Details

Autor(en) / Beteiligte

• Coffield, Shane R.
• Hemes, Kyle S.
• Koven, Charles D.
• Goulden, Michael L.
• Randerson, James T.

Titel

Climate‐Driven Limits to Future Carbon Storage in California's Wildland Ecosystems

Ist Teil von

• AGU advances, 2021-09, Vol.2 (3), p.n/a

Ort / Verlag

Hoboken: John Wiley & Sons, Inc

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Enhanced ecosystem carbon storage is a key component of many climate mitigation pathways. The State of California has set an ambitious goal of carbon neutrality by 2045, relying in part on enhanced carbon sequestration in natural and working lands. We used statistical modeling, including random forest and climate analog approaches, to explore the climate‐driven challenges and uncertainties associated with the goal of long‐term carbon sequestration in forests and shrublands. We found that seasonal patterns of temperature and precipitation are strong controllers of the spatial distribution of aboveground live carbon. RCP8.5 projections of temperature and precipitation are estimated to drive decreases of 16.1% ± 7.5% in aboveground live carbon by the end of the century, with coastal areas of central and northern California and low/mid‐elevation mountain areas being most vulnerable. With RCP4.5 projections, declines are less severe, with 8.8% ± 5.3% carbon loss. In either scenario, increases in temperature systematically cause biomass declines, and the spread of projected precipitation across 32 CMIP5 models contributes to substantial uncertainty in the magnitude of that decline. Projected changes in the environmental niche for the 20 most biomass‐dominant tree species revealed widespread replacement of conifers by oak species in low elevation regions of central and northern California, with a corresponding decline in carbon storage depending on expected migration rates. The spatial patterns of vulnerability we identify may allow policymakers to assess where carbon sequestration in aboveground biomass is an appropriate part of a climate mitigation portfolio, and where future climate‐driven carbon losses may be a liability. Plain Language Summary Many climate mitigation policies, including those of California, rely in part on increased carbon uptake by forests and shrublands. However, these natural ecosystems are also being impacted by climate change, likely making the goal of increasing biomass carbon more difficult to achieve. In this study, we used a variety of statistical models to estimate the impact of rising temperature and changing precipitation on California ecosystems' carbon storage. We found that in either moderate or severe warming scenarios, aboveground live carbon will decrease substantially. Decreases are driven by the rising temperature, while uncertainty in future precipitation leads to substantial uncertainty in the exact magnitude of those decreases. We also modeled several different tree species separately, finding that climate change will likely favor oak species at the expense of conifers. Lastly, some areas of California appear more vulnerable to carbon loss than others—in particular, the northern and central coasts, low/mid‐elevation mountain areas, and places where there are currently forest carbon offset projects. The spatially explicit projections we provide may help with the design of land management and climate policies to anticipate the impacts of climate change, and focus carbon offsets and conservation efforts where they will be most effective. Key Points Climate change will create new challenges for long‐term ecosystem carbon storage, relevant to California's carbon neutrality goals Rising temperature leads to carbon loss, while uncertainty in precipitation contributes large uncertainty to the magnitude of that loss Particularly vulnerable areas of California are the central and northern coasts, low/mid‐elevation mountains, and carbon offset projects