The recent climate agreement in
Paris reminds us that we need to drastically
reduce our use of fossil fuels to prevent the rise of emissions of carbon
dioxide (CO2), a greenhouse gas that causes climate warming. However,
reducing our dependence on fossil fuels is hard. We love the convenience of
getting in our cars and driving where we want to go. Our lifestyle and our
economy depend on energy driven in large part by burning fossil fuels. Yet
there is an alternative to reducing fossil fuel usage. Instead of reducing the
amount of CO2 we add to the atmosphere, we can pay to have someone
else to remove CO2 from the atmosphere somewhere else. This kind of
trading is called a carbon offset. For example, you can offset a flight across the
US by buying an offset
created by planting trees in the UK. The amount of CO2
you release into the atmosphere is offset by the CO2 absorbed by the
trees you paid for. You can fly or drive wherever you want with a clear
conscience because your carbon emissions are compensated by the offsets that
|Plantings of Douglas fir|
Planting trees is certainly an attractive option. Besides reducing atmospheric CO2, there are other benefits to the environment from planting trees and restoring forests. However, the practice of buying carbon offsets recently has come under increasing criticism. Some have compared it to indulgences sold by the Catholic Church in the Middle Ages. Similarly, now you can buy indulgences to offset your environmental sins.
Does this strategy of planting trees to offset our burning of fossil fuels actually reduce atmospheric CO2? Critics have documented serious problems with this approach. Vendors selling these offsets are notoriously untrustworthy. Often very little money from the offsets actually goes toward planting trees. The large projects promised by offset vendors often turn out to be a small fraction of what was promised. There is little oversight of these vendors to ensure that they are doing what they say they will do.
If we were to weed out the bad players in the carbon offset market, would it be possible to make a significant reduction in the emissions of CO2 by offsetting emissions with reforestation? There are several problems with offset schemes that undermine their effectiveness in reducing CO2 emissions.
The problem of additionality
If an offset is going to be genuine, it must pay for additional reductions in greenhouse gasses that would not have happened without the offset. If the project was going to happen anyway without the money from the offset, then buying the offset did nothing to reduce the greenhouse gasses. In many cases, offsets do not buy additional reductions. The offsets are sold for projects that had already been funded for other purposes. In some cases of tree plantings, offsets are sold for plantings that took place long before offsetting entered the picture.
|Burned forest on Mt. Hood|
The problem of permanence
The carbon stored in the trees in a forest does not stay there forever. Eventually the trees die. When they are destroyed by fire, insects, or disease, they release their carbon back into the atmosphere. Offset projects that finance tree plantations are particularly vulnerable to disease and insect infestations. Ironically, continued climate change can increase the threat of disease and fire. Natural forests can sequester large amounts of carbon, but it is important to maintain them in a healthy state to keep the carbon from returning to the atmosphere.
The problem of bad side effects
Most offset plantation projects are done in poor countries. These projects often displace local farmers and deprive local people of needed resources, particularly water. Critics view this practice of planting in poor countries to pacify emissions in the rich industrial countries as exploitation, calling it “carbon colonialism.”
The problem of future-based offsets
Offsets based on tree plantations do not reduce CO2 at the time of purchase. It takes many years to remove the CO2 already released into the atmosphere. For example, suppose I like to vacation in
every year. Each year I purchase an offset from a seller that plants trees. The
offset pays to plant a tree that over the next 90 years will absorb the CO2
released by my flight. The problem is that the CO2 was released all in
one day during the flight. As long as I continue flying and buying offsets, the
CO2 released will increase faster than the CO2 captured
by the trees. Offsets based on future CO2 reductions are
fundamentally flawed. We may think that we are doing the right thing, but the
results are continued climate warming from increases in atmospheric CO2.
|Healthy natural forest|
Tree planting offset schemes fail to deal with rising CO2 levels. Focusing on these flawed schemes is a dangerous distraction from dealing with the root cause of climate change. We must make serious reductions to our burning of fossil fuels if we have any hope of avoiding climate changes that will have dire consequences for the natural ecosystems of the earth and the people that live on the planet.
The bottom line is that it’s important that we focus on real reductions in fossil fuel use if we want to prevent climate changes that threaten the health of our forests and our planet. Preservation and restoration of forests is an important part of this effort. But we should not fool ourselves by thinking that we can continue to accommodate current levels of carbon emissions by offsetting them with tree planting.
|Old person and older Douglas fir|
Buying carbon offsets may ease eco-guilt but not globalwarming – Christian Science Monitor
Carbon offsetting - Explain that Stuff
The Carbon Neutral Myth (PDF)– Offset Indulgencies for your Climate Sins
Designed to fail? (PDF) – The concepts, practices and controversies behind carbon trading