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Topic 1f – Essential Climate Variables and megatrends

Essential Climate Variables and Megatrends
For climate change, satellite data are absolutely critical. The observations, which are needed for climate change, are organised through a body called the Global Climate Observing System, GCOS. That has developed over the last 10 years or so, a suite of variables called Essential Climate Variables. And these are a compendium of the most important facets of the planet, which we need to observe and understand in order to understand and adapt to and mitigate climate change. There are about 50 of these variables altogether looking at the atmosphere and the ocean and the land surface. Of the 50, something like 50%, half of those, can only be observed from space.
And of the remaining 50%, about half of those, again, are substantially observed from space with additional measurements being made on the ground. So around 60, 70% or so, 80% of these variables are essentially observable primarily or only by satellite data. So that tells you immediately just how important satellites are in providing us the information we need for climate. And that’s for climate prediction and modelling, but also for looking now into adaptation. How do we deal with climate change? Mitigation, how do we minimise the amount of change which is taking place? How do we reduce our emissions? How can we do that through processes like RED, through better agricultural practises?
How can we use the information that we have in order to mitigate the problem into the future? We’re looking into the future now to see how best we can sustain that in a long term basis. We developed in the European Space Agency an initiative called the Climate Change Initiative. And we have a Climate Office which was set up in Harwell in order to manage that programme. And that has selected a subset of these 50 ECVs, which are particularly relevant for ESA data. And we’re developing long term time series of these data using not only ESA data but data from all of the sources.
And that gives us the long term continuity and quality control of those variables because we’re looking at very precise measurements, very subtle measurements of how the earth behaves. And we need to make sure that when we have these long term time series we’re not seeing changes in the way that we make the observations reflected in apparent changes in the earth’s system. So it has to be very carefully calibrated, very carefully validated against in situ measurements so we can see what’s happening.
While we’re still considering ECVs as being divided into essentially the old Aristotelian divisions of earth, air, fire, water– so we have one’s for the atmosphere, one’s for the ocean, one for the land– we’re also looking at how they relate to different systems that they’re relevant to. So how do different combinations of these ECVs operate within the water cycle, within the energy cycle, within the carbon cycle on the earth’s system? How do they relate to the megatrends which we see in earth development today? The nexus of food, water, and energy? Developments in agriculture, developments in organisation. How are they going to change air quality in the cities? How can we measure that?
How can we use that information also to make long term sustainable decisions?
The Earth is a complex system, just like a human body. If there are unexpected or potentially harmful changes in the Earth system, we need a way of monitoring its health and status, and a method of detecting the level of change in order to deliver appropriate responses. Continuous, consistent sets of accurate observations are needed, made over sufficiently long periods of time to differentiate between natural variability and new trends. This helps us to form a coherent, trustable picture of how the Earth system operates and enables better forecasts and projections of how it will develop in the future.
(Subtitles and transcripts for this video are also available in Spanish and Chinese. Just click on the small pink square in the video controls to select your preferred language, or download transcripts from the bottom of this page).
The Global Climate Observing System (GCOS) has developed a set of 50 measureable Earth system parameters that are considered vital for the detection and quantification of climate-related changes, known as the Essential Climate Variables (ECVs). Of these 50 ECVs, around half are measurable largely from Space. In response to the need for these ECV datasets, ESA developed its Climate Change Initiative (CCI) programme, which aims to provide long-term satellite data products targeted directly at ECVs. Through this initiative, 15 CCI projects are currently producing 14 key ECV datasets, including information on greenhouse gases, aerosols, sea surface temperature, burned area and soil moisture to name just a few.
It is also essential to have continuous sets of data to inform other long term global trends, often referred to as ‘megatrends’, such as in urbanisation and resource depletion.
In this video Dr Stephen Briggs introduces the concept of Essential Climate Variables and ESA’s Climate Change Initiative, and explores how Earth observation techniques are at the centre of these initiatives.
Featured Experts:
  • Dr Stephen Briggs
Optional Further Reading:
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Monitoring Climate from Space

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