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Climate Change FAQ

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What is climate change?

Climate change is a change in the distribution of weather over periods of time. This may range from one decade, one century, even a millennia. It can be a change in the average weather or a change in the distribution of certain weather events. Climate change can be linked to specific regions or may occur across the whole planet.

Within recent history, especially in environmental policies, climate change links to the changes seen in our modern climate and how human activity has contributed to the warming of the earth.

Natural climate change has always occurred throughout the earth's history, however the problem we face now is the rate at which such changes are taking place. What we must now focus on reducing further human impact and to find ways of adapting to the changes that have already occurred.

For some useful FAQs, please see the list below.

If you have a question which is not answered here please email the Sustainability Team.

Some definitions...

1) What is the difference between weather and climate?

2) What is the relationship between climate change and weather?

3) What is the greenhouse effect?

4) What is a greenhouse gas?

The science...

5) What factors determine the earth's climate?

6) How do humans' contribute to climate change?

7) How is the climate changing?

8) How have temperatures changed?

9) How has precipitation changed?

10) How have extreme weather events changed?

11) How has snow and ice cover changed?

12) How has sea level changed?

13) Why is current climate change unusual?

14) What happens if we reduce levels of greenhouse gases?

Adaptation and mitigation...

15) What is the difference between adaptation and mitigation?

16) Why should we adapt to climate change?

17) Why should we mitigate against climate change?


Some definitions...

What is the difference between weather and climate?
Weather is what's happening in the atmosphere on any given day, in a specific place. Local or regional weather forecasts include temperature, humidity, winds, cloudiness, and prospects for storms or other changes over the next few days.
Climate is the average of these weather ingredients over many years. Some meteorologists say that "climate is what you expect and weather is what you get." The National Oceanic and Atmospheric Administration's National Weather Service calculates a 30-year average once a decade, so today's normal climate is based on data from 1971 to 2000.

What is the relationship between climate change and weather?
Climate is generally defined as average weather, therefore the two become intertwined. Observations show that there have been changes in weather, and through analyzing this data over time we can identify climate change. The variability of weather makes is unpredictable beyond a few days, but projecting climate change is a more manageable issue.

What is the greenhouse effect?
The Sun powers the earth’s climate, radiating energy that reaches the surface of our planet. About a third of incoming solar radiation is reflected directly back into space, with the remaining two thirds absorbed into the earth. Energy is taken in by the land and sea. The earth’s atmosphere and clouds act a barrier trapping energy and warming temperatures, the same affect the glass walls would have on a greenhouse. Without this natural process the average temperature of the earth would be below freezing.

What is a greenhouse gas?
The two most common greenhouse gases are water vapour and carbon dioxide (CO2) and they work by absorbing and emitting radiation, creating a warming effect. Human activities over the last few centuries, mainly burning fossil fuels and the clearing of forests, have greatly intensified the warming process. Concentrations of greenhouse have increased, meaning less radiation can escape naturally, raising the earth’s natural temperature.

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The science...

What factors determine the earth’s climate?
The climate system is very complex, made up of the atmosphere, land surface, snow and ice, oceans and water bodies and living organisms. The atmospheric component will affect climate the most, but it can also be affected by external factors such as volcanic eruptions as well as changes related to human activity. Solar radiation powers the climate system and there are 3 ways to change the radiation balance of the earth;
• Changing the incoming solar radiation- changes in the earth’s path around the sun.
• Changing the amount of radiation that is reflected- changes in land or cloud cover.
• Altering the radiation from earth back toward space- changing greenhouse gas concentrations.

Concentrations of greenhouse gases have significantly increased since the beginning of the industrial revolution, relating to the burning of fossil fuels, changes in land use and agricultural practice. Climate change has always happened throughout the earth’s history, concerns now stem from the rate at which such changes are occurring.

How do humans contribute to climate change?
Humans contribute to climate change by causing changes in the earth’s atmosphere and the amounts of greenhouse gases and aerosols (small particles). Burning fossil fuels such as coal or gas release carbon dioxide (CO2) into the atmosphere, in turn affecting the radiation balance of the earth. Changes in the amount of certain gases in the atmosphere can lead to warming or cooling in the climate system. The human impact on climate during the era we live now is far greater than any natural change in the past.

How is climate changing?
Many observations have been, for example increasing air and ocean temperatures, rising sea levels and melting of the ice and snow around the world. Some significant changes include;
• Temperatures have increased by 0.74°C across the earth between 1906-2005.
• Global sea levels have increased by 17cm during the 20th century.
• Regional changes include changing Arctic temperatures, ocean salinity, droughts and the frequency of heat waves, precipitation and wind patterns and increasing frequency of tropical storms.

How have temperatures changed?
Observations show that surface temperatures have risen globally in two phases; from 1910 to 1940 by 0.35°C and more strongly from the 1970s to the present by 0.55°C. An increasing amount of warming has taken place over the last 25 years, with 11 of the 12 warmest years on record occurring between 1996 and 2006. Confirmation of global warming comes from warming of the oceans, rising sea levels, glaciers melting , sea ice melting in the Arctic and loss of snow cover in the Northern Hemisphere.

How has precipitation changed?
This is the general term for rainfall, snowfall and all other forms of frozen/liquid water falling from the clouds. Changes are occurring in the amount, intensity, frequency and type of precipitation. For the UK, winter precipitation is expected to increase whilst summer precipitation will decrease. Already summer precipitation rates have fallen by 21.6% between 1914 and 2006. Widespread increases in heavy rainfall events can be seen increasing the likelihood of floods.

How have extreme weather events changed?
Severe weather events such as flood, heat wave and drought have been increasing in severity and frequency since the 1950s. The number of heat waves has increased along with the extent of regions affected by droughts. Flooding has increased linked to increasing precipitation rates and rising sea levels in some regions.

How has snow and ice cover changed?
Observations indicate a global scale decline of snow and ice over many years, especially since the 1980s. Mountain glaciers are retreating in addition to sea ice, permafrost and frozen ground cover. Coastal regions of ice sheets in Greenland and West Antarctica are also thinning and contributing to sea level rise.

How has sea level changed?
Evidence shows that global sea level has gradually risen throughout the 20th Century. It is anticipated that sea level is projected to rise at an even greater rate in this century. Sea level rise is caused by warming of the seas (Water increases in volume as it is warmed!) and the melting of ice sheets.

Why is current climate change unusual?
Climate has always changed throughout the earth’s history; however it is the rate at which such changes are occurring that is significant now. Concentrations of CO2 in the atmosphere have reached an all time high, greater than any amount seen over the last half-million years. Past changes in climate were natural, whereas warming now is being caused by human activities.

What happens if we reduce levels of greenhouse gases?
Concentrations of some greenhouse gases can disappear instantly in response to emission cuts, whilst others can continue to increase for centuries even with reduced emissions. Due to the length of time gases such as CO2 remain in the atmosphere, we are set for 30-40 years of climate change linked to our historical emissions.

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Climate change adaptation and mitigation...

What is the difference between adaptation and mitigation?
Adaptation is taking action to deal with the consequences of a changing climate.
Mitigation is taking action to tackle the cause of climate change, reducing the concentrations of greenhouse gases in the atmosphere.

Why should we adapt to climate change?
As climate change is already occurring, people must adapt to the impacts of climate change, for example solutions such as coastal defences. Such adaptation practices are already in action, with further efforts needed throughout the coming decades to reduce the economic cost of climate change and any adverse effects on the world’s populations.

The most vulnerable people are the poor, as they are those less equipped to adapt to climate change. Often their livelihoods are dependant upon the land and natural resources. These are also linked to climate and any change that could occur.

Why should we mitigate against climate change?
Mitigating against climate change involves reducing greenhouse gas emissions, reducing the impacts of climate change and the future costs associated with them. Changes in lifestyle and behaviour that support resource conservation can also contribute to climate change mitigation.

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If you have any queries, please contact us through the online query form.


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