An international team of scientists have reconstructed the longest ever record of past sunshine using pollen trapped in lake sediments collected in Ghana, Africa. The study published today in Scientific Reports enables us to understand past changes in solar input to the global system over the past 140,000 years. Previously we have had to rely upon computer models to mathematically determine past solar inputs to the Earth. “This work really is a first; being able to peer back in time to understand how the Sun has driven our global system over many of thousands of years is a very exciting prospect” said joint-lead author Dr. Phillip Jardine of The Open University.
The Sun is a key component of our natural environment, driving a multitude of processes at Earth’s surface, from photosynthesis generating energy within plants, through to global-scale circulation patterns in our oceans and atmosphere. Understanding more about how the Sun has behaved in the past, and the influence this had on Earth’s environment, will help scientists predict future climate change.
Dr. Jardine used a technique pioneered by one of his co-authors, Dr. Wesley Fraser of Oxford Brookes University, to determine past changes in solar input, specifically changes in ultraviolet (UV) radiation. Plants protect themselves from the harmful nature of ultraviolet radiation by incorporating a number of specific chemical compounds into their tissues that absorb and dissipate the energy of UV radiation. Pollen grains of flowering plants are also provided protection by these UV-absorbing chemicals, thus act as a long-term recorder of ultraviolet radiation from the Sun.
Pollen grains are readily trapped in lake sediments, where they can be preserved for millions of years. By extracting material from Lake Bosumtwi, Ghana, the pollen that was released by flowering plants thousands of years ago can be separated from the lake sediment and chemically analysed for UV-absorbing chemical compounds. It is this chemical signature within the ancient pollen grains that provides us with information about past levels of solar ultraviolet radiation.
“What we present here is a new opportunity to explore how the Earth has changed” said Dr. William Gosling (University of Amsterdam). “I am particularly excited about this because it will means that we can gain a better understanding of why vegetation changed in the past, and consequently this will allow us to anticipate better what the likely impacts of projected future climate change will be.”
When addressing climate change the focus often is on temperature. However precipitation is a climate variable that is at least as important, but much more difficult to assess. This mini symposium will address several aspects of the changes in the precipitation climate. William Gosling shows how climates in the far past can be reconstructed using proxies. One of these proxies, biomarkers, will be discussed by Susanna Mölkänen, who uses them to reconstruct altitudinal gradients. John van Boxel discusses 20th century climate change in the Netherlands focussing on changes in precipitation extremes. The models that are used to study climate change are the topic of the presentation by Geert Lenderink from KNMI. Some of these models were also used by Emma Daniels (WUR) to study the effect of urbanisation on precipitation in the Netherlands. For anyone involved in climate change and precipitation this should be an interesting afternoon.
2014 has seen more people visit this blog and more “clicks” through to articles than in any previous year (see Annual Report 2014). So thanks for reading! I hope that the information provided is useful. For me 2014 has been a big year of change; with the largest work related change being taking up my new post at the University of Amsterdam in September.
2015 promises to be an exciting year with a number of key projects generating exciting findings (including chironomid climate for the Neotropics, Andean flank evolution, and ‘deep time’ palynomorphs) , the start of the XPERT network, and new proposals and collaborations being developed here in the Netherlands (including new proposal to work in Europe!).
Any comments, thoughts or contributions on the blog welcome.
Insects, sediment and climate change
Frazer Bird and William Gosling talk about how to conduct palaeoecological research in the tropics for NERC’s Planet Earth pod-cast. Click here to here to listen to the conversation.
For other similar stories online visit the Planet Earth website.
I am delighted to be organizing a focus session at the first AfQUA meeting. The session seeks to bring together ecologists and palaeoecologists working in Africa. If you are interested in getting involved please contact me (William Gosling) directly. For further information on the conference visit the AfQUA website or twitter feed.
Focus session 1: African ecology in context
The African continent spans over 80 degrees of latitude, nearly 6000 m of altitude and around 30 million km2 consequently it contains a vast array of unique ecosystems. Many of the African ecosystems are under direct pressure from human activity and are threatened by on-going and projected climate change. However, management and conservation of the modern African ecosystems is hampered by a paucity of data on their natural history. Studies of observations of ecosystems spanning >30 years are rare so we are heavily reliant on examination of the fossil record to place modern ecology in a long-term (>50 year) context. Information on past ecosystems can be extracted through the examination of a range of biological indicators (e.g. pollen, carbon isotopes, charcoal) found within marine and lake sediments. However, interpretation of the sediments and the proxies they contain with the ecosystems observed today is challenging because of timescale and interpretation issues. The aim of this session is to bring together modern ecologists and paleo-ecologists working in Africa to present the state-of-the-art understanding of ecosystems past and present, and explore how we can improve understanding of timescales and proxy interpretation to place these threatened ecosystems in context.