Questions People Ask About Climate Change

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Questions People Ask About Climate Change This article will be appearing in the April 2003 issue of U-Turn Magazine

Author(s): Kenneth Green, Director of the Centre for Studies in Risk and Regulation

Release Date : March 27,2003

Many claims are made about the scientific understanding of climate that are not backed up by the core literature that dominates the field. But as most people read only summary versions of the scientific literature, they're easily led astray by alarmist groups that exaggerate the concerns, while waving away the uncertainties that pervade climate science. Let's consider some key questions about climate change.

IS THE ATMOSPHERE WARMING ABNORMALLY?

Assuming that we can trust the temperature data that we have available to us, the answer seems to be 'yes, in some places, in recent years, the average temperature of the Earth's atmosphere seems to be increasing slightly.' But the question of whether it's getting hotter is meaningless without a discussion of historical perspective and relevant measuring period. Climate has fluctuated, often wildly, for more than four billion years. Given that we have so little hard data about past climate conditions, the most intellectually honest answer to this question is 'maybe' and even that answer is meaningless without some kind of qualifying time frame, and standard of comparison.

Recently, we seem to be seeing a minor warming in the Earth's average temperature, as best as we can measure it (which isn't very well). That's because our hard temperature data spans only about 150 years. In fact, temperature records are spotty before about 40 years ago and only cover a tiny portion of the globe, mostly over land. In addition to that 150-year conventional surface temperature record, temperature readings taken from weather balloons cover the last 30 years, and satellite temperature readings cover the last 18 years. Given that fluctuating, and spotty temperature record, one can create the impression that the temperature is rising, falling, or staying the same simply by changing the start and end points of the period being examined.

HOW CERTAIN IS OUR UNDERSTANDING OF THE ROLE OF HUMANITY IN CAUSING CLIMATE CHANGE?

Between our incomplete understanding of the climate system, and the difficulty of 'scaling up' what we do know to the level of global climate effects, including effects on oceans, ecosystems, mountains, rivers, groundwater, solar variation, greenhouse gas emissions, clouds, aerosols, water vapor, and historical variation, then trying to scale the impacts back down to the local and regional level, we are left with a view best characterized as 'through a glass, darkly.'

One need not look beyond the landmark reports of the United Nations Intergovernmental Panel on Climate Change (IPCC) for expressions of that uncertainty. Of the twelve suspected 'forcings' that are considered capable of changing the climate (either warming or cooling), the latest report ranks scientific understanding of only one type of forcing (from greenhouse gases) as 'high.' Fully 2/3 of the potential climate forcings, are ranked as 'Very Low' in scientific understanding. Within those poorly understood forcings lies a climate cooling potential that could cancel out the theoreticized warming potential of the greenhouse gases altogether.

GIVEN WHAT WE KNOW, WHAT'S OUR BEST COURSE?

For any risk we face, there are many available risk-reduction actions available to us that let us move toward decreased environmental risk for ourselves and our children. But does the actual evidence tell us what to do? No. But it does suggest what we can do with any probability of success.

At the most generic level our options range from the resilient to the

And of course, you ask questions about a scientific issue to a nonscientist. Are you this big a fool?

Indeed. And terms like 'slightly' are meaningless unless quantified.

Oh my oh my. Suddenly, all the qualifications have gone! Here we have complete and utter certainty, about times when we know almost nothing. For all we know, temperatures were near constant at some unknown level for the period 3-4 billion years ago. And what about 'wildly'? Does that mean 'rapidly'? In which case, the only period over which we have any hope of checking that statment would be the 400kyr of the ice core record.

Sounds dubious.

Plenty of marine records out there.

...

by number, not effect

Or, just as easily, lead to extra warming.

What are they talking about here?

This will come as a surprise to the readers of sci.env.