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Widespread establishment of peatlands since the Last Glacial Maximum represents the activation of a globally important carbon sink, but the drivers of peat initiation are unclear. The role of climate in peat initiation is particularly poorly understood. We used a general circulation model to simulate local changes in climate during the initiation of 1,097 peatlands around the world. We find that peat initiation in deglaciated landscapes in both hemispheres was driven primarily by warming growing seasons, likely through enhanced plant productivity, rather than by any increase in effective precipitation. In Western Siberia, which remained ice-free throughout the last glacial period, the initiation of the world's largest peatland complex was globally unique in that it was triggered by an increase in effective precipitation that inhibited soil respiration and allowed wetland plant communities to establish. Peat initiation in the tropics was only weakly related to climate change, and appears to have been driven primarily by nonclimatic mechanisms such as waterlogging due to tectonic subsidence. Our findings shed light on the genesis and Holocene climate space of one of the world's most carbon-dense ecosystem types, with implications for understanding trajectories of ecological change under changing future climates.

The Triassic–Jurassic boundary (Tr–J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr–J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr–J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr–J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy.

Climate change is likely to have altered the ecological functioning of past ecosystems, and is likely to alter functioning in the future; however, the magnitude and direction of such changes are difficult to predict. Here we use a deep-time case study to evaluate the impact of a well-constrained CO-induced global warming event on the ecological functioning of dominant plant communities. We use leaf mass per area (LMA), a widely used trait in modern plant ecology, to infer the palaeoecological strategy of fossil plant taxa. We show that palaeo-LMA can be inferred from fossil leaf cuticles based on a tight relationship between LMA and cuticle thickness observed among extant gymnosperms. Application of this new palaeo-LMA proxy to fossil gymnosperms from East Greenland reveals significant shifts in the dominant ecological strategies of vegetation found across the Triassic-Jurassic transition. Late Triassic forests, dominated by low-LMA taxa with inferred high transpiration rates and short leaf lifespans, were replaced in the Early Jurassic by forests dominated by high-LMA taxa that were likely to have slower metabolic rates. We suggest that extreme CO-induced global warming selected for taxa with high LMA associated with a stress-tolerant strategy and that adaptive plasticity in leaf functional traits such as LMA contributed to post-warming ecological success.

There has been recent debate over stratigraphic markers used to demarcate the Anthropocene from the Holocene Epoch. However, many of the proposed markers are found only in limited areas of the world or do not reflect human impacts on the environment. Here we show that spheroidal carbonaceous particles (SCPs), a distinct form of black carbon produced from burning fossil fuels in energy production and heavy industry, provide unambiguous stratigraphic markers of the human activities that have rapidly changed planet Earth over the last century. SCPs are found in terrestrial and marine sediments or ice cores in every continent, including remote areas such as the high Arctic and Antarctica. The rapid increase in SCPs mostly occurs in the mid-twentieth century and is contemporaneous with the ‘Great Acceleration’. It therefore reflects the intensification of fossil fuel usage and can be traced across the globe. We integrate global records of SCPs and propose that the global rapid increase in SCPs in sedimentary records can be used to inform a Global Standard Stratigraphic Age for the Anthropocene. A high-resolution SCP sequence from a lake or peatland may provide the much-needed ‘Golden Spike’ (Global Boundary Stratotype Section and Point).

Summary Many peatland ecosystems in Europe have become degraded in the last century owing to the effects of drainage, burning, pollution and climate change. There is a need to understand the drivers of peatland degradation because management and restoration interventions are expensive and can affect the natural ecohydrological dynamics of such sensitive environments. However, if given enough time, peatlands may have the ability to recover spontaneously without deliberate action. We use a detailed multiproxy palaeoecological data set from a degraded raised bog in Northern England to examine its ecosystem stability and long‐term dynamics in response to anthropogenic disturbance over a variety of timescales. One feature of many degraded peatlands (including our study site) is the local dominance of Molinia caerulea (purple moor‐grass), which has expanded at the expense of characteristic peatland plants, including sedges and Sphagnum mosses. Our data show that there has been a long history of human impacts at the site which have culminated in its current unfavourable condition. Several distinct episodes of past peat cutting are evident as hiatuses in peat accumulation; however, peat accumulation and plant community structure have subsequently recovered spontaneously. The appearance of M. caerulea occurs coevally with an unprecedented variety of recent anthropogenic impacts, all of which have contributed to providing a suitable environment for its rise to dominance. We have dated the appearance of M. caerulea to the latter half of the twentieth century which corresponds to a number of anthropogenic press disturbances, including the following: dust loading from post‐war expansion of the adjacent quarry; burning; drainage; airborne pollution; and contamination from soil dust and agrochemicals. [Synthesis] Our study demonstrates the importance of palaeoecology for understanding the trajectories of peatland development and ecosystem dynamics, including their resilience and resistance to pulse and press disturbances. We show that peatlands have the capability to recover spontaneously from severe disturbances such as peat cutting, albeit on timescales much longer than those applied to contemporary monitoring of restoration efforts. The implications are relevant for determining whether it is preferable to manage and restore peatlands, or to allow them to recover naturally without human intervention.

The challenges facing higher education in response to COVID‐19 are significant and possibly none more so than in ecology and aligned disciplines. Not only did most ecology lecturers have to rush lectures and tutorials online, but also laboratory and field classes. We reflect on our experience of this move and also consider those of 30 other ecology‐aligned teaching academics to summarize the challenges faced in the move online early in 2020 and the developing plans for adapting ecology teaching and learning going into the 2020/21 academic year. The move online had the most significant impact on field classes, with more of these canceled than lectures or laboratory classes. Most respondents to an online poll also highlighted that many respondents (~45%) felt that ecology was more impacted by COVID‐19 that even other STEM disciplines. The availability of technological solutions is key to moving forward and will hopefully enhance the teaching and learning experience for many beyond the current crisis.

Developing a comprehensive understanding of the interactions between the atmosphere and the geosphere is an ever-more pertinent issue as global average temperatures continue to rise. The possibility of more frequent volcanic eruptions and more therefore more frequent volcanic ash clouds raises potential concerns for the general public and the aviation industry. This review describes the major processes involved in short-and longterm volcano-climate interactions with a focus on Iceland and northern Europe, illustrating a complex interconnected system, wherein volcanoes directly affect the climate and climate change may indirectly affect volcanic systems. In this paper we examine both the effect of volcanic inputs into the atmosphere on climate conditions, in addition to the reverse relationship that is, how global temperature fluctuations may influence the occurrence of volcanic eruptions. Explosive volcanic eruptions can cause surface cooling on regional and global scales through stratospheric injection of aerosols and fine ash particles, as documented in many historic eruptions, such as the Pinatubo eruption in 1991. The atmospheric effects of large-magnitude explosive eruptions are more pronounced when the eruptions occur in the tropics due to increased aerosol dispersal and effects on the meridional temperature gradient. Additionally, on a multicentennial scale, global temperature increase may affect the frequency of large-magnitude eruptions through deglaciation. Many conceptional models use the example of Iceland to suggest that post-glacial isostatic rebound will significantly increase decompression melting, and may already be increasing the amount of melt stored beneath Vatnajökull and several smaller Icelandic glaciers. Evidence for such a relationship existing in the past may be found in cryptotephra records from peat and lake sediments across northern Europe. At present, such records are incomplete, containing spatial gaps. As a significant increase in volcanic activity in Iceland would result in more frequent ash clouds over Europe, disrupting aviation and transport, developing an understanding of the relationship between the global climate and volcanism will greatly improve our ability to forecast and prepare for future events.