President Barack Obama has committed to fight global warming. In just his first few weeks in office, the president has already taken steps to move America in a direction that will reduce greenhouse gas emissions. The most important step so far is the indication that tailpipe emissions will be regulated as needed for improved fuel efficiency. Similar steps will be needed to improve energy efficiencies in buildings and homes.
In my opinion, and in the view of most economists, these steps must be accompanied by a rising price on carbon emissions, if we hope to stabilise atmospheric composition. Incentives must be provided for economic development that steadily replaces outdated fossil fuel based energy infrastructure. Such transformation is needed if we are to preserve for future generations the remarkable planet that we inherited from our elders.
Now Obama is on his first foreign trip - destination Canada. Few realise that Canada is America's number-one source of oil. And, unlike energy conversations in prior administrations, science and the environment are expected to be an important part of the agenda. Let us hope so.
The Canadian press is full of speculation that the Canadian government will push for special treatment and protections from global warming regulation of its fastest growing source of greenhouse gas emissions: the tar sands oil development in Alberta, where much of Canada's oil is derived. Such protection would be disastrous for life on our planet.
The tar sands of Canada constitute one of our planet's greatest threats. They are a double-barrelled threat. First, producing oil from tar sands emits two-to-three times the global warming pollution of conventional oil. But the process also diminishes one of the best carbon-reduction tools on the planet: Canada's Boreal Forest.
This forest plays a key role in the global carbon equation by serving as a major storehouse for terrestrial carbon - indeed, it is believed to store more carbon per hectare than any other ecosystem on Earth. When this pristine forest is strip mined for tar sands development, much of its stored carbon is lost. Canada's Boreal Forest is also the reservoir for a large fraction of North America's clean, fresh water, home to some five billion migratory birds, and some of largest remaining populations of caribou, moose, bear and wolves on the planet.
As a climate scientist, I am focused on what levels of atmospheric carbon dioxide can be considered safe. In the past few years, based on increasingly detailed information about the history of the Earth and observations of ongoing climate change, a startling conclusion has become apparent. The safe level of atmospheric carbon dioxide is no more than 350 parts per million (ppm), if we wish the diversity of other species on the planet to survive - as well as "amenities" that humans require, such as fresh water supplies, stable coastlines and a normal degree of extreme weather events.
Unfortunately, because of our fossil fuel use, our planet is already at 385 ppm. It is still practical, with improved agricultural and forestry practices to get future carbon dioxide levels below 350 ppm, provided we phase out emissions from the largest source, coal, in coming decades. It is a tough challenge to develop the needed renewable energies of the future, but it is doable. Together with improved energy efficiency we can move to the clean world of the future, beyond fossil fuels.
So an underlying fact has become crystal clear. The horrendously carbon-intensive unconventional fossil fuels, tar shale in the US and tar sands in Canada, cannot be developed. The carbon emissions from tar shale and tar sands would initiate a continual unfolding of climate disasters over the course of this century. We would be miserable stewards of creation. We would rob our own children and grandchildren.
Now is a critical moment in the history of our planet. The US and Canadian governments must agree that the unconventional fossil fuels, tar sands and tar shale, will not be developed. They will thus send a message that their statements recognising "a planet in peril" are not empty rhetoric. They will provide hope to young people and nature. We can preserve our heritage with its remarkable diversity of life.