1. Economy Before carbon can be traded, a quantitative limit must be set on the carbon emitted by emitters. The economic basis for carbon trading is linked to the concept of property rights (Goldemberg, 1996).1.1. Costs and valuation Greenhouse gas emitters do not bear the full cost of the consequences of their actions (IMF, 2008), thus causing an economic problem related to climate change. Emitters face certain costs, such as fuel used. However there are costs that are not necessarily included in the price of their products or services. These costs are known as external costs (Halsnaes, 2007). These costs are defined as “external” because they are not borne by the emitters. These costs can affect the well-being of others. The emission of greenhouse gases also affects the well-being of others and the natural environment (Toth, 2001). People living in the future will suffer from the actions of current greenhouse gas emitters. These external costs can be converted into a monetary unit, which can be added to the private costs. In this way, those who emit greenhouse gases can take full responsibility for their actions (IMF, 2008).1.2. Voluntary carbon markets Voluntary carbon markets apply to all those who are not subject to mandatory limits, such as individuals, companies and other entities, who wish to offset their emissions by purchasing CERs. They are used for various applications such as neutralizing their carbon footprints. There is no specific allocation of emissions, but the carbon footprint is used as a baseline from which to set emissions reduction targets. This type of market is called a "buyer-conscious market" because credits are subject to less rigorous verification methods. Overall, the carbon market grew to $126 billion in 2008 compared to $63 billion in…paper time. While nations that have fewer financial resources may find that they cannot afford the permits necessary to develop an industrial infrastructure, thus inhibiting the economic development of those countries. Some Chinese companies have started artificially producing greenhouse gases with the sole purpose of recycling and obtaining carbon credits. Practices similar to those mentioned above have occurred in India. Once earned, the credit is sold to companies in the United States and Europe.5. Crime The electronic nature of carbon credits and their ledgers make the carbon trading market particularly susceptible to technology crimes such as hacking. While carbon credits can be identified by unique serial numbers, making it possible to track stolen credits, this can be compromised by weak regulatory oversight, particularly when stolen credits are traded across different jurisdictions.