What will you be doing March 29 at 8.30pm? Having a drink with friends? Having dinner? Spending time with your family? Instead of sitting with the lights on, why not spend an hour by candlelight and support WWF’s worldwide event Earth Hour.

Starting in 2007, Earth Hour asks individuals, businesses and governments to switch out their lights for one hour – at 8.30pm local time, whatever your location around the globe. The idea is to allow those who take part to show they are taking steps to reduce their environmental impact, and for many people it is the first step to making more significant, sustainable changes to their lifestyle.

Last year 157 countries took part, with over 10 million people in the UK alone turning off their lights at 8.30pm [1]. This year organisers WWF hope even more people to join in, with “Amazing Spider Man 2” actors Andrew Garfield and Emma Stone each pledging their support to one of the Earth Hour Blue crowdfunding projects [2].

While not every light should be turned off, for example safety lights, traffic lights etc. [3], you can choose to turn off overhead room lights, lamps, computers and other electronic devices such as televisions, and other similar light sources.

An event like Earth Hour raises awareness all over the globe about the importance of conserving energy and becoming a more sustainable society. Making the focus lighting is highly relevant to this, as typically 7% of a household’s energy bill comes from lighting [4].

There are some easy and quick ways to instantly reduce your lighting costs:

• Use natural daylight – when it’s light outside keen curtains and blinds open to let in sunlight, rather than having lamps on.
• Turn off lights when you leave the room – having lights on in empty rooms keeps your bills higher than they need to be.
• Use sensors and timers so lights go off automatically when they aren’t needed.
• Make sure the bulbs you buy are energy efficient – Compact Fluorescent Lamps (CFLs) and Light Emitting Diodes (LEDs) are both readily available across the country.
• Shop for Energy Efficient lights at https://www.energysavingwarehouse.co.uk/store/Lights

References

[1] WWF. Earth Hour in 2013. 2014. https://earthhour.wwf.org.uk/about-wwfs-earth-hour/earth-hour-in-2013

[2] Earth Hour. Earth Hour & Spider-Man Join Forces to Save the Planet. 2014. http://www.earthhour.org/be-superhero-planet

[3] Earth Hour. Celebrating Earth Hour. 2014. http://www.earthhour.org/celebrating-earth-hour

[4] Energy Saving Trust. Lighting. 2014. http://www.energysavingtrust.org.uk/scotland/Electricity/Lighting

Aerosols are everywhere around us, ranging in size from the width of a virus up to the diameter of a human hair [1]. And although we cannot see them, these tiny particles can play havoc with both our health and the climate.

Aerosols are tiny particles or droplets found throughout the Earth’s atmosphere, and are often composed of sulfate, nitrate, ammonium, or sea salt. Aerosols are classed in terms of their size, with different terms used by different scientific fields. They range in size from nanometers to micrometers, and are most commonly referred to as particulate matter e.g PM_2.5 or PM₁₀, depending on their size.

The main natural sources of aerosols are volcanic eruptions, the sea, soils, wild animals and desertification. Aerosols are predominantly formed through natural processes, while roughly 10% [2] are produced by anthropogenic sources such as fossil fuel burning, land use changes, biomass burning, fires, aircraft and ship emissions and increasing numbers of domesticated animals.

Natural aerosols are spread over both land and ocean, while man made particles such as sulphate aerosols are often found in regions downwind of industrialised areas in the Northern Hemisphere, meaning that aerosol influence on the climate can be ‘…highly variable in space and time’ [3], due to winds. Particle cover over developed countries has started to decrease in recent years due to cleaner industrial processes, but there has been a steady increase across Asia, especially China, which has lead to worsening air conditions.

Aerosols impact the climate in two ways: (i) directly, by scattering and absorbing radiation in the atmosphere, and (ii) indirectly by acting as cloud condensing nuclei and so changing the microphysical structure of clouds [4]. Aerosols can influence both incoming and outgoing radiation, though they are most effective at scattering incoming radiation [5], meaning less energy will reach and warm the Earth’s atmosphere, resulting in a global cooling effect. Some aerosols also absorb light rather than just reflecting it, which warms the surrounding atmosphere, but shades and cools the surface below.

Aerosol particles also act as cloud condensing nuclei, which can effect the lifetime and composition of clouds. An increase in cloud cover will lead to more of the incoming radiation being reflected back into space, and therefore not reaching or warming the earth’s surface. A high concentration of particulate matter in the atmosphere will lead to brighter, denser clouds. These clouds are less likely to precipitate out, and will reflect more radiation than clouds formed when there are low concentrations of aerosols.

Due to their direct and indirect effect on the Earth’s climate, the negative radiative forcing (a change in the radiation balance due to the instantaneous release of a certain quantity of a radiatively active greenhouse gas – assuming that no other components of the climate system are affected) by aerosols is to create a cooling effect. Much research has been done over the years to try and identify whether or not aerosols mask the effects of global warming. If aerosols particles such as sulphites were reduced in the future, would the decrease in their cooling effects lead to an even more rapid increase in global temperatures than we are seeing at present? Despite decades of research, the potential magnitude of aerosol cooling is hard to quantify at present due to many uncertainties such as future emissions. The Intergovernmental Panel on Climate Change (IPCC) have attempted to try and quantify it somewhat, and came to the conclusion that although these microscopic particles do cause a cooling effect, they do not completely offset global warming [6].

While anthropogenic aerosol concentrations have decreased in developed regions, the rapid increase in industrialisation in developing countries such as China has meant that global aerosol concentrations have remained constant. The cooling effect that these particles create may have in some way acted to mask the effects of global warming, but with so many uncertainties in future emissions worldwide, the part that aerosols will play in the future of climate change remains to be seen.

References

[1] Voiland, A. 2010. Aerosols: Tiny Particles, Big Impact. NASA Earth Observatory. http://earthobservatory.nasa.gov/Features/Aerosols/

[2] As above.

[3] Andreae, M.O. 1996. ‘Raising dust in the greenhouse.’ Nature 380: 389-390

[4] Penner, J.E., 2000. ‘Aerosols, Effects on Climate.’ In Encyclopedia of Global Environmental Change, edited by M.C. MacCracken and J.S. Perry, 162-167. John Wiley and Sons.

[5] Andreae, M.O. 1996. ‘Raising dust in the greenhouse.’ Nature 380: 389-390

[6] Haywood, J. 2013. Climate Change and Aerosols. The Met Office. http://www.metoffice.gov.uk/climate-change/guide/science/explained/aerosols

Current research has shown that climate warming is having a large impact on many types of organisms, including insects, with a distribution shift to their preferred microclimates (Şekercioğlu et al, 2012). Warming of tropical areas will increase pressure on certain insects which are at their maximum temperature capabilities. Ectothermic insects, for example ants, in the tropics have been found to be among the most susceptible to climate warming due to their relatively lower warming tolerance than temperate or high latitude species. This is because tropical species are at their upper temperature limits for survival and so have optimal performance temperatures. Therefore, if the temperature rises, the colony may have to employ a range of strategies to overcome temperature stress, for example by adapting to start foraging at different times of the day to avoid extreme temperatures, or by migrating pole-ward to avoid the rise in temperatures (Andrew et al, 2013).

This dispersal of crop pests involves advances at rates of around 1.7 miles per year. This can have large implications to food security and agriculture, with around 10-16% of global crop production being lost to pests already – enough to feed 8.5% of the global population (The Guardian, 2013). Evidence of increasing food insecurity comes from recent studies of corn and soybean yield trends in the central United States. There was stronger than expected effects of a gradual change in temperature with 25% of corn and 32% of soybean yields being affected by temperature variations over 17 years. This was partly due to indirect factors such as plant pathogens, insects and weeds (Seherm and Coakley, 2003). As well as this the new species can outcompete with the native species already present, for example Switzerland has already observed the arrival of the invasive lady beetle, Harmonia axyridis, which has affected the ecosystem balance. It is predicted that there will be an increase in the number of insect species in Switzerland due to climate warming (Vittoz et al, 2013). The migration of insects due to climate change is therefore having an impact on food insecurity and so is a concern for future crop yields and its effect on future generations.

However it is not just food security that is being threatened by the pole-ward shift in insect populations, but the spread of pathogens. Yet the interaction between climate change, crops and pests are complex, and the extent to which the latitudinal changes in pathogens in response to global warming is largely unknown (Bebber, 2013). Climate influences the range of infectious diseases, while weather affects the timing and intensity of outbreaks. This means a long-term warming trend is encouraging the geographic expansion of several important infections, and since 1975 over 30 diseases have appeared that are new to medicine (for example AIDS, Ebola and Lyme disease). Of equal concern is the resurgence of old diseases, such as malaria and cholera, due to changing ecological and climatic conditions as well as social changes. This is because diseases, such as malaria, are carried by vectors (for example mosquitoes), which can be redistributed by climate change. Evidence of this happening in the past comes from fossils from the end of the last Ice Age, which demonstrate that rapid, pole-ward shifts of insects was accompanied by warming (Epstein, 2001).

As well as this, the spread of weeds may be linked to a changing climate. There are various species of aggressive weeds in tropical and subtropical origins which are currently restricted to Mediterranean environments. The future climatic conditions may lead to expansion of their range into temperate regions, for example Itchgrass, Rottboellia cochinchinensis, is currently found in sugarcane plantations in the southern US but a high-CO₂ world may change the photosynthetic pathway and therefore the prevalence of weeds with different plant species (Fuhrer, 2003). This means increased prevalence of certain weeds which could further reduce crop yields and effect agriculture.

Yet there are some benefits, for example there is some evidence that drier and warmer conditions could reduce several crop diseases, for example late potato blight due to reduced plant susceptibility. But at the same time, milder winters could increase other diseases, such as powdery mildew, brown leaf rust and strip rust (Fuhrer, 2003).

Overall the impacts will depend on the extent of the warming, and Vittoz et al., (2013) predict that the threshold of an average global warming of 2 K should not be exceeded in order to avoid catastrophic feedbacks. However there have been signs that small changes in temperatures have already been affecting a pole-ward migration of insects, for example the corn and soybean yield trends in the United States, leading to increasing risks to crop security and public health. So how do we stop this? Energy Saving Warehouse has various simple ways of reducing your carbon footprint, check it out for ideas!

References

Andrew, N.R, Hart, R.A, Jung, M, Hemmings, Z, Terblanche, J.S, (2013), Can temperate insects take the heat? A case study of the physiological and behavioural responses in a common ant, Iridomyrmex purpureus (Formicidae), with potential climate change, Journal of Insect Physiology, Vol 59 (9), Pp. 870–880

Bebber, D.P, Ramotowski, M.A.T, Gurr, S.J, (2013), Crop pests and pathogens move polewards in a warming world, Nature Climate Change, DOI: 10.1038/NCLIMATE1990

Epstein, P.R, (2001), Climate change and emerging infectious diseases, Microbes and Infection, Vol 3 (9), pp. 747–754

Fuhrer, J, (2003), Agroecosystem responses to combinations of elevated CO₂, ozone, and global climate change, Agriculture, Ecosystems & Environment, Vol 97 (1–3), pp. 1–20

Şekercioğlu, Ç.H, Primack, R.B, Wormworth, J, (2012), The effects of climate change on tropical birds, Biological Conservation, Vol 148 (1), pp. 1–18

Seherm, H, Coakley, S.M, (2003), Plant pathogens in a changing world, Australasian Plant Pathology, Vol32 (2), pp 157-165

The Guardian, (2013), Climate change makes pests move north from the tropics – study, available at: http://www.theguardian.com/environment/2013/sep/02/climate-change-crop-pests?CMP=twt_fd [Date accessed: 03/09/2013]

Vittoz, P, Cherix, D, Gonseth, Y, Lubini, V, Maggini, R, Zbinden, N, Zumbach, S, (2013), Climate change impacts on biodiversity in Switzerland: A review, Journal for Nature Conservation, Vol 21 (3), pp. 154–162