Dr. Cameron Wake, Climate Change Research Center, UNH
October 2008 Interview with Clean Air - Cool Planet's Chief Scientist, Cameron Wake. Dr. Wake is a paleoclimatologist and Research Associate Professor at the Climate Change Research Center of the University of New Hampshire.
CA-CP: Why are ice cores so important?
Wake: Climate scientists love ice cores because they hold really high resolution records of how and why our climate has changed. The ice of glaciers starts as snow, and that snow forms around particles in the atmosphere, and that snow accumulates on glaciers. Depending on the location of the glacier, this results in several feet of snow per year – with less in Antarctica and more in Greenland, for example. This annual accumulation of snow allows us to count back annual layers hundreds to thousands to tens of thousands of years and they allow us to observe changes in climate that happen very quickly, at least in geophysical terms. So this is why we say they are “high resolution” because they provide annual or decadal records.
CA-CP: What kinds of things can ice cores tell us?
Wake: There is a large number of analyses we can do that provide information on many different aspects of the climate system like temperature, atmospheric circulation, and dust loading and greenhouse gas content of the atmosphere. So, we can analyze the stable isotope content of the water that comes from the snow, and that provides information on the temperature at which the snow formed and also where the moisture came from, which in turn tells us something about the circulation of air and ocean currents. We can look at the salt, calcium, magnesium, potassium and ammonia, and they all tell us different things about the strength of atmospheric circulation, the amount of dust in the air and the and extent and activity of different large ecosystems. When we look at trace metals, like lead, for instance, that gives an indication of how humans are changing the environment over time. There are also air bubbles trapped in the glacial ice containing greenhouse gases, like carbon dioxide, methane, and nitrogen oxide. From this we can track the variability of greenhouse gases over time, and compare this to changes in temperature and atmospheric circulation. There is also dust from desert regions and volcanoes deposited on the glacier. How much there is and where it comes from and how it changes over time tells us about atmospheric circulation (both air currents and ocean currents), how desert regions of the globe have changed, and when volcanic eruptions have occurred in the past. For example, ice core data shows strong correlations between deposition of iron dust on the ice sheets and a decrease in the carbon dioxide content of the atmosphere. This suggests that increased iron deposition in the oceans (inferred from increased deposition on glaciers) is an important mechanism regulating how much carbon dioxide is removed from the surface ocean by phytoplankton in the oceans, since phytoplankton populations are increased by iron. Finally we can look at certain isotopes in the ice that represent records of solar activity. By comparing these with other analyses, we can get a picture of how the sun influences climate as well.
CA-CP: When you put all this together, what does it tell you?
Wake: We refer to the ice cores as a source of multi parameter information, and we first try to describe how climate has changed. Then, when we’ve determined how it has changed, we can use the information from these cores, and other sources of information, to help us determine why it has changed.
CA-CP: What is the reason for collecting core samples in so many remote places around the world?
Wake: Remote areas have no local sources of pollution, so they are useful in generating a true record on a broad scale, from regional to hemispheric. But we need to have cores from multiple locations in order to better understand the regional variability in the global climate system. From large ice sheets like West Antarctica and Greenland, we have very long global records, while from mountain glaciers we have regional pieces, and we can investigate regional similarities and differences. The data that originates from ice core records is also used to verify output from global climate models. Finally, ice core records from around the globe have provided valuable information on rapid climate change events (dramatic changes in climate that occur in a decades or less). Ice cores, because of the annual resolution, can add that kind of detail of changes over more refined time scales.
CA-CP: You were working on an ice core project in Denali National Park (home of Denali a.k.a. Mount McKinley, the highest peak in North America at 20,320 feet) this summer. Why?
Wake: One of our goals is to develop a more comprehensive understanding of how climate has changed throughout the Arctic. In order to do this most effectively, we are gathering the high-resolution, multiparameter records of ice cores from various ice caps and glaciers around the region. We have the long-term, hemispheric record from Greenland, and now we are compiling records from a network of other locations in order to better understand variations in sea ice, volcanism, pollution, and the regional characteristics of climate events like the Medieval Warm Period and the Little Ice Age. This network includes the Penny, Devon and Agassiz ice caps, glacier ice on Mt. Logan, and the Eclipse Icefield. Other groups are working in Scandinavia at Spitsbergen and Svalbard, and in northern Russia. We had records from coastal Alaska, but none from the interior, and our work in Denali will help fill that gap. A clear record from Denali will help round out the bigger paleoclimate picture by adding critical information gathered from ice cores recovered around the North Pacific, all of which can be compared to a wealth of climate data already gathered in the North Atlantic region. One of the particularly interesting and challenging pieces of this project is testing a long-standing hypothesis that the North Atlantic region drives global climate changes. But there are now indications that a change in the North Pacific might happen first and drive a North Atlantic response. We need to better understand the relationship in terms of the timing and magnitude of climate change between these two regions if we are going to really understand what drives climate change in the Arctic. And so developing these high-resolution records that are directly comparable is really important.
CA-CP: What do you hope those comparisons will tell us?
Wake: There are some really big questions to answer about the timing of climatic events, which is absolutely necessary to understanding the why climate changes question. We think that 1500 year cycles are driven by deep water circulation in the North Atlantic – so changes should appear first in the North Atlantic and then in Antarctica, where long records do not have the resolution of the shorter records we are getting here. Ice cores currently being recovered from the West Antarctic Ice Sheet will be compared with data from Greenland to help unravel timing, and then data from the tropics, from the Andes, for instance, will tell us about when changes occurred there. The data we will get from Alaska will help to explain what is going on in the North Pacific and when. Ultimately, we are trying to put together the puzzle of the global climate system – what are its drivers, what makes things happen, and why.
CA-CP: What did you accomplish this summer?
Wake: We started out this summer using a portable, ground-penetrating radar to determine the ice thickness and internal structure on various glaciers, looking for “layer-cake” ice with clear, well-defined annual strata. We also collected samples for chemical analysis from 20-foot-deep snowpits and firn (snow that has not turned to ice) cores drilled 60 feet deep from the bottom of the snowpits, and installed automatic weather stations at heights of 7,800 and 14,000 feet. The chemical analyses will be carried out at UMaine and UNH labs to decipher changes in temperature, atmospheric circulation, and environmental change – such as the phenomenon known as “Arctic haze,” which has brought heavily polluted air masses to the region for decades from North America, Europe, and Asia. We expect to spend one more field season at Denali next year – to download data from the weather stations – and then hope to begin the deep-drilling program in the spring of 2010, if we get NSF funding for the second phase of the project. Our goal is to recover surface-to-bedrock ice cores from glacial ice that is about 1,000 feet thick, which should provide a detailed record of climate and environmental change extending back several thousand years.
CA-CP: Where does all of this fit in the huge picture of the climate of the planet?
Wake: It’s a tiny piece, 800,000 years out of roughly 4.5 billion – but it’s the most recent piece. The farther back you go, the less we know. What we know about the distant past is from geological deposits, sediments, and glacial deposits – rocks. And rocks can’t tell us things with the resolution and subtlety of snow. On the other hand, we discovered most of what we know about the occurrence and reoccurrence of ice ages from studying glacial moraines. Some of what we know comes from our understanding of how changes in our orbit of the sun, combined with sometimes very small changes on the planet, magnified by feedback loops, can drive huge swings in the Earth’s climate. So, what starts a change may be very small – like the hole in the tire that eventually stops the car. If you look at what’s happening now with sea ice, for instance, and the loss of albedo or reflectivity and more and more heat-absorbing dark water being exposed, warming, and melting more ice, you get a sense of how something that starts out small can be magnified by a positive feedback. But we have a good understanding right now of a lot of the parameters – the water, air, and temperature, and how it’s changed at least in the last at least half million years. Now we’re working hard on the why.
CA-CP: Why are ice cores so important?
Wake: Climate scientists love ice cores because they hold really high resolution records of how and why our climate has changed. The ice of glaciers starts as snow, and that snow forms around particles in the atmosphere, and that snow accumulates on glaciers. Depending on the location of the glacier, this results in several feet of snow per year – with less in Antarctica and more in Greenland, for example. This annual accumulation of snow allows us to count back annual layers hundreds to thousands to tens of thousands of years and they allow us to observe changes in climate that happen very quickly, at least in geophysical terms. So this is why we say they are “high resolution” because they provide annual or decadal records.
CA-CP: What kinds of things can ice cores tell us?
Wake: There is a large number of analyses we can do that provide information on many different aspects of the climate system like temperature, atmospheric circulation, and dust loading and greenhouse gas content of the atmosphere. So, we can analyze the stable isotope content of the water that comes from the snow, and that provides information on the temperature at which the snow formed and also where the moisture came from, which in turn tells us something about the circulation of air and ocean currents. We can look at the salt, calcium, magnesium, potassium and ammonia, and they all tell us different things about the strength of atmospheric circulation, the amount of dust in the air and the and extent and activity of different large ecosystems. When we look at trace metals, like lead, for instance, that gives an indication of how humans are changing the environment over time. There are also air bubbles trapped in the glacial ice containing greenhouse gases, like carbon dioxide, methane, and nitrogen oxide. From this we can track the variability of greenhouse gases over time, and compare this to changes in temperature and atmospheric circulation. There is also dust from desert regions and volcanoes deposited on the glacier. How much there is and where it comes from and how it changes over time tells us about atmospheric circulation (both air currents and ocean currents), how desert regions of the globe have changed, and when volcanic eruptions have occurred in the past. For example, ice core data shows strong correlations between deposition of iron dust on the ice sheets and a decrease in the carbon dioxide content of the atmosphere. This suggests that increased iron deposition in the oceans (inferred from increased deposition on glaciers) is an important mechanism regulating how much carbon dioxide is removed from the surface ocean by phytoplankton in the oceans, since phytoplankton populations are increased by iron. Finally we can look at certain isotopes in the ice that represent records of solar activity. By comparing these with other analyses, we can get a picture of how the sun influences climate as well.
CA-CP: When you put all this together, what does it tell you?
Wake: We refer to the ice cores as a source of multi parameter information, and we first try to describe how climate has changed. Then, when we’ve determined how it has changed, we can use the information from these cores, and other sources of information, to help us determine why it has changed.
CA-CP: What is the reason for collecting core samples in so many remote places around the world?
Wake: Remote areas have no local sources of pollution, so they are useful in generating a true record on a broad scale, from regional to hemispheric. But we need to have cores from multiple locations in order to better understand the regional variability in the global climate system. From large ice sheets like West Antarctica and Greenland, we have very long global records, while from mountain glaciers we have regional pieces, and we can investigate regional similarities and differences. The data that originates from ice core records is also used to verify output from global climate models. Finally, ice core records from around the globe have provided valuable information on rapid climate change events (dramatic changes in climate that occur in a decades or less). Ice cores, because of the annual resolution, can add that kind of detail of changes over more refined time scales.
CA-CP: You were working on an ice core project in Denali National Park (home of Denali a.k.a. Mount McKinley, the highest peak in North America at 20,320 feet) this summer. Why?
Wake: One of our goals is to develop a more comprehensive understanding of how climate has changed throughout the Arctic. In order to do this most effectively, we are gathering the high-resolution, multiparameter records of ice cores from various ice caps and glaciers around the region. We have the long-term, hemispheric record from Greenland, and now we are compiling records from a network of other locations in order to better understand variations in sea ice, volcanism, pollution, and the regional characteristics of climate events like the Medieval Warm Period and the Little Ice Age. This network includes the Penny, Devon and Agassiz ice caps, glacier ice on Mt. Logan, and the Eclipse Icefield. Other groups are working in Scandinavia at Spitsbergen and Svalbard, and in northern Russia. We had records from coastal Alaska, but none from the interior, and our work in Denali will help fill that gap. A clear record from Denali will help round out the bigger paleoclimate picture by adding critical information gathered from ice cores recovered around the North Pacific, all of which can be compared to a wealth of climate data already gathered in the North Atlantic region. One of the particularly interesting and challenging pieces of this project is testing a long-standing hypothesis that the North Atlantic region drives global climate changes. But there are now indications that a change in the North Pacific might happen first and drive a North Atlantic response. We need to better understand the relationship in terms of the timing and magnitude of climate change between these two regions if we are going to really understand what drives climate change in the Arctic. And so developing these high-resolution records that are directly comparable is really important.
CA-CP: What do you hope those comparisons will tell us?
Wake: There are some really big questions to answer about the timing of climatic events, which is absolutely necessary to understanding the why climate changes question. We think that 1500 year cycles are driven by deep water circulation in the North Atlantic – so changes should appear first in the North Atlantic and then in Antarctica, where long records do not have the resolution of the shorter records we are getting here. Ice cores currently being recovered from the West Antarctic Ice Sheet will be compared with data from Greenland to help unravel timing, and then data from the tropics, from the Andes, for instance, will tell us about when changes occurred there. The data we will get from Alaska will help to explain what is going on in the North Pacific and when. Ultimately, we are trying to put together the puzzle of the global climate system – what are its drivers, what makes things happen, and why.
CA-CP: What did you accomplish this summer?
Wake: We started out this summer using a portable, ground-penetrating radar to determine the ice thickness and internal structure on various glaciers, looking for “layer-cake” ice with clear, well-defined annual strata. We also collected samples for chemical analysis from 20-foot-deep snowpits and firn (snow that has not turned to ice) cores drilled 60 feet deep from the bottom of the snowpits, and installed automatic weather stations at heights of 7,800 and 14,000 feet. The chemical analyses will be carried out at UMaine and UNH labs to decipher changes in temperature, atmospheric circulation, and environmental change – such as the phenomenon known as “Arctic haze,” which has brought heavily polluted air masses to the region for decades from North America, Europe, and Asia. We expect to spend one more field season at Denali next year – to download data from the weather stations – and then hope to begin the deep-drilling program in the spring of 2010, if we get NSF funding for the second phase of the project. Our goal is to recover surface-to-bedrock ice cores from glacial ice that is about 1,000 feet thick, which should provide a detailed record of climate and environmental change extending back several thousand years.
CA-CP: Where does all of this fit in the huge picture of the climate of the planet?
Wake: It’s a tiny piece, 800,000 years out of roughly 4.5 billion – but it’s the most recent piece. The farther back you go, the less we know. What we know about the distant past is from geological deposits, sediments, and glacial deposits – rocks. And rocks can’t tell us things with the resolution and subtlety of snow. On the other hand, we discovered most of what we know about the occurrence and reoccurrence of ice ages from studying glacial moraines. Some of what we know comes from our understanding of how changes in our orbit of the sun, combined with sometimes very small changes on the planet, magnified by feedback loops, can drive huge swings in the Earth’s climate. So, what starts a change may be very small – like the hole in the tire that eventually stops the car. If you look at what’s happening now with sea ice, for instance, and the loss of albedo or reflectivity and more and more heat-absorbing dark water being exposed, warming, and melting more ice, you get a sense of how something that starts out small can be magnified by a positive feedback. But we have a good understanding right now of a lot of the parameters – the water, air, and temperature, and how it’s changed at least in the last at least half million years. Now we’re working hard on the why.