A type of air conditioning system that uses freon as a refrigerant and air as a condensing medium in its chiller. This system is less energy efficient than a water-cooled air conditioning system.

The numbers and relative abundances of different genes (genetic diversity), species, and ecosystems (communities) in a particular area.

A tool to calculate the carbon footprint of an individual or an organization. See carbon footprint.

A measure of the impact human activities have on the environment in terms of the amount of green house gases produced, measured in units of carbon dioxide. The larger the size of the carbon footprint, the more severe the level of impact an individual or an organization is making on the environment in terms of carbon emissions.

Climate is usually defined as the "average weather," or more precisely, as the statistics showing the mean and variability of relevant weather quantities over time (e.g. months to thousands of years). Weather quantities usually include temperature, precipitation and wind, and the usual timeline is 3 months as defined by the World Meteorological Organization.

Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). Climate change may result from: natural factors, such as changes in the sun's intensity or slow changes in the Earth's orbit around the sun; natural processes within the climate system (e.g. changes in ocean circulation); human activities that change the atmosphere's composition (e.g. through burning fossil fuels) and the land surface (e.g. deforestation, reforestation, urbanization, desertification, etc.)

Also known as a compact fluorescent light bulb, is a type of fluorescent lamp. Many CFLs are designed to replace an incandescent lamp and can fit in the existing light fixtures formerly used for incandescents (traditional light bulbs). Compared to incandescent lamps of the same luminous flux, CFLs use less energy and have a longer rated life.

The phenomenon that exists when rainfall has been significantly below normal recorded levels, causing serious hydrological imbalances (negative balance) that adversely affect land resources.

Driving techniques or behaviours that are less harmful to the environment. These are techniques that drivers can use to optimize their automobile’s fuel efficiency, and varies considerably from car to car. The behavior of drivers can have a significant impact on their fuel mileage, as most energy used by automobiles does not go toward acceleration of the vehicle and is wasted.

A system of interacting living organisms together with their physical environment. The boundaries of what could be called an ecosystem are somewhat arbitrary, depending on the focus of interest or study. Thus, the extent of an ecosystem may range from very small spatial scales to, ultimately, the entire Earth.

A control device intended to limit and regulate the amount of current flowing in an electric circuit.

A disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is "expected".

An extreme weather event is an event that is rare within its statistical reference distribution at a particular place. Definitions of “rare” vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile. By definition, the characteristics of what is called extreme weather may vary from place to place. An extreme climate event is an average of a number of weather events over a certain period of time, an average which is itself extreme (e.g., rainfall over a season).

Carbon-based fuels from fossil carbon deposits, including coal, oil, and natural gas.

The increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation.

Any gas that absorbs infrared radiation in the atmosphere. Greenhouse gases include, but are not limited to, water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), ozone (O3), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

An acute condition which occurs when a person’s body produces or absorbs more heat than it can dissipate. It is usually due to excessive exposure to heat. This is a medical emergency that requires immediate medical attention.

The IPCC was established jointly by the United Nations Environment Programme and the World Meteorological Organization in 1988. The purpose of the IPCC is to assess information in the scientific and technical literature related to all significant components of the issue of climate change. The IPCC draws upon leading experts on climate change and environmental, social, and economic sciences from some 60 nations. The IPCC is regarded as the official advisory body to the world's governments on the state of the science of the climate change issue.

The total of arrangements, activities, and inputs undertaken in a certain land cover type (a set of human actions). The social and economic purposes for which land is managed (e.g., grazing, timber extraction, and conservation).

A light-emitting diode (LED) is a semiconductor diode that emits narrow-spectrum light by electroluminescence. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or near-ultraviolet. An LED can be used as a regular household light source.

Or a low flow toilet, is a flush toilet that uses significantly less water then a normal flush toilet, using as little as 6L per flush as opposed to 28L.

Water-conserving shower heads that provide a lower flow than conventional designs. These shower heads are sometimes called energy-efficient shower heads as they also use less energy due to less water being heated.

Mai Po Marshes is a nature reserve located near Yuen Long in Hong Kong. It is part of the Deep Bay which is listed as a Ramsar site. It supports globally important numbers of wetland birds that arrive in winter and during spring and autumn migrations.

Trees and shrubs that grow in saline coastal habitats in the tropics and subtropics.

Birds that make regular seasonal journeys of varied distances in response to changes in food availability, habitat or weather.

Ozone, the triatomic form of oxygen (O3), is a gaseous atmospheric constituent. It is created both naturally and by photochemical reactions involving gases resulting from human activities (photochemical “smog”).

Activated and aggravated by sunlight, smog is a kind of air pollution caused by the mixture of smoke and fog consisting of ground-level ozone, sulfur dioxide, nitrogen dioxide and carbon dioxide. Smog is especially harmful for senior citizens, children, and people with heart and lung conditions.

An increase in the mean level of the ocean. Eustatic sea-level rise is a change in global average sea level brought about by an alteration to the volume of the world ocean. Relative sea-level rise occurs where there is a net increase in the level of the ocean relative to local land movements. Climate modelers largely concentrate on estimating eustatic sea-level change. Impact researchers focus on relative sea-level change.

The temporary increase, at a particular locality, in the height of the sea due to extreme meteorological conditions (low atmospheric pressure and/or strong winds). The storm surge is defined as being the excess above the level expected from the tidal variation alone at that time and place.

Also known as a "tubular skylight" or "tubular daylighting device", a sunscoop is the oldest and most widespread type of light tube used for daylighting. The concept was originally developed by the ancient Egyptians; the first commercial systems were marketed in 1991.

An external building structure usually attached to and extending from the top of window frames to provide shading of the sun to avoid excessive heating of the building.

A thunderstorm, also called an electrical storm or lightning storm, is a form of weather characterized by the presence of lightning and its thunder. The lightning is caused by an electrical charge that builds up inside the storm due to the movement of water droplets or crystals carried by the wind. Thunderstorms are usually accompanied by heavy rainfall (heavy downpours), strong winds and sometimes hail.

A tropical cyclone is a meteorological term for a storm system characterized by a low pressure system center and thunderstorms that produces strong wind and flooding rain. A tropical cyclone feeds on the heat released when moist air rises and the water vapor it contains condenses.

An urban heat island (UHI) is a metropolitan area which is significantly warmer than its surroundings. The temperature difference usually is larger at night than during the day and larger in winter than in summer, and is most apparent when winds are weak. The main causes of the urban heat island are the change of the land surface due to urban development and waste heat generated by energy use.

The removal of the rural characteristics of a town or area that often denotes redistribution of populations from rural to urban settlements.

A type of air conditioning system that uses water as a condensing medium in its chiller which is more energy efficient than air-cooled system.

Atmospheric condition at any given time or place. It is measured in terms of wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation. In most places, weather can change from hour-to-hour, day-to-day, and season-to-season.