Matthew J. Pound

Are there pre-Quaternary geological analogues for a future greenhouse warming?

Given the inherent uncertainties in predicting how climate and environments will respond to anthropogenic emissions of greenhouse gases, it would be beneficial to society if science could identify geological analogues to the human race’s current grand climate experiment. This has been a focus of the geological and palaeoclimate communities over the last 30 years, with many scientific papers claiming that intervals in Earth history can be used as an analogue for future climate change. Using a coupled ocean–atmosphere modelling approach, we test this assertion for the most probable pre-Quaternary candidates of the last 100 million years: the Mid- and Late Cretaceous, the Palaeocene–Eocene Thermal Maximum (PETM), the Early Eocene, as well as warm intervals within the Miocene and Pliocene epochs. These intervals fail as true direct analogues since they either represent equilibrium climate states to a long-term CO2 forcing—whereas anthropogenic emissions of greenhouse gases provide a progressive (transient) forcing on climate—or the sensitivity of the climate system itself to CO2 was different. While no close geological analogue exists, past warm intervals in Earth history provide a unique opportunity to investigate processes that operated during warm (high CO2) climate states. Palaeoclimate and environmental reconstruction/modelling are facilitating the assessment and calculation of the response of global temperatures to increasing CO2 concentrations in the longer term (multiple centuries); this is now referred to as the Earth System Sensitivity, which is critical in identifying CO2 thresholds in the atmosphere that must not be crossed to avoid dangerous levels of climate change in the long term. Palaeoclimatology also provides a unique and independent way to evaluate the qualities of climate and Earth system models used to predict future climate.

Palynological Evidence for a Warmer Boreal Climate in the Late Pliocene of the Yukon Territory, Canada

The Late Pliocene (3.6–2.6 Ma) was a period of significant global warmth, considered a potential analogue for future anthropogenic climate change. Newly discovered fine-grained sediments from between the gold-bearing lower and upper White Channel Gravels show the presence of a wetland or lake within Bonanza Creek, Dawson Mining District, Yukon. This environment was surrounded by a diverse Pinaceae-dominated boreal forest with significant stands of angiosperms in favourable sites. Quantitative climate reconstructions derived from pollen and spores reveal a mean annual temperature at least 6 °C warmer than today with warm summers and relatively mild winters. Finally, the new pollen assemblage is used to discuss the age of the White Channel Gravels.

The John Williams Index of Palaeopalynology

The John Williams Index of Palaeopalynology (JWIP) is the result of the lifetimes work of Dr John E. Williams. Housed at the Department of Palaeontology of The Natural History Museum (NHM) in London, the JWIP is publically available and provides probably the most comprehensive fully cross-referenced catalogue on palaeopalynology in the world. It has 23,350 references to fossil palynomorph genera or species as of February 2012. Since its inception in 1971, every publication in the collection referring to a fossil palynomorph genus or species has been critiqued by John E. Williams. Each item is given an accession number and appropriately referenced within the JWIP using index cards which are sorted alphabetically. Once added to the main reference subindex, further entries are completed for four themed subindexes. The first three of these are sets of cards on the three major palynomorph groups (acritarchs/dinoflagellate cysts, chitinozoa and pollen/spores), 26 stratigraphical intervals and 17 geographical areas. The fourth themed subindex is where each palynomorph taxon has a card (or cards) listing all the records of that species in the literature within six categories (acritarchs, dinoflagellate cysts, chitinozoa, fungal spores, pollen/spores and miscellaneous). Due to the sustained and meticulous recording of data since 1971, users can therefore search the database by major palynomorph group, species, age and/or geographical region. The comprehensive and cross-referenced nature of the JWIP means that researchers can readily identify key publications on, for example, specific palynomorph types over a particular interval in a prescribed area. The JWIP is currently entirely analogue, but the NHM is currently evaluating potential strategies for digitisation.

Heterogeneity in global vegetation and terrestrial climate change during the late Eocene to early Oligocene transition

Rapid global cooling at the Eocene – Oligocene Transition (EOT), ~33.9–33.5 Ma, is widely considered to mark the onset of the modern icehouse world. A large and rapid drop in atmospheric pCO2 has been proposed as the driving force behind extinctions in the marine realm and glaciation on Antarctica. However, the global terrestrial response to this cooling is uncertain. Here we present the first global vegetation and terrestrial temperature reconstructions for the EOT. Using an extensive palynological dataset, that has been statistically grouped into palaeo-biomes, we show a more transitional nature of terrestrial climate change by indicating a spatial and temporal heterogeneity of vegetation change at the EOT in both hemispheres. The reconstructed terrestrial temperatures show for many regions a cooling that started well before the EOT and continued into the Early Oligocene. We conclude that the heterogeneous pattern of global vegetation change has been controlled by a combination of multiple forcings, such as tectonics, sea-level fall and long-term decline in greenhouse gas concentrations during the late Eocene to early Oligocene, and does not represent a single response to a rapid decline in atmospheric pCO2 at the EOT.

Palaeoenvironment, palaeoclimate and age of the Brassington Formation (Miocene) of Derbyshire, UK

The Brassington Formation is the most extensive Miocene sedimentary succession onshore in the UK. Because of its unique position at the margin of NW Europe, the pollen from this lithostratigraphical unit provides evidence on the development of vegetation affected by North Atlantic currents and hypothesized atmospheric circulation changes during the Middle to Late Miocene climate cooling. Palynostratigraphy suggests that the uppermost Kenslow Member of the Brassington Formation is not coeval. Previously, all occurrences of the Kenslow Member were assumed to be contemporary. The oldest pollen assemblage is from the more southern Bees Nest Pit, which represents a subtropical conifer-dominated forest of late Serravallian age (c. 12 Ma). A younger assemblage was observed from the more northern Kenslow Top Pit; this indicates that a subtropical mixed forest was present during the early Tortonian (11.6–9 Ma). The shift from a conifer-dominated to a mixed forest was related to precipitation. Although the total precipitation did not change between the two assemblages, the younger assemblage had more uniform rainfall throughout the year. The diachronous nature of the Kenslow Member means that the depositional model of the Brassington Formation needs revising, and this will have implications for Neogene to recent uplift of the southern Pennines. Supplementary material: All valid formally defined palynomorph taxa below the generic level that are mentioned in this paper, with full author citations, are available at http://www.geolsoc.org.uk/SUP18889.

Melissopalynology of honey from Ponteland, UK, shows the role of Brassica napus in supporting honey production in a suburban to rural setting

ABSTRACT Whether honeybees utilise oilseed rape (Brassica napus), and thus come into contact with neonicotinoid pesticides, has been questioned in the UK. Here we report the melissopalynology of honey samples taken from hives in the northeast of the UK from 2014 to 2015. The results show that Brassica pollen is predominant in honey extractions from June, following the mass bloom of oilseed rape. Honey extractions from July and September show more diverse sources of nectar from entomophilous crops, weeds and garden plants. Our results clearly show that honeybees will extensively utilise oilseed rape mass blooms in spring, and any change in the current European Union moratorium on neonicotinoids should be carefully considered. We also confirm the importance of gardens (when planted with ‘beefriendly flowers’) in sustaining pollinators within suburban to rural environments.

A reassessment of the Brassington Formation (Miocene) of Derbyshire, UK and a review of related hypogene karst suffosion processes

The Brassington Formation of the Pennines is the most extensive onshore Miocene succession in the UK. It is preserved as outliers in Lower Carboniferous Limestone. During the Cenozoic, central England underwent uplift, with erosion of post-Mississippian strata from the Pennine axis in the Peak District. The Brassington Formation is hence significant in reconstructing Cenozoic geological history. It is non-marine, derived from Triassic sandstone and of Mid–Late Miocene age. The c. 60 outliers occur in three clusters over c. 220 km2. They are remnants of a sedimentary prism at least 75 m thick and with a volume of c. 10 km3. Suffosion of bedrock, conditioned by aggressive precursor fluids of hypogenic origin, was the major control on subsidence. The calculated volume of the fills in the Bees Nest and Green Clay outliers is 3.7–5.0 × 106 m3. Referenced to a sub-Miocene surface at c. 450 m OD in pre-subsidence times, the original volume of this subsidence complex was c. 21.8 × 106 m3 and the aggregated volume of the Late Neogene White Peak palaeokarst was at least 0.66 km3. Subsidence was concomitant with Pliocene uplift of the Pennine Axis, suggesting suffosion accommodation of 3 × 106 m3 per km2 or 244 m3 per annum.