It is well-known that anthropogenic – or human-driven – carbon emissions have contributed significantly to climate change, but what about natural sources of carbon and their impact on the global climate? As global temperatures continue to increase, traditional carbon sinks have begun to transition to net carbon sources. One example of this is permafrost.
What is permafrost? It is soil that is frozen for 24 consecutive months. It is also very carbon-rich or carbonaceous which is why it has historically been considered a carbon sink or a way to prevent carbon from re-entering the environment. As the Earth’s surface gets warmer these soils are at risk of thawing thus resulting in the decomposition of previously stored carbon into greenhouse gases. The image on the left depicts the gradient of frozen sub-surface soils in permafrost-containing lands. The upper most section of soil undergoes a seasonal freeze-thaw pattern before giving way to persistently frozen soil that even contains sections of ice.
Why should we be concerned with thawing permafrost? Because estimates state there is about twice the amount of carbon stored in permafrost soils as we currently have in the atmosphere! The release of that much additional carbon could drive climate change forward and dramatically impact Earth’s climate. Most of the world’s permafrost is contained within the Arctic Circle which is warming twice as fast as the rest of our planet. The figure on the right shows permafrost extent in the northern hemisphere. "Continuous permafrost" is represented in blue and indicate areas where more than 90% of the underlying soil is classified as permafrost. The mid-tone blue represents "discontinuous permafrost" and those lands can contain anywhere from 10 to 90% permafrost extent. The lightest blue represents areas with less than 10% permafrost content.
When will thawing permafrost become an issue? Knowing when enough permafrost will thaw to negatively impact the environment is the hard part. Climate modelers have recently started to focus on incorporating permafrost thaw into their models. Experts suggest that more dramatic impacts – like infrastructure failure as a result of collapsing soils – will not occur on widespread scales for decades to come. However, for those whose homes and communities are built above this frozen ground this is just a race against time.
How can we help? One way to better understand permafrost thaw and its contributions to global climate change are through in situ measurements that can help refine global climate models. Our work employs both the LuftSinn sensors for localized measurements of carbon dioxide and an open-path laser sensor to collect spatially-integrated measurements of carbon dioxide and methane (see the GW Laser Analytics Research page for more information). Collecting this data above a variety of permafrost-containing ecosystems allows for a robust dataset that modelers can pull from to improve the predictive quality of their models.
page last edited on February 11, 2018 by DMB