Resource: Climate Change Info, by Vibhati Bhatia
This post is meant to be a beginner’s guide to climate change. Visit South Asians for Sustainability for more info and action items to combat climate change.
Sustainability is an ideal state where human activity does not degrade the environment but maintains natural systems and resources for future generations.
Sustainable development is the process that moves us closer to sustainability.
Sustainable Development Goals (SDGs) are a collection of 17 interlinked global goals designed to be a "blueprint to achieve a better and more sustainable future for all". They were agreed in September 2015 by the United Nation’s 193 Member States. The aim is to achieve 17 Sustainable Development Goals by 2030.
Climate change
When we refer to the climate, we are often talking about things like the temperature and rainfall patterns that we see over a large area on a yearly basis. This is different from weather, which happens over the short term and on a smaller scale.
The climate system is powered by energy from the Sun. The Sun’s energy is absorbed by the Earth’s surface and then redistributed, mainly from the hotter tropics towards the cooler poles, causing circulation patterns in the oceans and atmosphere. These climate patterns, along with other factors, like the shape of the land and areas of water, create our local weather.
Is the climate changing?
There has always been some change in the Earth’s climate because of natural processes. We know that in the past the climate has moved between cold periods (ice ages) and warmer periods. The current period is no exception.
The atmosphere contains greenhouse gases (GHGs) which allow the atmosphere to capture and store the Sun’s energy. The most important GHG is water vapour, followed by carbon dioxide (CO2). Plants, animals and humans can affect the climate system by increasing or decreasing the amount of GHG in the atmosphere.
Over millions of years, large quantities of carbon were removed from the atmosphere and locked away in carbon sinks, which include deposits of coal, gas and oil. The idea that human activity may have an impact on the global climate by releasing carbon from sinks into the atmosphere was first suggested in 1896. With decades of research, scientists have been able to build a clearer picture of how the climate works, how it has changed and the part human activity has played.
Climate change is caused by a variety of factors including changes in solar activity, aerosols (particles) in the atmosphere and the reflectivity of the planet’s surface, and some of the climate change that we have experienced is natural. However, now the release of GHGs by human activity is the most important factor in the exponential rise that we are seeing.
Carbon dioxide (CO2) is the greenhouse gas largely responsible for the climate change caused by human activity. We add CO2 to the atmosphere mainly when we burn fossil fuels like oil, gas and coal so we often talk about our carbon emissions, or our carbon footprint. This goes beyond the carbon we emit while driving our cars or heating our homes. It also includes all the embodied carbon in the products we consume. This often comes from the energy used to make or transport those products.
Climate change mitigation refers to our efforts to prevent the effects of climate change. We do this mainly by reducing the amount of GHGs we produce, as part of a global effort. We have to do this because we are required to do so by national policy, but also because we have an obligation to help meet national and international goals.
Climate change adaptation refers to our efforts to adapt to a changing climate. There is a lag of several decades between the release of greenhouse gas and the effect it has on the climate. This means that even if the world drastically reduces its GHG emissions today there will still be decades of climate change impacts in the pipeline. Adaptation means changing our behaviour to respond to both the current and projected future impacts of climate change.
It is clear from the science that the amount of carbon dioxide (CO2) in the atmosphere as a result of human activity largely determines the extent of global warming. This means that to prevent catastrophic climate change, CO2 emissions need to be reduced to zero. The science led to governments worldwide agreeing to achieve a balance between emissions and removal of greenhouses gases, in the Paris Agreement.
‘Net zero’ refers to achieving an overall balance between emissions produced and emissions taken out of the atmosphere. Like a bath with the taps on, an approach to achieving this balance can either be to turn down the taps (the emissions) or to drain an equal amount down the plug (removals of emissions from the atmosphere, including storage for the emissions such as ‘carbon sinks’).
In contrast to a gross-zero target, which would reduce emissions from all sources uniformly to zero, a net-zero emissions target is more realistic because it allows for some residual emissions.
This takes into account that some emissions are produced by ‘hard-to-treat’ sectors, such as aviation and manufacturing, where reducing emissions is either too expensive, technologically too complex or simply not possible.
In a net-zero scenario the residual emissions from these sectors are allowed as long as they are offset by removing emissions using natural or engineered sinks – gross negative emissions.
Negative emissions can be achieved in a variety of ways, by utilising nature or engineering. Most straightforwardly, this can involve planting more trees to absorb the CO2 in the atmosphere through photosynthesis – afforestation (planting new forests) and reforestation.
There are also negative emission technologies: some of the most commonly used involve carbon capture and storage (CCS). This works by capturing CO2 before it is released into the atmosphere, by removing carbon from the gases produced by burning fossil fuels, or using hydrogen or oxygen in the process. Once the CO2 has been captured, it is compressed into liquid state and transported so that it can then be pumped underground, usually at depths of 1km or more, to be stored into depleted oil and gas reservoirs, coalbeds or deep saline aquifers.
The technology can capture up to 90% of CO2 released by burning fossil fuels in electricity generation and industrial processes such as cement production.
Combining these approaches, bioenergy with carbon capture and storage (BECCS is the process of growing plants, crops or trees, harvesting them for energy generation and then capturing the carbon given off so it can be stored underground.
In addition, Direct Air Capture (DAC) removes carbon dioxide directly from the air to convert it into oxygen and store the carbon. This has historically been used in closed environments where oxygen is not available, such as submarines and space craft, to remove CO2 from the air before concentrations become too high for humans. However, there are still real questions about how economically viable this technology currently is at scale, meaning it is not a silver bullet.
What is a circular economy?
Looking beyond the current take-make-waste extractive industrial model, a circular economy aims to redefine growth, focusing on positive society-wide benefits. It entails gradually decoupling economic activity from the consumption of finite resources, and designing waste out of the system. Underpinned by a transition to renewable energy sources, the circular model builds economic, natural, and social capital. It is based on three principles:
Design out waste and pollution
Keep products and materials in use
Regenerate natural systems
The concept of a circular economy
In a circular economy, economic activity builds and rebuilds overall system health. The concept recognises the importance of the economy needing to work effectively at all scales – for large and small businesses, for organisations and individuals, globally and locally.
Transitioning to a circular economy does not only amount to adjustments aimed at reducing the negative impacts of the linear economy. Rather, it represents a systemic shift that builds long-term resilience, generates business and economic opportunities, and provides environmental and societal benefits.
Technical and biological cycles
The model distinguishes between technical and biological cycles. Consumption happens only in biological cycles, where food and biologically-based materials (such as cotton or wood) are designed to feed back into the system through processes like composting and anaerobic digestion. These cycles regenerate living systems, such as soil, which provide renewable resources for the economy. Technical cycles recover and restore products, components, and materials through strategies like reuse, repair, remanufacture or (in the last resort) recycling.
Origins of the circular economy concept
The notion of circularity has deep historical and philosophical origins. The idea of feedback, of cycles in real-world systems, is ancient and has echoes in various schools of philosophy. It enjoyed a revival in industrialised countries after World War II when the advent of computer-based studies of non-linear systems unambiguously revealed the complex, interrelated, and therefore unpredictable nature of the world we live in – more akin to a metabolism than a machine. With current advances, digital technology has the power to support the transition to a circular economy by radically increasing virtualisation, de-materialisation, transparency, and feedback-driven intelligence.
Renewable Energy
any naturally occurring, theoretically inexhaustible source of energy, as biomass, solar, wind, tidal, wave, and hydroelectric power, that is not derived from fossil or nuclear fuel.
Non-Renewable
not able to be restored, replaced, recommenced, etc nonrenewable resources
Climate Risks
Promoting understanding of impacts of, and vulnerability to, climate change, current and future climate variability and extreme events, and the implications for sustainable development.
Climate related risks are created by a range of hazards. Some are slow in their onset (such as changes in temperature and precipitation leading to droughts, or agricultural losses), while others happen more suddenly (such as tropical storms and floods). It is now widely recognised that climate-related impacts are not just a future threat. Furthermore, past and current experiences in dealing with climate variability and extreme events, irrespective of attribution to climate change, hold valuable lessons for reducing vulnerability and enhancing resilience for future climate-related adverse impacts.
Greenhouse gases
Greenhouse gases in the atmosphere absorb heat energy and prevent it escaping into space. This keeps the Earth warmer than it would be without these gases. Greenhouse gases are not a bad thing in themselves, but too much of them in the atmosphere leads to an increase in the greenhouse effect and global warming.
There are many greenhouse gases but these are some of the most important:
water vapour, H2O
carbon dioxide, CO2
methane, CH4
nitrous oxide, N2O
CFCs (chlorofluorocarbons)
The greenhouse effect
Sunlight passes through the Earth’s atmosphere.
The ground warms up and heat is emitted from the Earth’s surface.
Some heat escapes into space but some is absorbed by greenhouse gases. It is re-emitted and does not escape.
The Earth’s atmosphere warms up.
Methane
The global climate has been changing since time began and will continue to change into the future. The Earth's temperature has fluctuated in the last few hundred years. However, since around 1950 there has been a dramatic increase in global temperatures. This increase is known as global warming.
Evidence of global warming
Thermometer readings
Ongoing temperature recordings using thermometers have shown a clear warming of the Earth's temperature over the past few decades. By using this data, scientists have seen an average combined land and ocean surface temperature increase of 0.85°C since the end of the 19th century. In the northern hemisphere, the period between 1983 and 2012 was the warmest 30-year period of the last 1,400 years. The degree to which the climate warms in the future will depend on natural climate variability and the level of greenhouse gas emissions. If greenhouse gas emissions continue then average global temperatures will rise. However, some regions such as the Arctic will warm faster than others.
Glacier retreat
Over the past 50 to 100 years, photographic evidence has shown that the world's glaciers have been melting, which has caused them to retreat. The increase in global temperatures is causing glaciers to disappear and is increasing the melting of sea ice in the Arctic.
Ice cores
Scientists often use ice cores to detect changes in temperatures. When snow falls it traps air into the ice. When scientists take a sample of ice it reveals the atmospheric gas concentrations at the time the snow fell. This is used to calculate temperature at that time. The ice can reveal the temperature of each year for the past 400,000 years. Scientists that study the ice cores say there is clear evidence that there has been a rapid increase in temperature in the past decades.
Early spring
In recent years there have been signs of a seasonal shift - spring arrives earlier and winters tend to be less severe. These seasonal changes affect the nesting and migration patterns of wildlife.
Rising sea levels
Between 1901 and 2010, average global sea level rose by 0.19 m.
Climate change
Evidence has shown that Earth’s temperature is rising due to an increase in greenhouse gases. This has created and will continue to create, a number of negative effects.
Causes of climate change - human and natural factors
A natural function of the Earth's atmosphere is to keep in some of the heat that is lost from the Earth. This is known as the greenhouse effect.
The atmosphere allows the heat from the Sun (short-wave radiation) to pass through to heat the Earth's surface.
The Earth's surface then gives off heat (long-wave radiation).
This heat is trapped by greenhouse gases (eg methane, carbon dioxide and nitrous oxide), which radiate the heat back towards Earth.
This process heats up the Earth.
Human factors increasing global warming
Some human activities increase the greenhouse gases in the atmosphere:
Burning fossil fuels, eg coal, gas and oil - these release carbon dioxide into the atmosphere.
Deforestation - trees absorb carbon dioxide during photosynthesis. If they are cut down, there will be higher amounts of carbon dioxide in the atmosphere.
Dumping waste in landfill - when the waste decomposes it produces methane.
Agriculture - agricultural practices lead to the release of nitrogen oxides into the atmosphere.
Natural factors increasing global warming
There are also natural factors which contribute to increased global warming:
Orbital changes - the Earth has natural warming and cooling periods caused by Milankovitch cycles or variations in the tilt and/or orbit of the Earth around the Sun (Wobble, roll and stretch theory).
Volcanic activity - during a volcanic eruption carbon dioxide is released into the atmosphere.
Solar output - there can be fluctuations in the amount of radiation from the sun. If there is high amount emitted there will be an increase in Earth's temperatures
Impacts of climate change
Impacts of climate change in the UK
sea levels could rise, covering low lying areas, in particular east England
Scottish ski resorts may have to close due to lack of snow
droughts and floods become more likely as extreme weather increases
increased demand for water in hotter summers puts pressure on water supplies
Impacts of climate change around the world
sea level rise will affect 80 million people
tropical storms will increase in magnitude (strength)
species in affected areas (eg Arctic) may become extinct
diseases such as malaria increase, an additional 280 million people may be affected
Managing the impacts of climate change
Mitigation strategies
Mitigation means to reduce or prevent the effects of something from happening. Mitigation strategies include:
Alternative energy - using alternative energy such as solar, wind or tidal can reduce the use of fossil fuels. This will reduce the amount of carbon dioxide released into the atmosphere.
Carbon capture - this is the removal of carbon dioxide from waste gases from power stations and then storing it in old oil and gas fields or coal mines underground. This reduces the amount of emissions into the atmosphere.
Planting trees - encouraging afforestation, means that there will be more trees to absorb the carbon dioxide in the atmosphere during the process of photosynthesis.
International agreements - in 2005 the Kyoto Protocol became international law. The countries that signed up to the treaty pledged to reduce their carbon emissions by 5 per cent. However, this ran out in 2012 and its overall impact has been small. The US refused to join and major developing countries like China and India were not required to make any reductions.
Adaptation strategies
Adaptation strategies do not aim to reduce or stop global warming. Instead they aim to respond to climate change by limiting its negative effects. Strategies include:
Agriculture - farmers will have to adapt as some crops may not be able to grow in a warmer climate. However, other crops (eg oranges and grapes) will be able to be planted.
Water supply - water transfer schemes could be used. This is where water is transferred from an area of water surplus to an area of water shortage.
Reducing risk from sea level rise - areas at risk from sea level rise may use sea defences to protect the land from being eroded away.