Response of pan-Arctic permafrost peatlands to rapid climate warming

泛北极永久冻土泥炭地对气候快速变暖的响应

• 批准号: 2115070
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2115070
• 关键词: Response; pan; Arctic; permafrost; peatlands

Despite their relatively small global areal extent (3% of the earth's land surface), peatlands are disproportionately important to the future of global-scale ecosystem-climate feedbacks. Organic-rich permafrost peat stores approximately 277 Pg of carbon (C), equivalent to 14 % of the global soil C store (Tarnocai et al., 2009). Until recently this huge soil C store has been rendered effectively inert, protected from decomposition by lethargic microbial activity in frozen soil conditions. However, twenty-first century climatic warming is projected to be greatest in high-latitude areas of the Northern Hemisphere, where the majority of permafrost peatlands occur (Christensen et al., 2013). Widespread permafrost thaw exposes this C store to rapid rates of decay which leads to increased emissions of greenhouse gases to the atmosphere and further global warming (Hartmann et al., 2013). However, recent research indicates that this global warming effect may be partially compensated by increased C sequestration through newly invigorated ecosystem productivity and peat accumulation under warmer conditions (Swindles et al., 2015a). The project aims to evaluate whether this compensation mechanism is occurring in permafrost peatlands at a hemispheric scale and whether it has the potential to impact on future climate.Will carbon release from permafrost peatlands at high latitudes lead to the much discussed "carbon bomb" and further warming of climate through positive feedback mechanisms? Or, alternatively, will the peatlands act as climate buffers through invigorated carbon sequestration driven by increased productivity under a warmer climate and/or suppressed decomposition in newly saturated conditions from thawing permafrost? These are pressing questions with important global implications for the future of climate-biosphere interactions. The objective of this project is to test a five-phase model of permafrost peatland degradation from Swindles et al. (2015a) at a hemispheric scale. Currently, our model is based on a small number of peatlands in subarctic Sweden. However, the majority (by area) of permafrost peatlands occur in the continental regions of Canada and Siberia. To assess potential feedbacks from permafrost peatlands on a hemispheric scale a broader range of permafrost peatlands must be subject to rigorous palaeoenvironmental investigation. We will focus on regions characterised by recent rapid climate warming using the high-resolution multi-proxy palaeoecological approach developed in Swindles et al. (2015a). We will test the following key hypotheses: permafrost peatlands have undergone a (i) rapid shift in hydrology to wetter conditions and; (ii) increased carbon accumulation during the twentieth century in response to rapid climate warming.We have identified a number of key regions characterised by rapid climate warming that contain a significant area of permafrost peatland, including: Arctic Canada, Alaska, Russia and Sweden. In the laboratory we will carry out bulk density and loss-on-ignition analyses following standard methods (Chambers et al., 2011). Carbon accumulation will be calculated following Tolonen and Turunen (1996). We will analyse for testate amoebae in cores from each location and apply statistical transfer functions to develop a water-table depth reconstruction (Swindles et al., 2015b). We will develop an accurate, precise chronology for each core using 210Pb, AMS radiocarbon, spheroidal carbonaceous particles and tephrochronology. We will compile available data on active layer thickness and instrumental climate data to compare with the peat-based data. In addition, we will use freely-available remote-sensed images to investigate whether there has been changing wetness (e.g. increase in open water areas) in the study sites over the last few decades. A new model of permafrost peatland response to climate warming will be informed by the new palaeo-data sets and future climate-model predictions.

尽管泥炭地在全球范围内的面积相对较小（占地球陆地面积的3%），但泥炭地对全球规模的生态系统-气候反馈的未来具有不成比例的重要性。富含有机物的永久冻土泥炭储存约277 Pg的碳（C），相当于全球土壤C储存的14%（Tarnocai等人，2009年）。直到最近，这一巨大的土壤碳储存已被有效地惰性化，在冻土条件下被昏昏欲睡的微生物活动保护不被分解。然而，预计21世纪世纪气候变暖在北方半球的高纬度地区最严重，那里有大部分永久冻土泥炭地（Christensen等人，2013年）。广泛的永久冻土融化使这种C储存暴露于快速的衰变速率，这导致温室气体向大气的排放增加和进一步的全球变暖（Hartmann等人，2013年）。然而，最近的研究表明，这种全球变暖效应可以通过在更温暖的条件下通过新增加的生态系统生产力和泥炭积累增加的C螯合来部分补偿（Swindles等人，2015年a）。该项目旨在评估这种补偿机制是否在半球尺度上发生在永久冻土泥炭地，以及它是否有可能影响未来的气候。高纬度永久冻土泥炭地的碳释放是否会通过正反馈机制导致备受讨论的“碳炸弹”和气候进一步变暖？或者，泥炭地是否会作为气候缓冲区，通过在温暖的气候条件下提高生产力和/或在融化的永久冻土层中抑制新饱和条件下的分解来增加碳固存？这些都是对未来气候-生物圈相互作用具有重要全球影响的紧迫问题。该项目的目的是在半球尺度上测试Swindles等人（2015年a）的永久冻土泥炭地退化五阶段模型。目前，我们的模型是基于少量的泥炭地在亚北极瑞典。然而，大多数（按面积）永久冻土泥炭地出现在加拿大和西伯利亚的大陆地区。为了评估潜在的反馈从永久冻土泥炭地在半球尺度上更广泛的永久冻土泥炭地必须受到严格的古环境调查。我们将使用Swindles等人开发的高分辨率多代理古生态学方法关注近期气候快速变暖的地区。我们将测试以下关键假设：永久冻土泥炭地经历了（一）水文条件迅速转变为湿润的条件;（二）增加碳积累在二十世纪世纪在应对快速气候变暖。我们已经确定了一些关键地区的特点是快速气候变暖，包含一个显着的永久冻土泥炭地面积，包括：北极加拿大，阿拉斯加，俄罗斯和瑞典。在实验室中，我们将按照标准方法（Chambers等人，2011年）。将按照Tolonen和Turunen（1996年）计算碳积累。我们将分析每个位置的岩芯中的有壳变形虫，并应用统计传递函数来重建地下水位深度（Swindles等人，2015年b）。我们将使用210 Pb、AMS放射性碳、球状碳质颗粒和火山灰年代学为每个岩心建立准确、精确的年代学。我们将汇编有关活动层厚度和仪器气候数据的现有数据，以与基于泥炭的数据进行比较。此外，我们将使用免费提供的遥感图像来调查在过去几十年中研究地点的湿度是否发生了变化（例如开放水域面积的增加）。新的古数据集和未来的气候模型预测将为永久冻土泥炭地对气候变暖的反应提供信息。

项目成果

Ecology of peatland testate amoebae in Svalbard and the development of transfer functions for reconstructing past water-table depth and pH

• DOI: 10.1016/j.ecolind.2021.108122
• 发表时间: 2021-08
• 期刊: Ecological Indicators
• 影响因子: 6.9
• 作者: T. Sim;G. Swindles;P. Morris;A. Baird;D. Charman;M. Amesbury;D. Beilman;A. Channon;A. Gallego-Sala

Divergent responses of permafrost peatlands to recent climate change

• DOI: 10.1088/1748-9326/abe00b
• 发表时间: 2021-03-01
• 期刊: ENVIRONMENTAL RESEARCH LETTERS
• 影响因子: 6.7
• 作者: Sim, Thomas G.;Swindles, Graeme T.;Galka, Mariusz
• 通讯作者: Galka, Mariusz