What is happening to the Earth’s Climate?All About Geography, Physical Geography Elective, p. 98

What is Climate Change?

► Recap Climate: average weather condition of a particular place over a period of 30 years.

► Climate change: variations in the general climatic patterns of a place.

How does it look like?

► Climate change can take on many forms.

► E.g. Based on what you have learnt in the previous topic about the three diff. climatic types, what plausible climatic changes might occur in those areas?

► How will it affect the people living there?

Possible outcomes:

► E.g. more extreme weather events like tropical storms

► Delayed monsoon seasons

► Hotter mean daily temperatures

► Colder winters

► Drought

► Floods

Natural or man-made?

► Since its inception, the Earth has gone through numerous periods of cooling and warming. Global warming Global cooling

► In other words, the earth has been going though climatic changes naturally for thousands of years.

Climate Change Data:

What are some natural causes of climate change?All About Geography, Physical Geography Elective, p. 98

Natural causes:

► i.e. without man-made interference.

► Two types: Variations in solar output Volcanic eruptions

Variations in Solar Output

• The North and South pole of the Sun changes every 11 years, resulting in a somewhat unstable magnetic field.

• This causes the surface of the sun to become very unstable, generating “sunspots”

Variations in Solar Output

• The amount of magnetic activity emitted by the sun varies with time in a cycle known as the solar or sunspot cycle.

• This cycle lasts 11 years on average.• At its peak, the surface of the sun will

erupt to form numerous sunspots.• Sunspots are areas of regions where

the solar magnetic field is very strong, which causes high solar radiation to be emitted.

Variations in Solar Output

• Some sunspots can even erupt into powerful solar storms that shoot streams of charged particles into space, occasionally in the direction of Earth.

• These powerful solar storms can bombard Earth's magnetic field and disrupt power grids or knock out satellites in orbit around the planet.

• In general ↑ sunspots = ↑ temperatures on Earth

Solar activity and Temperature

Q: Is there a correlation btw the amount of solar activity and the Earth’s temperature?

Solar activity and Temperature

► Q: Is there a correlation btw the amount of solar activity and the Earth’s temperature? Yes and No. Between 1880 to 1980, the increase in

solar activity did correspond to an increase in the Earth’s temperature.

But from 1980 onwards, despite a decrease in solar activity, the Earth’s temperature has continued to rise.

This suggests that other factors are at play.

What about volcanic eruptions? How do they

affect the Earth’s climate?

Volcanic eruptions

► Q: how to volcanic eruptions affect the Earth’s temperature? While most people would assume that

the ash and carbon particles will cause the earth’s temperature to increase, in reality, the reverse is true.

Such eruptions only release a small amount of carbon emissions. Instead, volcanic eruptions release a lot of sulphur dioxide which react to form sulphur based-particles that reflect solar energy back to space!

Volcanic eruptions

► …continued This process is called global dimming

which leads to global cooling. The 1815 eruption of Mount Tambora in

Indonesia released so much sulphur particles into the air that it reduced global temperatures by 0.5°C for around 2 years!

Other notable cases: Mount Pinatubo (see textbook p.101).

But these effects are usually short-term. Once the particles settle, temperatures will return to normal.

Nature vs. Man

► In the past 50 years however, temperatures have increased drastically.

► This rate of increase does not appear to be natural, causing many scientists to worry.

► This has created many new and largely unfamiliar challenges for us (humans)

Nature vs. Man

► Since the mid-1980s, human activities have released more than 100X the amount of carbon dioxide emitted by volcanoes.

► As global populations increase, so are our likely emissions.

The Greenhouse Effect

► A natural process by which gases in the atmosphere helps to trap heat from the Earth’s surface (longwave radiation)

► Examples include: water vapour, carbon dioxide, methane, nitrous oxide, and ozone

► Stabilizes the temperature and climatic system on Earth (average of around 15°C), thereby allowing life to exist

Enhanced Greenhouse Effect

► However, increase in greenhouse gases over the years has led to more heat being trapped in the atmosphere.

► Results in ENHANCED G.H. EFFECT

► Due to mainly to anthropogenic factors Anthropogenic means

caused by human activities

Causes of Climate Change

Human

► Deforestation

► Burning of fossil fuels

► Agriculture

► Industrial Manufacturing

► Urbanization

Natural

► Sunspots

► Volcanic eruption

Q: Of the two (human vs. natural), which is more responsible for the current increase in global temperatures? Why?

Agriculture:

http://chartsbin.com/view/10771

Agriculture accounts for 18% of the world’s GHG emissions

NOTE: The world cattle population is estimated to be about 1.3 billion.

Rising demand for Industrial and Urban Land

http://chartsbin.com/view/2079

Find out your CO2 footprint:http://www.mycarbonfootprint.sg/

Causes of Climate Change

Human

► Deforestation

► Burning of fossil fuels

► Agriculture

► Industrial Manufacturing

► Urbanization

Natural

► Sunspots

► Volcanic eruption

Q: Of the two (human vs. natural), which is more responsible for the current increase in global temperatures? Why?

What are the impacts of Climate Change?http://webarchive.nationalarchives.gov.uk/20100623194820/http:/www.actoncopenhagen.decc.gov.uk/content/en/embeds/flash/4-degrees-large-map-final

Discuss:

► Visit the following site: http://webarchive.nationalarchives.gov

.uk/20100623194820/http:/www.actoncopenhagen.decc.gov.uk/content/en/embeds/flash/4-degrees-large-map-final

► Is climate change bad? Are there any countries out there that actually benefit from climate change?

What are governments doing about it?

Measures:

► Two levels: International level

► Kyoto Protocol► Copenhgen Conference

National level► Refer to Textbook on case studies of SG

and India

Measures:

► International organisations tend to act as general advisory boards and set guidelines and targets for countries to follow.

► Ultimately, it is still up to the countries themselves to decide whether to make climate change a priority!

► Some countries do: E.g. Germany

► Others don’t want to: E.g. United States

► Why?