Glaciers as sentinels of climate change

I recently had the opportunity to meet with Wendell Tangborn who is a renowned U.S. Geological Survey glaciologist, now retired, based on Vashon Island, Washington. He is originally from Minnesota and is a graduate of the University of Minnesota. His life took him to the Pacific Northwest because there's not much for a glacial scientist to study in Minnesota, no matter how cold it gets.

Tangborn has over half a century of field knowledge with significant experience measuring glacier mass balance, runoff and related variables. If anyone questions the impact of glaciers on Minnesota, they should read on because our location in North America makes us particularly susceptible to climate change. We are also sitting in the middle of one of the largest supplies of freshwater in the world and the global population is thirsty, and getting thirstier.

It was a great privilege to sit down with Tangborn and talk about the outlook for our future. I only wish the news was a bit brighter, but there are still things we can do as a society to prepare for what's coming. The sooner we prepare, the better we can weather the challenges climate change will bring. Here's the Q&A I had with Tangborn:

Q: In what ways are glaciers serving as a bellweather for climate change?

Tangborn: "The Earth's 190,000 glaciers are sentinels of climate change and appear to be more sensitive to the climate than are humans. But we have ignored what they are telling us. Most of the world's glaciers began changing in the late 1980s from relative stability to negative mass balances. Mass balance is the difference between ice gain derived from snow accumulation and ice loss from snow and ice melting. Thus, negative balances mean a glacier is losing mass from melting faster than it is gaining mass as snow. (See www.ptaagmb.com for detailed explanations and examples.)

The relatively abrupt change to negative glacier mass balances strongly suggests a climate tipping point, when the climate changes from one stable state to another.

Q: That term "tipping point" comes up often when talking about climate change, but many speculate as to what that point will look like. What evidence is there to support these claims?

Q: How will the loss of Arctic sea ice impact the world?

Tangborn: "Reduction of northern-hemisphere sea ice is a positive feedback mechanism: More incoming solar radiation or insolation (light) is absorbed into darker ocean water instead of being reflected by ice and then re-radiated into the atmosphere as infrared radiation (heat). This, in turn, reduces the extent of the annual northern-hemisphere snow cover, which further accelerates global warming. A related positive feedback mechanism that could be even more environmentally devastating is the release of methane from permafrost and seafloor hydrates as the ocean warms."

Q: What other evidence is there that we've already experienced a tipping point?

Tangborn: "Another tipping-point indicator is the Greenland and West Antarctic ice sheets, which have shown signs of disintegrating during the past two decades. Just partial melting of these ice sheets will raise sea level several meters."

Q: Much of this has been in the works for over 30 years. What's the impact of a lack of action when we first saw these signs?

Q: Sounds pretty bleak. What can be done at this point?

Tangborn: "The implications are stark. For civilization to survive, fossil fuel burning must taper off dramatically and be replaced with renewable sources of energy. The United Nation's International Panel of Climate Change (IPCC) could provide guidance on how this might be accomplished. The panel is composed of climatologists and other scientists from more than 100 member countries. Thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis.

The recent visit of President Obama, Secretary of State Kerry and Interior Secretary Jewell to Alaska to observe glaciers and the effect of climate change symbolically emphasized the problem of global climate warming and its impact on the well-being of humans. The GLACIER conference as it was called was organized to increase awareness of the environmental problems that face Alaskans such as coastal erosion, wildfires, sea level rise and permafrost thawing – problems that the entire world will soon be facing."

Tangborn lives on Puget Sound on an island made of glacial till. That large body of water is fed by glacial meltwater so he is among the many who are seeing incremental changes creeping up. The impact of global warming is already mounting in many places and that will only increase. Will many Americans continue to deny that it's a problem, only to realize too late that they could have been better prepared?

Planet Earth will survive either way and the cyclical nature of the geologic time scale will allow for the pendulum to swing. The problem is that geologic time gets counted in millennia as human time is counted in seconds. The clock is ticking.