Dr Michael MacCracken
Nigel Allan: When and why did you get involved in climate science in the first place?
Mike MacCracken: I became involved in studies of climate change as part of my graduate studies during the mid and late 1960s.
My graduate dissertation examined how changes in Arctic sea ice extent might be contributing to the cycling of ice ages, to their advances and retreats. My first task was to construct one of the very first climate models and the second was to use the model to try and understand what would happen if the Arctic Ocean were free of ice or if there were a more extensive glacial cover over the northern hemisphere.
I then got interested after that in both natural and human influences on the climate, including investigating the potential effects of the proposed international fleet of super-sonic aircraft and of volcanic eruptions and increasing concentrations of greenhouse gases, which were a concern way back in the 1970s.
NA: Beyond “doing the science”, what role do you think scientists can play to encourage policy-makers to adequately address climate change?
MM: There are two important roles.
Firstly a very important role is helping build public awareness and that includes understanding by the policy-makers themselves. But for policy-makers to act they have to be able to talk to the public and have a public that understands what is happening and what could happen.
A second role for scientists is to help the policy-makers understand what the options are for taking action. Not only which technologies might be able to have an effect, but to understand the influences of each of the different compounds we’re putting into the atmosphere, whether carbon dioxide or methane or nitrous oxide or soot, and which ones can be most effectively dealt with?
NA: What role do you think a programme like Climate Witness can play in addressing climate change?
MM: Well, during the late 1990s I was in charge of co-ordinating the US National Assessment of the Consequences of Climate Change. There was clear recognition through the Intergovernmental Panel on Climate Change (IPCC) that the climate was changing and now the question was what was happening in various areas around the United States.
We had a number of regional workshops where we described the kinds of things that could happen and then we asked people what was happening. We heard a lot of stories about how climate change was affecting their region, whether sea level rise or changes in water resources. Then we had these groups look and talk about what they thought the implications for their region would be as a result of these kinds of changes.
So, we learned a lot by just listening to the people about what was happening, because impacts happen locally; climate change is looked at from the global to local scale, but impacts start locally.
"People often recognise subtleties about what’s happening that scientists who are looking at the longer-range and larger-scale changes just don’t pick up. Yet these finer scale responses can be very important when thinking about impacts." - Mike MacCracken
That assessment activity went on from 1997 to 2000 but it was largely discontinued by the Bush Administration. So, I was glad to hear Climate Witness was getting started because it was, again, listening to the people about the kinds of changes they are seeing. People often recognise subtleties about what’s happening that scientists who are looking at the longer-range and larger-scale changes just don’t pick up. Yet these finer scale responses can be very important when thinking about impacts.
NA: As a member of the Climate Witness Science Advisory Panel, what do you think is the significance of the Panel in the Climate Witness Programme’s work?
MM: It’s very helpful when the witnesses themselves identify changes they are seeing and experiencing, but it is also important to recognise that there are many things changing in the world and not all the changes people see are going to be due to climate change. They might be due to other kind of factors, including how increasing development is changing the landscape.
"We found it was just very useful to talk to people and to listen to them and have a good interaction about what they were seeing and how the changes might be explained or consistent with or sometimes inconsistent with what the scientific community is projecting to occur as a result of global warming." - Mike MacCracken
Having a scientist go over what is being suggested to look at whether the identified changes are likely to be consistent with scientific findings helps clarify some of the issues. Based on my familiarity with the larger scale changes, I can try to put what is happening locally in a larger context and that can help give people some appreciation about what they’re observing and also give a sense of what might be happening regionally and why it’s happening. So it’s a very useful linkage.
Encouraging interactions between those focused on large and on local scales was also something we did a lot during the National Assessment, where we had the scientists sit down with the resource, business, and government experts who had a real interest in local conditions and talk through what the issues were, what they were seeing, and what they wanted to know. We found it was just very useful to talk to people and to listen to them and have a good interaction about what they were seeing and how the changes might be explained or consistent with or sometimes inconsistent with what the scientific community is projecting to occur as a result of global warming.
Even with many climate models, we are not yet able to make detailed projections down to the local scale, so we can learn a lot by listening to what people are observing. Observations of small changes can be very important.
NA: Are there Climate Witness observations that stand out for you?
MM: Well the two Climate Witness submissions that I have responded to were very thoughtful observations about what was happening.
Joe Schaedler in Minnesota was observing how not only the warming of winter was affecting the dates of freezing and melting of the region’s lakes and the effects on lake fishing, ice fishing and other kinds of things, but he was also noticing how the ground was not freezing as deeply and this turns out to be important in determining how long the snow cover lasts. If you don’t freeze the ground, then the snow cover tends to melt more quickly. If you don’t get an early winter cooling from cold air coming out of the Arctic the ground doesn’t get cold enough to really sustain the snow that does fall, so that starts affecting what happens when the snow melts and water penetrates into the ground.
The other submission was from Cheryl Aldrich, a horticulturalist in Georgia, and she seemed to have all kinds of interesting observations about what was happening with respect to how the plants were responding. I know up here in Washington where I live the flower-plant zone that we are in has changed. We are now part of the southern plant zone instead of the mid-Atlantic zone. This change was made because plants more typical of the southern US are surviving through the winter and so we are getting different mixes of vegetation; simultaneously, more northern are not surviving because conditions get too hot in the summer and do not get cold enough to shut them down in the right way.
So I thought both of the witness statements that I got to comment on were very thoughtful and represented well-informed views about what was happening.