These countries have carbon prices. Work;

The idea of ​​putting a price on carbon dioxide emissions to help tackle climate change has been slowly spreading around the world over the past two decades.

This week, Canada's federal government took the latest step when it expanded its carbon pricing program nationwide with imposing a tax on fossil fuels in four provinces who had refused to write their own climate plans.

More than 40 governments around the world they have now adopted some kind of carbon price, either through direct taxes on fossil fuels or through cap-and-trade programs. In Britain, coal use plummeted after the introduction of a carbon tax in 2013. In the northeastern United States, nine states have set a cap on emissions from the power sector and require companies to buy tradable pollution permits.

Economists have long suggested that raising the cost of burning coal, oil and natural gas can be a cost-effective way to curb emissions. But in practice, most countries have found it politically difficult to set prices high enough to cause really deep reductions. Many carbon pricing schemes today are quite modest. In France and Australia, efforts to raise carbon taxes stalled after a backlash from voters angry about rising energy prices.

Partly for this reason, carbon pricing has, so far, played only a supporting role in efforts to mitigate global warming. Here are some efforts to date:

Canada currently has one of the most ambitious carbon pricing programs in the world. Under Prime Minister Justin Trudeau, the Liberal government has enacted national tax on oil, coal and natural gas which starts at $15 per tonne of carbon dioxide this year and will rise to $38 per tonne by 2022. Most of the revenue will go back to Canadians on their tax bills. the government estimates these rebates will offset higher energy costs for around 70 per cent of people.

Some key industries that face intense trade competition, such as steel and chemicals, are exempt from Canada's tax. Instead, they will participate in separate program in which the dirtiest companies in each sector would either have to pay the government for their excess emissions or buy carbon credits awarded to the cleanest companies.

Individual provinces can opt out of the federal program by designing their own local climate policies. British Columbia, for example, has its own highest carbon tax, which rose to $30 a tonne this year, and Quebec has instituted a local cap-and-trade system. But four provinces, including Ontario, have refused to create their own plans and the federal tax entered into force in these parts on April 1st.

The tax is a key part of Mr. Trudeau's plan to cut Canada's emissions 30 percent below 2005 levels by 2030. But Canada is expected to hold a national election in October and the opposition Conservatives have pledged to abolish the tax if they take power.

In Britain, the birthplace of the Industrial Revolution, greenhouse gas emissions have fallen to their lowest level since 1890. One key factor: A carbon tax that pushed utilities away from coal.

Technically, Britain is covered by the wider European Union cap-and-trade system, which sets an overall cap on emissions from key industries and allows companies to buy and sell carbon permits. But due to the abundance of permits on the market, carbon prices in Europe remained low for years and the program had a relatively limited effect on emissions.

So in 2013, Parliament introduced a carbon price floor under the scheme for some sectors, including electricity, a policy that essentially works as a carbon tax of about $25 per tonne. This tax has encouraged electric utilities to quickly transition from coal to somewhat cleaner natural gas. This is perhaps the clearest example in the world of a carbon tax leading to a significant reduction in emissions.

With Congress largely deadlocked on climate policy, the main efforts to price carbon in the United States have unfolded at the state level.

In the Northeast, nine states currently participate in the Regional Greenhouse Gas Initiative, a cap-and-trade system that auctions to power plants a steadily declining supply of carbon pollution permits. Carbon prices under this system have been fairly modest to date, and it is unclear how much the prices themselves have led to reduced emissions in the region. But states used the money raised from the auctions to invest in efficiency and clean energy programs.

California, meanwhile, has enacted its own cap-and-trade program that goes beyond power plants and also covers manufacturers, refiners and other polluters. Here, too, carbon prices under the scheme have remained modest to date, in part because the initial cap was set quite high, and most of California's emissions cuts to date have come from other climate policies. These include the state's building performance standards and aggressive renewable energy targets. State officials are now scrambling to tighten the cap so it leads to bigger cuts in the coming years.

There is some evidence that carbon pricing could be extended further to the states. Virginia and New Jersey are making moves to join the Regional Greenhouse Gas Initiative, and several northeastern states are planning a similar program for cars and trucks that would put a price on transportation fuel and invest in mass transit, electric buses or other low-cost solutions. carbon emissions.

Since 2011, China has been experimenting with cap-and-trade programs in several pilot cities, including Shanghai and Shenzhen. The country plans to gradually roll out a national cap-and-trade program starting in 2020, with several years of testing before expanding to major sectors such as electricity, steel and concrete.

If China follows through, it will have created the world's largest carbon pricing program. However, the government has yet to finalize key details, such as how high it will set the overall emissions cap. Chinese officials have spoken to representatives from California and the European Union, trying to learn from their often difficult experiences designing cap-and-trade programs.

In 2012, the Australian Labor Government launched a cap-and-trade program that effectively set a carbon price of $23 per tonne. Emissions were reduced nationwide under the program, but the policy faced fierce political backlash from industry groups and voters. When the more conservative Liberal Party swept into power in 2013, it quickly scrapped the program.

Australia currently has a much more lenient carbon pricing scheme, called the Assurance Mechanism, in which large industrial polluters that exceed a baseline level of pollution can buy carbon credits to compensate. In 2017, only a few companies, including many coal mines, spent about $6 million credit market. Australia is currently well on its way to lose its general objectives to reduce emissions.

Carbon pricing could still come back. Australia is expected to hold a federal election in May and the Labor Party suggested reset a scaled-down version of cap-and-trade for the nation's biggest polluters. However, carbon pricing remains a contentious issue in the country, which has been hit hard by global warming but is also the world's largest coal exporter.