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Introduction to climate data


last_modification Published: Jan 1, 1970
last_modification Last Updated: Apr 17, 2024

What do we mean by “Climate”?

Wikipedia: Climate is defined as the average state of everyday’s weather condition over a period of 30 years. It is measured by assessing the patterns of variation in terms of temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time.

Climate word cloud

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Weather versus climate

Climate differs from weather, in that weather only describes the short-term conditions of these variables in a given region.

Weather versus Climate

Watch this Video to get an illustration of the difference between climate and weather.

Source: Animated short on statistics from Norwegian infotainment program Siffer. Produced by TeddyTV for NRK. Animation by Ole Christoffer Haga

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Types of climate data resources

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What is available for the period of time you are interested in?

Climate data types

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Direct observations     Observations

WMO global observing system


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Indirect observations     Observations

They are derived from other observations, including:

These indirect observations are sometimes referred to as “climate proxies”.

Tree rings


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Reanalysis            Re-analysis

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What is a model?

Numerical models are a mathematical representation of the climate developed by scientists to understand and predict the climate system.

Atmospheric Model Schematic


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Climate Models            Climate model type

Various types of models are used for different aspects of the climate. All have different ways to represent the real world, depending on how researchers prioritize and perform these simplifications (in terms of parameterizations, etc.) in the numerical climate model.

How good are climate models?

Climate models are continuously improving but they still have biases and weaknesses, also some models perform “better” in the atmosphere, others in the hydrosphere, etc. As a result, a single climate simulation cannot be considered as providing the “truth”. Usually a good overview can be obtained when considering several model “families” rather than any single model, or several model run in slightly different conditions (also called “ensemble runs”).

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Climate prediction vs. projection

Climate prediction

A climate prediction (or climate forecast) is an attempt to produce an estimate of the actual evolution of the natural climate in the future, for example, at seasonal, inter-annual or long-term time scales.

Climate projections

Climate projections are distinct from climate predictions in that projections depend upon emission/concentration/radiative forcing scenarios, which are based on assumptions concerning, for example, future socio-economic and technological developments that may or may not be realized and are therefore subject to substantial uncertainty.

Within the Coupled Model Intercomparison Project (CMIP), now in its 6th phase, project simulations of the research community provide model output that will fuel climate research and climate impact studies for the next 5 to 10 years, while its careful analysis will form the basis for future climate assessments.

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Shared Socio-economic Pathway (SSP) Climate model type

= societal development pathway

The SSPs were developed as a joint community effort and describe global developments that together would lead to different challenges for mitigation and adaptation to climate change. SSPs comprise five alternative narratives that describe the main characteristics of the pathways in qualitative terms as well as quantitative descriptions for key elements including population, economic growth and urbanization.

Different pathways are defined by the magnitude of the challenges a future society would face in adapting to or mitigating climate change if that socioeconomic pathway was pursued.

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SSPs and Shared Policy Assumptions (SPAs)

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SSPs and Shared Policy Assumptions (SPAs)

Shared Socio-economic Pathway and Shared POLicy Assumptions


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Where to start to get climate data?

There is a wealth of data and information available on the web about the past, current and future climate.

Not all of it is up-to-date and trustworthy

Not all the variables/parameters are necessarily relevant for your study

Not all the variables are reliable

Prefer authoritative data providers

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Thank you!

This material is the result of a collaborative work. Thanks to the Galaxy Training Network and all the contributors! Galaxy Training Network Tutorial Content is licensed under Creative Commons Attribution 4.0 International License.