It’s true that climate varies naturally over both short and long time-scales, but it’s possible to distinguish natural climate change from human caused climate change.
Scientists have conducted a number of “attribution studies” that compare observed changes in the global climate with those factors that are known to influence climate. These studies indicate that the climate change observed over the 20th century is due to a combination of changes in solar radiation, volcanic activity, land-use change, and increases in atmospheric greenhouse gases. Of these, greenhouse gases appear to be the dominant driver of climate change over the past few decades.
But that doesn’t prove that human activity is responsible for increases in greenhouse gases.
Not true. Some greenhouse gases, such as industrial halocarbons, are only made by humans, and thus their presence in the atmosphere can only be explained by human activity.
CO2 and CH4 are naturally occurring, generated by plant and animal respiration and decomposition. But, again, scientists can quantify the various sources (both natural and human) of such gases and measure their contribution to atmospheric concentrations. Current concentrations of the primary greenhouse gases (see above) cannot be accounted for without considering human activities, particularly the combustion of fossil fuels. Worse, global warming may increase the release of greenhouse gases from natural resources.
It’s naïve to think we can live without fossil fuels.
We can actually move away from fossil fuels, but not overnight. Just because our economy is dependent on fossil fuels now doesn’t mean it always has to be. In the medium to long term, with innovation, market incentives, and the right policies, we can transition to different fuels, different infrastructure, higher efficiency, and different technologies. We need to concentrate on the development of alternative energy sources such as wind energy and solar power. Technological innovation in energy efficiency is also important.
But the economic costs of transitioning are too high economically. What about the folks whose jobs are dependent on fossil-fuels?
True, the costs of addressing climate change are likely to fall disproportionately on certain industries, communities, and workers. But that’s not an argument for inaction on global warming; it’s an argument for designing and implementing programs that help workers adversely affected by climate change policies. These could include retraining and education for laid-off workers, advance notice of layoffs when possible, substantial income support for program participants, and maintenance of laid-off workers’ health and pension benefits until they find suitable employment.
What about the cost to the economy at large?
Economic costs of climate change policies are defined as opportunity costs – in this case what must be sacrificed or changed in order to reduce emissions. Categories of economic costs include discouraged investment, slowed innovation, disrupted production, increased capital and operating expenditures, monitoring and enforcement costs, legal and other transaction costs.
However, there are “positive costs”, or benefits, including productivity improvements from a cleaner environment and innovation-stimulating effects of regulation. And don’t forget the benefits arise from avoiding big problems, like scarcer water resources, damages to human-built environment; coastal flooding due to sea-level rise, and human-health impacts.
Well, if you want to talk about benefits, won’t climate change produce as many good effects as bad?
Current assessments indicate that agriculture and forestry in the United States are likely to benefit from low to moderate climate change, although these benefits will not be evenly distributed geographically, and some regions will experience damages. With continued warming, however, benefits will likely peak and subsequently decline, and the effects of climate change for the nation as a whole in these sectors will turn negative.
Other benefits such as increased water availability, reduced energy demands, and greater ecosystem productivity may also occur in specific regions over the short or long-term. Such benefits will likely be balanced by opposite effects in other regions.
Well, OK, but if climate change is a real problem, it’s a global problem. Why should the US be expected to take the lead on this?
Because the United States is responsible for approximately 25 percent of global greenhouse gas (GHG) emissions to date, and its emissions continue to increase. As the world’s largest economy, and the world’s largest emitter of greenhouse gases, the United States is central to any long-term strategy to address global climate change.
Fine, but it’s an issue for governments to sort out. Ordinary citizens can’t do anything about global warming.
On the contrary, the two levels of engagement go hand in hand. Simple but effective things that individuals can start doing NOW include: reducing energy use at home by purchasing energy efficient home appliances; planting trees to absorb carbon from the atmosphere; walking or taking public transportation instead of driving; making smart consumer choices by purchasing environmentally sound products and energy-efficient vehicles; and practicing waste minimization, product reuse, and recycling.
OK, but what’s the rush? Shouldn’t we wait till we know more about the problem, if it is a problem, before rushing to turn our lives upside-down?
The scientific literature on global warming is very clear: we do not need to know more in order to conclude with confidence that the trend towards a warmer global climate is real, and that action should begin now. Waiting to take action ignores the strong evidence that GHG concentrations in the atmosphere are building and if left unchecked will exceed a doubling of their pre-industrial levels. Other compelling reasons to begin taking action include the potential for catastrophes that defy the assumption that climate change damages will be incremental and linear; the risk of irreversible environmental impacts; the need to learn about the pace at which society can begin a transition to a climate-stable economy; the likelihood of imposing unconscionable burdens and impossible tasks on future generations; the need to create incentives to accelerate technological development the address climate change; and the ready availability of “no regrets” policies that have very low or even no costs to the economy. Moving forward with a real and rational program to reduce GHGs allows us to address this challenge in a way that is timely, consistent, meaningful, and cost-effective.
