The United Nations Framework Convention on Climate Change (UNFCCC) leads international efforts to tackle climate change.

To strengthen the global response, 194 countries plus the EU, have committed to the goals of the Paris Agreement - a legally binding international treaty that aims to hold average global temperature rise to well below 2.0^oC above pre-industrial levels, and ideally 1.5^oC; adapt to unavoidable consequences of climate change; and support climate-resilient development.

Specifically, article 7 demands that “Parties should strengthen [. . . ] scientific knowledge on climate, including research, systematic observation of the climate system and early warning systems, in a manner that informs climate services and supports decision-making."

This request of the UNFCCC expresses the need of climate monitoring based on best available science, which is globally coordinated through the Global Climate Observing System (GCOS).

The Global Climate Observing System (GCOS) defines the key components required to systematically monitor Earth's climate system to support the UNFCCC and are known as Essential Climate Variables (ECVs).

A set of currently 55 “essential climate variables” have been defined by GCOS that must be observed in a sustained and consistent manner to enable detection of climate trends and provide data suitable for climate model evaluation and climate change attribution.

Climate data records draw on a combination of satellite and in-situ observations.

It is satellites, however that form the backbone of the Global Climate Observing System (GCOS).

The Committee on Earth Observation Satellites (CEOS) and Coordination Group for Meteorological Satellites (CGMS) coordinate Space Agencies' response and contribution to providing of climate information.

Satellites are valuable tools provide accurate and consistent, decades long time series to detect changes in the climate. Of the 55 Essential Climate Variables defined by GCOS and used to characterise the climate system, two-thirds (38) are exclusively or largely measured from Space.

To generate sufficiently long time series – usually 40 years - ESA's Climate Change Initiative undertakes the necessary R&D to combine and inter-calibrate data from several satellites to contribute to the global climate record.

Since 2008, European Space Agency's Climate Change Initiative, a major research and development programme has focussed on the generation, and continued expansion, of a suite of multi-decade satellite observation records that address three-quarters (27 of 38) of the Essential Climate Variables that are measurable from space.

These robust observation records, derived from ESA’s 40-year satellite archive, current ESA missions, the Copernicus Sentinels and ESA third-party missions, support the UNFCCC and IPCC by

providing the scientific evidence on climate change to steer decision-making.

The Climate Change Initiative contributes a growing body of evidence to strengthen climate science, support IPCC assessments on the state of the climate and validate the state-of-the-art models used to predict future change.