How are
people changing
the climate?

Basics

3. How can we hinder
man-made climate change?

We can hinder man-made climate change by emitting less greenhouse gases such as CO₂. The less we emit, the less warming there will be in the future.

Burning less fossil fuels

People can slow down and eventually stop the climate change we have started. But the climate system reacts slowly. The gases we have already emitted will keep affecting the climate for many years to come – even if we work hard to limit our emissions. Reducing emissions will slow down the rate of climate change, but the climate will keep changing as long as we live. Our children and grandchildren, however, will be able to fully enjoy our efforts we make today to limit emissions.

The most important thing we can do to hinder climate change is to burn less fossil fuel so that we emit less CO₂. 

Technological improvements and lifestyle changes can reduce the amount of energy we use on transportation, heating, cooling, lighting, appliances that run on electricity, industrial production, and so on.
  

Using sources of energy other than fossil fuels can reduce emissions of greenhouse gases considerably. Alternative sources include renewable sources such as wind power, solar power, and hydropower (although in some cases greenhouse gases are formed when remains of vegetation rot in the hydropower pools); biomass, such as wood, straw and other plant material (as along as new trees and vegetation are planted to compensate); and nuclear power, although it is controversial for other reasons. 
  

Technological innovation may give us new energy sources that will replace fossil fuels in the future. For example, cars may run on hydrogen instead of gasoline. (Hydrogen engines do not emit CO₂. But to produce hydrogen we need lots of energy. If this energy comes from coal, oil or gas then we could end up with CO₂ emissions just as big as if cars were still running on gasoline.)

Can’t we just filter out the CO₂?

Many types of pollution can be “cleaned up” by using filters or the like. Today, there is no cleaning technology that can effectively remove CO₂ emissions from furnaces, power plants, and engines at a reasonable enough price. But both governments and private companies in many countries are working to develop cost-effective technologies that can capture CO₂ from burning coal, oil, or gas before it is released into the atmosphere. It can then be stored far underground, for example in empty oil wells.

Each year the oil company Statoil stores about 1 million tons CO₂ 1000 meters under the ocean floor in a sandstone formation in the Sleipner field in the North Sea. The CO₂ is separated from the natural gas that is pumped from the Sleipner field and injected into the sandstone that is found under the ocean floor. This sandstone formation has room for at least 600 billion tons of CO₂, which is roughly equivalent to the emissions from all of the power plants in Europe for the next 600 years.

Two obstacles must be overcome before this technology can be applied on a large scale. First, we must be sure that the storage areas really are safe and the gas will not leak out. Second, the price of capturing and storing CO₂ must drop to levels low enough that industry can afford to use the technology. Today no one knows whether or when CO₂ can be captured and stored at a reasonable price. And in any case, the process can only be used for large, single sources of emissions – such as power plants and factories. Emissions from smaller, dispersed sources – such as cars, planes, paraffin stoves, or gas ovens – cannot be reduced using this technology.

Reduce emissions of other greenhouse gasses

We can also reduce emissions of greenhouse gases from sources other than fossil fuels.

• By stopping deforestation, we can avoid the release of CO₂ to the atmosphere. Today, deforestation is especially prevalent in tropical regions where forests are cut down to make grazing lands or raise crops, for example.
   
• Garbage dumps (land fills) release the powerful greenhouse gas methane (CH₄) from the rotting of organic waste. By capturing this gas and using it as fuel, we get both heat and reduced emissions of greenhouse gases.
    
• Agriculture contributes to emissions of CO₂, methane, and nitrous oxide (N₂O). More environmentally sound farming methods can reduce these emissions.  
   
• Many types of industrial manufacturing release greenhouse gases, especially those that contain fluorine (HFCs, PFCs, and SF₆). These emissions can be reduced with new production methods.

Trapping CO₂ from the atmosphere

We can also increase the absorption of CO₂ in forests, land, and sea.

• When we plant forests where there has been an open landscape, carbon from the atmosphere is absorbed by the growing trees. This removes some of the CO₂ we emit to the atmosphere. But the possibility of increasing the absorption of CO₂ in this way is so limited that it cannot make up for more than a fraction of the emissions that we humans are responsible for. Planting forests can also create problems – in some cases, it encroaches upon agriculture or destroys the habitats of wild animal and plant species that thrive in the existing landscape.
   
• The oceans absorb large amounts of CO₂ from the atmosphere. One proposal is to increase this absorption by fertilizing plant plankton that binds carbon through photosynthesis. The effectiveness of such a step has not been documented, and the growth in algae after fertilization can have other, unfortunate consequences.

Emissions of greenhouse gases come from a large number of sources, thus many different steps need to be taken to limit them. But such a large amount of the emissions come from fossil fuels that effective strategies would have to focus on emissions from fossil fuels.

Why burning wood does not contribute to climate change

When we use fuel from biomass, such as wood or wood chips, energy is released in the form of heat, and carbon is returned to the atmosphere in the form of CO₂. If new trees grow where the other trees were cut down for wood, the new trees will absorb CO₂ from the atmosphere and bind it in new biomass. This re-establishes balance in the CO₂ cycle. Over time, the amount of CO₂ in the atmosphere will be constant. This is why biofuels are considered to be CO₂-neutral.

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Author: Camilla Schreiner - CICERO (Center for International Climate and Environmental Research - Oslo) - Norway. Scientific reviewers: Andreas Tjernshaugen - CICERO (Center for International Climate and Environmental Research - Oslo) - Norway - 2004-01-20 and Knut Alfsen - Statistics Norway - Norway - 2003-09-12. Educational reviewer: Nina Arnesen - Marienlyst school in Oslo - Norway - 2004-03-10. Last update: 2004-03-27.