A little while after the Cop21 negotiations in Paris have come to an end, I thought it would be good to take a moment to reflect on the outcomes of the meetings.
Just from a quick glance in the media, I can't help but feel that the agreements reached are a little general and nothing other than what we knew needed to happen. Hailed as an historic moment in getting nearly 200 countries to reach an agreement on climate change, here is a summary of the Cop21 outcomes:
- To keep global temperatures "well below" 2.0C above pre-industrial times and "endeavour to limit them even more, to 1.5C".
- To limit the amount of greenhouse gases emitted by human activity to the same level that trees, soils and the ocean can absorb naturally, beginning at some point between 2050 and 2100.
- To review each country's contribution to cutting emissions every five years so they scale up the challenge.
- For rich nations to help poorer nations by providing "climate finances" to adapt to climate change and switch to renewable energy.
(Source: http://www.bbc.co.uk/news/science-environment-35073297)
The full draft agreement can be found here
As I'm writing a blog focusing on the effects of climate change on the oceans, I was disappointed to note that the word "ocean" only appears once in the draft agreement... The oceans are so fundamental to our Earth system and yet endure climate change's effects in silence and we are only really beginning to realise exactly what is going on beneath the pristine surface. Surely they deserve more of our attention?
One of the other things which stands out to me is a phrase in the second target, 'beginning at some point between 2050 and 2100'. What does this mean? Surely whether we begin limiting the amount of greenhouse gases emitted into the atmosphere in the earlier part of this timeframe or towards the end will make a massive difference to the effects on our planet and the chance of us reaching the "2C target"?
You've probably guessed from reading this that I am a little cynical about the outcomes of Cop21. I guess only time will tell to see if we really can cut our emissions and keep global temperatures below that golden 2C above pre-industrialisation values. Feel free to post your thoughts in the comments section and I'll be putting a poll up so you can share your feelings on the outcomes of Cop21.
Sunday, 20 December 2015
Friday, 18 December 2015
Just Jellyfish
Yesterday, I visited the Natural History Museum's Wildlife Photographer of the Year Exhibition which displays a selection of the most outstanding wildlife photography of the year.
Many of the photos are relevant to the wider theme of global environmental change especially those which show the impacts of human activity on wildlife however, a photo which particularly struck a chord with me was this one taken by Thomas Peschak:
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| 'Just Jellyfish' (Source: http://www.nhm.ac.uk/visit/wpy/gallery/2015/images/under-water/5020/just-jellyfish.html) |
Friday, 11 December 2015
Past Marine Ecosystem Changes
We are well aware that our oceans are undergoing vast changes as a result of human activity and given their role as climate regulators and their huge contribution to primary productivity, understanding these changes is extremely important.
Looking back at the paleoecological record, many marine responses to climate change can be observed and these past insights are incredibly valuable in predicting the response of marine communities to human-induced climate change in the future.
Changes in temperature, sea level, circulation patterns and acidification are the major drivers of marine response to climate change with communities responding with range changes, changes in composition and changes in body size.
Temperature Change
The most significant effect of temperature change in the oceans is on species' distributions and records dating back several million years reveal range changes in response to temperature. For example, warmer temperatures in the Miocene (15-17 million years ago) led to range extensions of mollusks and plankton, with many species that are currently found in the tropics and subtropics extending much further to the north - some as far as Alaska. As the climate cooled again after the mid-Miocene global temperature peak, these species' distributions altered, retreating southwards once more.
Changes in species' ranges can lead to changes in community composition, some of which are transitory while others are longer-lasting. Global cooling that occurred around 3.5 million years ago led to the loss of larger predatory species such as crabs, sharks and many fish from Antarctic communities and as a result, these communities today are dominated by invertebrates such as star fish even at higher trophic levels.
Fossil data for the Pleistocene (last 2 million years) are abundant and indicate clear responses to temperature change such as latitudinal shifts whereby species' distributions shift polewards with warming and towards the equator with cooling: species that existed between Santa Barbara and Ensenada (both California) during a warm interglacial 125,000 years ago, exist only in (sub)tropical waters today (Roy et al. 1996).
Sea level change
Global warming fuels sea level change in two main ways: from thermal expansion of the oceans and from the melting of land ice. If the ice in Antarctica and greenland alone was to melt, global sea level would rise by approximately 75m (Hannah, 2011). It is important to note that melting of sea ice in comparison while having profound impacts on food webs, would not be a major contributor to global sea level rise (this is because sea ice already displaces water).
Past warming and cooling has raised and lowered sea levels continuously with Pleistocene glacial-interglacial cycles being one of the main drivers for change. Range shifts of marine organisms in response to sea level change exist as far back as 55 million years ago. For instance, bivalves in tropical Pacific islands changed distribution repeatedly, affecting community composition. Similar effects have also been observed in bivalves, gastropods and other species in places such as Fiji and Kenya.
Ocean Circulation
Ocean circulation plays an important role in all of the major functions of the ocean (heat and carbon dioxide absorption, the transportation of these and their mixing into deep waters). Evaluation of paleoecological data reveals that changes in two major types of ocean circulation have had exceptional influence on both climate and biodiversity in the past- these are thermohaline changes and changes in teleconnections.
Thermohaline circulation helps to maintain nutrient levels in the deep ocean which is linked to high productivity in phytoplankton and thus high biodiversity and abundance in other trophic levels o the food chain. When the breakdown of this circulation system occurs (often as a result of a large input in freshwater in the North Atlantic), deep waters become oxygen deprived which can lead to the death of many organisms. Oxygen deprivation in deep waters is believed to be linked to many of the major extinction events in the past.
Teleconnections include El Nino as well as the North Atlantic Oscillation (NAO). These result in sea surface temperature changes (see previous blog post) and El Nino episodes are associated with decreased upwelling of deep nutrient-rich waters and changed air circulation patterns over the Pacific. Marine systems respond rapidly to these changes, changes in fish stocks of species such as Atlantic cod, sardines and Pacific salmon, are particularly widespread.
Ocean Chemistry
Major changes in ocean chemistry (primarily carbon dioxide and pH levels) are recorded in the fossil record, especially in the shells and skeletons of marine organisms. Both ocean pH and carbon dioxide affect the ability of organisms to form hard calcium carbonate shells and remains of these shells can provide a useful indication of past sea condition. Corals and foraminifera are the leading indicators of past climate- analysis of the isotopic composition of their shells allow reconstruction of past ocean temperatures and conditions.
In my next post, more on the distribution of coral reefs through history and the fate of our reefs in the future.
Looking back at the paleoecological record, many marine responses to climate change can be observed and these past insights are incredibly valuable in predicting the response of marine communities to human-induced climate change in the future.
Changes in temperature, sea level, circulation patterns and acidification are the major drivers of marine response to climate change with communities responding with range changes, changes in composition and changes in body size.
Temperature Change
The most significant effect of temperature change in the oceans is on species' distributions and records dating back several million years reveal range changes in response to temperature. For example, warmer temperatures in the Miocene (15-17 million years ago) led to range extensions of mollusks and plankton, with many species that are currently found in the tropics and subtropics extending much further to the north - some as far as Alaska. As the climate cooled again after the mid-Miocene global temperature peak, these species' distributions altered, retreating southwards once more.
Changes in species' ranges can lead to changes in community composition, some of which are transitory while others are longer-lasting. Global cooling that occurred around 3.5 million years ago led to the loss of larger predatory species such as crabs, sharks and many fish from Antarctic communities and as a result, these communities today are dominated by invertebrates such as star fish even at higher trophic levels.
Fossil data for the Pleistocene (last 2 million years) are abundant and indicate clear responses to temperature change such as latitudinal shifts whereby species' distributions shift polewards with warming and towards the equator with cooling: species that existed between Santa Barbara and Ensenada (both California) during a warm interglacial 125,000 years ago, exist only in (sub)tropical waters today (Roy et al. 1996).
Sea level change
Global warming fuels sea level change in two main ways: from thermal expansion of the oceans and from the melting of land ice. If the ice in Antarctica and greenland alone was to melt, global sea level would rise by approximately 75m (Hannah, 2011). It is important to note that melting of sea ice in comparison while having profound impacts on food webs, would not be a major contributor to global sea level rise (this is because sea ice already displaces water).
Past warming and cooling has raised and lowered sea levels continuously with Pleistocene glacial-interglacial cycles being one of the main drivers for change. Range shifts of marine organisms in response to sea level change exist as far back as 55 million years ago. For instance, bivalves in tropical Pacific islands changed distribution repeatedly, affecting community composition. Similar effects have also been observed in bivalves, gastropods and other species in places such as Fiji and Kenya.
Ocean Circulation
Ocean circulation plays an important role in all of the major functions of the ocean (heat and carbon dioxide absorption, the transportation of these and their mixing into deep waters). Evaluation of paleoecological data reveals that changes in two major types of ocean circulation have had exceptional influence on both climate and biodiversity in the past- these are thermohaline changes and changes in teleconnections.
Thermohaline circulation helps to maintain nutrient levels in the deep ocean which is linked to high productivity in phytoplankton and thus high biodiversity and abundance in other trophic levels o the food chain. When the breakdown of this circulation system occurs (often as a result of a large input in freshwater in the North Atlantic), deep waters become oxygen deprived which can lead to the death of many organisms. Oxygen deprivation in deep waters is believed to be linked to many of the major extinction events in the past.
Teleconnections include El Nino as well as the North Atlantic Oscillation (NAO). These result in sea surface temperature changes (see previous blog post) and El Nino episodes are associated with decreased upwelling of deep nutrient-rich waters and changed air circulation patterns over the Pacific. Marine systems respond rapidly to these changes, changes in fish stocks of species such as Atlantic cod, sardines and Pacific salmon, are particularly widespread.
Ocean Chemistry
Major changes in ocean chemistry (primarily carbon dioxide and pH levels) are recorded in the fossil record, especially in the shells and skeletons of marine organisms. Both ocean pH and carbon dioxide affect the ability of organisms to form hard calcium carbonate shells and remains of these shells can provide a useful indication of past sea condition. Corals and foraminifera are the leading indicators of past climate- analysis of the isotopic composition of their shells allow reconstruction of past ocean temperatures and conditions.
In my next post, more on the distribution of coral reefs through history and the fate of our reefs in the future.
Cleaning up the oceans...one trainer at a time
It has been revealed today that Adidas has teamed up with Parley for the Oceans (an organisation dedicated to reducing plastic waste in the oceans) to make a 3D printed trainer made out of recycled ocean plastic.
The shoe has an upper made of ocean plastic and a midsole produced from recycled polyster and gillnets (a type of fishing net). At the moment, the trainer is just a prototype but according to Adidas the goal is to "rethink design and help stop ocean plastic pollution".
The shoe has an upper made of ocean plastic and a midsole produced from recycled polyster and gillnets (a type of fishing net). At the moment, the trainer is just a prototype but according to Adidas the goal is to "rethink design and help stop ocean plastic pollution".
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| Adidas' recycled ocean plastic trainer (Image source: https://metrouk2.files.wordpress.com/2015/12/adidas-3d-printed-trainers.jpg?w=620&h=414&crop=1) |
No word yet as to when the shoe will be available in the shops but good on Adidas for raising awareness of this important issue.
Monday, 7 December 2015
So what is El Niño?
In my previous post, you may have noticed I referred to something called El Niño as a driver for coral bleaching events. But what is El Niño?
El Niño is a phase in the El Niño Southern Oscillation (ENSO) cycle, the other phase being La Niña. The ENSO describes the fluctuations in temperature between the ocean and atmosphere in the East-Central Equatorial Pacific, as measured by sea surface temperatures (SST) with La Niña being the cold phase and El Niño the warm phase. The frequency of these events can be quite irregular but they occur, on average, every 2-7 years with El Niño typically occurring more frequently than La Niña.
The last largest El Niño event was in 1997-98 which killed 20,000 people and cost billions in damage as a result of changed weather patterns causing cyclones, floods, droughts, fires and mudslides. It also caused the largest global coral bleaching event to date with 16% of the world's coral lost, with some areas, for example, The Maldives, experiencing catastrophic reef coverage losses of up to 90%.
In October this year, NOAA announced the 3rd ever global coral bleaching event as many forecast the current El Niño event to be the strongest yet. The El Niño of 1997-98 saw sea surface temperatures in the Pacific rise to 2.8 degrees Celsius above average; on 18th November 2015, this figure was 3.1 degrees Celsius, with NOAA expecting El Niño conditions to peak in early winter 2015-16.
El Niño is a phase in the El Niño Southern Oscillation (ENSO) cycle, the other phase being La Niña. The ENSO describes the fluctuations in temperature between the ocean and atmosphere in the East-Central Equatorial Pacific, as measured by sea surface temperatures (SST) with La Niña being the cold phase and El Niño the warm phase. The frequency of these events can be quite irregular but they occur, on average, every 2-7 years with El Niño typically occurring more frequently than La Niña.
The last largest El Niño event was in 1997-98 which killed 20,000 people and cost billions in damage as a result of changed weather patterns causing cyclones, floods, droughts, fires and mudslides. It also caused the largest global coral bleaching event to date with 16% of the world's coral lost, with some areas, for example, The Maldives, experiencing catastrophic reef coverage losses of up to 90%.
In October this year, NOAA announced the 3rd ever global coral bleaching event as many forecast the current El Niño event to be the strongest yet. The El Niño of 1997-98 saw sea surface temperatures in the Pacific rise to 2.8 degrees Celsius above average; on 18th November 2015, this figure was 3.1 degrees Celsius, with NOAA expecting El Niño conditions to peak in early winter 2015-16.
Tuesday, 1 December 2015
Coral Bleaching: A global catastrophe... Part I
Perhaps one of the most severe and obvious indications of the harm we are doing to our oceans is the problem of coral bleaching which threatens the existence of one of our most precious ecosystems, coral reefs.
Coral reefs, sometimes called the ‘rainforests of the sea’ cover less than 0.015% of the world’s ocean surface but provide a home for at least 25% of all marine species. They also provide vital ecosystem services to tourism and fisheries, for example, with their annual global economic value estimated to be between US$29.8-375 billion.
So what is coral bleaching and how does it occur?
Corals are unique in that they possess microscopic algae (zooxanthellae) which inhabit their cells and form a symbiotic relationship with the coral: the algae pass nutrients produced by photosynthesis to the coral while in turn the coral provides a physical structure that protects the algae and the right conditions for photosynthesis.
However, when corals are exposed to high water temperatures, they expel their algae. The term coral ‘bleaching’ comes from the fact that as the zooxanthellae are lost from the coral, the photosynthetic pigments in the algae are also lost, resulting in the coral losing its colour. All that remains is their calcium carbonate skeleton which appears white.
Just 50 years ago, coral bleaching was practically unheard of; the rise in this catastrophic phenomenon is a direct result of human-induced warming of the oceans. As corals live in shallow surface waters, they are most easily and quickly affected because as the atmosphere has warmed due to the greenhouse effect, some of the heat has been transferred to the surface of the ocean. This has led to an increase in global mean sea surface temperatures (STT).
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| Images of healthy v bleached coral (Source: http://dlnr.hawaii.gov/reefresponse/files/2014/04/bleachedVShealthy.jpg) |
For bleaching to occur, SST must rise by 1 or 2°C above normal temperatures for periods longer than 3-5 weeks. This usually occurs when higher sea surface baseline temperatures are combined with El Nino events when warming of the waters occurs naturally.
Once bleached, corals usually die. Recovery is possible though this is strongly dependent on the severity of the bleaching event and the conditions which follow. Corals that have already been weakened by other factors such as pollution or disturbance by tourism, are much less likely to survive a bleaching event.
Once bleached, corals usually die. Recovery is possible though this is strongly dependent on the severity of the bleaching event and the conditions which follow. Corals that have already been weakened by other factors such as pollution or disturbance by tourism, are much less likely to survive a bleaching event.
The problem of coral bleaching is on the rise with seven major events, affecting reefs the world over, between 1979 and 2002 with the 1997-98 El Nino the worst of the last century for coral bleaching: over 10% of the world’s corals died in this event with mortality as high as 46% in some regions (the Indian Ocean).
Unfortunately, it is not only rising sea surface temperatures that are causing problems for our coral reefs, ocean acidification as a result of more CO2 being absorbed by the oceans, is also a worrying issue…
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| The process of coral bleaching and why it occurs (Source: http://oceanservice.noaa.gov/facts/coralbleaching-large.jpg) |
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