International agreement - Kyoto Treaty from Xinyi National response - Singapore Green Buildings from Ahmad

lecture notes on impacts and responses to climate change

Impacts from estee seetoh

International agreements from estee seetoh

National responses from estee seetoh

Deforestation is the main cause of global warming. How far do you agree with this statement? Support your answer with evidence.

I disagree with this statement as there are many other causes of global warming besides Deforestation.

Explain why DEFORESTATION causes global warming 

P = Deforestation is the loss of forests due to the removal or clearance of trees in forested areas. Deforestation takes place as wood is required to make products such as paper, building materials and space is needed for mining and farming. 

E = With deforestation, there are fewer trees and plants to take in carbon dioxide, leading to an increase in carbon dioxide in the atmosphere. Carbon in the soil accumulates through the decay of organic matter like dead leaves and animals. Deforestation increases carbon oxidation in the soil to produce carbon dioxide that traps heat. 

Eg = Between 2000 to 2010, 52,000 square kilometres of forest were lost every year. The greatest loss was in South America followed by Southeast Asia. 

However, there are Other causes of global warming :

1. FOSSIL FUEL

P = Burning of fossil fuels like coal, oil and natural gases are formed from dead organic matter that has decomposed over many millions of years.

E = This will produce large amount of energy for man’s daily use and release large amount of carbon dioxide which is a greenhouse gas. 

Eg = Large consumers of fossil fuels include China, the United States of America, Canada and the United Kingdom. In 2010, global carbon dioxide emissions totaled 30.6 billion tonnes, which was 5.6 per cent increase from 2009.

2. AGRICULTURE

P = Agriculture which is the practice of cultivating land, producing crops and raising livestock.

E= This contributes to production of greenhouse gases such as methane and nitrous oxide. Organic matter such as dead leaves and manure releases huge amount of methane during rapid decomposition in the rice fields due to the high level of moisture in the soil. The use of inorganic fertilisers increases the amount nitrous oxide in soil and it is released when soil is ploughed or when rain flows through the soil. 

Eg= In rice producing countries such as China and India, million tonnes of methane are released each year from cattle ranching.  

3. NATURAL CAUSE = SOLAR OUTPUT

P = Variation in solar output is another factor causing global warming. The sun emits varying amount of solar radiation due to changes in its magnetic field. Occurrence of sunspots may cause an increase in the global temperature. 

E = Sunspots are cooler regions on the sun’s surface that appear as dark spots. The areas surrounding the sunspots will radiate more energy, which compensates for the lower temperature of the sunspot areas.

EG = example, a peak in the number of sunspots in 2000 coincided with higher solar activity.  

In conclusion, there are many causes of global warming, and deforestation is not the main cause of greenhouse gases. The other human activities also contributes to global warming with other greenhouse gases being produced besides carbon dioxide. Deforestation has also been strictly monitored by governments now to control the logging of forests for land clearance. 

Impacts of climate change

Video from Xuan Qi Q: Why are there more growth of rag weed in different countries when it was only found in North America in the past? Video from Sijie Q: How is sea level and weather affected by global warming?

Anthropogenic Activities

Greenhouse gases, enhanced greenhouse effect and global warming

Video from Gigi: Question - Are Greenhouse gases good or bad? Video from Liyi : Question - Do natural causes of climate change have a permanent effect on our global temperatures?

Variation in solar output

1. Explain how does the varying amount of solar output affect global warming? [3]

a)    Magnetic field –  An increase in magnetic activity results in an increase in solar radiation. 

b)    Sunspots – When there are more sunspots, solar activity is high as these areas radiate more energy.

c)     Temperature – Temperatures increases when there is higher solar activity and Temperature decreases when there is lower solar activity.

Volcanic eruptions

2. Explain how does volcanic eruption affects global temperatures? [4]

a)    Gases released – During an eruption, large volumes of carbon dioxide, water vapour, sulphur dioxide, dust and ask are released into the atmosphere.

b)    Global dimming – These gases mix with dust and ash and reflect the solar energy back into space, which results in global dimming

c)     Effect on temperature - Global dimming reduces the amount of sunlight from reaching the earth's surface and temporarily lowers the earth temperature for months or years.

d)    Examples - In 1991, Mount Pinatubo in the Philippines released 17 tonnes of sulphur dioxide and lower the temperatures for 2 years in some locations.

Level Descriptor Questions (LDQ) Format

Volcanic eruptions are the main cause of global climate change. Do you agree? [8]

Introduction

-  I disagree to a large extent that volcanic eruptions are the main cause of global climate change.

Point - Explain how volcanic eruption affects climate.	Although volcanic eruptions releases huge amount of gases that results in global dimming. However this has a temporary effect on the global temperature.
Elaborate - Elaborate on gases released and global dimming.	A large portion of sulphur dioxide are being released during eruptions, and it mixes with dust and ash which results in global dimming as the sunlight is being blocked and reduces the global temperatures.
Examples - Country - Year of eruption - Volcano name	This occured in Mt Pinatubo in Philippines during 1991. The eruption lowered the global temperatures temporarily for two years in some locations.
Limitations - Explain that variations in solar output also affect climate change.	The variation in the amount of solar output also affects the climate change. When there is higher solar activity such as sunspots, temperature is higher. When the solar activity is lower the global temperature decreases.

In conclusion, volcanic eruptions only affects the global climate changes for a temporary period. When the dust and ash settles, the cooling effect does not impact the climate in the long run. Furthermore, solar radiation and human activities may also affect global climate changes.

Corrections - P43, P44

GREENHOUSE EFFECT

With reference to Fig. 7, describe the relationship between atmospheric carbon dioxide and global warming and their changes over the years. [4]

BEST ANSWER: Ahmad

• Global warming increases with increase in carbon dioxide/Global temperature has a direct relationship with carbon dioxide.
• During pre-industrial level, carbon dioxide increased gradually to 260ppm with only 1 degree celsius increase in atmospheric temperature.
• However during industrial period, carbon dioxide accounting for anthropogenic warming has increased rapidly. Carbon dioxide accounting for natural warming has remained constant.
• Therefore Carbon dioxide given out during industrialisation has resulted in a rapid increase of temperature of 6.5 degree celsius.

Common mistake
- never use data (or use wrong data)
- never describe what type of 'increase' - can use words like 'gradual increase', 'rapid increase', 'steady increase'


Explain how any three activities have brought about an increase in the greenhouse gases shown in Fig. 10. [3]

BEST ANSWER: Haikal, Ammar, Gigi

• The burning of fossil fuels for electricity during industrialization has increase the amount of carbon dioxide released to the atmosphere.
• 
• During Deforestation whereby trees are being destroyed faster than the rate of growth, there is an increase in carbon dioxide level. This is because there are not enough trees to photosynthesize and take up carbon dioxide in the air.
• 
• In agriculture, Cattle increases methane level due to the gas it releases.
• 

Common mistake: 

- Lump Deforestation and burning fossil fuel together

- Water vapour - leads to sea level rise (How does this links to greenhouse gas?

Natural causes of climate change - Volcanic eruption

Natural causes of climate change - Sunspots

http://www.space.com/14736-sunspots-sun-spots-explained.html

What Are Sunspots?

SPACE.com Staff   |   February 29, 2012 05:44pm ET

Images taken July 1 and 2, 2010 by the New Solar Telescope at the Big Bear Solar Observatory reveals up-close details of a sunspot like never before. Credit: BBSO View full size image

Sunspots are darker, cooler areas on the surface of the sun in a region called the photosphere.

The photosphere has a temperature of 5,800 degrees Kelvin. Sunspots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them.

Sunspots can be very large, up to 50,000 kilometers in diameter. They are caused by interactions with the Sun's magnetic field which are not fully understood. But a sunspot is somewhat like the cap on a soda bottle: shake it up, and you can generate a big eruption. Sunspots occur over regions of intense magnetic activity, and when that energy is released, solar flares and big storms called coronal mass ejections erupt from sunspots.