The United States has been internally conflicted about climate change, until now, it seems. With the release of the Third National Climate Assessment, the Obama administration has drawn on a wide range of observations about weather, precipitation patterns, water quality and availability, health, infrastructure, agriculture and the oceans to arrive at firm conclusions about humanity’s responsibility for increasing levels of greenhouse gases in the atmosphere. The arguments in the assessment report are bolstered by including descriptions of impacts and feedback loops that are specific to each region of the United States. There is nothing like examples to demonstrate concreteness. Overall, the conclusions echo those of the International Panel on Climate Change (IPCC) but with a uniquely American flavour. Despite its 800+ pages, it is written in a way that is accessible to general readers.

Energy use and in particular fossil fuel consumption feature prominently in the report. To put things in perspective, between 1963 and 2008 annual American GHG emissions doubled. But from 2008 and 2012 the US achieved a 9% reduction. This is largely attributable to the substitution of gas for coal in electricity generation and significant improvements in fuel efficiency. Some might claim this transition was inevitable given the price of natural gas and that a large number of facilities would have been retired anyway. In any case, this has meant is a 20% reduction in net US electricity generation from coal.[1] Like many OECD countries, the US has also reduced its energy intensity, owing to the substitution response just noted as well as changes in the composition of the capital stock, technological change and the ongoing shift of the US economy toward services. The Obama administration is moving to eventually eliminate the direct burning of coal for electricity generation unless there is carbon capture and storage. A similar constraint may be imposed on electricity generated from natural gas in the more distant future. Substitution of biofuels and electricity for fossil fuel has potential to cut emissions in the transportation sector.

Current US emissions represent 18% of the global total, ranking the US second next to China (25%). The challenge from a mitigation and adaptation perspective, which is the main focus of the report, is how to react and manage past contributions of greenhouse gases while planning to reduce the volume of emissions going forward. The past cannot be changed but it presents an interesting conundrum when considering choices for the future. All of this is described in an excellent and useful section of the report on risk and risk perceptions. Most people have a short time horizon for perceiving risk and for thinking about the payback on investments that might be made to mitigate risk. Climate change is a long term challenge with the potential for significant consequences. It is difficult for most people to comprehend investment decisions with very long payback periods, particularly when they are accompanied by short-term costs.

Despite this and the significant political pressures to do nothing, the new US report is more measured than other recent apocalyptic climate change musings. As a result, many of the arguments for changes in policies and practices are persuasive. There is acknowledgement of uncertainties and of the uneven distributional effects of measures to address GHGs. The report also notes options for adaptation. At the same time there is talk about the benefits of taking action now. Overall, the content is believable and supports a market-based approach that puts a price on GHG emissions, as well as setting regulations and standards for activities that cause emissions, overhauling subsidy programs, and using direct federal government expenditures to accelerate change.

In contrast, Canada’s latest submission to the United Nations sounds defensive. At the same time, an assessment by Scotiabank (May 9, 2014), using data from Environment Canada, shows that GHG emissions are stable at 700 megatonnes. Good news? Importantly, emissions appear to have decoupled from economic and population growth. However, Canada remains one of the highest per capita emitters, reflecting our geographic size, modest population, cold climate, and huge endowment of energy and other natural resources. Most analysts believe Canada won’t be able to meet the GHG reduction goals adopted by the federal government at the Copenhagen climate change conference in 2009. Perhaps we can take a page or two from our neighbour in terms of at least laying out what might be possible.