And he made a pitch to increase the use of nuclear power, describing it is a green energy source that would use uranium produced in Canada as its fuel.
It's a message Mr. Harper and other government officials have often repeated for domestic audiences but he is now taking to the international stage in advance of the G8 summit in Japan in July.
"The bottom line is that global warming is a global problem," Mr. Harper said in a speech to the Canada-U.K.
Chamber of Commerce. "We will not solve it unless our environmental plans are economically balanced. Environmental progress will never be achieved unless the economic needs of the population are being met."
Mr. Harper then outlined Canada's plans to cut greenhouse gas emissions by 20% below 2006 levels and to do that by 2020.
"Our mid-term, 2020 target is... one of the most aggressive emissions-reduction goals in the world," Mr. Harper said.
Britain and other European Union countries, however, are finalizing plans to bring down greenhouse gas emissions by 20% to 40% by 2020 and the baseline Europe will use will be 1990.
Greenhouse gas emissions were much higher in 2006 than they were in 1990 so using a baseline year that is farther in the past means that the European target, should it be implemented, will be more aggressive.
Britain and other countries have also been pressing Canada to aim for the European target.
Mr. Harper, however, has rejected targets based on any year prior to when his government took office.
"Our targets are ambitious but realistic," he said.
He is expected to further elaborate on his plans in a private meeting with British Prime Minister Gordon Brown.
Britain and Canada do not agree on an approach to cutting the greenhouse gas emissions that cause climate change.
Mr. Harper also believes that a more modest target for emissions cuts has a better chance of being endorsed by the United States, which never signed on to the Kyoto Protocol, and the fast growing economies of India and China.
"The next UN protocol on climate change must be truly global," Mr. Harper said. "It must include binding targets for all the world's major emitters, including China and the United States.
"We will never see the United States ratify a protocol that does not require genuinely global action."
Mr. Harper spoke to U.S. President George W. Bush by telephone recently and, according to PMO officials, the two discussed climate change.
Mr. Harper told the business crowd that nuclear energy must play a key role as a replacement for other power sources, such as coal-fired electricity plants, which produce greenhouse gas emissions.
"As the largest producer of uranium, we can contribute to the renaissance of nuclear energy, a no-emissions source that will be expanding here in Britain and around the world," Mr. Harper said.