© Crown copyright 2004 Debunking the myths of Climate Change Helen Young Former Lead Presenter BBC Weather Centre

© Crown copyright 2004

Debunking the myths of

Climate Change

Helen Young

Former Lead Presenter

BBC Weather Centre


CLIMATE CHANGE:- A HOT TOPIC


CLIMATE CHANGE:- IN THE MEDIA


CLIMATE CHANGE:- weather events


WEATHER and CLIMATE

Weather – instantaneous atmospheric conditions - temperature, rainfall, pressure, wind etc

Climate - the long-term signal derived from individual weather events.

‘Averaged out’ weather over a long period of time.

- Climate scientists normally use a period of 30 years


WEATHER 1990ish


WEATHER 2005ish


CLIMATE CHANGE:- A GLOBAL ISSUE


SCIENTIFIC COMMUNITIES- IPCC

Recognizing the problem of potential global climate change, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988. It is open to all members of the UN and WMO.


NATURE

The Met Office’s first Super Computer!

1981

Changes in Met Office Computing


Arrival of NEC SX-6, One of the Worlds Fastest Supercomputers

2003




Ferranti Mercury - ‘Meteor’ 3000 calculations per second

The ‘Cray twins’ 160,000 million calculations per second

The NEC SX-6 computer installed Exeter 2004, 6 times more powerful

2005, 2 million, million calculations per second


0

2

4

6

8

10

Numerical Model Accuracy

Area: North Atlantic

New modelintroduced

RM

S M

SLP

New modelintroduced

New modelintroduced

24-hr forecast

48-hr forecast

72-hr forecast


Myth 1

Our climate has always changed, this is just another natural change and nothing to do with humans.



Grape vines


Three Cranes Wharf near Blackfriars in the City


CLIMATE 1000 - 2000AD Source: IPCC 2000


How much climate change has there really been?

GLOBAL TEMPERATURES have risen by about 0.7ºC between 1861 and 2003


Tem

per

atu

re c

han

ge

ºC

1.0

0.5

0.0

-0.51850 1900 1950 2000

observed

model simulation

+

Observed and simulated change

Natural factors

observedmodel simulation

SUN

Sunlightpasses

through the atmosphere..

..and warms the earth.

..most escapes to outer spaceand cools the earth...

Infra-red radiationis given off by the earth...

…but some IR is trapped by some gases in the air, thus reducing the cooling.

THE GREENHOUSE EFFECT


The most important greenhouse gases are:-

carbon dioxidemethanenitrous oxide hydrofluorocarbons Perfluorocarbonssulphur hexafluoride. These are the gases that are covered by the Kyoto Protocol.

Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are also powerful greenhouse gases but they are being progressively phased out under the Montreal Protocol as they also damage the stratospheric ozone layer.

GREENHOUSE GASES


HUMAN ACTIVITIES HAVE CHANGED THE ATMOSPHERE


Current (2005)

CO

2 C

on

cen

trat

ion

(p

pm

v)

Projected (2100)


Myth 2

Carbon dioxide is not driving our current warming.

Carbon Dioxide only makes up a small part of the atmosphere therefore it cannot be responsible for this

current Global Warming.


EARTH’S ORBIT

Orbit for Northern Hemisphere


Current (2007)

CO

2 C

on

cen

trat

ion

(p

pm

v)

Projected levels of atmospheric CO2 during the next 100 years would be higher than at anytime in the last 440,000 yrs

Projected (2100)

CO2 concentrations have risen by over 30% due to human activities


CO

2 C

on

cen

trat

ion

(p

pm

v)

Projected levels of atmospheric CO2 during the next 100 years would be higher than at anytime in the last 440,000 yrs

Projected (2100)

CO2 concentrations have risen by over 30% due to human activities

Current (2005)


Observed and simulated change

Natural & man-made factors

Tem

per

atu

re c

han

ge

ºC

1.0

0.5

0.0

-0.51850 1900 1950 2000

observed

model simulation

+

+

observedmodel simulation


RELATIVE WARMING OF GREENHOUSE GASES current emissions, effect over next 100 years

Methane24%

Carbondioxide

63%Nitrous

oxide 10%

Others3%


ATMOSPHERIC CONSTITUENTS which affect climate; sources and lifetimes

Carbon dioxide Fossil fuels, deforestation 100 years

Methane Agriculture, natural gas 10 years

Other gases

(nitrous oxide, CFCs, ground-level ozone..)

Aerosols Power generation, transport 2 weeks


CARBON DIOXIDE (CO2)

The most important man-made greenhouse gas

About half of the CO2 emitted by Man remains in the

atmosphere; remainder absorbed by vegetation and

oceans

CO2 risen by 1/3 since the industrial revolution

CO2 emissions would have to be reduced by about 70%

to stabilise climate change


Myth 3

Computer models are unreliable.

How can you predict 100 years ahead when you can’t predict the weather for the next 5 days?

THE CLIMATE SYSTEM

OCEAN

PrecipitationSea-ice

LAND

Ice- sheetssnow

Biomass

Clouds

Solarradiation

Terrestrialradiation

Greenhouse gases and aerosol

ATMOSPHERE


ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE SULPHURSULPHUR CARBON CARBON CHEMISTRYCHEMISTRY

ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE SULPHURSULPHUR CARBON CARBON

ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE SULPHURSULPHUR

ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE

ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN

ATMOSPHEREATMOSPHERE LANDLAND

ATMOSPHEREATMOSPHERE

19991999

19971997

19921992

19851985

Development of Hadley Centre Climate Models

1960s1960s


Projections of Climate Change


Model Projections – Global temperature riseG

lob

al t

emp

erat

ure

ris

e, d

egre

es C

High emissionsMedium-high emissionsMedium-low emissionsLow emissions

Start to diverge from mid-century

Other climatemodels:1.5 - 6°C


Myth 4

It’s all to do with the sun-

There’s a strong link between increasing temperatures on earth and the number of sunspots on the sun.


Solar influence

Temperature anomaly relative to late 19 th century.


1374

1372

1370

1368

1850 1900 1950 2000

So

lar

rad

iati

on

/

W m

–2

CHANGES IN SOLAR ENERGYGJJ1999


Myth 6

The NAD will be cut off and we’ll be heading for another ice age

GLOBAL OCEAN CIRCULATION

COOLING

WARMSURFACECURRENT

INTERMEDIATEWATERS

WARM AND LESS SALINE ANTARCTIC CIRCUMPOLAR CURRENT

GJ J1999


The Gulf Stream


NORTH ATLANTIC OCEAN CIRCULATIONC

ircu

lati

on

str

en

gth

No changeSRES A1FISRES B2SRES B1SRES A2


The Day After Tomorrow? Very unlikely!


Myth 5

Everyone jumps on the negative effects of Climate Change there’s no need for urgent action.


Global-average temperature and sea level are projected to rise under all scenarios

Global-average surface temperature projected to increase by 1.4 ºC (~2.5 °F) to 5.8 ºC (~10.5 °F) by 2100 Rate of warming likely unprecedented in at least last 10,000 yrs Land areas will warm more than the global average

Global average precipitation will increase over 21st century

Very likely to be more intense precipitation events

Snow cover and sea-ice extent projected to decrease further

Glaciers and icecaps projected to continue widespread retreat

Global mean sea-level projected to increase by 9 cm (~3.5 in) to 88 cm (~34.5 in) by 2100


COASTAL POPULATIONS AT RISKChange from the present day to the 2080s

University of Middlesex


Coastal flooding from sea-level rise

River flooding from more heavy rain events

Health risks

Water supply threatened by droughts

Increased storminess?

IMPACTS ON THE UK


HOW QUICKLY WILL THE CLIMATE CHANGE IN FUTURE

Depends on…………

How much greenhouse gas emissions grow this depends on population growth, energy use, new

technologies, etc

How sensitive the climate system is to emissionshow clouds, ice, oceans etc respond to the extra heating;

we build a mathematical model of the earth’s climate system to calculate this


WHAT CAN BE DONE?

Adaptationcoping with the effects of climate change

Mitigationreducing emissions of greenhouse gasessoaking up CO2 by forests, etcreducing sensitivities



•Turn off lights when you leave a room •Only boil the amount of water you need in your kettle •Turn off televisions, videos, stereos and computers when they are not in use - they can use between 10 and 60% of the power they use when on •Don't leave fridge doors open for longer than necessary, let food cool down fully before putting in the fridge or freezer, defrost regularly and keep at the right temperature •Close curtains at dusk to keep in heat •Let your clothes dry naturally rather than using a tumble drier •Turning down the thermostat for your heating by 1 degree could cut your heating bill by 10% •Set your water thermostat for 60 degrees - this is plenty warm enough for bathing and washing and will save money too •Use economy programmes on dishwashers or washing machines •Where possible don't stand cookers and fridges/freezers next to each other

Things you can do today at no cost:


Things you could do in the future

•Put foil behind radiators fitted on external walls •Use energy saving lightbulbs - they use a quarter of the electricity and last much longer •Insulate your hot water tank and pipes •Speak to your energy provider about their 'green tariff' - they may be able to match your energy consumption with an equivalent amount of energy from renewable sources •Fit seals to externals doors, skirting boards and floor boards to reduce heat loss - 15% of heat is lost through draughts and 15% through the floor •Make your windows draught proof or fit double glazing - this cuts heat loss in half - up to 10% of heat is lost through uninsulated windows•Fit loft insulation - which should be at least 200mm thick to be most effective - 25% of heat is lost through an uninsulated roof •Fit wall insulation - up to 33% of heat is lost through uninsulated walls •Replace old inefficient boilers •Fit solar panels or solar tiles to your roof


Links: www.metoffice.gov.ukwww.bbc.co.uk/climate

www.royalsoc.ac.ukwww.ipcc.ch

Documents

© Crown copyright 2004 Debunking the myths of Climate Change Helen Young Former Lead Presenter BBC Weather Centre