Sarah Jose – Page 2 – Cabot Institute for the Environment blog

Global carbon budget reveals dangerous footprints

Posted on November 20, 2013April 19, 2023 by janet.crompton

Carbon dioxide is the most important greenhouse gas produced by human activities, and one which is likely to cause significant global climate change if levels continue to increase at the current rates. This year’s Global Carbon Budget holds disappointing yet hardly unexpected news; in 2012, carbon dioxide (CO₂) emissions rose by 2.1% to the highest levels in human history, a total of 9.7 billion tonnes.

CDIAC Data; Le Quiere et al 2013. Global Carbon Project 2013. Data not adjusted for leap year.

The annual Carbon Budget report is compiled by the Global Carbon Project, a collaboration of 77 scientists from around the world including the Cabot Institute’s own Dr Jo House. They predict that in 2013, global carbon emissions will have increased by a further 2.1%, setting a new record high.

Major CO₂ emitters

China produced the most CO₂ in 2012 (27% of total), which was almost twice as much as the second worst offender, the USA (14%). The European Union (EU) contributed 10% of emissions. China’s emissions increased 5.9% between 2011 and 2012, whilst the USA and EU continued to decrease their CO₂ output (by 3.7% and 1.3% respectively).

CDIAC Data; Le Quiere et al 2013. Global Carbon Project 2013.

While developing nations like China and India have high levels of greenhouse gas emissions, it is important to note that per capita the USA has by far the highest emission rate at 4.4 tonnes of carbon per person per year (tC/p/yr). China has reached EU levels of 1.9 tC/p/yr, while India produces just 0.5tC/p/yr. Since the Industrial Revolution the USA and Europe still have the highest cumulative output of CO₂ from burning fossil fuels, something to consider before we become too self-righteous.

CDIAC Data; Le Quiere et al 2013. Global Carbon Project 2013.

Carbon sinks

Image by Manfred Heyde

Increased CO₂ emissions are absorbed by carbon sinks, specifically the atmosphere, the oceans and the land. On land, trees and other plants absorb around 27% of emitted CO₂ for photosynthesis, which results in more growth and eventually more carbon stored as leaf litter in the soil.

In the oceans, algae may absorb some CO₂ for photosynthesis (although not as much as was once hoped), but the water itself absorbs most of the 27% of CO₂ stored in the oceans. Unfortunately when carbon dioxide dissolves in water it can react to form carbonic acid, a leading cause of ocean acidification. Since the Industrial Revolution, oceans have become approximately 30% more acidic. If present trends continue, oceans will be 170% more acidic by 2100, a devastating change for shellfish and corals which rely on an alkaline calcium carbonate exoskeleton, and the other marine life that depend on these species.

The atmosphere absorbs the remaining 45% of CO₂ emissions. Over the past 250 years the atmospheric CO₂ concentration has risen from 227 parts per million (ppm) to an average of 393ppm in 2012. Back in May, the first CO2 reading of 400ppm was recorded, a significant milestone in the relentlessly increasing greenhouse gas levels. We are now on track to see a ‘likely’ 3.2-5.4°C increase in global temperature by 2100, causing severe droughts and desertification of agricultural land around the world and flooding of low lying coastal areas.

The Kyoto protocol

In 1992, 37 industrialised countries agreed to reduce their carbon dioxide emissions by an average of 5% below 1990 levels during the period of 2008 to 2012. The Global Carbon Budget reported that whilst some regions such as Europe did reduce their CO₂ output, other areas (eg. Asia, Africa, Middle East) doubled or even tripled their emissions, resulting in a net gain of 58% more CO₂ emissions in 2012 than in 1990.

The biggest CO₂ emitter, China, recently joined almost 200 other countries in agreeing to sign the pledge to reduce their carbon emissions at a summit in Paris in 2015. It is hoped that this climate change summit will follow on from the work started by the Kyoto protocol to reduce CO₂ emissions to a more sustainable level.

What’s your carbon footprint?

We are at a critical stage in history. The Global Carbon Budget suggests that we have already produced 70% of the carbon dioxide it is possible to emit without causing a significant and irreversible change to the planet’s climate. It is vital that all nations work together to reduce carbon emissions to a sustainable level, preventing a 2°C increase in global temperature.

If you would like to calculate your carbon footprint, visit the government’s carbon calculator.

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

You can follow Sarah on Twitter @JoseSci

Sarah Jose

Will global food security be affected by climate change?

Posted on September 30, 2013April 20, 2023 by janet.crompton

The Intergovernmental Panel on Climate Change (IPCC) has just released an important report outlining the evidence for past and future climate change. Unfortunately it confirms our fears; climate change is occurring at an unprecedented rate and humans have been the dominant cause since the 1950s. Atmospheric carbon dioxide (CO₂) has reached the highest level for the past 800,000 years, which has contributed to the increased temperatures and extreme weather we have already started to see.

As a plant scientist, I’m interested in the complicated effects that increased temperatures, carbon dioxide and changes in rainfall will have on global food security. Professor David Lobell and Dr Sharon Gourdji wrote about some of the possible effects of climate change on crop yield last year, summarised below alongside IPCC data.

Increased CO₂

Plants produce their food in a process called photosynthesis, which uses the energy of the sun to combine CO₂ and water into sugars (food) and oxygen (a rather useful waste product). The IPCC reports that we have already increased atmospheric CO₂ levels by 40% since pre-industrial times, which means it is at the highest concentration for almost a million years. Much of this has accumulated in the atmosphere (terrible for global warming) or been absorbed into the ocean (causing ocean acidification) however it may be good news for plants.

Lobell and Gourdji wrote that higher rates of photosynthesis are likely to increase growth rates and yields of many crop plants. Unfortunately, rapid growth can actually reduce the yields of grain crops like wheat, rice and maize. The plants mature too quickly and do not have enough time to move the carbohydrates that we eat into their grains.

High temperatures

The IPCC predicts that by the end of the 21st century, temperatures will be 1.5C to 4.5C higher than they were at the start of it. There will be longer and more frequent heat waves and cold weather will become less common.

Extremely high temperatures can directly damage plants, however even a small increase in temperature can impact yields. High temperatures means plants can photosynthesise and grow more quickly, which can either improve or shrink yields depending on the crop species (see above). Lobell and Gourdji noted that milder spring and autumn seasons would extend the growing period for plants into previously frosty times of year allowing new growth periods to be exploited, although heat waves in the summer may be problematic.

Image credit: IPCC AR5 executive summary

Flooding and droughts

In the future, dry regions will become drier whilst rainy places will get wetter. The IPCC predicts that monsoon areas will expand and increase flooding, but droughts will become longer and more intense in other regions.

In flooded areas, waterlogged soils could prevent planting and damage those crops already established. Drought conditions mean that plants close the pores on the leaves (stomata) to prevent water loss, however this means that carbon dioxide cannot enter the leaves for photosynthesis and growth will stop. This may be partly counteracted by the increased carbon dioxide in the air, allowing plants to take in more CO₂ without fully opening their stomata, reducing further water loss and maintaining growth.

Image credit: IPCC AR5 executive summary

These factors (temperature, CO₂ levels and water availability) interact to complicate matters further. High carbon dioxide levels may mean plants need fewer stomata, which would reduce the amount of water they lose to the air. On the other hand, higher temperatures and/or increased rainfall may mean that crop diseases spread more quickly and reduce yields.

Overall Lobell and Gourdji state that climate change is unlikely to result in a net decline in global crop yields, although there will likely be regional losses that devastate local communities. They argue that climate change may prevent the increases in crop yields required to support the growing global population however.

The effect of climate change on global crop yields is extremely complex and difficult to predict, however floods, drought and extreme temperatures will mean that its impact on global food security (“when all people at all times have access to sufficient, safe, nutritious food to maintain a healthy and active life”) will almost certainly be devastating.

On the basis of the IPCC report and the predicted impact of climate change on all aspects of our planet, not just food security, it is critical that we act quickly to prevent temperature and CO₂ levels rising any further.

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

You can follow Sarah on Twitter @JoseSci

Sarah Jose

Neonicotinoids: Are they killing our bees?

Posted on September 11, 2013April 20, 2023 by janet.crompton

The UK government has announced that whilst it accepts the European Union ban on neonicotinoid pesticides, it does not believe that there is enough scientific evidence to support this action.

In April, the EU banned the use of neonicotinoid pesticides for two years starting in December because of concerns over their effect on bees. The use of these pesticides will not be allowed on flowering crops that attract bees or by the general public, however winter crops may still be treated. Fifteen countries voted for this ban, with eight voting against it (including the UK and Germany) and four countries abstaining.

Neonicotinoids were originally thought to have less of an impact on the environment and human health than other leading pesticides. They are systemic insecticides, which means they are transported throughout the plant in the vascular system making all tissues toxic to herbivorous insects looking for an easy meal. The most common application in the UK is to treat seeds before they are sown to ensure that even tiny seedlings are protected against pests.

Image by Kath Baldock

The major concern over neonicotinoids is whether nectar and pollen contains levels of pesticide is high enough to cause problems for bees. It has already been shown that they do not contain a lethal dose, however this is not the full story. Bees live in complex social colonies and work together to ensure that there is enough food for developing larvae and the queen. Since neonicotinoids were introduced in the early 1990s bee populations have been in decline and there is a growing feeling of unease that the two may be connected. Scientific research has provided evidence both for and against a possible link leaving governments, farmers, chemical companies environmentalists and beekeepers in an endless debate about whether or not a ban would save our bees.

Several studies on bees have shown that sublethal levels of neonicotinoids disrupt bee behaviour and memory. These chemicals target nicotinic acetylcholine receptors, one of the major ways that signals are sent through the insect central nervous system. Scientists at Newcastle University recently showed that bees exposed to neonicotinoids were less able to form long-term memories associating a smell with a reward, an important behaviour when foraging for pollen and nectar in the wild.

Researchers at the University of Stirling fed bumble bee colonies on pollen and sugar water laced with neonicotinoids for two weeks to simulate field-like exposure to flowering oil seed rape. When the colonies were placed into the field, those that had been fed the pesticides grew more slowly and produced 85% less queens compared with those fed on untreated pollen and nectar. The production of new queens is vital for bee survival because they start new colonies the next year. Studies in other bee species have found that only the largest colonies produce queens, so if neonicotinoids have even a small effect on colony size it may have a devastating effect on queen production.

So why does the government argue that there is not enough scientific evidence to support a ban on neonicotinoids?

Image by Kath Baldock

In 2012, the Food and Environment Research Agency set up a field trial using bumble bee colonies placed on sites growing either neonicotinoid-treated oil seed rape or untreated seeds. They found no significant difference between the amount of queens produced on each site, although the colonies near neonicotinoid-treated crops grew more slowly. The study also found that the levels of pesticide present in the crops was much lower than previously reported.

I personally think that both laboratory and field studies bring important information to the debate, however neither has the full answer. Whilst more realistic, the government’s field trial suffered from a lack of replication, variation in flowering times and various alternative food sources available to bees. Only 35% of pollen collected by the bees was from the oil seed rape plants, so where oil seed rape comprises the majority of flowering plants available to bees the effect on neonicotinoids may be more pronounced. The laboratory research can control more variables to establish a more clear picture, however the bees in these studies were often given only neonicotinoid-treated pollen and nectar to eat, which clearly is not the case in a rural landscape. Flies and beetles have been shown to avoid neonicotinoids, which could mean that bees would find alternative food sources where possible. This would have a major impact on crop pollination.

We desperately need well-designed field studies looking at the effect of neonicotinoids on bees and the environment in general. Despite an EU moratorium on growing neonicotinoid treated crops, an allowance should be made for scientists to set up controlled field trials to study the effect of these pesticides on bees during the two year ban. It could be our only chance to determine the danger these chemicals pose to vital pollinators and the wider environment.

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

Sarah Jose

Sustainable landscapes for the future

Posted on July 23, 2013April 20, 2023 by janet.crompton

On the 18th of July, the Cabot Institute at the University of Bristol hosted a one day conference for academics, landscape designers, industrial partners and policy makers to discuss how to create sustainable urban landscapes for the future. The event was organised to promote the exchange of ideas and to combine expertise from all stages of the process to determine how to create spaces that would maximise biodiversity and environmental benefits whilst remaining somewhere that people love to use.

City Academy Meadow, Bristol

A common theme throughout the conference was whether green spaces in cities can be designed to accommodate the needs of both local wildlife and people. Professor Nigel Dunnett from the University of Sheffield was one of the principle designers of the Olympic Park landscape, where he created a stunning biodiverse pictorial meadow with a long flowering season. His presentation highlighted the importance of creating a landscape that wildlife will benefit from, but critically that people will use and love. Professor Dunnett argued that we take more joy from seeing a beautiful expanse of flowers than a lawn monoculture and that “beauty in biodiversity is about people in ecology”. Landscape architect Kym Jones echoed this, describing landscapes that people don’t want to use as “socially unsustainable”, no matter how many environmentally-friendly boxes they tick.

Professor Dunnett’s urban meadows are controversial because he often uses non-native plant species in his design to increase the flowering period. Professor Jane Memmott of the University of Bristol Urban Pollinators research group presented data collected at nature reserves, farms and urban green spaces around Bristol that suggest most pollinators don’t really mind whether native or non-indigenous plant species are used, as long as they produce a lot of flowers. She reported that whilst pollinators are more numerous in nature reserves than urban sites, the cities retain a high level of species diversity that it is important to protect in the future. This called into question the BREEAM system of measuring sustainability in new developments, which does not usually allow non-native species to be incorporated into a design.

Professor Graham Stone

The debate about whether people would accept more biodiverse landscapes continued by questioning public opinion. Many established parks are attached to historical expectations of that place; typically well-manicured lawns and pruned trees. The group agreed that it was time to try and change the public’s perception to accept a little wilderness in parks and gardens as a habitat for local wildlife. Urban meadows begin to look neglected after flowering, however Professor Graham Stone of the University of Edinburgh mentioned that it is important to let the plants produce their seeds to provide birds with an important food source in the autumn. Bristol City Council have been trialling annual meadows in central reservations around the approaches to the city, and reported that they had not had any complaints from local residents about plants looking untidy when dying back at the end of the season. With sustainable landscaping becoming more popular in UK schools and communities, it is hoped that the public perception towards ecologically friendly designs have already begun to change.

Dr. Sarah Webster presented DEFRA’s hopes for sustainable urban developments. The 2010 Making Space for Nature report outlined new guidelines for reducing the huge pressures on wildlife, which state that new landscapes should enhance the UK’s ecological network by being bigger, better and more connected to existing habitats. DEFRA is currently trialling “biodiversity offsets”, where companies restore an equivalent area for every habitat that is unavoidably lost during a development. It is currently undecided whether or not these offsets will be mandatory if introduced, and it remains difficult to quantify the importance of a habitat in order to produce a new site of equal value to the environment. If this scheme goes ahead, careful planning could ensure that urban landscapes become more connected and form ecological networks within cities.

One of the major difficulties facing the landscape industry is how to measure the economic benefits of sustainability. Howard Wood presented his work with Lyon Parks Department in France, an ambitious project that saved hundreds of thousands of Euros over a year using ecologically-friendly design and maintenance. His team made their own compost from green plant waste and horse manure, killed weeds using hot water, used bio-control methods to remove pests, planted annual meadows to reduce mowing and maintenance of lawns, and used wood chippings as mulch to reduce weeds and improve soil water retention. The group decided that one of the key aims for the future is to improve the baseline knowledge of how much money different types of sustainable landscape cost to create or maintain, and whether they will cost councils and developers less in contrast to the traditional landscape designs.

The day ended with a request from the landscape industry partners for academics to make new sustainability research more easily accessible and understandable. Kym Jones mentioned that sustainability is now an integral part of landscape design, but landscape architects need to have the facts about its importance and value to be able to sell it to their clients. The overwhelming feeling was that green lawns alone are not enough; urban meadows promote biodiversity whilst producing beautiful displays of colour for people to enjoy. Professor Dunnett summed the day up best for me when he said, “we need to mix aesthetics and beauty with the science”. We are building places for people and local wildlife, and innovative new approaches

This blog is written by Sarah Jose, Biological Sciences, University of Bristol

Sarah Jose