The Climate Dictionary: An everyday guide to climate change

Weather vs. Climate

Weather refers to atmospheric conditions at a particular time in a particular location, including temperature, humidity, precipitation, cloudiness, wind, and visibility. Weather conditions do not happen in isolation, they have a ripple effect. The weather in one region will eventually affect the weather hundreds or thousands of kilometers away.

Climate is the average of weather patterns in a specific area over a longer period of time, usually 30 or more years, that represents the overall state of the climate system.

Human activity in the industrial age, and particularly during the last century, is significantly altering our planet’s climate through the release of harmful greenhouse gases.

Greenhouse gas emissions

Greenhouse gases are gases that trap heat from the sun in our planet’s atmosphere, keeping it warm. Since the industrial era began, human activities have led to the release of dangerous levels of greenhouse gases, causing global warming and climate change.

The main greenhouse gases released by human activities are carbon dioxide, methane, nitrous oxide, and fluorinated gases used for cooling and refrigeration. Carbon dioxide is the primary greenhouse gas resulting from human activities, particularly from burning fossil fuels, deforestation, and changing the way land is used. Our reliance on fossil fuels has led to a 50 percent increase in the concentrations of carbon dioxide in the atmosphere over the last 200 years. Methane is another important greenhouse gas that is responsible for 25 percent of global warming. Methane is released during the extraction and transport of coal, gas, and oil, and by waste landfills and agricultural practices.

To prevent catastrophic climate change, the world’s governments must work together to significantly reduce greenhouse gas emissions now and in the coming decades and keep global warming below the dangerous threshold of 1.5°C.

Global warming vs. Climate change

Global warming is an increase in the Earth’s average surface temperature that occurs when the concentration of greenhouse gases in the atmosphere increases. These gases absorb more solar radiation and trap more heat, thus causing the planet to get hotter. Burning fossil fuels, cutting down forests, and farming livestock are some human activities that release greenhouse gases and contribute to global warming.

Climate change refers to the long-term changes in the Earth’s climate that are warming the atmosphere, ocean and land. Climate change is affecting the balance of ecosystems that support life and biodiversity, and impacting health. It also causes more extreme weather events, such as more intense and/or frequent hurricanes, floods, heat waves, and droughts, and leads to sea level rise and coastal erosion as a result of ocean warming, melting of glaciers, ad loss of ice sheets.

Local communities

Climate crisis

The climate crisis refers to the serious problems that are being caused, or are likely to be caused, by changes in the planet’s climate, including weather extremes and natural disasters, ocean acidification and sea-level rise, loss of biodiversity, food and water insecurity, health risks, economic disruption, displacement, and even violent conflict.

Since the 1800s, human activities have caused the Earth’s average temperature to increase by about 1.2° C – with more than two-thirds of this warming occurring since 1975. This is already causing significant damage to human societies and natural ecosystems in many parts of the world. More than 3 billion people live in places that are very vulnerable to the climate crisis, with lower income countries being disproportionately affected.

Scientists expect that an increase beyond 1.5°C would begin to lead to a series of dangerous tipping points that would make many changes irreversible and pose a very serious threat to human civilization. This is why governments must act now to drastically reduce greenhouse gas emissions and chart a course for reaching net zero in the coming decades, invest in adaptation to the unavoidable impacts of climate change, and protect and restore natural ecosystems and biomes upon which the planet depends.

Feedback loop

Climate feedback loops happen when one change in the climate triggers further changes, in a chain reaction that reinforces itself as time goes on. Ultimately, feedback loops can trigger tipping points, at which point the changes to our planet’s climate systems become severe and irreversible.

Tipping point

A tipping point is a threshold after which certain changes caused by global warming and climate change become irreversible, even if future interventions are successful in driving down average global temperatures. These changes may lead to abrupt and dangerous impacts with very serious implications for the future of humanity and our planet.

As the world gets hotter, several tipping points are becoming very likely. One of them is the collapse of the Greenland and West Antarctic ice sheets, which would lead to significant sea level rise and threaten coastal communities and ecosystems. Another is the thawing of the permafrost in the tundra regions, which will release huge quantities of trapped greenhouse gases, further accelerating global warming and climate change. Mass coral bleaching events and the destruction of rainforests are two other major tipping points with immense implications for both biodiversity and human societies.

Climate overshoot

Under the Paris Agreement, countries are expected to take the necessary measures to limit global warming to 1.5° C. But even best-case scenarios now indicate a significant chance of overshooting these goals, even if temporarily. Climate overshoot refers to the period during which warming will have increased past 1.5° C, before falling back down. This period will probably occur around the middle of this century.

The longer the climate overshoot lasts, the more dangerous it will become. A prolonged period of higher global temperatures will have devastating and irreversible impacts on natural ecosystems, biodiversity, and human communities, particularly in dry areas, coastal zones, and other vulnerable locations. Making deep emission cuts during this decade is of extreme importance to limiting the duration and impacts of the climate overshoot.

Climate Dictionary - Mitigation

Mitigation

Climate change mitigation refers to any action taken by governments, businesses, and people to reduce or prevent greenhouse gas emissions, or to enhance carbon sinks that remove these gases from the atmosphere.

Reducing or preventing greenhouse gas emissions can be achieved by transitioning to renewable energy sources like wind and solar, using energy more efficiently, adopting low carbon or carbon-free transportation modalities, promoting sustainable agriculture and land use, and changing production and consumption models and diet behaviours. Enhancing carbon sinks can be achieved by restoring forests, wetlands, and marshlands, maintaining soil health, and protecting terrestrial and marine ecosystems.

In order for mitigation actions to be successful, it is crucial that countries develop supportive environments through legislation, policies, and investments.

Did you know: To limit global warming to 1.5° C, which is the critical goal of the Paris Agreement, the world must implement climate change mitigation actions to reduce greenhouse gas emissions by 45 percent before 2030 and reach net-zero by mid-century.

Adaptation

Climate change adaptation refers to actions that help reduce vulnerability to the current or expected impacts of climate change like weather extremes and natural disasters, sea-level rise, biodiversity loss, or food and water insecurity.

Even in very positive scenarios in which we manage to significantly and swiftly cut greenhouse gas emissions, climate change will continue to impact our world for decades to come because of the energy already trapped in the system. This means widespread adaptation is needed to limit these impacts and safeguard people and nature.

Many adaptation measures need to happen at the local level, so rural communities and cities have a big role to play. Such measures include planting crop varieties that are more resistant to drought and practicing regenerative agriculture, improving water storage and use, managing land to reduce wildfire risks, and building stronger defenses against extreme weather like floods and heat waves.

However, adaptation also needs to be driven at the national and international levels. In addition to developing the policies needed to guide adaptation, governments need to look at large-scale measures such as strengthening or relocating infrastructure from coastal areas affected by sea-level rise, building infrastructure able to withstand more extreme weather conditions, enhancing early warning systems and access to disaster information, developing insurance mechanisms specific to climate-related threats, and creating new protections for wildlife and natural ecosystems.

Resilience

Climate resilience is the capacity of a community or environment to anticipate and manage climate impacts, minimize their damage, and recover and transform as needed after the initial shock.

To best safeguard societal wellbeing, economic activity, and the environment, people, communities, and governments need to be equipped to deal with the unavoidable impacts of climate change. This can be done by training people to obtain new skills and diversify the sources of their household income, building more robust disaster response and recovery capacities, enhancing climate information and early warning systems, and working on long-term planning, among others.

Ultimately, a truly climate-resilient society is a low-carbon one, because drastically reducing greenhouse gas emissions is the best way to limit how severe climate impacts will be in the future. It is also a society based in equity and climate justice that prioritizes support for people and communities most exposed to climate impacts or least able to cope with them.