anopheline mosquito

Respiratory Diseases• Just as vector-borne diseases such as malaria are

highly dependent on the weather, so too are respiratory illnesses such pneumonia and bacterial (CSM) meningitis

• Dry air may desiccate the upper respiratory tract (nasopharyngeal tract or NPT)

• Since air entering lungs must have 43 gm-3 of absolute humidity and shortfall must be supplied by the NPT

Impacts• The following changes to our climate will make the

prevalence of diseases such as malaria, meningitis and cholera more acute:

Enhanced precipitation in wet seasonWarmer temperatures in upland areas as temperatures riseDrier air – with very low absolute humidities in dry seasonChanges in vegetation patternsFloods in lowland areasMigration of refugees as a result of extreme weather

Impacts

Future Impacts• In the 2080s it is estimated that some 290 million

additional people worldwide will be exposed to malaria – due to climate change (McMichael et al, 2003)

• In the 2080s about 9 billion people (~80% of world pop) would live in areas potentially able to support malaria

Extreme Weather• Extreme weather may be regarded as an

anomalously high magnitude weather event leading to deleterious effects upon natural or human systems

• Extreme weather events are a potential response to climate change

• These events, when they occur over land, will often lead to damage to crops and buildings or loss of life and economic hardship

Storm Events• Of all the extreme weather events – storm events

cause greatest loss of life and damage to property

• Hurricanes – centres of intense low pressure that feed of heat and moisture over warm seas and land

• Tropical cyclones – primarily the result of above normal SSTs

• Intense hailstorms and associated high winds and rainfall

Storm Events

Fires• During periods of prolonged drought natural

vegetation will begin to die back and dry

• Environments of this type will be highly susceptible to either accidental or naturally occurring fire events

• Some ecosystems rely upon fire events to allow seeds to germinate and release nutrients into the soil

• Climate change may enhance both the magnitude and frequency of fire events

Fires

Floods and Drought• Floods may be caused by excessive rainfall or

changes to the natural hydrology leading to saturation of soils

• Apart from damage to property, crops and loss of life, flood events may damage the landscape – making it more vulnerable to wind erosion

• Floods will become more common in areas where climate change generates enhanced precipitation

Floods and Drought• Drought is caused both by diminished precipitation

due to climate change or human activities

• Droughts can make environments more vulnerable – affecting wind erosion, soil moisture, crop/food security and human health

• Prolonged droughts may lead to a higher incidence of fires

Floods and Drought

Societal Impacts

Amount of evidence (observations, model output and theory)

Leve

l of

agre

emen

t/co

nsen

sus

LOW

HIGH

HIGH

Established but incomplete•Increased vulnerability of infrastructure to urban flooding and landslides•Tropical cyclones more destructive•Fire danger to urban/rural fringe increased•Sea-level rise increases cost/vulnerability•Water supplies more vulnerable

Well-Established•Sea-level rise increases cost/vulnerability of coastal infrastructure•Energy demand sensitive; parts of energy supply vulnerable•Local capacity critical to successful adaptation•Infrastructure in permafrost regions vulnerable

Speculative•Fire damage to key resources increased•More hail and windstorm damage

Competing Explanations•Agroindustry and fisheries vulnerable•Heat-waves more serious for human health•Heat island effects increase summer energy demand and reduce winter energy demand•Increased air and water quality problems

From: IPCC 2001 – Impacts, adaptation and vulnerability

“Climate change poses a real threat to the developing world.

Unchecked it will become a major obstacle to continued poverty

reduction”

“Climate change poses a real threat to the developing world.

Unchecked it will become a major obstacle to continued poverty

reduction”

The Stern Review (2007)The economics of climate change (page 104)

“Developing countries are especially vulnerable to

climate change because of their geographic exposure, low incomes and greater

reliance on climate sensitive sectors such as agriculture”

“Developing countries are especially vulnerable to

climate change because of their geographic exposure, low incomes and greater

reliance on climate sensitive sectors such as agriculture”

The Stern Review (2007)The economics of climate change (page 104)

“Severe deterioration in the local climate could lead, in some parts of the developing world, to

mass migration and conflict, especially as another 2-3 billion people are added to the

developing world’s population in the next few decades”

“Severe deterioration in the local climate could lead, in some parts of the developing world, to

mass migration and conflict, especially as another 2-3 billion people are added to the

developing world’s population in the next few decades”

The Stern Review (2007)The economics of climate change (page 105)

“Little can now be done to change the likely adverse effects that some developing

countries will face in the next few decades, and so some adaptation will be essential.

Strong and early mitigation is the only way to avoid some of the more severe impacts that

could occur in the second half of this century”

“Little can now be done to change the likely adverse effects that some developing

countries will face in the next few decades, and so some adaptation will be essential.

Strong and early mitigation is the only way to avoid some of the more severe impacts that

could occur in the second half of this century”

Reading

• UKMO: http://www.meto.gov.uk• ECMWF: http://www.ecmwf.int• IPCC: http://www.ipcc.ch• Stern Report:

http://www.hm-treasury.gov.uk/independent_reviews/stern_review_economics_climate_change/stern_review_report.cfm

• Check papers with Science Direct/Web of Knowledge and library texts