How concerned should we be about climate change? Threats such as ISIS, ebola and shaky economies seem much more immediate and tangible than global warming. We asked two of Tech’s top experts in the field to discuss the issue.
Uncertainty Doesn’t Mean We Shouldn’t Take Action
By Judith Curry
At the recent United Nations Climate Summit, U.N. Secretary-General Ban Ki-moon warned that “without significant cuts in emissions by all countries, and in key sectors, the window of opportunity to stay within less than 2 degrees [of warming] will soon close forever.” The premise of dangerous human-caused climate change is the foundation for President Barack Obama’s plan to reduce greenhouse gas emissions. So, is there an overwhelming scientific justification for the premise of dangerous human-caused climate change and the urgency for immediate action? I am concerned that the problem and its solution have been vastly oversimplified.
The climate has always changed and will continue to change. Humans are adding carbon dioxide to the atmosphere, and carbon dioxide and other greenhouse gases have a warming effect. However, there is enduring uncertainty beyond these basic facts, and the most consequential aspects of climate science are the subject of vigorous scientific debate: whether the warming since 1950 has been dominated by human causes, and how the climate will evolve in the 21st century due to both natural and human causes.
There is growing evidence that the climate is less sensitive to adding greenhouse gases than has been predicted by climate models. Solar variability, volcanic eruptions and long-term ocean oscillations will continue to be sources of unpredictable climate surprises. Societal uncertainties further cloud the issues as to whether warming is “dangerous” and whether we can afford to radically reduce carbon dioxide emissions in the near term.
Can we make good decisions under conditions of deep uncertainty about climate change? Uncertainty in itself is not a reason for inaction. Research to develop low-emission energy technologies and energy efficiency measures are examples of “robust” policies that have little downside. It is in America’s long-term political and economic interests to develop a renewable alternative to fossil fuels. However, attempts to modify the climate by reducing carbon dioxide emissions may turn out to be futile. The hiatus in warming since 1998 demonstrates carbon dioxide is not a control knob on climate variability on decadal time scales. Even if carbon dioxide mitigation strategies are successful and projections are correct, any climate impact would not be expected until the latter part of this century.
Whether or not human-caused climate change is exacerbating extreme weather events, vulnerability to these events will continue—owing to increasing population and wealth in vulnerable regions. Climate change may be less important than rising populations, land use practices and ecosystem degradation. Regions that find solutions to problems of climate variability and extreme weather, and address relevant challenges of an increasing population, are likely to be well prepared to cope with any additional stresses from climate change.
— Judith Curry is Professor in the School of Earth and Atmospheric Sciences at Georgia Tech, specializing in the dynamics of weather, climate and the atmosphere.
We Have to Start Paying Down Our Climate Debt Now
By Kim Cobb
As a climate scientist, I firmly believe that if Americans understood the facts about climate change, they would be concerned enough to support a comprehensive, data-driven plan to reduce greenhouse gas emissions. Nobody with any knowledge on the subject denies that carbon dioxide (CO2) derived from the burning of fossil fuels is measurably warming the planet. Nobody denies that the risks of climate change will accelerate as greenhouse gas emissions accelerate. And nobody denies that, given the long lifetime of CO2 in the atmosphere, the climatic response of our current emissions will play out over the lifetimes of our children and our grandchildren. They will inherit our generation’s climate debt, and its accrued interest, potentially in the form of irreversible impacts.
Opponents of climate action cite grave uncertainties about the magnitude of future climate change impacts, but such uncertainties are two-sided. It is equally likely that future impacts will be less than or greater than those projected by climate models. So yes, there is a very small chance that climate change impacts will be relatively benign over the next century, with modest damages. But there is also a very small chance that those impacts will translate into economic “catastrophe”— in the jargon of economists who attempt to quantify climate change risks.
In this sense, inaction on climate change is like betting against the house when you know the deck is stacked in its favor. You might be willing to lose a few bucks for a small chance of a huge payout, but you wouldn’t bet your life’s savings.
For those who are concerned, it’s often unclear what, if anything, can be done to avert climate change. It is true that whatever steps we take today to limit greenhouse gas emissions, climate change will still accelerate over the next decades—the climate system and energy infrastructure both carry appreciable momentum.
But by the same token, the longer we wait to begin curbing emissions in earnest, the tighter we lock future generations into a path of accelerating climate change. For every year we delay, we accept (knowingly or not) that the stabilization level for greenhouse gas concentrations in the atmosphere will be ever higher, and the associated climate risks ever greater. The recent agreement between the United States and China to limit emissions growth over the next decades is an important down payment towards collective climate action, but the most effective action will come when each and every American understands that they have a role to play in reducing emissions.
The power of collective action is demonstrated during a class project in my “Energy, the Environment, and Society” course that I teach at Tech each spring. In the Carbon Reduction Challenge, student teams compete to reduce CO2 emissions over the course of two short months. The most successful teams engage with private-sector partners, and the savings they achieve are remarkable. One winning team averted over 180,000 pounds of CO2 emissions by recycling wooden pallets at a large manufacturing plant. That’s equivalent to taking 15 cars off the road for an entire year.
If each American began to rethink how they conduct their own “business as usual,” and that of their workplace, we could begin to pay down the climate debt while paving the way for a sustainable energy and climate future for our children and grandchildren. A collective effort to reduce energy use, when combined with the continued development and deployment of affordable, low-carbon energy technologies, puts such a goal in reach.
— Kim Cobb is Associate Professor in the School of Earth and Atmospheric Sciences at Georgia Tech, specializing in paleoclimates, climate change and geochemistry.