Dr. John S. Kimball
Flathead Lake Biological Station, University of Montana
What questions related to the Arctic are you trying to answer? The effects of global warming are magnified in the Arctic. The tundra is frozen for most of the year with a very short growing season in summer. Global warming has not only increased summer temperatures, but the growing season is now several weeks longer than it was when we first started our measurements in the 1980s. This has had a big impact on plant growth. The tundra is becoming shrubbier as plant growth has increased with warmer, longer growing seasons. The warming Arctic is also becoming more favorable for tree growth and the northern tree line is now moving north into the tundra. Satellites looking down at the Earth observe this response as a general greening of the entire Arctic. One benefit of this greening is that more carbon dioxide (CO2) is pulled out of the atmosphere by increased photosynthesis from the additional plant growth. This may act to buffer the global warming effects of all the greenhouse gasses we increasingly put into the atmosphere from fossil fuel burning. I’m trying to find out how much CO2 the increasing plant growth is eating up and whether these trends will continue under future warming.
How will answers to those questions help us understand more about our world? We’re now very confident that global warming is largely driven by fossil fuel burning and the release of CO2 into the atmosphere. The Earth has various checks and balances that have maintained a fairly stable climate for thousands of years. However, we’re now coming to realize that our actions are pushing this global balance into a new regime that may not be so favorable for human populations. My research is helping us understand how the Arctic is responding to global warming and whether this response will help buffer or reinforce continued warming.
How are you trying to find the answers to those questions? I help to develop new ways of measuring plant growth from satellites, which have the advantage of being able to observe the Earth from space and take measurements of the entire Arctic every day over years to decades. These measurements include vegetation color and temperature, which we translate into more useful information such as plant growth. These satellite observations provide a relatively precise measurement of global warming effects over the entire region and help us to interpret more detailed measurements of plant structure and growth from field stations scattered across the Arctic.
Recount for us one of your field days in the Arctic. My favorite part of being in the Arctic is the vast emptiness of the region. Last summer was a record warm, dry year in Northern Alaska. As we were servicing a new weather station I noticed a large plume of smoke rising from the tundra a few miles up wind of us. Living in western Montana I’m used to wildfire season and smoky summers, but I’d never seen a tundra fire as the tundra is usually very wet and spongy. However, last summer it was bone dry and the fire was heading right for us. Luckily we had enough time to drive to safety, but it was an exciting trip!
What do you find most rewarding about being a scientist? My generation helped create the problem of global warming that will now impact everyone on the planet in some way for generations to come. As a scientist I have the opportunity to study this problem and hopefully be part of the solution.