iLEAPS has a focus on the biosphere as a mediator of Earth system processes. We study the land and atmosphere together as a system involving physical, chemical and biological processes.
The systems can span a range of space and time scales and share some common science issues:
How does the exchange of CO2 between ecosystems and atmosphere respond to extreme events? How quickly and how much does the land responds to changes in atmospheric conditions? How does the atmosphere respond to biogenic emissions?
In iLEAPS, we focus on land-atmosphere systems that include important feedbacks between atmospheric chemistry and plants that have an impact on society and on the Earth system. The 5 core themes that drives our science for the next few years are:
1.Urban
Societal issues: a large, and increasing, percentage of humans live in cities. Air quality and heat affect humans and plants health, especially in extreme conditions. Cities are also mainly responsible for GHG emissions, and will be affected by climate risk.
System: Green infrastructures can be used to mediate the air quality and heat (Grote et al. 2016).
Science issues: How do individual trees affect air quality? How do complex nature-based solutions such as trees, parks, and gardens affect heat? What is the detrimental effect of bad air quality on plants? What is the possible feedback of biogenic emissions on urban air quality?
2. Managed Land
Societal issues: Food and fuel requirements for increasing human population.
System: Downstream of cities can include high ozone levels which damage crops and decrease forest productivity, deforestation affects carbon, water and heat exchanges with the atmosphere, carbon sequestration affected by management.
Science issues: Can we predict and quantify the impact of ozone on vegetation? What the difference in carbon, heat and water budgets is of managed versus natural land?
3. Forests
Societal issues: Biodiversity and global carbon.
System: While Forests store as much as 30% of annual global anthropogenic CO2 emission, they emit reactive chemicals that affect the physical atmospheric system: rainfall, radiation diffusiveness. They respond to increased carbon dioxide in the atmosphere and nitrogen deposition by growing at high rates with reduced water losses.
Science issues: To what extend adaptive strategies of forests affect carbon and water budgets around the world? How do extreme events impact the system? How do different elements of biodiversity influence forests responses to climate change? Do trees in different growth stages have different responses to atmospheric conditions?
4. Arctic and Mountain Regions
Societal issues: Rapid changes of the Arctic sea ice extent and atmospheric-terrestrial water circulations due to global warming (Fedorov et al., 2014; Hiyama et al., 2016; Suzuki et al., 2018). Changes in terrestrial carbon (CO2 and CH4) budgets in northern Eurasia and Alaska (Iwata et al., 2015; Ohta et al., 2014; Ueyama et al., 2014) are global concerns.
System: Extensive wetlands in the Arctic are largest natural source of CH4. Changes to climate affect vegetation, Longer growing season increases vegetation growth.
Science issues: How does permafrost thaw affect hydrology and wetlands? How does methane from wetlands respond to freeze-thaw cycle? How does vegetation respond to changes in snow conditions?
Purposes: One of the aims of the iLEAPS is to characterize behaviours of SLCFs (short-lived climate forcers, such as black carbon and CH4) and other GHGs in the Arctic atmosphere and to quantify contributions of individual sources and sinks or fluxes of these compounds. To study GHG flux, we combine top-down and bottom-up approaches. In the former method, we estimate fluxes from atmospheric concentration measurements using numerical models. In the latter method, we directly measure fluxes at numbers of representative sites and estimate fluxes from a wide area over the Arctic. By conducting these high-accuracy measurements and using advanced numerical models, we characterize temporal and spatial variations in sources and sinks of GHGs. We also estimate responses of sources and sinks with respect to climate and environmental changes. We need better understanding of land ecosystems, especially possible changes in GHG fluxes in response to future climate changes. This knowledge can then be utilized with the dynamic vegetation model to construct the Earth system model.
Collaborations: We can collaborate with AMAP (Arctic Monitoring and Assessment Programme) and GCP (Global Carbon Project), contributing to the global CO2 and CH4 budget estimates.
5. Arid and Semi-Arid
Societal issues: Need for food and fuel.
System: Fires clear the vegetation for new growth and produce significant atmospheric particles. Vegetation has different strategies with high seasonal and inter-annual variability of rainfall. Bush encroachment changing the landscape.
Science issues: How does fire affect downstream nutrients? What are the carbon, water and energy exchanges of complex (tree-grass-soil mixture) land structures?
At the interface between open (arid and semi-arid) and closed (forest) ecosystems there is a region which potentially could be in either state - depending on past history and management. In these ecosystems human activities can have a large impact on carbon and water cycles - what is the appropriate management of these non-deterministic ecosystems?