The Greenhouse Effect
Greenhouse Effect: Natural phenomenom
Greenhouse gases absorb outgoing long wave radiation from the earth and send some of it back to the earth's surface
Enhanced Greenhouse Effect: More heat is trapped by greenhouse gases, causing the earth to warm
Why is solving the problem of global warming complex?
- Hard to make accurate predictions about the nature and impact of global warming
- Requires international agreement to cut greenhouse gas emissions and this is politcally and economically unacceptable for many countries
Evidence for Climate Change
Long Term: Ice cores
Records the climate of the last 800,000 years
Interglacial- Warm and high concentration of CO2 Glacial-Cold, low concentrations
Oceans: carbon dioxide sinks, can collect ocean sediment cores, oxygen isotopes and carbon dioxide records correlate. Thermohaline circulation, north atlantic drift could essentially turn off
Medium Term: Proxy records, Medieval Warm Period, Little Ice Age
Recent: Instrumental records from weather stations exist for the last 100 years or so
Causes of Climate Change:Milankovitch
- The surface temperature of the earth changes over time because the Earth's orbit and axis tilt vary over time. These variations lead to changes in the amount and distribution of solar radiation recieved by the earth.
- The eath's orbit changes from circular to eliptical, this changes the amount of radiation recieved from the sun
- The earth's tilt changes the seasonality of the earth's climate. The smaller the tilt, the smaller the difference between summer and winter.
Feedback effects are those that can either amplify a small change and make it larger or diminish the change and make it smaller
E.g Snow and ice cover, dramatically raises surface albedo which causes further cooling
Causes of Climate Change
The amount of energy emitted by the sun varies as a result of sunspots. Sunspots are caused by intense magnetic storms, they blast more solar radiation towards the earth on an 11 year cycle. A long period with almost no sunspots known as the Mauder Minimum occured between 1645 and 1715 and this is linked to Little Ice Age.
Volcanic and Cosmic Causes
Major eruptions eject material into the stratosphere and high levels of wind distibute it around the globe. The 1991 MT Pintubo eruption in the Philippines ekected 17 million tonnes. This forms a haze of sulphate aerosols which reduces the amount of sunlight recieved. The temperature cools, the same would happen if an asteroid struck.
Atmospheric Forcing-Enhanced Greenhouse Effect
Causes of Climate Change:Global Dimming
Atmospheric pollutants like soot reflect solar energy back into space and so have a net cooling effect. The earth may be cooling and warming at the same time, some pollutants like sulfur dioxide may be reducing the full effect of climate change.
- In 2007, greenhouse gas levels stood at 430 ppm carbon dioxide
- Annual emissions are still rising. With a 'business as usual' senario with no attempts at reduction they will reach 55 ppm by 2035
- Most future emissions will come from developing countries. India and China will contribute 75% of the increase
There is uncertainty becasue it's hard to predict the following:
- The level and nature of economic development
- What degree of international action will be taken to reduce emissions
- Inertia in the system, even if greenhouse gases stabalise, climate change will continue
- Impact of positive feedback
The tipping point is reached when climate change occurs irreversibly and at an increasing rste. Scientists believe it's around 2 degrees.
There are also visible manifestations of the tipping point, such as the loss of the massive Greenland icesheet, the destruction of the Amazon rainforest and collapse of the global ocean current, system aka. thermohaline circulation
Reaching the tipping point could trigger abrupt changes on a reigonal scale, which are likely to be ireversible.
Mitigation or Adaptation
Mitigation- reducing the output of greenhouse gases and increasing the size of greenhouse gas sinks
Adaptation- changing our lifestyles to cope with a new environment rather than trying to stop climate change
How would natural systems repsond to mitigation or adaptation?
Mitigation could limit damage, adaptation might condemn natural systems which could not adapt to a changing climate.
How would human systems repsond to mitigation or adaptation?
Mitigation would involve an upfront cost, adaptation mean cost is spread over a longer timescale
Parts of the poorer world lack the adpative capacity to cope, Increasing adaptive capacity requires:
- Reducing poverty, to meet costs of adaptation
- Increasing access to resources
- Improving education and skills to develop understanding of the challenges and ability to change
- Improving health
- Improving infrastructure such as roads
Examples of Mitigation or Adaptation
Examples of Adaptation:
- Managed retreat of coastlines vulnerable to sea level rise
- Developing drought resistant crops
- Enlarging exsistent conservation areas to allow for shifting habitat zones
Examples of Mitigation:
- Setting targets to reduce carbon dioxide emissions
- Switching to renewable energy resources
- Capturing carbon emissions
The Kyoto Protocol
At the 1992 Earth Summit in Rio de Janeiro, the United Nations Framework Convention on Climate Change was agreed. The aim was to:
Achieve stabalisation of greenhouse gas concentrations in the atmosphere at a low enough level to prevent dangerous anthropogenic interference with the climate system
190 countries including the USA and negogiations began on a protocol, which was adopted at a UNFCCC confrence in Kyoto in 1997
- 55 countries had to ratify it
- Emissions reduction targets are country specific, EU=8%
- Trading of carbon credits; buying unused emissions
- Carbon sinks were allowed
- For years, businesses argued that reducing pollution would cost money, profits and jobs.
- TNC's funded the Global Climate Coalition, this opposed action on climate change and funded research to counter the warnings about global warming
- TNC's began to change there attitudes because:
- Moral and public pressure
- Fears about energy supply
- Increasing movements by governments towards taxing carbon emissions
- New technology, such as renewables
Putting a Price on Climate Change
In 2006 the Stern Reviews was published, it concluded that if climate change is allowed to continue it could cost at least 5% and possibly 20% of global annual GDP. If the world decided to mitigate climIate change the cost would be about 1% of GDP per anum.
- Implementing energy effcient strategies
- Switching to renewable energy resources
- Investing in public transport to reduce car use
- Taxing on carbon emissions
- Capturing and storing carbon
Do nothing costs:
- Icreased cost of farming and food
- Increased water costs
- Higher insurance premiums in more hazardous climates
Key Players: National Strategies
- International climate change agreement after 2012 might set a 550 ppm target, it will be up to national governments to decide on strategies to achieve it
- The UK aims to reduce carbon dioxide emissions by 60% by 2050, 10% of electricity supply is to come from renewable sources
- The USA are subsidising farmers to grow biofuels
Key Players:Taxing &Trading
Many countries have taxing systems to raise the cost of polluting. In the UK car tax is priced by carbon dioxide emissions, bigger engine, high tax
Air travel is likely to be taxed in the future
- Carbon credit cards would give each person a 'carbon budget' which would be debited as resources were bought. Any above your personal budget, you have to pay for.
- In 2005, the EU began a carbon trading system called EU ETS, it sets a limit on emissions but allows companies within the limit to sell carbon credits to companies that need to pollute more
- This covers around 50% of EU's carbon emissions
- EU countries can also purchase certified emissions reduction credits by investing in environmentally friendly prjects in developing nations
Key Players:Local Action& Individuals
Local Agenda 21 emerged from the 1992 Rio Earth Summit, it calls on governments to encourage local authorities to implement sustainable strategies. Without local action it's hard for individuals to do their bit.
Case Study: London's Climate Change Strategy
We can help by reducing our carbon footprint, but small action can make a difference if everyone joins in. Switching every lightbulb in London to an energy effcient light bulb would save 575,000 tonnes of of carbon dioxide emissions per year.
Asking everyone to reduce footprint can be unfair as some people consume far less than others
Contraction and Convergence Model
Convergence: Developing nations can increase carbon emissions
Contraction: Developed countries work to reduce carbon footprint
- Individuals and groups that keep climate change in the news:climate crusaders
- Common Characteristics:
- Usually famous
- Passionate about climate change
- Used climate change as a selling point
- Al Gore, US President runner up
- Cold play, planted 10,000 mago trees for villagers in India to make up for the energy it took to make the CD's
- Being sustainable is often used to attract customers
Why is mitigation progress slow?
- Uncertainty. We can't say how much climate change will effect the future
- Costs. The costs of mitigating are higher and would damge economic growth but evidence from the Stern Reviews suggest mitigating cost are lower
- Political Inertia. Mitigation policies such as carbon taxes are vote losers. So this one reason why progress is gradual
- Economic Systems. Business and industry inevitably pollute. Major investment is needed to implement clean systems and businesses are reluctant to invest in something that does not make profit for them.
- International Agreements. They take time to negotiate and not all countries agree. Kyoto agreements have partially worked, but do all countries need to agree. China, USA and the EU account for 50%.